diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml index 3503bc852cd..e5bef18d7d8 100644 --- a/doc/src/sgml/catalogs.sgml +++ b/doc/src/sgml/catalogs.sgml @@ -1,4 +1,4 @@ - + @@ -168,11 +168,6 @@ metadata for large objects - - pg_listener - asynchronous notification support - - pg_namespace schemas @@ -3253,68 +3248,6 @@ - - <structname>pg_listener</structname> - - - pg_listener - - - - The catalog pg_listener supports the - and - - commands. A listener creates an entry in - pg_listener for each notification name - it is listening for. A notifier scans pg_listener - and updates each matching entry to show that a notification has occurred. - The notifier also sends a signal (using the PID recorded in the table) - to awaken the listener from sleep. - - - - <structname>pg_listener</> Columns - - - - - Name - Type - Description - - - - - - relname - name - - Notify condition name. (The name need not match any actual - relation in the database; the name relname is historical.) - - - - - listenerpid - int4 - PID of the server process that created this entry - - - - notification - int4 - - Zero if no event is pending for this listener. If an event is - pending, the PID of the server process that sent the notification - - - - -
- - - - <structname>pg_namespace</structname> diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml index 71952ee1fc4..54369711155 100644 --- a/doc/src/sgml/func.sgml +++ b/doc/src/sgml/func.sgml @@ -1,4 +1,4 @@ - + Functions and Operators @@ -11529,6 +11529,12 @@ postgres=# select * from unnest2(array[[1,2],[3,4]]); + + pg_listening_channels() + setof text + channel names that the session is currently listening on + + inet_client_addr() inet @@ -11674,6 +11680,16 @@ SET search_path TO schema , schema, .. + + pg_listening_channels + + + + pg_listening_channels returns a set of names of + channels that the current session is listening to. See for more information. + + inet_client_addr diff --git a/doc/src/sgml/libpq.sgml b/doc/src/sgml/libpq.sgml index 4972a8c2592..0bdb6401c34 100644 --- a/doc/src/sgml/libpq.sgml +++ b/doc/src/sgml/libpq.sgml @@ -1,4 +1,4 @@ - + <application>libpq</application> - C Library @@ -307,28 +307,28 @@ Description - + - + disable only try a non-SSL connection - + allow first try a non-SSL connection; if that fails, try an SSL connection - + prefer (default) first try an SSL connection; if that fails, try a non-SSL connection - + require only try an SSL connection @@ -481,7 +481,7 @@ - If expand_dbname is non-zero and + If expand_dbname is non-zero and dbname contains an = sign, it is taken as a conninfo string in exactly the same way as if it had been passed to PQconnectdb(see below). Previously @@ -4111,50 +4111,48 @@ typedef struct { PostgreSQL offers asynchronous notification via the LISTEN and NOTIFY commands. A client session registers its interest in a particular - notification condition with the LISTEN command (and + notification channel with the LISTEN command (and can stop listening with the UNLISTEN command). All - sessions listening on a particular condition will be notified + sessions listening on a particular channel will be notified asynchronously when a NOTIFY command with that - condition name is executed by any session. No additional information - is passed from the notifier to the listener. Thus, typically, any - actual data that needs to be communicated is transferred through a - database table. Commonly, the condition name is the same as the - associated table, but it is not necessary for there to be any associated - table. + channel name is executed by any session. A payload string can + be passed to communicate additional data to the listeners. libpq applications submit - LISTEN and UNLISTEN commands as + LISTEN, UNLISTEN, + and NOTIFY commands as ordinary SQL commands. The arrival of NOTIFY messages can subsequently be detected by calling PQnotifies.PQnotifies - The function PQnotifies - returns the next notification from a list of unhandled - notification messages received from the server. It returns a null pointer if - there are no pending notifications. Once a notification is - returned from PQnotifies, it is considered handled and will be - removed from the list of notifications. + The function PQnotifies returns the next notification + from a list of unhandled notification messages received from the server. + It returns a null pointer if there are no pending notifications. Once a + notification is returned from PQnotifies, it is considered + handled and will be removed from the list of notifications. + PGnotify *PQnotifies(PGconn *conn); typedef struct pgNotify { - char *relname; /* notification condition name */ + char *relname; /* notification channel name */ int be_pid; /* process ID of notifying server process */ - char *extra; /* notification parameter */ + char *extra; /* notification payload string */ } PGnotify; + After processing a PGnotify object returned by PQnotifies, be sure to free it with PQfreemem. It is sufficient to free the PGnotify pointer; the relname and extra - fields do not represent separate allocations. (At present, the - extra field is unused and will always point - to an empty string.) + fields do not represent separate allocations. (The names of these fields + are historical; in particular, channel names need not have anything to + do with relation names.) diff --git a/doc/src/sgml/protocol.sgml b/doc/src/sgml/protocol.sgml index e4364ec305f..f0a2aeba03a 100644 --- a/doc/src/sgml/protocol.sgml +++ b/doc/src/sgml/protocol.sgml @@ -1,4 +1,4 @@ - + Frontend/Backend Protocol @@ -354,7 +354,7 @@ This message contains the response data from the previous step of GSSAPI or SSPI negotiation (AuthenticationGSS, AuthenticationSSPI - or a previous AuthenticationGSSContinue). If the GSSAPI + or a previous AuthenticationGSSContinue). If the GSSAPI or SSPI data in this message indicates more data is needed to complete the authentication, the frontend must send that data as another PasswordMessage. If @@ -992,7 +992,7 @@ In the event of a backend-detected error during copy-in mode (including - receipt of a CopyFail message), the backend will issue an ErrorResponse + receipt of a CopyFail message), the backend will issue an ErrorResponse message. If the COPY command was issued via an extended-query message, the backend will now discard frontend messages until a Sync message is received, then it will issue ReadyForQuery and return to normal @@ -1117,7 +1117,7 @@ backend will send a NotificationResponse message (not to be confused with NoticeResponse!) whenever a NOTIFY command is executed for the same - notification name. + channel name. @@ -1340,7 +1340,7 @@ This section describes the base data types used in messages. value that will appear, otherwise the value is variable. Eg. String, String("user"). - + There is no predefined limit on the length of a string @@ -1951,7 +1951,7 @@ Bind (F) (denoted R below). This can be zero to indicate that there are no result columns or that the result columns should all use the default format - (text); + (text); or one, in which case the specified format code is applied to all result columns (if any); or it can equal the actual number of result columns of the query. @@ -2500,7 +2500,7 @@ CopyOutResponse (B) separated by separator characters, etc). 1 indicates the overall copy format is binary (similar to DataRow format). See for more information. + endterm="sql-copy-title"> for more information. @@ -3187,7 +3187,7 @@ NotificationResponse (B) - The name of the condition that the notify has been raised on. + The name of the channel that the notify has been raised on. @@ -3197,9 +3197,7 @@ NotificationResponse (B) - Additional information passed from the notifying process. - (Currently, this feature is unimplemented so the field - is always an empty string.) + The payload string passed from the notifying process. @@ -4353,7 +4351,7 @@ the backend. The NotificationResponse ('A') message has an additional string -field, which is presently empty but might someday carry additional data passed +field, which can carry a payload string passed from the NOTIFY event sender. @@ -4364,5 +4362,4 @@ string parameter; this has been removed. - diff --git a/doc/src/sgml/ref/listen.sgml b/doc/src/sgml/ref/listen.sgml index 93ca74c5722..57577c1f6ac 100644 --- a/doc/src/sgml/ref/listen.sgml +++ b/doc/src/sgml/ref/listen.sgml @@ -1,5 +1,5 @@ @@ -21,7 +21,7 @@ PostgreSQL documentation -LISTEN name +LISTEN channel @@ -30,24 +30,23 @@ LISTEN name LISTEN registers the current session as a - listener on the notification condition name. + listener on the notification channel named channel. If the current session is already registered as a listener for - this notification condition, nothing is done. + this notification channel, nothing is done. Whenever the command NOTIFY name is invoked, either + class="PARAMETER">channel is invoked, either by this session or another one connected to the same database, all - the sessions currently listening on that notification condition are + the sessions currently listening on that notification channel are notified, and each will in turn notify its connected client - application. See the discussion of NOTIFY for - more information. + application. - A session can be unregistered for a given notify condition with the + A session can be unregistered for a given notification channel with the UNLISTEN command. A session's listen registrations are automatically cleared when the session ends. @@ -78,16 +77,31 @@ LISTEN name - name + channel - Name of a notify condition (any identifier). + Name of a notification channel (any identifier). + + Notes + + + LISTEN takes effect at transaction commit. + If LISTEN or UNLISTEN is executed + within a transaction that later rolls back, the set of notification + channels being listened to is unchanged. + + + A transaction that has executed LISTEN cannot be + prepared for two-phase commit. + + + Examples diff --git a/doc/src/sgml/ref/notify.sgml b/doc/src/sgml/ref/notify.sgml index 563fbbe9638..b612bb4cb2a 100644 --- a/doc/src/sgml/ref/notify.sgml +++ b/doc/src/sgml/ref/notify.sgml @@ -1,5 +1,5 @@ @@ -21,7 +21,7 @@ PostgreSQL documentation -NOTIFY name +NOTIFY channel [ , payload ] @@ -29,35 +29,39 @@ NOTIFY name Description - The NOTIFY command sends a notification event to each - client application that has previously executed - LISTEN name - for the specified notification name in the current database. + The NOTIFY command sends a notification event together + with an optional payload string to each client application that + has previously executed + LISTEN channel + for the specified channel name in the current database. - NOTIFY provides a simple form of signal or + NOTIFY provides a simple interprocess communication mechanism for a collection of processes accessing the same PostgreSQL database. - Higher-level mechanisms can be built by using tables in the database to - pass additional data (beyond a mere notification name) from notifier to - listener(s). + A payload string can be sent along with the notification, and + higher-level mechanisms for passing structured data can be built by using + tables in the database to pass additional data from notifier to listener(s). - The information passed to the client for a notification event includes the notification - name and the notifying session's server process PID. It is up to the - database designer to define the notification names that will be used in a given - database and what each one means. + The information passed to the client for a notification event includes the + notification channel + name, the notifying session's server process PID, and the + payload string, which is an empty string if it has not been specified. - Commonly, the notification name is the same as the name of some table in + It is up to the database designer to define the channel names that will + be used in a given database and what each one means. + Commonly, the channel name is the same as the name of some table in the database, and the notify event essentially means, I changed this table, take a look at it to see what's new. But no such association is enforced by the NOTIFY and LISTEN commands. For - example, a database designer could use several different notification names - to signal different sorts of changes to a single table. + example, a database designer could use several different channel names + to signal different sorts of changes to a single table. Alternatively, + the payload string could be used to differentiate various cases. @@ -89,19 +93,22 @@ NOTIFY name - NOTIFY behaves like Unix signals in one important - respect: if the same notification name is signaled multiple times in quick - succession, recipients might get only one notification event for several executions - of NOTIFY. So it is a bad idea to depend on the number - of notifications received. Instead, use NOTIFY to wake up - applications that need to pay attention to something, and use a database - object (such as a sequence) to keep track of what happened or how many times - it happened. + If the same channel name is signaled multiple times from the same + transaction with identical payload strings, the + database server can decide to deliver a single notification only. + On the other hand, notifications with distinct payload strings will + always be delivered as distinct notifications. Similarly, notifications from + different transactions will never get folded into one notification. + Except for dropping later instances of duplicate notifications, + NOTIFY guarantees that notifications from the same + transaction get delivered in the order they were sent. It is also + guaranteed that messages from different transactions are delivered in + the order in which the transactions committed. It is common for a client that executes NOTIFY - to be listening on the same notification name itself. In that case + to be listening on the same notification channel itself. In that case it will get back a notification event, just like all the other listening sessions. Depending on the application logic, this could result in useless work, for example, reading a database table to @@ -111,12 +118,7 @@ NOTIFY name notification event message) is the same as one's own session's PID (available from libpq). When they are the same, the notification event is one's own work bouncing - back, and can be ignored. (Despite what was said in the preceding - paragraph, this is a safe technique. - PostgreSQL keeps self-notifications - separate from notifications arriving from other sessions, so you - cannot miss an outside notification by ignoring your own - notifications.) + back, and can be ignored. @@ -125,16 +127,61 @@ NOTIFY name - name + channel - Name of the notification to be signaled (any identifier). + Name of the notification channel to be signaled (any identifier). + + + + + payload + + + The payload string to be communicated along with the + notification. This string must be shorter than 8000 bytes, and + is treated as text. + (If binary data or large amounts of information need to be communicated, + it's best to put it in a database table and send the key of the record.) + + Notes + + + pg_notify + + + + To send a notification you can also use the function + pg_notify(text, + text). The function takes the channel name as the + first argument and the payload as the second. The function is much easier + to use than the NOTIFY command if you need to work with + non-constant channel names and payloads. + + + There is a queue that holds notifications that have been sent but not + yet processed by all listening sessions. If this queue becomes full, + transactions calling NOTIFY will fail at commit. + The queue is quite large (8GB in a standard installation) and should be + sufficiently sized for almost every use case. However, no cleanup can take + place if a session executes LISTEN and then enters a + transaction for a very long time. Once the queue is half full you will see + warnings in the log file pointing you to the session that is preventing + cleanup. In this case you should make sure that this session ends its + current transaction so that cleanup can proceed. + + + A transaction that has executed NOTIFY cannot be + prepared for two-phase commit. + + + Examples @@ -146,6 +193,12 @@ NOTIFY name LISTEN virtual; NOTIFY virtual; Asynchronous notification "virtual" received from server process with PID 8448. +NOTIFY virtual, 'This is the payload'; +Asynchronous notification "virtual" with payload "This is the payload" received from server process with PID 8448. + +LISTEN foo; +SELECT pg_notify('fo' || 'o', 'pay' || 'load'); +Asynchronous notification "foo" with payload "payload" received from server process with PID 14728. diff --git a/doc/src/sgml/ref/unlisten.sgml b/doc/src/sgml/ref/unlisten.sgml index 7cdd7394cb9..9e22ea4edc4 100644 --- a/doc/src/sgml/ref/unlisten.sgml +++ b/doc/src/sgml/ref/unlisten.sgml @@ -1,5 +1,5 @@ @@ -21,7 +21,7 @@ PostgreSQL documentation -UNLISTEN { name | * } +UNLISTEN { channel | * } @@ -33,8 +33,8 @@ UNLISTEN { name | * } registration for NOTIFY events. UNLISTEN cancels any existing registration of the current PostgreSQL session as a - listener on the notification name. The special wildcard + listener on the notification channel named channel. The special wildcard * cancels all listener registrations for the current session. @@ -52,10 +52,10 @@ UNLISTEN { name | * } - name + channel - Name of a notification (any identifier). + Name of a notification channel (any identifier). @@ -83,6 +83,11 @@ UNLISTEN { name | * } At the end of each session, UNLISTEN * is automatically executed. + + + A transaction that has executed UNLISTEN cannot be + prepared for two-phase commit. + @@ -100,7 +105,7 @@ Asynchronous notification "virtual" received from server process with PID 8448. Once UNLISTEN has been executed, further NOTIFY - commands will be ignored: + messages will be ignored: UNLISTEN virtual; diff --git a/doc/src/sgml/storage.sgml b/doc/src/sgml/storage.sgml index e0cef7dd7b0..c4b38ddb6c8 100644 --- a/doc/src/sgml/storage.sgml +++ b/doc/src/sgml/storage.sgml @@ -1,4 +1,4 @@ - + @@ -77,6 +77,11 @@ Item (used for shared row locks) + + pg_notify + Subdirectory containing LISTEN/NOTIFY status data + + pg_stat_tmp Subdirectory containing temporary files for the statistics diff --git a/src/backend/access/transam/slru.c b/src/backend/access/transam/slru.c index d5f999f494b..6226acc9283 100644 --- a/src/backend/access/transam/slru.c +++ b/src/backend/access/transam/slru.c @@ -41,7 +41,7 @@ * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $PostgreSQL: pgsql/src/backend/access/transam/slru.c,v 1.48 2010/01/02 16:57:35 momjian Exp $ + * $PostgreSQL: pgsql/src/backend/access/transam/slru.c,v 1.49 2010/02/16 22:34:43 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -59,25 +59,6 @@ #include "miscadmin.h" -/* - * Define segment size. A page is the same BLCKSZ as is used everywhere - * else in Postgres. The segment size can be chosen somewhat arbitrarily; - * we make it 32 pages by default, or 256Kb, i.e. 1M transactions for CLOG - * or 64K transactions for SUBTRANS. - * - * Note: because TransactionIds are 32 bits and wrap around at 0xFFFFFFFF, - * page numbering also wraps around at 0xFFFFFFFF/xxxx_XACTS_PER_PAGE (where - * xxxx is CLOG or SUBTRANS, respectively), and segment numbering at - * 0xFFFFFFFF/xxxx_XACTS_PER_PAGE/SLRU_PAGES_PER_SEGMENT. We need - * take no explicit notice of that fact in this module, except when comparing - * segment and page numbers in SimpleLruTruncate (see PagePrecedes()). - * - * Note: this file currently assumes that segment file names will be four - * hex digits. This sets a lower bound on the segment size (64K transactions - * for 32-bit TransactionIds). - */ -#define SLRU_PAGES_PER_SEGMENT 32 - #define SlruFileName(ctl, path, seg) \ snprintf(path, MAXPGPATH, "%s/%04X", (ctl)->Dir, seg) @@ -183,6 +164,8 @@ SimpleLruInit(SlruCtl ctl, const char *name, int nslots, int nlsns, shared = (SlruShared) ShmemInitStruct(name, SimpleLruShmemSize(nslots, nlsns), &found); + if (!shared) + elog(ERROR, "out of shared memory"); if (!IsUnderPostmaster) { diff --git a/src/backend/access/transam/twophase_rmgr.c b/src/backend/access/transam/twophase_rmgr.c index 0ea8e42ca56..86a1d12f93d 100644 --- a/src/backend/access/transam/twophase_rmgr.c +++ b/src/backend/access/transam/twophase_rmgr.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/access/transam/twophase_rmgr.c,v 1.12 2010/01/02 16:57:35 momjian Exp $ + * $PostgreSQL: pgsql/src/backend/access/transam/twophase_rmgr.c,v 1.13 2010/02/16 22:34:43 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -16,7 +16,6 @@ #include "access/multixact.h" #include "access/twophase_rmgr.h" -#include "commands/async.h" #include "pgstat.h" #include "storage/lock.h" @@ -25,7 +24,6 @@ const TwoPhaseCallback twophase_recover_callbacks[TWOPHASE_RM_MAX_ID + 1] = { NULL, /* END ID */ lock_twophase_recover, /* Lock */ - NULL, /* notify/listen */ NULL, /* pgstat */ multixact_twophase_recover /* MultiXact */ }; @@ -34,7 +32,6 @@ const TwoPhaseCallback twophase_postcommit_callbacks[TWOPHASE_RM_MAX_ID + 1] = { NULL, /* END ID */ lock_twophase_postcommit, /* Lock */ - notify_twophase_postcommit, /* notify/listen */ pgstat_twophase_postcommit, /* pgstat */ multixact_twophase_postcommit /* MultiXact */ }; @@ -43,7 +40,6 @@ const TwoPhaseCallback twophase_postabort_callbacks[TWOPHASE_RM_MAX_ID + 1] = { NULL, /* END ID */ lock_twophase_postabort, /* Lock */ - NULL, /* notify/listen */ pgstat_twophase_postabort, /* pgstat */ multixact_twophase_postabort /* MultiXact */ }; @@ -52,7 +48,6 @@ const TwoPhaseCallback twophase_standby_recover_callbacks[TWOPHASE_RM_MAX_ID + 1 { NULL, /* END ID */ lock_twophase_standby_recover, /* Lock */ - NULL, /* notify/listen */ NULL, /* pgstat */ NULL /* MultiXact */ }; diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index c239c098fd6..46a842bb9a8 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -10,7 +10,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/access/transam/xact.c,v 1.285 2010/02/13 16:15:46 sriggs Exp $ + * $PostgreSQL: pgsql/src/backend/access/transam/xact.c,v 1.286 2010/02/16 22:34:43 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -1736,8 +1736,12 @@ CommitTransaction(void) /* close large objects before lower-level cleanup */ AtEOXact_LargeObject(true); - /* NOTIFY commit must come before lower-level cleanup */ - AtCommit_Notify(); + /* + * Insert notifications sent by NOTIFY commands into the queue. This + * should be late in the pre-commit sequence to minimize time spent + * holding the notify-insertion lock. + */ + PreCommit_Notify(); /* Prevent cancel/die interrupt while cleaning up */ HOLD_INTERRUPTS(); @@ -1825,6 +1829,7 @@ CommitTransaction(void) /* Check we've released all catcache entries */ AtEOXact_CatCache(true); + AtCommit_Notify(); AtEOXact_GUC(true, 1); AtEOXact_SPI(true); AtEOXact_on_commit_actions(true); diff --git a/src/backend/catalog/Makefile b/src/backend/catalog/Makefile index 837865efbe5..a73971d1627 100644 --- a/src/backend/catalog/Makefile +++ b/src/backend/catalog/Makefile @@ -2,7 +2,7 @@ # # Makefile for backend/catalog # -# $PostgreSQL: pgsql/src/backend/catalog/Makefile,v 1.76 2010/01/06 19:56:29 tgl Exp $ +# $PostgreSQL: pgsql/src/backend/catalog/Makefile,v 1.77 2010/02/16 22:34:43 tgl Exp $ # #------------------------------------------------------------------------- @@ -30,7 +30,7 @@ POSTGRES_BKI_SRCS = $(addprefix $(top_srcdir)/src/include/catalog/,\ pg_attrdef.h pg_constraint.h pg_inherits.h pg_index.h pg_operator.h \ pg_opfamily.h pg_opclass.h pg_am.h pg_amop.h pg_amproc.h \ pg_language.h pg_largeobject_metadata.h pg_largeobject.h pg_aggregate.h \ - pg_statistic.h pg_rewrite.h pg_trigger.h pg_listener.h pg_description.h \ + pg_statistic.h pg_rewrite.h pg_trigger.h pg_description.h \ pg_cast.h pg_enum.h pg_namespace.h pg_conversion.h pg_depend.h \ pg_database.h pg_db_role_setting.h pg_tablespace.h pg_pltemplate.h \ pg_authid.h pg_auth_members.h pg_shdepend.h pg_shdescription.h \ diff --git a/src/backend/commands/async.c b/src/backend/commands/async.c index afc5e5fabc1..f5863480f5e 100644 --- a/src/backend/commands/async.c +++ b/src/backend/commands/async.c @@ -7,109 +7,280 @@ * Portions Copyright (c) 1994, Regents of the University of California * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/commands/async.c,v 1.150 2010/01/02 16:57:36 momjian Exp $ + * $PostgreSQL: pgsql/src/backend/commands/async.c,v 1.151 2010/02/16 22:34:43 tgl Exp $ * *------------------------------------------------------------------------- */ /*------------------------------------------------------------------------- - * New Async Notification Model: - * 1. Multiple backends on same machine. Multiple backends listening on - * one relation. (Note: "listening on a relation" is not really the - * right way to think about it, since the notify names need not have - * anything to do with the names of relations actually in the database. - * But this terminology is all over the code and docs, and I don't feel - * like trying to replace it.) + * Async Notification Model as of 9.0: * - * 2. There is a tuple in relation "pg_listener" for each active LISTEN, - * ie, each relname/listenerPID pair. The "notification" field of the - * tuple is zero when no NOTIFY is pending for that listener, or the PID - * of the originating backend when a cross-backend NOTIFY is pending. - * (We skip writing to pg_listener when doing a self-NOTIFY, so the - * notification field should never be equal to the listenerPID field.) + * 1. Multiple backends on same machine. Multiple backends listening on + * several channels. (Channels are also called "conditions" in other + * parts of the code.) * - * 3. The NOTIFY statement itself (routine Async_Notify) just adds the target - * relname to a list of outstanding NOTIFY requests. Actual processing - * happens if and only if we reach transaction commit. At that time (in - * routine AtCommit_Notify) we scan pg_listener for matching relnames. - * If the listenerPID in a matching tuple is ours, we just send a notify - * message to our own front end. If it is not ours, and "notification" - * is not already nonzero, we set notification to our own PID and send a - * PROCSIG_NOTIFY_INTERRUPT signal to the receiving process (indicated by - * listenerPID). - * BTW: if the signal operation fails, we presume that the listener backend - * crashed without removing this tuple, and remove the tuple for it. + * 2. There is one central queue in disk-based storage (directory pg_notify/), + * with actively-used pages mapped into shared memory by the slru.c module. + * All notification messages are placed in the queue and later read out + * by listening backends. * - * 4. Upon receipt of a PROCSIG_NOTIFY_INTERRUPT signal, the signal handler + * There is no central knowledge of which backend listens on which channel; + * every backend has its own list of interesting channels. + * + * Although there is only one queue, notifications are treated as being + * database-local; this is done by including the sender's database OID + * in each notification message. Listening backends ignore messages + * that don't match their database OID. This is important because it + * ensures senders and receivers have the same database encoding and won't + * misinterpret non-ASCII text in the channel name or payload string. + * + * Since notifications are not expected to survive database crashes, + * we can simply clean out the pg_notify data at any reboot, and there + * is no need for WAL support or fsync'ing. + * + * 3. Every backend that is listening on at least one channel registers by + * entering its PID into the array in AsyncQueueControl. It then scans all + * incoming notifications in the central queue and first compares the + * database OID of the notification with its own database OID and then + * compares the notified channel with the list of channels that it listens + * to. In case there is a match it delivers the notification event to its + * frontend. Non-matching events are simply skipped. + * + * 4. The NOTIFY statement (routine Async_Notify) stores the notification in + * a backend-local list which will not be processed until transaction end. + * + * Duplicate notifications from the same transaction are sent out as one + * notification only. This is done to save work when for example a trigger + * on a 2 million row table fires a notification for each row that has been + * changed. If the application needs to receive every single notification + * that has been sent, it can easily add some unique string into the extra + * payload parameter. + * + * When the transaction is ready to commit, PreCommit_Notify() adds the + * pending notifications to the head of the queue. The head pointer of the + * queue always points to the next free position and a position is just a + * page number and the offset in that page. This is done before marking the + * transaction as committed in clog. If we run into problems writing the + * notifications, we can still call elog(ERROR, ...) and the transaction + * will roll back. + * + * Once we have put all of the notifications into the queue, we return to + * CommitTransaction() which will then do the actual transaction commit. + * + * After commit we are called another time (AtCommit_Notify()). Here we + * make the actual updates to the effective listen state (listenChannels). + * + * Finally, after we are out of the transaction altogether, we check if + * we need to signal listening backends. In SignalBackends() we scan the + * list of listening backends and send a PROCSIG_NOTIFY_INTERRUPT signal + * to every listening backend (we don't know which backend is listening on + * which channel so we must signal them all). We can exclude backends that + * are already up to date, though. We don't bother with a self-signal + * either, but just process the queue directly. + * + * 5. Upon receipt of a PROCSIG_NOTIFY_INTERRUPT signal, the signal handler * can call inbound-notify processing immediately if this backend is idle * (ie, it is waiting for a frontend command and is not within a transaction * block). Otherwise the handler may only set a flag, which will cause the * processing to occur just before we next go idle. * - * 5. Inbound-notify processing consists of scanning pg_listener for tuples - * matching our own listenerPID and having nonzero notification fields. - * For each such tuple, we send a message to our frontend and clear the - * notification field. BTW: this routine has to start/commit its own - * transaction, since by assumption it is only called from outside any - * transaction. + * Inbound-notify processing consists of reading all of the notifications + * that have arrived since scanning last time. We read every notification + * until we reach either a notification from an uncommitted transaction or + * the head pointer's position. Then we check if we were the laziest + * backend: if our pointer is set to the same position as the global tail + * pointer is set, then we move the global tail pointer ahead to where the + * second-laziest backend is (in general, we take the MIN of the current + * head position and all active backends' new tail pointers). Whenever we + * move the global tail pointer we also truncate now-unused pages (i.e., + * delete files in pg_notify/ that are no longer used). * - * Like NOTIFY, LISTEN and UNLISTEN just add the desired action to a list - * of pending actions. If we reach transaction commit, the changes are - * applied to pg_listener just before executing any pending NOTIFYs. This - * method is necessary because to avoid race conditions, we must hold lock - * on pg_listener from when we insert a new listener tuple until we commit. - * To do that and not create undue hazard of deadlock, we don't want to - * touch pg_listener until we are otherwise done with the transaction; - * in particular it'd be uncool to still be taking user-commanded locks - * while holding the pg_listener lock. - * - * Although we grab ExclusiveLock on pg_listener for any operation, - * the lock is never held very long, so it shouldn't cause too much of - * a performance problem. (Previously we used AccessExclusiveLock, but - * there's no real reason to forbid concurrent reads.) - * - * An application that listens on the same relname it notifies will get + * An application that listens on the same channel it notifies will get * NOTIFY messages for its own NOTIFYs. These can be ignored, if not useful, * by comparing be_pid in the NOTIFY message to the application's own backend's * PID. (As of FE/BE protocol 2.0, the backend's PID is provided to the * frontend during startup.) The above design guarantees that notifies from - * other backends will never be missed by ignoring self-notifies. Note, - * however, that we do *not* guarantee that a separate frontend message will - * be sent for every outside NOTIFY. Since there is only room for one - * originating PID in pg_listener, outside notifies occurring at about the - * same time may be collapsed into a single message bearing the PID of the - * first outside backend to perform the NOTIFY. + * other backends will never be missed by ignoring self-notifies. + * + * The amount of shared memory used for notify management (NUM_ASYNC_BUFFERS) + * can be varied without affecting anything but performance. The maximum + * amount of notification data that can be queued at one time is determined + * by slru.c's wraparound limit; see QUEUE_MAX_PAGE below. *------------------------------------------------------------------------- */ #include "postgres.h" +#include #include #include -#include "access/heapam.h" -#include "access/twophase_rmgr.h" +#include "access/slru.h" +#include "access/transam.h" #include "access/xact.h" -#include "catalog/pg_listener.h" +#include "catalog/pg_database.h" #include "commands/async.h" +#include "funcapi.h" #include "libpq/libpq.h" #include "libpq/pqformat.h" #include "miscadmin.h" #include "storage/ipc.h" +#include "storage/lmgr.h" #include "storage/procsignal.h" #include "storage/sinval.h" #include "tcop/tcopprot.h" #include "utils/builtins.h" -#include "utils/fmgroids.h" #include "utils/memutils.h" #include "utils/ps_status.h" -#include "utils/tqual.h" +/* + * Maximum size of a NOTIFY payload, including terminating NULL. This + * must be kept small enough so that a notification message fits on one + * SLRU page. + */ +#define NOTIFY_PAYLOAD_MAX_LENGTH 8000 + +/* + * Struct representing an entry in the global notify queue + * + * This struct declaration has the maximal length, but in a real queue entry + * the data area is only big enough for the actual channel and payload strings + * (each null-terminated). AsyncQueueEntryEmptySize is the minimum possible + * entry size, if both channel and payload strings are empty (but note it + * doesn't include alignment padding). + * + * The "length" field should always be rounded up to the next QUEUEALIGN + * multiple so that all fields are properly aligned. + */ +typedef struct AsyncQueueEntry +{ + int length; /* total allocated length of entry */ + Oid dboid; /* sender's database OID */ + TransactionId xid; /* sender's XID */ + int32 srcPid; /* sender's PID */ + char data[NAMEDATALEN + NOTIFY_PAYLOAD_MAX_LENGTH]; +} AsyncQueueEntry; + +/* Currently, no field of AsyncQueueEntry requires more than int alignment */ +#define QUEUEALIGN(len) INTALIGN(len) + +#define AsyncQueueEntryEmptySize (offsetof(AsyncQueueEntry, data) + 2) + +/* + * Struct describing a queue position, and assorted macros for working with it + */ +typedef struct QueuePosition +{ + int page; /* SLRU page number */ + int offset; /* byte offset within page */ +} QueuePosition; + +#define QUEUE_POS_PAGE(x) ((x).page) +#define QUEUE_POS_OFFSET(x) ((x).offset) + +#define SET_QUEUE_POS(x,y,z) \ + do { \ + (x).page = (y); \ + (x).offset = (z); \ + } while (0) + +#define QUEUE_POS_EQUAL(x,y) \ + ((x).page == (y).page && (x).offset == (y).offset) + +/* choose logically smaller QueuePosition */ +#define QUEUE_POS_MIN(x,y) \ + (asyncQueuePagePrecedesLogically((x).page, (y).page) ? (x) : \ + (x).page != (y).page ? (y) : \ + (x).offset < (y).offset ? (x) : (y)) + +/* + * Struct describing a listening backend's status + */ +typedef struct QueueBackendStatus +{ + int32 pid; /* either a PID or InvalidPid */ + QueuePosition pos; /* backend has read queue up to here */ +} QueueBackendStatus; + +#define InvalidPid (-1) + +/* + * Shared memory state for LISTEN/NOTIFY (excluding its SLRU stuff) + * + * The AsyncQueueControl structure is protected by the AsyncQueueLock. + * + * When holding the lock in SHARED mode, backends may only inspect their own + * entries as well as the head and tail pointers. Consequently we can allow a + * backend to update its own record while holding only SHARED lock (since no + * other backend will inspect it). + * + * When holding the lock in EXCLUSIVE mode, backends can inspect the entries + * of other backends and also change the head and tail pointers. + * + * In order to avoid deadlocks, whenever we need both locks, we always first + * get AsyncQueueLock and then AsyncCtlLock. + * + * Each backend uses the backend[] array entry with index equal to its + * BackendId (which can range from 1 to MaxBackends). We rely on this to make + * SendProcSignal fast. + */ +typedef struct AsyncQueueControl +{ + QueuePosition head; /* head points to the next free location */ + QueuePosition tail; /* the global tail is equivalent to the + tail of the "slowest" backend */ + TimestampTz lastQueueFillWarn; /* time of last queue-full msg */ + QueueBackendStatus backend[1]; /* actually of length MaxBackends+1 */ + /* DO NOT ADD FURTHER STRUCT MEMBERS HERE */ +} AsyncQueueControl; + +static AsyncQueueControl *asyncQueueControl; + +#define QUEUE_HEAD (asyncQueueControl->head) +#define QUEUE_TAIL (asyncQueueControl->tail) +#define QUEUE_BACKEND_PID(i) (asyncQueueControl->backend[i].pid) +#define QUEUE_BACKEND_POS(i) (asyncQueueControl->backend[i].pos) + +/* + * The SLRU buffer area through which we access the notification queue + */ +static SlruCtlData AsyncCtlData; + +#define AsyncCtl (&AsyncCtlData) +#define QUEUE_PAGESIZE BLCKSZ +#define QUEUE_FULL_WARN_INTERVAL 5000 /* warn at most once every 5s */ + +/* + * slru.c currently assumes that all filenames are four characters of hex + * digits. That means that we can use segments 0000 through FFFF. + * Each segment contains SLRU_PAGES_PER_SEGMENT pages which gives us + * the pages from 0 to SLRU_PAGES_PER_SEGMENT * 0x10000 - 1. + * + * It's of course possible to enhance slru.c, but this gives us so much + * space already that it doesn't seem worth the trouble. + * + * The most data we can have in the queue at a time is QUEUE_MAX_PAGE/2 + * pages, because more than that would confuse slru.c into thinking there + * was a wraparound condition. With the default BLCKSZ this means there + * can be up to 8GB of queued-and-not-read data. + * + * Note: it's possible to redefine QUEUE_MAX_PAGE with a smaller multiple of + * SLRU_PAGES_PER_SEGMENT, for easier testing of queue-full behaviour. + */ +#define QUEUE_MAX_PAGE (SLRU_PAGES_PER_SEGMENT * 0x10000 - 1) + +/* + * listenChannels identifies the channels we are actually listening to + * (ie, have committed a LISTEN on). It is a simple list of channel names, + * allocated in TopMemoryContext. + */ +static List *listenChannels = NIL; /* list of C strings */ + /* * State for pending LISTEN/UNLISTEN actions consists of an ordered list of * all actions requested in the current transaction. As explained above, - * we don't actually modify pg_listener until we reach transaction commit. + * we don't actually change listenChannels until we reach transaction commit. * * The list is kept in CurTransactionContext. In subtransactions, each * subtransaction has its own list in its own CurTransactionContext, but @@ -126,7 +297,7 @@ typedef enum typedef struct { ListenActionKind action; - char condname[1]; /* actually, as long as needed */ + char channel[1]; /* actually, as long as needed */ } ListenAction; static List *pendingActions = NIL; /* list of ListenAction */ @@ -134,9 +305,9 @@ static List *pendingActions = NIL; /* list of ListenAction */ static List *upperPendingActions = NIL; /* list of upper-xact lists */ /* - * State for outbound notifies consists of a list of all relnames NOTIFYed - * in the current transaction. We do not actually perform a NOTIFY until - * and unless the transaction commits. pendingNotifies is NIL if no + * State for outbound notifies consists of a list of all channels+payloads + * NOTIFYed in the current transaction. We do not actually perform a NOTIFY + * until and unless the transaction commits. pendingNotifies is NIL if no * NOTIFYs have been done in the current transaction. * * The list is kept in CurTransactionContext. In subtransactions, each @@ -149,12 +320,18 @@ static List *upperPendingActions = NIL; /* list of upper-xact lists */ * condition name, it will get a self-notify at commit. This is a bit odd * but is consistent with our historical behavior. */ -static List *pendingNotifies = NIL; /* list of C strings */ +typedef struct Notification +{ + char *channel; /* channel name */ + char *payload; /* payload string (can be empty) */ +} Notification; + +static List *pendingNotifies = NIL; /* list of Notifications */ static List *upperPendingNotifies = NIL; /* list of upper-xact lists */ /* - * State for inbound notifies consists of two flags: one saying whether + * State for inbound notifications consists of two flags: one saying whether * the signal handler is currently allowed to call ProcessIncomingNotify * directly, and one saying whether the signal has occurred but the handler * was not allowed to call ProcessIncomingNotify at the time. @@ -168,57 +345,259 @@ static volatile sig_atomic_t notifyInterruptOccurred = 0; /* True if we've registered an on_shmem_exit cleanup */ static bool unlistenExitRegistered = false; +/* has this backend sent notifications in the current transaction? */ +static bool backendHasSentNotifications = false; +/* has this backend executed its first LISTEN in the current transaction? */ +static bool backendHasExecutedInitialListen = false; +/* GUC parameter */ bool Trace_notify = false; - -static void queue_listen(ListenActionKind action, const char *condname); +/* local function prototypes */ +static bool asyncQueuePagePrecedesPhysically(int p, int q); +static bool asyncQueuePagePrecedesLogically(int p, int q); +static void queue_listen(ListenActionKind action, const char *channel); static void Async_UnlistenOnExit(int code, Datum arg); -static void Exec_Listen(Relation lRel, const char *relname); -static void Exec_Unlisten(Relation lRel, const char *relname); -static void Exec_UnlistenAll(Relation lRel); -static void Send_Notify(Relation lRel); +static void Exec_ListenPreCommit(void); +static void Exec_ListenCommit(const char *channel); +static void Exec_UnlistenCommit(const char *channel); +static void Exec_UnlistenAllCommit(void); +static bool IsListeningOn(const char *channel); +static void asyncQueueUnregister(void); +static bool asyncQueueIsFull(void); +static bool asyncQueueAdvance(QueuePosition *position, int entryLength); +static void asyncQueueNotificationToEntry(Notification *n, AsyncQueueEntry *qe); +static ListCell *asyncQueueAddEntries(ListCell *nextNotify); +static void asyncQueueFillWarning(void); +static bool SignalBackends(void); +static void asyncQueueReadAllNotifications(void); +static bool asyncQueueProcessPageEntries(QueuePosition *current, + QueuePosition stop, + char *page_buffer); +static void asyncQueueAdvanceTail(void); static void ProcessIncomingNotify(void); -static void NotifyMyFrontEnd(char *relname, int32 listenerPID); -static bool AsyncExistsPendingNotify(const char *relname); +static void NotifyMyFrontEnd(const char *channel, + const char *payload, + int32 srcPid); +static bool AsyncExistsPendingNotify(const char *channel, const char *payload); static void ClearPendingActionsAndNotifies(void); +/* + * We will work on the page range of 0..QUEUE_MAX_PAGE. + * + * asyncQueuePagePrecedesPhysically just checks numerically without any magic + * if one page precedes another one. This is wrong for normal operation but + * is helpful when clearing pg_notify/ during startup. + * + * asyncQueuePagePrecedesLogically compares using wraparound logic, as is + * required by slru.c. + */ +static bool +asyncQueuePagePrecedesPhysically(int p, int q) +{ + return p < q; +} + +static bool +asyncQueuePagePrecedesLogically(int p, int q) +{ + int diff; + + /* + * We have to compare modulo (QUEUE_MAX_PAGE+1)/2. Both inputs should + * be in the range 0..QUEUE_MAX_PAGE. + */ + Assert(p >= 0 && p <= QUEUE_MAX_PAGE); + Assert(q >= 0 && q <= QUEUE_MAX_PAGE); + + diff = p - q; + if (diff >= ((QUEUE_MAX_PAGE+1)/2)) + diff -= QUEUE_MAX_PAGE+1; + else if (diff < -((QUEUE_MAX_PAGE+1)/2)) + diff += QUEUE_MAX_PAGE+1; + return diff < 0; +} + +/* + * Report space needed for our shared memory area + */ +Size +AsyncShmemSize(void) +{ + Size size; + + /* This had better match AsyncShmemInit */ + size = mul_size(MaxBackends, sizeof(QueueBackendStatus)); + size = add_size(size, sizeof(AsyncQueueControl)); + + size = add_size(size, SimpleLruShmemSize(NUM_ASYNC_BUFFERS, 0)); + + return size; +} + +/* + * Initialize our shared memory area + */ +void +AsyncShmemInit(void) +{ + bool found; + int slotno; + Size size; + + /* + * Create or attach to the AsyncQueueControl structure. + * + * The used entries in the backend[] array run from 1 to MaxBackends. + * sizeof(AsyncQueueControl) already includes space for the unused zero'th + * entry, but we need to add on space for the used entries. + */ + size = mul_size(MaxBackends, sizeof(QueueBackendStatus)); + size = add_size(size, sizeof(AsyncQueueControl)); + + asyncQueueControl = (AsyncQueueControl *) + ShmemInitStruct("Async Queue Control", size, &found); + + if (!asyncQueueControl) + elog(ERROR, "out of shared memory"); + + if (!found) + { + /* First time through, so initialize it */ + int i; + + SET_QUEUE_POS(QUEUE_HEAD, 0, 0); + SET_QUEUE_POS(QUEUE_TAIL, 0, 0); + asyncQueueControl->lastQueueFillWarn = 0; + /* zero'th entry won't be used, but let's initialize it anyway */ + for (i = 0; i <= MaxBackends; i++) + { + QUEUE_BACKEND_PID(i) = InvalidPid; + SET_QUEUE_POS(QUEUE_BACKEND_POS(i), 0, 0); + } + } + + /* + * Set up SLRU management of the pg_notify data. + */ + AsyncCtl->PagePrecedes = asyncQueuePagePrecedesLogically; + SimpleLruInit(AsyncCtl, "Async Ctl", NUM_ASYNC_BUFFERS, 0, + AsyncCtlLock, "pg_notify"); + /* Override default assumption that writes should be fsync'd */ + AsyncCtl->do_fsync = false; + + if (!found) + { + /* + * During start or reboot, clean out the pg_notify directory. + * + * Since we want to remove every file, we temporarily use + * asyncQueuePagePrecedesPhysically() and pass INT_MAX as the + * comparison value; every file in the directory should therefore + * appear to be less than that. + */ + AsyncCtl->PagePrecedes = asyncQueuePagePrecedesPhysically; + (void) SlruScanDirectory(AsyncCtl, INT_MAX, true); + AsyncCtl->PagePrecedes = asyncQueuePagePrecedesLogically; + + /* Now initialize page zero to empty */ + LWLockAcquire(AsyncCtlLock, LW_EXCLUSIVE); + slotno = SimpleLruZeroPage(AsyncCtl, QUEUE_POS_PAGE(QUEUE_HEAD)); + /* This write is just to verify that pg_notify/ is writable */ + SimpleLruWritePage(AsyncCtl, slotno, NULL); + LWLockRelease(AsyncCtlLock); + } +} + + +/* + * pg_notify - + * SQL function to send a notification event + */ +Datum +pg_notify(PG_FUNCTION_ARGS) +{ + const char *channel; + const char *payload; + + if (PG_ARGISNULL(0)) + channel = ""; + else + channel = text_to_cstring(PG_GETARG_TEXT_PP(0)); + + if (PG_ARGISNULL(1)) + payload = ""; + else + payload = text_to_cstring(PG_GETARG_TEXT_PP(1)); + + Async_Notify(channel, payload); + + PG_RETURN_VOID(); +} + + /* * Async_Notify * * This is executed by the SQL notify command. * - * Adds the relation to the list of pending notifies. + * Adds the message to the list of pending notifies. * Actual notification happens during transaction commit. * ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ */ void -Async_Notify(const char *relname) +Async_Notify(const char *channel, const char *payload) { + Notification *n; + MemoryContext oldcontext; + if (Trace_notify) - elog(DEBUG1, "Async_Notify(%s)", relname); + elog(DEBUG1, "Async_Notify(%s)", channel); + + /* a channel name must be specified */ + if (!channel || !strlen(channel)) + ereport(ERROR, + (errcode(ERRCODE_INVALID_PARAMETER_VALUE), + errmsg("channel name cannot be empty"))); + + if (strlen(channel) >= NAMEDATALEN) + ereport(ERROR, + (errcode(ERRCODE_INVALID_PARAMETER_VALUE), + errmsg("channel name too long"))); + + if (payload) + { + if (strlen(payload) >= NOTIFY_PAYLOAD_MAX_LENGTH) + ereport(ERROR, + (errcode(ERRCODE_INVALID_PARAMETER_VALUE), + errmsg("payload string too long"))); + } /* no point in making duplicate entries in the list ... */ - if (!AsyncExistsPendingNotify(relname)) - { - /* - * The name list needs to live until end of transaction, so store it - * in the transaction context. - */ - MemoryContext oldcontext; + if (AsyncExistsPendingNotify(channel, payload)) + return; - oldcontext = MemoryContextSwitchTo(CurTransactionContext); + /* + * The notification list needs to live until end of transaction, so store + * it in the transaction context. + */ + oldcontext = MemoryContextSwitchTo(CurTransactionContext); - /* - * Ordering of the list isn't important. We choose to put new entries - * on the front, as this might make duplicate-elimination a tad faster - * when the same condition is signaled many times in a row. - */ - pendingNotifies = lcons(pstrdup(relname), pendingNotifies); + n = (Notification *) palloc(sizeof(Notification)); + n->channel = pstrdup(channel); + if (payload) + n->payload = pstrdup(payload); + else + n->payload = ""; - MemoryContextSwitchTo(oldcontext); - } + /* + * We want to preserve the order so we need to append every + * notification. See comments at AsyncExistsPendingNotify(). + */ + pendingNotifies = lappend(pendingNotifies, n); + + MemoryContextSwitchTo(oldcontext); } /* @@ -226,11 +605,11 @@ Async_Notify(const char *relname) * Common code for listen, unlisten, unlisten all commands. * * Adds the request to the list of pending actions. - * Actual update of pg_listener happens during transaction commit. - * ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + * Actual update of the listenChannels list happens during transaction + * commit. */ static void -queue_listen(ListenActionKind action, const char *condname) +queue_listen(ListenActionKind action, const char *channel) { MemoryContext oldcontext; ListenAction *actrec; @@ -244,9 +623,9 @@ queue_listen(ListenActionKind action, const char *condname) oldcontext = MemoryContextSwitchTo(CurTransactionContext); /* space for terminating null is included in sizeof(ListenAction) */ - actrec = (ListenAction *) palloc(sizeof(ListenAction) + strlen(condname)); + actrec = (ListenAction *) palloc(sizeof(ListenAction) + strlen(channel)); actrec->action = action; - strcpy(actrec->condname, condname); + strcpy(actrec->channel, channel); pendingActions = lappend(pendingActions, actrec); @@ -259,12 +638,12 @@ queue_listen(ListenActionKind action, const char *condname) * This is executed by the SQL listen command. */ void -Async_Listen(const char *relname) +Async_Listen(const char *channel) { if (Trace_notify) - elog(DEBUG1, "Async_Listen(%s,%d)", relname, MyProcPid); + elog(DEBUG1, "Async_Listen(%s,%d)", channel, MyProcPid); - queue_listen(LISTEN_LISTEN, relname); + queue_listen(LISTEN_LISTEN, channel); } /* @@ -273,16 +652,16 @@ Async_Listen(const char *relname) * This is executed by the SQL unlisten command. */ void -Async_Unlisten(const char *relname) +Async_Unlisten(const char *channel) { if (Trace_notify) - elog(DEBUG1, "Async_Unlisten(%s,%d)", relname, MyProcPid); + elog(DEBUG1, "Async_Unlisten(%s,%d)", channel, MyProcPid); /* If we couldn't possibly be listening, no need to queue anything */ if (pendingActions == NIL && !unlistenExitRegistered) return; - queue_listen(LISTEN_UNLISTEN, relname); + queue_listen(LISTEN_UNLISTEN, channel); } /* @@ -303,29 +682,64 @@ Async_UnlistenAll(void) queue_listen(LISTEN_UNLISTEN_ALL, ""); } +/* + * SQL function: return a set of the channel names this backend is actively + * listening to. + * + * Note: this coding relies on the fact that the listenChannels list cannot + * change within a transaction. + */ +Datum +pg_listening_channels(PG_FUNCTION_ARGS) +{ + FuncCallContext *funcctx; + ListCell **lcp; + + /* stuff done only on the first call of the function */ + if (SRF_IS_FIRSTCALL()) + { + MemoryContext oldcontext; + + /* create a function context for cross-call persistence */ + funcctx = SRF_FIRSTCALL_INIT(); + + /* switch to memory context appropriate for multiple function calls */ + oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx); + + /* allocate memory for user context */ + lcp = (ListCell **) palloc(sizeof(ListCell *)); + *lcp = list_head(listenChannels); + funcctx->user_fctx = (void *) lcp; + + MemoryContextSwitchTo(oldcontext); + } + + /* stuff done on every call of the function */ + funcctx = SRF_PERCALL_SETUP(); + lcp = (ListCell **) funcctx->user_fctx; + + while (*lcp != NULL) + { + char *channel = (char *) lfirst(*lcp); + + *lcp = lnext(*lcp); + SRF_RETURN_NEXT(funcctx, CStringGetTextDatum(channel)); + } + + SRF_RETURN_DONE(funcctx); +} + /* * Async_UnlistenOnExit * - * Clean up the pg_listener table at backend exit. - * - * This is executed if we have done any LISTENs in this backend. - * It might not be necessary anymore, if the user UNLISTENed everything, - * but we don't try to detect that case. + * This is executed at backend exit if we have done any LISTENs in this + * backend. It might not be necessary anymore, if the user UNLISTENed + * everything, but we don't try to detect that case. */ static void Async_UnlistenOnExit(int code, Datum arg) { - /* - * We need to start/commit a transaction for the unlisten, but if there is - * already an active transaction we had better abort that one first. - * Otherwise we'd end up committing changes that probably ought to be - * discarded. - */ - AbortOutOfAnyTransaction(); - /* Now we can do the unlisten */ - StartTransactionCommand(); - Async_UnlistenAll(); - CommitTransactionCommand(); + Exec_UnlistenAllCommit(); } /* @@ -337,71 +751,144 @@ Async_UnlistenOnExit(int code, Datum arg) void AtPrepare_Notify(void) { - ListCell *p; - - /* It's not sensible to have any pending LISTEN/UNLISTEN actions */ - if (pendingActions) + /* It's not allowed to have any pending LISTEN/UNLISTEN/NOTIFY actions */ + if (pendingActions || pendingNotifies) ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), - errmsg("cannot PREPARE a transaction that has executed LISTEN or UNLISTEN"))); - - /* We can deal with pending NOTIFY though */ - foreach(p, pendingNotifies) - { - const char *relname = (const char *) lfirst(p); - - RegisterTwoPhaseRecord(TWOPHASE_RM_NOTIFY_ID, 0, - relname, strlen(relname) + 1); - } - - /* - * We can clear the state immediately, rather than needing a separate - * PostPrepare call, because if the transaction fails we'd just discard - * the state anyway. - */ - ClearPendingActionsAndNotifies(); + errmsg("cannot PREPARE a transaction that has executed LISTEN, UNLISTEN or NOTIFY"))); } /* - * AtCommit_Notify + * PreCommit_Notify * - * This is called at transaction commit. + * This is called at transaction commit, before actually committing to + * clog. * - * If there are pending LISTEN/UNLISTEN actions, insert or delete - * tuples in pg_listener accordingly. + * If there are pending LISTEN actions, make sure we are listed in the + * shared-memory listener array. This must happen before commit to + * ensure we don't miss any notifies from transactions that commit + * just after ours. * * If there are outbound notify requests in the pendingNotifies list, - * scan pg_listener for matching tuples, and either signal the other - * backend or send a message to our own frontend. - * - * NOTE: we are still inside the current transaction, therefore can - * piggyback on its committing of changes. + * add them to the global queue. We do that before commit so that + * we can still throw error if we run out of queue space. */ void -AtCommit_Notify(void) +PreCommit_Notify(void) { - Relation lRel; ListCell *p; if (pendingActions == NIL && pendingNotifies == NIL) return; /* no relevant statements in this xact */ - /* - * NOTIFY is disabled if not normal processing mode. This test used to be - * in xact.c, but it seems cleaner to do it here. - */ - if (!IsNormalProcessingMode()) + if (Trace_notify) + elog(DEBUG1, "PreCommit_Notify"); + + Assert(backendHasExecutedInitialListen == false); + + /* Preflight for any pending listen/unlisten actions */ + foreach(p, pendingActions) { - ClearPendingActionsAndNotifies(); - return; + ListenAction *actrec = (ListenAction *) lfirst(p); + + switch (actrec->action) + { + case LISTEN_LISTEN: + Exec_ListenPreCommit(); + break; + case LISTEN_UNLISTEN: + /* there is no Exec_UnlistenPreCommit() */ + break; + case LISTEN_UNLISTEN_ALL: + /* there is no Exec_UnlistenAllPreCommit() */ + break; + } } + /* Queue any pending notifies */ + if (pendingNotifies) + { + ListCell *nextNotify; + + /* + * Make sure that we have an XID assigned to the current transaction. + * GetCurrentTransactionId is cheap if we already have an XID, but + * not so cheap if we don't, and we'd prefer not to do that work + * while holding AsyncQueueLock. + */ + (void) GetCurrentTransactionId(); + + /* + * Serialize writers by acquiring a special lock that we hold till + * after commit. This ensures that queue entries appear in commit + * order, and in particular that there are never uncommitted queue + * entries ahead of committed ones, so an uncommitted transaction + * can't block delivery of deliverable notifications. + * + * We use a heavyweight lock so that it'll automatically be released + * after either commit or abort. This also allows deadlocks to be + * detected, though really a deadlock shouldn't be possible here. + * + * The lock is on "database 0", which is pretty ugly but it doesn't + * seem worth inventing a special locktag category just for this. + * (Historical note: before PG 9.0, a similar lock on "database 0" was + * used by the flatfiles mechanism.) + */ + LockSharedObject(DatabaseRelationId, InvalidOid, 0, + AccessExclusiveLock); + + /* Now push the notifications into the queue */ + backendHasSentNotifications = true; + + nextNotify = list_head(pendingNotifies); + while (nextNotify != NULL) + { + /* + * Add the pending notifications to the queue. We acquire and + * release AsyncQueueLock once per page, which might be overkill + * but it does allow readers to get in while we're doing this. + * + * A full queue is very uncommon and should really not happen, + * given that we have so much space available in the SLRU pages. + * Nevertheless we need to deal with this possibility. Note that + * when we get here we are in the process of committing our + * transaction, but we have not yet committed to clog, so at this + * point in time we can still roll the transaction back. + */ + LWLockAcquire(AsyncQueueLock, LW_EXCLUSIVE); + asyncQueueFillWarning(); + if (asyncQueueIsFull()) + ereport(ERROR, + (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED), + errmsg("too many notifications in the NOTIFY queue"))); + nextNotify = asyncQueueAddEntries(nextNotify); + LWLockRelease(AsyncQueueLock); + } + } +} + +/* + * AtCommit_Notify + * + * This is called at transaction commit, after committing to clog. + * + * Update listenChannels and clear transaction-local state. + */ +void +AtCommit_Notify(void) +{ + ListCell *p; + + /* + * Allow transactions that have not executed LISTEN/UNLISTEN/NOTIFY to + * return as soon as possible + */ + if (!pendingActions && !pendingNotifies) + return; + if (Trace_notify) elog(DEBUG1, "AtCommit_Notify"); - /* Acquire ExclusiveLock on pg_listener */ - lRel = heap_open(ListenerRelationId, ExclusiveLock); - /* Perform any pending listen/unlisten actions */ foreach(p, pendingActions) { @@ -410,281 +897,640 @@ AtCommit_Notify(void) switch (actrec->action) { case LISTEN_LISTEN: - Exec_Listen(lRel, actrec->condname); + Exec_ListenCommit(actrec->channel); break; case LISTEN_UNLISTEN: - Exec_Unlisten(lRel, actrec->condname); + Exec_UnlistenCommit(actrec->channel); break; case LISTEN_UNLISTEN_ALL: - Exec_UnlistenAll(lRel); + Exec_UnlistenAllCommit(); break; } - - /* We must CCI after each action in case of conflicting actions */ - CommandCounterIncrement(); } - /* Perform any pending notifies */ - if (pendingNotifies) - Send_Notify(lRel); - /* - * We do NOT release the lock on pg_listener here; we need to hold it - * until end of transaction (which is about to happen, anyway) to ensure - * that notified backends see our tuple updates when they look. Else they - * might disregard the signal, which would make the application programmer - * very unhappy. Also, this prevents race conditions when we have just - * inserted a listening tuple. + * If we did an initial LISTEN, listenChannels now has the entry, so + * we no longer need or want the flag to be set. */ - heap_close(lRel, NoLock); + backendHasExecutedInitialListen = false; + /* And clean up */ ClearPendingActionsAndNotifies(); - - if (Trace_notify) - elog(DEBUG1, "AtCommit_Notify: done"); } /* - * Exec_Listen --- subroutine for AtCommit_Notify + * Exec_ListenPreCommit --- subroutine for PreCommit_Notify * - * Register the current backend as listening on the specified relation. + * This function must make sure we are ready to catch any incoming messages. */ static void -Exec_Listen(Relation lRel, const char *relname) +Exec_ListenPreCommit(void) { - HeapScanDesc scan; - HeapTuple tuple; - Datum values[Natts_pg_listener]; - bool nulls[Natts_pg_listener]; - NameData condname; - bool alreadyListener = false; - - if (Trace_notify) - elog(DEBUG1, "Exec_Listen(%s,%d)", relname, MyProcPid); - - /* Detect whether we are already listening on this relname */ - scan = heap_beginscan(lRel, SnapshotNow, 0, NULL); - while ((tuple = heap_getnext(scan, ForwardScanDirection)) != NULL) - { - Form_pg_listener listener = (Form_pg_listener) GETSTRUCT(tuple); - - if (listener->listenerpid == MyProcPid && - strncmp(NameStr(listener->relname), relname, NAMEDATALEN) == 0) - { - alreadyListener = true; - /* No need to scan the rest of the table */ - break; - } - } - heap_endscan(scan); - - if (alreadyListener) + /* + * Nothing to do if we are already listening to something, nor if we + * already ran this routine in this transaction. + */ + if (listenChannels != NIL || backendHasExecutedInitialListen) return; + if (Trace_notify) + elog(DEBUG1, "Exec_ListenPreCommit(%d)", MyProcPid); + /* - * OK to insert a new tuple + * We need this variable to detect an aborted initial LISTEN. + * In that case we would set up our pointer but not listen on any channel. + * This flag gets cleared in AtCommit_Notify or AtAbort_Notify(). */ - memset(nulls, false, sizeof(nulls)); - - namestrcpy(&condname, relname); - values[Anum_pg_listener_relname - 1] = NameGetDatum(&condname); - values[Anum_pg_listener_listenerpid - 1] = Int32GetDatum(MyProcPid); - values[Anum_pg_listener_notification - 1] = Int32GetDatum(0); /* no notifies pending */ - - tuple = heap_form_tuple(RelationGetDescr(lRel), values, nulls); - - simple_heap_insert(lRel, tuple); - -#ifdef NOT_USED /* currently there are no indexes */ - CatalogUpdateIndexes(lRel, tuple); -#endif - - heap_freetuple(tuple); + backendHasExecutedInitialListen = true; /* - * now that we are listening, make sure we will unlisten before dying. + * Before registering, make sure we will unlisten before dying. + * (Note: this action does not get undone if we abort later.) */ if (!unlistenExitRegistered) { on_shmem_exit(Async_UnlistenOnExit, 0); unlistenExitRegistered = true; } + + /* + * This is our first LISTEN, so establish our pointer. + * + * We set our pointer to the global tail pointer and then move it forward + * over already-committed notifications. This ensures we cannot miss any + * not-yet-committed notifications. We might get a few more but that + * doesn't hurt. + */ + LWLockAcquire(AsyncQueueLock, LW_SHARED); + QUEUE_BACKEND_POS(MyBackendId) = QUEUE_TAIL; + QUEUE_BACKEND_PID(MyBackendId) = MyProcPid; + LWLockRelease(AsyncQueueLock); + + /* + * Try to move our pointer forward as far as possible. This will skip over + * already-committed notifications. Still, we could get notifications that + * have already committed before we started to LISTEN. + * + * Note that we are not yet listening on anything, so we won't deliver + * any notification to the frontend. + * + * This will also advance the global tail pointer if possible. + */ + asyncQueueReadAllNotifications(); } /* - * Exec_Unlisten --- subroutine for AtCommit_Notify + * Exec_ListenCommit --- subroutine for AtCommit_Notify * - * Remove the current backend from the list of listening backends - * for the specified relation. + * Add the channel to the list of channels we are listening on. */ static void -Exec_Unlisten(Relation lRel, const char *relname) +Exec_ListenCommit(const char *channel) { - HeapScanDesc scan; - HeapTuple tuple; + MemoryContext oldcontext; + + /* Do nothing if we are already listening on this channel */ + if (IsListeningOn(channel)) + return; + + /* + * Add the new channel name to listenChannels. + * + * XXX It is theoretically possible to get an out-of-memory failure here, + * which would be bad because we already committed. For the moment it + * doesn't seem worth trying to guard against that, but maybe improve this + * later. + */ + oldcontext = MemoryContextSwitchTo(TopMemoryContext); + listenChannels = lappend(listenChannels, pstrdup(channel)); + MemoryContextSwitchTo(oldcontext); +} + +/* + * Exec_UnlistenCommit --- subroutine for AtCommit_Notify + * + * Remove the specified channel name from listenChannels. + */ +static void +Exec_UnlistenCommit(const char *channel) +{ + ListCell *q; + ListCell *prev; if (Trace_notify) - elog(DEBUG1, "Exec_Unlisten(%s,%d)", relname, MyProcPid); + elog(DEBUG1, "Exec_UnlistenCommit(%s,%d)", channel, MyProcPid); - scan = heap_beginscan(lRel, SnapshotNow, 0, NULL); - while ((tuple = heap_getnext(scan, ForwardScanDirection)) != NULL) + prev = NULL; + foreach(q, listenChannels) { - Form_pg_listener listener = (Form_pg_listener) GETSTRUCT(tuple); + char *lchan = (char *) lfirst(q); - if (listener->listenerpid == MyProcPid && - strncmp(NameStr(listener->relname), relname, NAMEDATALEN) == 0) + if (strcmp(lchan, channel) == 0) { - /* Found the matching tuple, delete it */ - simple_heap_delete(lRel, &tuple->t_self); - - /* - * We assume there can be only one match, so no need to scan the - * rest of the table - */ + listenChannels = list_delete_cell(listenChannels, q, prev); + pfree(lchan); break; } + prev = q; } - heap_endscan(scan); /* * We do not complain about unlistening something not being listened; * should we? */ + + /* If no longer listening to anything, get out of listener array */ + if (listenChannels == NIL) + asyncQueueUnregister(); } /* - * Exec_UnlistenAll --- subroutine for AtCommit_Notify + * Exec_UnlistenAllCommit --- subroutine for AtCommit_Notify * - * Update pg_listener to unlisten all relations for this backend. + * Unlisten on all channels for this backend. */ static void -Exec_UnlistenAll(Relation lRel) +Exec_UnlistenAllCommit(void) { - HeapScanDesc scan; - HeapTuple lTuple; - ScanKeyData key[1]; + if (Trace_notify) + elog(DEBUG1, "Exec_UnlistenAllCommit(%d)", MyProcPid); + + list_free_deep(listenChannels); + listenChannels = NIL; + + asyncQueueUnregister(); +} + +/* + * ProcessCompletedNotifies --- send out signals and self-notifies + * + * This is called from postgres.c just before going idle at the completion + * of a transaction. If we issued any notifications in the just-completed + * transaction, send signals to other backends to process them, and also + * process the queue ourselves to send messages to our own frontend. + * + * The reason that this is not done in AtCommit_Notify is that there is + * a nonzero chance of errors here (for example, encoding conversion errors + * while trying to format messages to our frontend). An error during + * AtCommit_Notify would be a PANIC condition. The timing is also arranged + * to ensure that a transaction's self-notifies are delivered to the frontend + * before it gets the terminating ReadyForQuery message. + * + * Note that we send signals and process the queue even if the transaction + * eventually aborted. This is because we need to clean out whatever got + * added to the queue. + * + * NOTE: we are outside of any transaction here. + */ +void +ProcessCompletedNotifies(void) +{ + bool signalled; + + /* Nothing to do if we didn't send any notifications */ + if (!backendHasSentNotifications) + return; + + /* + * We reset the flag immediately; otherwise, if any sort of error + * occurs below, we'd be locked up in an infinite loop, because + * control will come right back here after error cleanup. + */ + backendHasSentNotifications = false; if (Trace_notify) - elog(DEBUG1, "Exec_UnlistenAll"); + elog(DEBUG1, "ProcessCompletedNotifies"); - /* Find and delete all entries with my listenerPID */ - ScanKeyInit(&key[0], - Anum_pg_listener_listenerpid, - BTEqualStrategyNumber, F_INT4EQ, - Int32GetDatum(MyProcPid)); - scan = heap_beginscan(lRel, SnapshotNow, 1, key); + /* + * We must run asyncQueueReadAllNotifications inside a transaction, + * else bad things happen if it gets an error. + */ + StartTransactionCommand(); - while ((lTuple = heap_getnext(scan, ForwardScanDirection)) != NULL) - simple_heap_delete(lRel, &lTuple->t_self); + /* Send signals to other backends */ + signalled = SignalBackends(); - heap_endscan(scan); + if (listenChannels != NIL) + { + /* Read the queue ourselves, and send relevant stuff to the frontend */ + asyncQueueReadAllNotifications(); + } + else if (!signalled) + { + /* + * If we found no other listening backends, and we aren't listening + * ourselves, then we must execute asyncQueueAdvanceTail to flush + * the queue, because ain't nobody else gonna do it. This prevents + * queue overflow when we're sending useless notifies to nobody. + * (A new listener could have joined since we looked, but if so this + * is harmless.) + */ + asyncQueueAdvanceTail(); + } + + CommitTransactionCommand(); + + /* We don't need pq_flush() here since postgres.c will do one shortly */ } /* - * Send_Notify --- subroutine for AtCommit_Notify + * Test whether we are actively listening on the given channel name. * - * Scan pg_listener for tuples matching our pending notifies, and - * either signal the other backend or send a message to our own frontend. + * Note: this function is executed for every notification found in the queue. + * Perhaps it is worth further optimization, eg convert the list to a sorted + * array so we can binary-search it. In practice the list is likely to be + * fairly short, though. + */ +static bool +IsListeningOn(const char *channel) +{ + ListCell *p; + + foreach(p, listenChannels) + { + char *lchan = (char *) lfirst(p); + + if (strcmp(lchan, channel) == 0) + return true; + } + return false; +} + +/* + * Remove our entry from the listeners array when we are no longer listening + * on any channel. NB: must not fail if we're already not listening. */ static void -Send_Notify(Relation lRel) +asyncQueueUnregister(void) { - TupleDesc tdesc = RelationGetDescr(lRel); - HeapScanDesc scan; - HeapTuple lTuple, - rTuple; - Datum value[Natts_pg_listener]; - bool repl[Natts_pg_listener], - nulls[Natts_pg_listener]; + bool advanceTail; - /* preset data to update notify column to MyProcPid */ - memset(nulls, false, sizeof(nulls)); - memset(repl, false, sizeof(repl)); - repl[Anum_pg_listener_notification - 1] = true; - memset(value, 0, sizeof(value)); - value[Anum_pg_listener_notification - 1] = Int32GetDatum(MyProcPid); + Assert(listenChannels == NIL); /* else caller error */ - scan = heap_beginscan(lRel, SnapshotNow, 0, NULL); + LWLockAcquire(AsyncQueueLock, LW_SHARED); + /* check if entry is valid and oldest ... */ + advanceTail = (MyProcPid == QUEUE_BACKEND_PID(MyBackendId)) && + QUEUE_POS_EQUAL(QUEUE_BACKEND_POS(MyBackendId), QUEUE_TAIL); + /* ... then mark it invalid */ + QUEUE_BACKEND_PID(MyBackendId) = InvalidPid; + LWLockRelease(AsyncQueueLock); - while ((lTuple = heap_getnext(scan, ForwardScanDirection)) != NULL) + /* If we were the laziest backend, try to advance the tail pointer */ + if (advanceTail) + asyncQueueAdvanceTail(); +} + +/* + * Test whether there is room to insert more notification messages. + * + * Caller must hold at least shared AsyncQueueLock. + */ +static bool +asyncQueueIsFull(void) +{ + int nexthead; + int boundary; + + /* + * The queue is full if creating a new head page would create a page that + * logically precedes the current global tail pointer, ie, the head + * pointer would wrap around compared to the tail. We cannot create such + * a head page for fear of confusing slru.c. For safety we round the tail + * pointer back to a segment boundary (compare the truncation logic in + * asyncQueueAdvanceTail). + * + * Note that this test is *not* dependent on how much space there is on + * the current head page. This is necessary because asyncQueueAddEntries + * might try to create the next head page in any case. + */ + nexthead = QUEUE_POS_PAGE(QUEUE_HEAD) + 1; + if (nexthead > QUEUE_MAX_PAGE) + nexthead = 0; /* wrap around */ + boundary = QUEUE_POS_PAGE(QUEUE_TAIL); + boundary -= boundary % SLRU_PAGES_PER_SEGMENT; + return asyncQueuePagePrecedesLogically(nexthead, boundary); +} + +/* + * Advance the QueuePosition to the next entry, assuming that the current + * entry is of length entryLength. If we jump to a new page the function + * returns true, else false. + */ +static bool +asyncQueueAdvance(QueuePosition *position, int entryLength) +{ + int pageno = QUEUE_POS_PAGE(*position); + int offset = QUEUE_POS_OFFSET(*position); + bool pageJump = false; + + /* + * Move to the next writing position: First jump over what we have just + * written or read. + */ + offset += entryLength; + Assert(offset <= QUEUE_PAGESIZE); + + /* + * In a second step check if another entry can possibly be written to the + * page. If so, stay here, we have reached the next position. If not, then + * we need to move on to the next page. + */ + if (offset + QUEUEALIGN(AsyncQueueEntryEmptySize) > QUEUE_PAGESIZE) { - Form_pg_listener listener = (Form_pg_listener) GETSTRUCT(lTuple); - char *relname = NameStr(listener->relname); - int32 listenerPID = listener->listenerpid; + pageno++; + if (pageno > QUEUE_MAX_PAGE) + pageno = 0; /* wrap around */ + offset = 0; + pageJump = true; + } - if (!AsyncExistsPendingNotify(relname)) - continue; + SET_QUEUE_POS(*position, pageno, offset); + return pageJump; +} - if (listenerPID == MyProcPid) +/* + * Fill the AsyncQueueEntry at *qe with an outbound notification message. + */ +static void +asyncQueueNotificationToEntry(Notification *n, AsyncQueueEntry *qe) +{ + size_t channellen = strlen(n->channel); + size_t payloadlen = strlen(n->payload); + int entryLength; + + Assert(channellen < NAMEDATALEN); + Assert(payloadlen < NOTIFY_PAYLOAD_MAX_LENGTH); + + /* The terminators are already included in AsyncQueueEntryEmptySize */ + entryLength = AsyncQueueEntryEmptySize + payloadlen + channellen; + entryLength = QUEUEALIGN(entryLength); + qe->length = entryLength; + qe->dboid = MyDatabaseId; + qe->xid = GetCurrentTransactionId(); + qe->srcPid = MyProcPid; + memcpy(qe->data, n->channel, channellen + 1); + memcpy(qe->data + channellen + 1, n->payload, payloadlen + 1); +} + +/* + * Add pending notifications to the queue. + * + * We go page by page here, i.e. we stop once we have to go to a new page but + * we will be called again and then fill that next page. If an entry does not + * fit into the current page, we write a dummy entry with an InvalidOid as the + * database OID in order to fill the page. So every page is always used up to + * the last byte which simplifies reading the page later. + * + * We are passed the list cell containing the next notification to write + * and return the first still-unwritten cell back. Eventually we will return + * NULL indicating all is done. + * + * We are holding AsyncQueueLock already from the caller and grab AsyncCtlLock + * locally in this function. + */ +static ListCell * +asyncQueueAddEntries(ListCell *nextNotify) +{ + AsyncQueueEntry qe; + int pageno; + int offset; + int slotno; + + /* We hold both AsyncQueueLock and AsyncCtlLock during this operation */ + LWLockAcquire(AsyncCtlLock, LW_EXCLUSIVE); + + /* Fetch the current page */ + pageno = QUEUE_POS_PAGE(QUEUE_HEAD); + slotno = SimpleLruReadPage(AsyncCtl, pageno, true, InvalidTransactionId); + /* Note we mark the page dirty before writing in it */ + AsyncCtl->shared->page_dirty[slotno] = true; + + while (nextNotify != NULL) + { + Notification *n = (Notification *) lfirst(nextNotify); + + /* Construct a valid queue entry in local variable qe */ + asyncQueueNotificationToEntry(n, &qe); + + offset = QUEUE_POS_OFFSET(QUEUE_HEAD); + + /* Check whether the entry really fits on the current page */ + if (offset + qe.length <= QUEUE_PAGESIZE) { - /* - * Self-notify: no need to bother with table update. Indeed, we - * *must not* clear the notification field in this path, or we - * could lose an outside notify, which'd be bad for applications - * that ignore self-notify messages. - */ - if (Trace_notify) - elog(DEBUG1, "AtCommit_Notify: notifying self"); - - NotifyMyFrontEnd(relname, listenerPID); + /* OK, so advance nextNotify past this item */ + nextNotify = lnext(nextNotify); } else { - if (Trace_notify) - elog(DEBUG1, "AtCommit_Notify: notifying pid %d", - listenerPID); - /* - * If someone has already notified this listener, we don't bother - * modifying the table, but we do still send a NOTIFY_INTERRUPT - * signal, just in case that backend missed the earlier signal for - * some reason. It's OK to send the signal first, because the - * other guy can't read pg_listener until we unlock it. - * - * Note: we don't have the other guy's BackendId available, so - * this will incur a search of the ProcSignal table. That's - * probably not worth worrying about. + * Write a dummy entry to fill up the page. Actually readers will + * only check dboid and since it won't match any reader's database + * OID, they will ignore this entry and move on. */ - if (SendProcSignal(listenerPID, PROCSIG_NOTIFY_INTERRUPT, - InvalidBackendId) < 0) - { - /* - * Get rid of pg_listener entry if it refers to a PID that no - * longer exists. Presumably, that backend crashed without - * deleting its pg_listener entries. This code used to only - * delete the entry if errno==ESRCH, but as far as I can see - * we should just do it for any failure (certainly at least - * for EPERM too...) - */ - simple_heap_delete(lRel, &lTuple->t_self); - } - else if (listener->notification == 0) - { - /* Rewrite the tuple with my PID in notification column */ - rTuple = heap_modify_tuple(lTuple, tdesc, value, nulls, repl); - simple_heap_update(lRel, &lTuple->t_self, rTuple); + qe.length = QUEUE_PAGESIZE - offset; + qe.dboid = InvalidOid; + qe.data[0] = '\0'; /* empty channel */ + qe.data[1] = '\0'; /* empty payload */ + } -#ifdef NOT_USED /* currently there are no indexes */ - CatalogUpdateIndexes(lRel, rTuple); -#endif - } + /* Now copy qe into the shared buffer page */ + memcpy(AsyncCtl->shared->page_buffer[slotno] + offset, + &qe, + qe.length); + + /* Advance QUEUE_HEAD appropriately, and note if page is full */ + if (asyncQueueAdvance(&(QUEUE_HEAD), qe.length)) + { + /* + * Page is full, so we're done here, but first fill the next + * page with zeroes. The reason to do this is to ensure that + * slru.c's idea of the head page is always the same as ours, + * which avoids boundary problems in SimpleLruTruncate. The + * test in asyncQueueIsFull() ensured that there is room to + * create this page without overrunning the queue. + */ + slotno = SimpleLruZeroPage(AsyncCtl, QUEUE_POS_PAGE(QUEUE_HEAD)); + /* And exit the loop */ + break; } } - heap_endscan(scan); + LWLockRelease(AsyncCtlLock); + + return nextNotify; +} + +/* + * Check whether the queue is at least half full, and emit a warning if so. + * + * This is unlikely given the size of the queue, but possible. + * The warnings show up at most once every QUEUE_FULL_WARN_INTERVAL. + * + * Caller must hold exclusive AsyncQueueLock. + */ +static void +asyncQueueFillWarning(void) +{ + int headPage = QUEUE_POS_PAGE(QUEUE_HEAD); + int tailPage = QUEUE_POS_PAGE(QUEUE_TAIL); + int occupied; + double fillDegree; + TimestampTz t; + + occupied = headPage - tailPage; + + if (occupied == 0) + return; /* fast exit for common case */ + + if (occupied < 0) + { + /* head has wrapped around, tail not yet */ + occupied += QUEUE_MAX_PAGE+1; + } + + fillDegree = (double) occupied / (double) ((QUEUE_MAX_PAGE+1)/2); + + if (fillDegree < 0.5) + return; + + t = GetCurrentTimestamp(); + + if (TimestampDifferenceExceeds(asyncQueueControl->lastQueueFillWarn, + t, QUEUE_FULL_WARN_INTERVAL)) + { + QueuePosition min = QUEUE_HEAD; + int32 minPid = InvalidPid; + int i; + + for (i = 1; i <= MaxBackends; i++) + { + if (QUEUE_BACKEND_PID(i) != InvalidPid) + { + min = QUEUE_POS_MIN(min, QUEUE_BACKEND_POS(i)); + if (QUEUE_POS_EQUAL(min, QUEUE_BACKEND_POS(i))) + minPid = QUEUE_BACKEND_PID(i); + } + } + + ereport(WARNING, + (errmsg("pg_notify queue is %.0f%% full", fillDegree * 100), + (minPid != InvalidPid ? + errdetail("PID %d is among the slowest backends.", minPid) + : 0), + (minPid != InvalidPid ? + errhint("Cleanup can only proceed if this backend ends its current transaction.") + : 0))); + + asyncQueueControl->lastQueueFillWarn = t; + } +} + +/* + * Send signals to all listening backends (except our own). + * + * Returns true if we sent at least one signal. + * + * Since we need EXCLUSIVE lock anyway we also check the position of the other + * backends and in case one is already up-to-date we don't signal it. + * This can happen if concurrent notifying transactions have sent a signal and + * the signaled backend has read the other notifications and ours in the same + * step. + * + * Since we know the BackendId and the Pid the signalling is quite cheap. + */ +static bool +SignalBackends(void) +{ + bool signalled = false; + int32 *pids; + BackendId *ids; + int count; + int i; + int32 pid; + + /* + * Identify all backends that are listening and not already up-to-date. + * We don't want to send signals while holding the AsyncQueueLock, so + * we just build a list of target PIDs. + * + * XXX in principle these pallocs could fail, which would be bad. + * Maybe preallocate the arrays? But in practice this is only run + * in trivial transactions, so there should surely be space available. + */ + pids = (int32 *) palloc(MaxBackends * sizeof(int32)); + ids = (BackendId *) palloc(MaxBackends * sizeof(BackendId)); + count = 0; + + LWLockAcquire(AsyncQueueLock, LW_EXCLUSIVE); + for (i = 1; i <= MaxBackends; i++) + { + pid = QUEUE_BACKEND_PID(i); + if (pid != InvalidPid && pid != MyProcPid) + { + QueuePosition pos = QUEUE_BACKEND_POS(i); + + if (!QUEUE_POS_EQUAL(pos, QUEUE_HEAD)) + { + pids[count] = pid; + ids[count] = i; + count++; + } + } + } + LWLockRelease(AsyncQueueLock); + + /* Now send signals */ + for (i = 0; i < count; i++) + { + pid = pids[i]; + + /* + * Note: assuming things aren't broken, a signal failure here could + * only occur if the target backend exited since we released + * AsyncQueueLock; which is unlikely but certainly possible. + * So we just log a low-level debug message if it happens. + */ + if (SendProcSignal(pid, PROCSIG_NOTIFY_INTERRUPT, ids[i]) < 0) + elog(DEBUG3, "could not signal backend with PID %d: %m", pid); + else + signalled = true; + } + + pfree(pids); + pfree(ids); + + return signalled; } /* * AtAbort_Notify * - * This is called at transaction abort. + * This is called at transaction abort. * - * Gets rid of pending actions and outbound notifies that we would have - * executed if the transaction got committed. + * Gets rid of pending actions and outbound notifies that we would have + * executed if the transaction got committed. */ void AtAbort_Notify(void) { + /* + * If we LISTEN but then roll back the transaction we have set our pointer + * but have not made any entry in listenChannels. In that case, remove + * our pointer again. + */ + if (backendHasExecutedInitialListen) + { + /* + * Checking listenChannels should be redundant but it can't hurt doing + * it for safety reasons. + */ + if (listenChannels == NIL) + asyncQueueUnregister(); + + backendHasExecutedInitialListen = false; + } + + /* And clean up */ ClearPendingActionsAndNotifies(); } @@ -939,31 +1785,299 @@ DisableNotifyInterrupt(void) return result; } +/* + * Read all pending notifications from the queue, and deliver appropriate + * ones to my frontend. Stop when we reach queue head or an uncommitted + * notification. + */ +static void +asyncQueueReadAllNotifications(void) +{ + QueuePosition pos; + QueuePosition oldpos; + QueuePosition head; + bool advanceTail; + /* page_buffer must be adequately aligned, so use a union */ + union { + char buf[QUEUE_PAGESIZE]; + AsyncQueueEntry align; + } page_buffer; + + /* Fetch current state */ + LWLockAcquire(AsyncQueueLock, LW_SHARED); + /* Assert checks that we have a valid state entry */ + Assert(MyProcPid == QUEUE_BACKEND_PID(MyBackendId)); + pos = oldpos = QUEUE_BACKEND_POS(MyBackendId); + head = QUEUE_HEAD; + LWLockRelease(AsyncQueueLock); + + if (QUEUE_POS_EQUAL(pos, head)) + { + /* Nothing to do, we have read all notifications already. */ + return; + } + + /*---------- + * Note that we deliver everything that we see in the queue and that + * matches our _current_ listening state. + * Especially we do not take into account different commit times. + * Consider the following example: + * + * Backend 1: Backend 2: + * + * transaction starts + * NOTIFY foo; + * commit starts + * transaction starts + * LISTEN foo; + * commit starts + * commit to clog + * commit to clog + * + * It could happen that backend 2 sees the notification from backend 1 in + * the queue. Even though the notifying transaction committed before + * the listening transaction, we still deliver the notification. + * + * The idea is that an additional notification does not do any harm, we + * just need to make sure that we do not miss a notification. + * + * It is possible that we fail while trying to send a message to our + * frontend (for example, because of encoding conversion failure). + * If that happens it is critical that we not try to send the same + * message over and over again. Therefore, we place a PG_TRY block + * here that will forcibly advance our backend position before we lose + * control to an error. (We could alternatively retake AsyncQueueLock + * and move the position before handling each individual message, but + * that seems like too much lock traffic.) + *---------- + */ + PG_TRY(); + { + bool reachedStop; + + do + { + int curpage = QUEUE_POS_PAGE(pos); + int curoffset = QUEUE_POS_OFFSET(pos); + int slotno; + int copysize; + + /* + * We copy the data from SLRU into a local buffer, so as to avoid + * holding the AsyncCtlLock while we are examining the entries and + * possibly transmitting them to our frontend. Copy only the part + * of the page we will actually inspect. + */ + slotno = SimpleLruReadPage_ReadOnly(AsyncCtl, curpage, + InvalidTransactionId); + if (curpage == QUEUE_POS_PAGE(head)) + { + /* we only want to read as far as head */ + copysize = QUEUE_POS_OFFSET(head) - curoffset; + if (copysize < 0) + copysize = 0; /* just for safety */ + } + else + { + /* fetch all the rest of the page */ + copysize = QUEUE_PAGESIZE - curoffset; + } + memcpy(page_buffer.buf + curoffset, + AsyncCtl->shared->page_buffer[slotno] + curoffset, + copysize); + /* Release lock that we got from SimpleLruReadPage_ReadOnly() */ + LWLockRelease(AsyncCtlLock); + + /* + * Process messages up to the stop position, end of page, or an + * uncommitted message. + * + * Our stop position is what we found to be the head's position + * when we entered this function. It might have changed + * already. But if it has, we will receive (or have already + * received and queued) another signal and come here again. + * + * We are not holding AsyncQueueLock here! The queue can only + * extend beyond the head pointer (see above) and we leave our + * backend's pointer where it is so nobody will truncate or + * rewrite pages under us. Especially we don't want to hold a lock + * while sending the notifications to the frontend. + */ + reachedStop = asyncQueueProcessPageEntries(&pos, head, + page_buffer.buf); + } while (!reachedStop); + } + PG_CATCH(); + { + /* Update shared state */ + LWLockAcquire(AsyncQueueLock, LW_SHARED); + QUEUE_BACKEND_POS(MyBackendId) = pos; + advanceTail = QUEUE_POS_EQUAL(oldpos, QUEUE_TAIL); + LWLockRelease(AsyncQueueLock); + + /* If we were the laziest backend, try to advance the tail pointer */ + if (advanceTail) + asyncQueueAdvanceTail(); + + PG_RE_THROW(); + } + PG_END_TRY(); + + /* Update shared state */ + LWLockAcquire(AsyncQueueLock, LW_SHARED); + QUEUE_BACKEND_POS(MyBackendId) = pos; + advanceTail = QUEUE_POS_EQUAL(oldpos, QUEUE_TAIL); + LWLockRelease(AsyncQueueLock); + + /* If we were the laziest backend, try to advance the tail pointer */ + if (advanceTail) + asyncQueueAdvanceTail(); +} + +/* + * Fetch notifications from the shared queue, beginning at position current, + * and deliver relevant ones to my frontend. + * + * The current page must have been fetched into page_buffer from shared + * memory. (We could access the page right in shared memory, but that + * would imply holding the AsyncCtlLock throughout this routine.) + * + * We stop if we reach the "stop" position, or reach a notification from an + * uncommitted transaction, or reach the end of the page. + * + * The function returns true once we have reached the stop position or an + * uncommitted notification, and false if we have finished with the page. + * In other words: once it returns true there is no need to look further. + */ +static bool +asyncQueueProcessPageEntries(QueuePosition *current, + QueuePosition stop, + char *page_buffer) +{ + bool reachedStop = false; + bool reachedEndOfPage; + AsyncQueueEntry *qe; + + do + { + if (QUEUE_POS_EQUAL(*current, stop)) + break; + + qe = (AsyncQueueEntry *) (page_buffer + QUEUE_POS_OFFSET(*current)); + + /* + * Advance *current over this message, possibly to the next page. + * As noted in the comments for asyncQueueReadAllNotifications, we + * must do this before possibly failing while processing the message. + */ + reachedEndOfPage = asyncQueueAdvance(current, qe->length); + + /* Ignore messages destined for other databases */ + if (qe->dboid == MyDatabaseId) + { + if (TransactionIdDidCommit(qe->xid)) + { + /* qe->data is the null-terminated channel name */ + char *channel = qe->data; + + if (IsListeningOn(channel)) + { + /* payload follows channel name */ + char *payload = qe->data + strlen(channel) + 1; + + NotifyMyFrontEnd(channel, payload, qe->srcPid); + } + } + else if (TransactionIdDidAbort(qe->xid)) + { + /* + * If the source transaction aborted, we just ignore its + * notifications. + */ + } + else + { + /* + * The transaction has neither committed nor aborted so far, + * so we can't process its message yet. Break out of the loop. + */ + reachedStop = true; + break; + } + } + + /* Loop back if we're not at end of page */ + } while (!reachedEndOfPage); + + if (QUEUE_POS_EQUAL(*current, stop)) + reachedStop = true; + + return reachedStop; +} + +/* + * Advance the shared queue tail variable to the minimum of all the + * per-backend tail pointers. Truncate pg_notify space if possible. + */ +static void +asyncQueueAdvanceTail(void) +{ + QueuePosition min; + int i; + int oldtailpage; + int newtailpage; + int boundary; + + LWLockAcquire(AsyncQueueLock, LW_EXCLUSIVE); + min = QUEUE_HEAD; + for (i = 1; i <= MaxBackends; i++) + { + if (QUEUE_BACKEND_PID(i) != InvalidPid) + min = QUEUE_POS_MIN(min, QUEUE_BACKEND_POS(i)); + } + oldtailpage = QUEUE_POS_PAGE(QUEUE_TAIL); + QUEUE_TAIL = min; + LWLockRelease(AsyncQueueLock); + + /* + * We can truncate something if the global tail advanced across an SLRU + * segment boundary. + * + * XXX it might be better to truncate only once every several segments, + * to reduce the number of directory scans. + */ + newtailpage = QUEUE_POS_PAGE(min); + boundary = newtailpage - (newtailpage % SLRU_PAGES_PER_SEGMENT); + if (asyncQueuePagePrecedesLogically(oldtailpage, boundary)) + { + /* + * SimpleLruTruncate() will ask for AsyncCtlLock but will also + * release the lock again. + */ + SimpleLruTruncate(AsyncCtl, newtailpage); + } +} + /* * ProcessIncomingNotify * * Deal with arriving NOTIFYs from other backends. * This is called either directly from the PROCSIG_NOTIFY_INTERRUPT * signal handler, or the next time control reaches the outer idle loop. - * Scan pg_listener for arriving notifies, report them to my front end, - * and clear the notification field in pg_listener until next time. + * Scan the queue for arriving notifications and report them to my front + * end. * * NOTE: since we are outside any transaction, we must create our own. */ static void ProcessIncomingNotify(void) { - Relation lRel; - TupleDesc tdesc; - ScanKeyData key[1]; - HeapScanDesc scan; - HeapTuple lTuple, - rTuple; - Datum value[Natts_pg_listener]; - bool repl[Natts_pg_listener], - nulls[Natts_pg_listener]; bool catchup_enabled; + /* Do nothing if we aren't actively listening */ + if (listenChannels == NIL) + return; + /* Must prevent catchup interrupt while I am running */ catchup_enabled = DisableCatchupInterrupt(); @@ -974,62 +2088,13 @@ ProcessIncomingNotify(void) notifyInterruptOccurred = 0; + /* + * We must run asyncQueueReadAllNotifications inside a transaction, + * else bad things happen if it gets an error. + */ StartTransactionCommand(); - lRel = heap_open(ListenerRelationId, ExclusiveLock); - tdesc = RelationGetDescr(lRel); - - /* Scan only entries with my listenerPID */ - ScanKeyInit(&key[0], - Anum_pg_listener_listenerpid, - BTEqualStrategyNumber, F_INT4EQ, - Int32GetDatum(MyProcPid)); - scan = heap_beginscan(lRel, SnapshotNow, 1, key); - - /* Prepare data for rewriting 0 into notification field */ - memset(nulls, false, sizeof(nulls)); - memset(repl, false, sizeof(repl)); - repl[Anum_pg_listener_notification - 1] = true; - memset(value, 0, sizeof(value)); - value[Anum_pg_listener_notification - 1] = Int32GetDatum(0); - - while ((lTuple = heap_getnext(scan, ForwardScanDirection)) != NULL) - { - Form_pg_listener listener = (Form_pg_listener) GETSTRUCT(lTuple); - char *relname = NameStr(listener->relname); - int32 sourcePID = listener->notification; - - if (sourcePID != 0) - { - /* Notify the frontend */ - - if (Trace_notify) - elog(DEBUG1, "ProcessIncomingNotify: received %s from %d", - relname, (int) sourcePID); - - NotifyMyFrontEnd(relname, sourcePID); - - /* - * Rewrite the tuple with 0 in notification column. - */ - rTuple = heap_modify_tuple(lTuple, tdesc, value, nulls, repl); - simple_heap_update(lRel, &lTuple->t_self, rTuple); - -#ifdef NOT_USED /* currently there are no indexes */ - CatalogUpdateIndexes(lRel, rTuple); -#endif - } - } - heap_endscan(scan); - - /* - * We do NOT release the lock on pg_listener here; we need to hold it - * until end of transaction (which is about to happen, anyway) to ensure - * that other backends see our tuple updates when they look. Otherwise, a - * transaction started after this one might mistakenly think it doesn't - * need to send this backend a new NOTIFY. - */ - heap_close(lRel, NoLock); + asyncQueueReadAllNotifications(); CommitTransactionCommand(); @@ -1051,20 +2116,17 @@ ProcessIncomingNotify(void) * Send NOTIFY message to my front end. */ static void -NotifyMyFrontEnd(char *relname, int32 listenerPID) +NotifyMyFrontEnd(const char *channel, const char *payload, int32 srcPid) { if (whereToSendOutput == DestRemote) { StringInfoData buf; pq_beginmessage(&buf, 'A'); - pq_sendint(&buf, listenerPID, sizeof(int32)); - pq_sendstring(&buf, relname); + pq_sendint(&buf, srcPid, sizeof(int32)); + pq_sendstring(&buf, channel); if (PG_PROTOCOL_MAJOR(FrontendProtocol) >= 3) - { - /* XXX Add parameter string here later */ - pq_sendstring(&buf, ""); - } + pq_sendstring(&buf, payload); pq_endmessage(&buf); /* @@ -1074,20 +2136,51 @@ NotifyMyFrontEnd(char *relname, int32 listenerPID) */ } else - elog(INFO, "NOTIFY for %s", relname); + elog(INFO, "NOTIFY for \"%s\" payload \"%s\"", channel, payload); } -/* Does pendingNotifies include the given relname? */ +/* Does pendingNotifies include the given channel/payload? */ static bool -AsyncExistsPendingNotify(const char *relname) +AsyncExistsPendingNotify(const char *channel, const char *payload) { ListCell *p; + Notification *n; + + if (pendingNotifies == NIL) + return false; + + if (payload == NULL) + payload = ""; + + /*---------- + * We need to append new elements to the end of the list in order to keep + * the order. However, on the other hand we'd like to check the list + * backwards in order to make duplicate-elimination a tad faster when the + * same condition is signaled many times in a row. So as a compromise we + * check the tail element first which we can access directly. If this + * doesn't match, we check the whole list. + * + * As we are not checking our parents' lists, we can still get duplicates + * in combination with subtransactions, like in: + * + * begin; + * notify foo '1'; + * savepoint foo; + * notify foo '1'; + * commit; + *---------- + */ + n = (Notification *) llast(pendingNotifies); + if (strcmp(n->channel, channel) == 0 && + strcmp(n->payload, payload) == 0) + return true; foreach(p, pendingNotifies) { - const char *prelname = (const char *) lfirst(p); + n = (Notification *) lfirst(p); - if (strcmp(prelname, relname) == 0) + if (strcmp(n->channel, channel) == 0 && + strcmp(n->payload, payload) == 0) return true; } @@ -1108,21 +2201,3 @@ ClearPendingActionsAndNotifies(void) pendingActions = NIL; pendingNotifies = NIL; } - -/* - * 2PC processing routine for COMMIT PREPARED case. - * - * (We don't have to do anything for ROLLBACK PREPARED.) - */ -void -notify_twophase_postcommit(TransactionId xid, uint16 info, - void *recdata, uint32 len) -{ - /* - * Set up to issue the NOTIFY at the end of my own current transaction. - * (XXX this has some issues if my own transaction later rolls back, or if - * there is any significant delay before I commit. OK for now because we - * disallow COMMIT PREPARED inside a transaction block.) - */ - Async_Notify((char *) recdata); -} diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c index 271a7a2129b..371d1f245eb 100644 --- a/src/backend/nodes/copyfuncs.c +++ b/src/backend/nodes/copyfuncs.c @@ -15,7 +15,7 @@ * Portions Copyright (c) 1994, Regents of the University of California * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.461 2010/02/12 17:33:20 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.462 2010/02/16 22:34:43 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -2777,6 +2777,7 @@ _copyNotifyStmt(NotifyStmt *from) NotifyStmt *newnode = makeNode(NotifyStmt); COPY_STRING_FIELD(conditionname); + COPY_STRING_FIELD(payload); return newnode; } diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c index 001c2096b4e..7dfc1969f5d 100644 --- a/src/backend/nodes/equalfuncs.c +++ b/src/backend/nodes/equalfuncs.c @@ -22,7 +22,7 @@ * Portions Copyright (c) 1994, Regents of the University of California * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.382 2010/02/12 17:33:20 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.383 2010/02/16 22:34:43 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -1325,6 +1325,7 @@ static bool _equalNotifyStmt(NotifyStmt *a, NotifyStmt *b) { COMPARE_STRING_FIELD(conditionname); + COMPARE_STRING_FIELD(payload); return true; } diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c index 593fe397d3f..878e4b3b94c 100644 --- a/src/backend/nodes/outfuncs.c +++ b/src/backend/nodes/outfuncs.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/nodes/outfuncs.c,v 1.382 2010/02/12 17:33:20 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/nodes/outfuncs.c,v 1.383 2010/02/16 22:34:43 tgl Exp $ * * NOTES * Every node type that can appear in stored rules' parsetrees *must* @@ -1820,6 +1820,7 @@ _outNotifyStmt(StringInfo str, NotifyStmt *node) WRITE_NODE_TYPE("NOTIFY"); WRITE_STRING_FIELD(conditionname); + WRITE_STRING_FIELD(payload); } static void diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c index 35ba22203fe..f28191d2d00 100644 --- a/src/backend/nodes/readfuncs.c +++ b/src/backend/nodes/readfuncs.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/nodes/readfuncs.c,v 1.231 2010/02/12 17:33:20 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/nodes/readfuncs.c,v 1.232 2010/02/16 22:34:43 tgl Exp $ * * NOTES * Path and Plan nodes do not have any readfuncs support, because we @@ -231,6 +231,7 @@ _readNotifyStmt(void) READ_LOCALS(NotifyStmt); READ_STRING_FIELD(conditionname); + READ_STRING_FIELD(payload); READ_DONE(); } diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y index da70ee089c5..235a7001adf 100644 --- a/src/backend/parser/gram.y +++ b/src/backend/parser/gram.y @@ -11,7 +11,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.708 2010/02/12 17:33:20 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.709 2010/02/16 22:34:49 tgl Exp $ * * HISTORY * AUTHOR DATE MAJOR EVENT @@ -400,7 +400,7 @@ static TypeName *TableFuncTypeName(List *columns); %type Iconst SignedIconst %type Iconst_list -%type Sconst comment_text +%type Sconst comment_text notify_payload %type RoleId opt_granted_by opt_boolean ColId_or_Sconst %type var_list %type ColId ColLabel var_name type_function_name param_name @@ -6123,14 +6123,20 @@ DropRuleStmt: * *****************************************************************************/ -NotifyStmt: NOTIFY ColId +NotifyStmt: NOTIFY ColId notify_payload { NotifyStmt *n = makeNode(NotifyStmt); n->conditionname = $2; + n->payload = $3; $$ = (Node *)n; } ; +notify_payload: + ',' Sconst { $$ = $2; } + | /*EMPTY*/ { $$ = NULL; } + ; + ListenStmt: LISTEN ColId { ListenStmt *n = makeNode(ListenStmt); diff --git a/src/backend/storage/ipc/ipci.c b/src/backend/storage/ipc/ipci.c index 01a9fabc8c9..b4923d278a7 100644 --- a/src/backend/storage/ipc/ipci.c +++ b/src/backend/storage/ipc/ipci.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/storage/ipc/ipci.c,v 1.103 2010/01/15 09:19:03 heikki Exp $ + * $PostgreSQL: pgsql/src/backend/storage/ipc/ipci.c,v 1.104 2010/02/16 22:34:50 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -20,6 +20,7 @@ #include "access/nbtree.h" #include "access/subtrans.h" #include "access/twophase.h" +#include "commands/async.h" #include "miscadmin.h" #include "pgstat.h" #include "postmaster/autovacuum.h" @@ -122,6 +123,7 @@ CreateSharedMemoryAndSemaphores(bool makePrivate, int port) size = add_size(size, WalRcvShmemSize()); size = add_size(size, BTreeShmemSize()); size = add_size(size, SyncScanShmemSize()); + size = add_size(size, AsyncShmemSize()); #ifdef EXEC_BACKEND size = add_size(size, ShmemBackendArraySize()); #endif @@ -225,6 +227,7 @@ CreateSharedMemoryAndSemaphores(bool makePrivate, int port) */ BTreeShmemInit(); SyncScanShmemInit(); + AsyncShmemInit(); #ifdef EXEC_BACKEND diff --git a/src/backend/storage/lmgr/lwlock.c b/src/backend/storage/lmgr/lwlock.c index 4e635d1e8aa..7a6cab968bb 100644 --- a/src/backend/storage/lmgr/lwlock.c +++ b/src/backend/storage/lmgr/lwlock.c @@ -15,7 +15,7 @@ * Portions Copyright (c) 1994, Regents of the University of California * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/storage/lmgr/lwlock.c,v 1.55 2010/01/02 16:57:52 momjian Exp $ + * $PostgreSQL: pgsql/src/backend/storage/lmgr/lwlock.c,v 1.56 2010/02/16 22:34:50 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -24,6 +24,7 @@ #include "access/clog.h" #include "access/multixact.h" #include "access/subtrans.h" +#include "commands/async.h" #include "miscadmin.h" #include "pg_trace.h" #include "storage/ipc.h" @@ -174,6 +175,9 @@ NumLWLocks(void) /* multixact.c needs two SLRU areas */ numLocks += NUM_MXACTOFFSET_BUFFERS + NUM_MXACTMEMBER_BUFFERS; + /* async.c needs one per Async buffer */ + numLocks += NUM_ASYNC_BUFFERS; + /* * Add any requested by loadable modules; for backwards-compatibility * reasons, allocate at least NUM_USER_DEFINED_LWLOCKS of them even if diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c index 15d0808ad24..2ae15d5ce02 100644 --- a/src/backend/tcop/postgres.c +++ b/src/backend/tcop/postgres.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/tcop/postgres.c,v 1.589 2010/02/16 20:15:14 momjian Exp $ + * $PostgreSQL: pgsql/src/backend/tcop/postgres.c,v 1.590 2010/02/16 22:34:50 tgl Exp $ * * NOTES * this is the "main" module of the postgres backend and @@ -3779,7 +3779,8 @@ PostgresMain(int argc, char *argv[], const char *username) * collector, and to update the PS stats display. We avoid doing * those every time through the message loop because it'd slow down * processing of batched messages, and because we don't want to report - * uncommitted updates (that confuses autovacuum). + * uncommitted updates (that confuses autovacuum). The notification + * processor wants a call too, if we are not in a transaction block. */ if (send_ready_for_query) { @@ -3795,6 +3796,7 @@ PostgresMain(int argc, char *argv[], const char *username) } else { + ProcessCompletedNotifies(); pgstat_report_stat(false); set_ps_display("idle", false); diff --git a/src/backend/tcop/utility.c b/src/backend/tcop/utility.c index 4879970632a..07f4d0c57ad 100644 --- a/src/backend/tcop/utility.c +++ b/src/backend/tcop/utility.c @@ -10,7 +10,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/tcop/utility.c,v 1.332 2010/02/14 18:42:15 rhaas Exp $ + * $PostgreSQL: pgsql/src/backend/tcop/utility.c,v 1.333 2010/02/16 22:34:50 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -926,17 +926,17 @@ standard_ProcessUtility(Node *parsetree, case T_NotifyStmt: { NotifyStmt *stmt = (NotifyStmt *) parsetree; - PreventCommandDuringRecovery(); - Async_Notify(stmt->conditionname); + PreventCommandDuringRecovery(); + Async_Notify(stmt->conditionname, stmt->payload); } break; case T_ListenStmt: { ListenStmt *stmt = (ListenStmt *) parsetree; - PreventCommandDuringRecovery(); + PreventCommandDuringRecovery(); CheckRestrictedOperation("LISTEN"); Async_Listen(stmt->conditionname); } @@ -945,8 +945,8 @@ standard_ProcessUtility(Node *parsetree, case T_UnlistenStmt: { UnlistenStmt *stmt = (UnlistenStmt *) parsetree; - PreventCommandDuringRecovery(); + PreventCommandDuringRecovery(); CheckRestrictedOperation("UNLISTEN"); if (stmt->conditionname) Async_Unlisten(stmt->conditionname); @@ -1105,8 +1105,8 @@ standard_ProcessUtility(Node *parsetree, case T_ReindexStmt: { ReindexStmt *stmt = (ReindexStmt *) parsetree; - PreventCommandDuringRecovery(); + PreventCommandDuringRecovery(); switch (stmt->kind) { case OBJECT_INDEX: diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c index b2127a3129a..294c7c904bb 100644 --- a/src/backend/utils/adt/ruleutils.c +++ b/src/backend/utils/adt/ruleutils.c @@ -9,7 +9,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.322 2010/02/14 18:42:16 rhaas Exp $ + * $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.323 2010/02/16 22:34:50 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -3465,6 +3465,11 @@ get_utility_query_def(Query *query, deparse_context *context) 0, PRETTYINDENT_STD, 1); appendStringInfo(buf, "NOTIFY %s", quote_identifier(stmt->conditionname)); + if (stmt->payload) + { + appendStringInfoString(buf, ", "); + simple_quote_literal(buf, stmt->payload); + } } else { diff --git a/src/bin/initdb/initdb.c b/src/bin/initdb/initdb.c index 06df8f6af8d..733d8ef74d2 100644 --- a/src/bin/initdb/initdb.c +++ b/src/bin/initdb/initdb.c @@ -42,7 +42,7 @@ * Portions Copyright (c) 1994, Regents of the University of California * Portions taken from FreeBSD. * - * $PostgreSQL: pgsql/src/bin/initdb/initdb.c,v 1.184 2010/01/26 16:18:12 tgl Exp $ + * $PostgreSQL: pgsql/src/bin/initdb/initdb.c,v 1.185 2010/02/16 22:34:50 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -2458,6 +2458,7 @@ main(int argc, char *argv[]) "pg_xlog", "pg_xlog/archive_status", "pg_clog", + "pg_notify", "pg_subtrans", "pg_twophase", "pg_multixact/members", diff --git a/src/bin/psql/common.c b/src/bin/psql/common.c index 8422bb76ab5..9661f0cd803 100644 --- a/src/bin/psql/common.c +++ b/src/bin/psql/common.c @@ -3,7 +3,7 @@ * * Copyright (c) 2000-2010, PostgreSQL Global Development Group * - * $PostgreSQL: pgsql/src/bin/psql/common.c,v 1.143 2010/01/02 16:57:59 momjian Exp $ + * $PostgreSQL: pgsql/src/bin/psql/common.c,v 1.144 2010/02/16 22:34:50 tgl Exp $ */ #include "postgres_fe.h" #include "common.h" @@ -555,8 +555,13 @@ PrintNotifications(void) while ((notify = PQnotifies(pset.db))) { - fprintf(pset.queryFout, _("Asynchronous notification \"%s\" received from server process with PID %d.\n"), - notify->relname, notify->be_pid); + /* for backward compatibility, only show payload if nonempty */ + if (notify->extra[0]) + fprintf(pset.queryFout, _("Asynchronous notification \"%s\" with payload \"%s\" received from server process with PID %d.\n"), + notify->relname, notify->extra, notify->be_pid); + else + fprintf(pset.queryFout, _("Asynchronous notification \"%s\" received from server process with PID %d.\n"), + notify->relname, notify->be_pid); fflush(pset.queryFout); PQfreemem(notify); } diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c index 19b9b1f3ef5..0b10472c12e 100644 --- a/src/bin/psql/tab-complete.c +++ b/src/bin/psql/tab-complete.c @@ -3,7 +3,7 @@ * * Copyright (c) 2000-2010, PostgreSQL Global Development Group * - * $PostgreSQL: pgsql/src/bin/psql/tab-complete.c,v 1.193 2010/02/15 02:55:01 itagaki Exp $ + * $PostgreSQL: pgsql/src/bin/psql/tab-complete.c,v 1.194 2010/02/16 22:34:50 tgl Exp $ */ /*---------------------------------------------------------------------- @@ -1864,7 +1864,7 @@ psql_completion(char *text, int start, int end) /* NOTIFY */ else if (pg_strcasecmp(prev_wd, "NOTIFY") == 0) - COMPLETE_WITH_QUERY("SELECT pg_catalog.quote_ident(relname) FROM pg_catalog.pg_listener WHERE substring(pg_catalog.quote_ident(relname),1,%d)='%s'"); + COMPLETE_WITH_QUERY("SELECT pg_catalog.quote_ident(channel) FROM pg_catalog.pg_listening_channels() AS channel WHERE substring(pg_catalog.quote_ident(channel),1,%d)='%s'"); /* OPTIONS */ else if (pg_strcasecmp(prev_wd, "OPTIONS") == 0) @@ -2105,7 +2105,7 @@ psql_completion(char *text, int start, int end) /* UNLISTEN */ else if (pg_strcasecmp(prev_wd, "UNLISTEN") == 0) - COMPLETE_WITH_QUERY("SELECT pg_catalog.quote_ident(relname) FROM pg_catalog.pg_listener WHERE substring(pg_catalog.quote_ident(relname),1,%d)='%s' UNION SELECT '*'"); + COMPLETE_WITH_QUERY("SELECT pg_catalog.quote_ident(channel) FROM pg_catalog.pg_listening_channels() AS channel WHERE substring(pg_catalog.quote_ident(channel),1,%d)='%s' UNION SELECT '*'"); /* UPDATE */ /* If prev. word is UPDATE suggest a list of tables */ diff --git a/src/include/access/slru.h b/src/include/access/slru.h index 8e820ae72dd..4cc40ba5f70 100644 --- a/src/include/access/slru.h +++ b/src/include/access/slru.h @@ -6,7 +6,7 @@ * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $PostgreSQL: pgsql/src/include/access/slru.h,v 1.25 2010/01/02 16:58:00 momjian Exp $ + * $PostgreSQL: pgsql/src/include/access/slru.h,v 1.26 2010/02/16 22:34:50 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -17,6 +17,25 @@ #include "storage/lwlock.h" +/* + * Define SLRU segment size. A page is the same BLCKSZ as is used everywhere + * else in Postgres. The segment size can be chosen somewhat arbitrarily; + * we make it 32 pages by default, or 256Kb, i.e. 1M transactions for CLOG + * or 64K transactions for SUBTRANS. + * + * Note: because TransactionIds are 32 bits and wrap around at 0xFFFFFFFF, + * page numbering also wraps around at 0xFFFFFFFF/xxxx_XACTS_PER_PAGE (where + * xxxx is CLOG or SUBTRANS, respectively), and segment numbering at + * 0xFFFFFFFF/xxxx_XACTS_PER_PAGE/SLRU_PAGES_PER_SEGMENT. We need + * take no explicit notice of that fact in slru.c, except when comparing + * segment and page numbers in SimpleLruTruncate (see PagePrecedes()). + * + * Note: slru.c currently assumes that segment file names will be four hex + * digits. This sets a lower bound on the segment size (64K transactions + * for 32-bit TransactionIds). + */ +#define SLRU_PAGES_PER_SEGMENT 32 + /* * Page status codes. Note that these do not include the "dirty" bit. * page_dirty can be TRUE only in the VALID or WRITE_IN_PROGRESS states; @@ -55,8 +74,8 @@ typedef struct SlruSharedData /* * Optional array of WAL flush LSNs associated with entries in the SLRU * pages. If not zero/NULL, we must flush WAL before writing pages (true - * for pg_clog, false for multixact and pg_subtrans). group_lsn[] has - * lsn_groups_per_page entries per buffer slot, each containing the + * for pg_clog, false for multixact, pg_subtrans, pg_notify). group_lsn[] + * has lsn_groups_per_page entries per buffer slot, each containing the * highest LSN known for a contiguous group of SLRU entries on that slot's * page. */ @@ -94,7 +113,7 @@ typedef struct SlruCtlData /* * This flag tells whether to fsync writes (true for pg_clog and multixact - * stuff, false for pg_subtrans). + * stuff, false for pg_subtrans and pg_notify). */ bool do_fsync; diff --git a/src/include/access/twophase_rmgr.h b/src/include/access/twophase_rmgr.h index a42d7745205..1d4d1cb2217 100644 --- a/src/include/access/twophase_rmgr.h +++ b/src/include/access/twophase_rmgr.h @@ -7,7 +7,7 @@ * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $PostgreSQL: pgsql/src/include/access/twophase_rmgr.h,v 1.11 2010/01/02 16:58:00 momjian Exp $ + * $PostgreSQL: pgsql/src/include/access/twophase_rmgr.h,v 1.12 2010/02/16 22:34:50 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -23,9 +23,8 @@ typedef uint8 TwoPhaseRmgrId; */ #define TWOPHASE_RM_END_ID 0 #define TWOPHASE_RM_LOCK_ID 1 -#define TWOPHASE_RM_NOTIFY_ID 2 -#define TWOPHASE_RM_PGSTAT_ID 3 -#define TWOPHASE_RM_MULTIXACT_ID 4 +#define TWOPHASE_RM_PGSTAT_ID 2 +#define TWOPHASE_RM_MULTIXACT_ID 3 #define TWOPHASE_RM_MAX_ID TWOPHASE_RM_MULTIXACT_ID extern const TwoPhaseCallback twophase_recover_callbacks[]; diff --git a/src/include/catalog/catversion.h b/src/include/catalog/catversion.h index 9a1d19380c7..2d63232b9b5 100644 --- a/src/include/catalog/catversion.h +++ b/src/include/catalog/catversion.h @@ -37,7 +37,7 @@ * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $PostgreSQL: pgsql/src/include/catalog/catversion.h,v 1.584 2010/02/12 17:33:20 tgl Exp $ + * $PostgreSQL: pgsql/src/include/catalog/catversion.h,v 1.585 2010/02/16 22:34:54 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -53,6 +53,6 @@ */ /* yyyymmddN */ -#define CATALOG_VERSION_NO 201002121 +#define CATALOG_VERSION_NO 201002161 #endif diff --git a/src/include/catalog/pg_listener.h b/src/include/catalog/pg_listener.h deleted file mode 100644 index 4d1a77d6602..00000000000 --- a/src/include/catalog/pg_listener.h +++ /dev/null @@ -1,59 +0,0 @@ -/*------------------------------------------------------------------------- - * - * pg_listener.h - * Asynchronous notification - * - * - * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group - * Portions Copyright (c) 1994, Regents of the University of California - * - * $PostgreSQL: pgsql/src/include/catalog/pg_listener.h,v 1.28 2010/01/05 01:06:56 tgl Exp $ - * - * NOTES - * the genbki.pl script reads this file and generates .bki - * information from the DATA() statements. - * - *------------------------------------------------------------------------- - */ -#ifndef PG_LISTENER_H -#define PG_LISTENER_H - -#include "catalog/genbki.h" - -/* ---------------------------------------------------------------- - * pg_listener definition. - * - * cpp turns this into typedef struct FormData_pg_listener - * ---------------------------------------------------------------- - */ -#define ListenerRelationId 2614 - -CATALOG(pg_listener,2614) BKI_WITHOUT_OIDS -{ - NameData relname; - int4 listenerpid; - int4 notification; -} FormData_pg_listener; - -/* ---------------- - * Form_pg_listener corresponds to a pointer to a tuple with - * the format of pg_listener relation. - * ---------------- - */ -typedef FormData_pg_listener *Form_pg_listener; - -/* ---------------- - * compiler constants for pg_listener - * ---------------- - */ -#define Natts_pg_listener 3 -#define Anum_pg_listener_relname 1 -#define Anum_pg_listener_listenerpid 2 -#define Anum_pg_listener_notification 3 - -/* ---------------- - * initial contents of pg_listener are NOTHING. - * ---------------- - */ - -#endif /* PG_LISTENER_H */ diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h index 727b13e264c..1c87a94a0de 100644 --- a/src/include/catalog/pg_proc.h +++ b/src/include/catalog/pg_proc.h @@ -7,7 +7,7 @@ * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $PostgreSQL: pgsql/src/include/catalog/pg_proc.h,v 1.568 2010/02/07 20:48:11 tgl Exp $ + * $PostgreSQL: pgsql/src/include/catalog/pg_proc.h,v 1.569 2010/02/16 22:34:56 tgl Exp $ * * NOTES * The script catalog/genbki.pl reads this file and generates .bki @@ -4131,8 +4131,12 @@ DATA(insert OID = 2599 ( pg_timezone_abbrevs PGNSP PGUID 12 1 1000 0 f f f t t DESCR("get the available time zone abbreviations"); DATA(insert OID = 2856 ( pg_timezone_names PGNSP PGUID 12 1 1000 0 f f f t t s 0 0 2249 "" "{25,25,1186,16}" "{o,o,o,o}" "{name,abbrev,utc_offset,is_dst}" _null_ pg_timezone_names _null_ _null_ _null_ )); DESCR("get the available time zone names"); -DATA(insert OID = 2730 ( pg_get_triggerdef PGNSP PGUID 12 1 0 0 f f f t f s 2 0 25 "26 16" _null_ _null_ _null_ _null_ pg_get_triggerdef_ext _null_ _null_ _null_ )); +DATA(insert OID = 2730 ( pg_get_triggerdef PGNSP PGUID 12 1 0 0 f f f t f s 2 0 25 "26 16" _null_ _null_ _null_ _null_ pg_get_triggerdef_ext _null_ _null_ _null_ )); DESCR("trigger description with pretty-print option"); +DATA(insert OID = 3035 ( pg_listening_channels PGNSP PGUID 12 1 10 0 f f f t t s 0 0 25 "" _null_ _null_ _null_ _null_ pg_listening_channels _null_ _null_ _null_ )); +DESCR("get the channels that the current backend listens to"); +DATA(insert OID = 3036 ( pg_notify PGNSP PGUID 12 1 0 0 f f f f f v 2 0 2278 "25 25" _null_ _null_ _null_ _null_ pg_notify _null_ _null_ _null_ )); +DESCR("send a notification event"); /* non-persistent series generator */ DATA(insert OID = 1066 ( generate_series PGNSP PGUID 12 1 1000 0 f f f t t i 3 0 23 "23 23 23" _null_ _null_ _null_ _null_ generate_series_step_int4 _null_ _null_ _null_ )); diff --git a/src/include/commands/async.h b/src/include/commands/async.h index 5c9e8ab8906..a9e4d42853d 100644 --- a/src/include/commands/async.h +++ b/src/include/commands/async.h @@ -6,28 +6,44 @@ * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $PostgreSQL: pgsql/src/include/commands/async.h,v 1.39 2010/01/02 16:58:03 momjian Exp $ + * $PostgreSQL: pgsql/src/include/commands/async.h,v 1.40 2010/02/16 22:34:57 tgl Exp $ * *------------------------------------------------------------------------- */ #ifndef ASYNC_H #define ASYNC_H +#include "fmgr.h" + +/* + * The number of SLRU page buffers we use for the notification queue. + */ +#define NUM_ASYNC_BUFFERS 8 + extern bool Trace_notify; +extern Size AsyncShmemSize(void); +extern void AsyncShmemInit(void); + /* notify-related SQL statements */ -extern void Async_Notify(const char *relname); -extern void Async_Listen(const char *relname); -extern void Async_Unlisten(const char *relname); +extern void Async_Notify(const char *channel, const char *payload); +extern void Async_Listen(const char *channel); +extern void Async_Unlisten(const char *channel); extern void Async_UnlistenAll(void); +/* notify-related SQL functions */ +extern Datum pg_listening_channels(PG_FUNCTION_ARGS); +extern Datum pg_notify(PG_FUNCTION_ARGS); + /* perform (or cancel) outbound notify processing at transaction commit */ +extern void PreCommit_Notify(void); extern void AtCommit_Notify(void); extern void AtAbort_Notify(void); extern void AtSubStart_Notify(void); extern void AtSubCommit_Notify(void); extern void AtSubAbort_Notify(void); extern void AtPrepare_Notify(void); +extern void ProcessCompletedNotifies(void); /* signal handler for inbound notifies (PROCSIG_NOTIFY_INTERRUPT) */ extern void HandleNotifyInterrupt(void); @@ -40,7 +56,4 @@ extern void HandleNotifyInterrupt(void); extern void EnableNotifyInterrupt(void); extern bool DisableNotifyInterrupt(void); -extern void notify_twophase_postcommit(TransactionId xid, uint16 info, - void *recdata, uint32 len); - #endif /* ASYNC_H */ diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h index 0c3aecfa6e6..ca229c8e23d 100644 --- a/src/include/nodes/parsenodes.h +++ b/src/include/nodes/parsenodes.h @@ -13,7 +13,7 @@ * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $PostgreSQL: pgsql/src/include/nodes/parsenodes.h,v 1.429 2010/02/12 17:33:20 tgl Exp $ + * $PostgreSQL: pgsql/src/include/nodes/parsenodes.h,v 1.430 2010/02/16 22:34:57 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -2097,6 +2097,7 @@ typedef struct NotifyStmt { NodeTag type; char *conditionname; /* condition name to notify */ + char *payload; /* the payload string, or NULL if none */ } NotifyStmt; /* ---------------------- diff --git a/src/include/storage/lwlock.h b/src/include/storage/lwlock.h index f0beb20a24b..2ace9585009 100644 --- a/src/include/storage/lwlock.h +++ b/src/include/storage/lwlock.h @@ -7,7 +7,7 @@ * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $PostgreSQL: pgsql/src/include/storage/lwlock.h,v 1.44 2010/02/07 20:48:13 tgl Exp $ + * $PostgreSQL: pgsql/src/include/storage/lwlock.h,v 1.45 2010/02/16 22:34:57 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -68,6 +68,8 @@ typedef enum LWLockId AutovacuumScheduleLock, SyncScanLock, RelationMappingLock, + AsyncCtlLock, + AsyncQueueLock, /* Individual lock IDs end here */ FirstBufMappingLock, FirstLockMgrLock = FirstBufMappingLock + NUM_BUFFER_PARTITIONS, diff --git a/src/test/regress/expected/guc.out b/src/test/regress/expected/guc.out index 83cacbdd209..59c120c99a3 100644 --- a/src/test/regress/expected/guc.out +++ b/src/test/regress/expected/guc.out @@ -532,9 +532,9 @@ CREATE TEMP TABLE tmp_foo (data text) ON COMMIT DELETE ROWS; CREATE ROLE temp_reset_user; SET SESSION AUTHORIZATION temp_reset_user; -- look changes -SELECT relname FROM pg_listener; - relname ------------ +SELECT pg_listening_channels(); + pg_listening_channels +----------------------- foo_event (1 row) @@ -571,9 +571,9 @@ SELECT current_user = 'temp_reset_user'; -- discard everything DISCARD ALL; -- look again -SELECT relname FROM pg_listener; - relname ---------- +SELECT pg_listening_channels(); + pg_listening_channels +----------------------- (0 rows) SELECT name FROM pg_prepared_statements; diff --git a/src/test/regress/expected/sanity_check.out b/src/test/regress/expected/sanity_check.out index 4dc59d9b5de..1d9e1100448 100644 --- a/src/test/regress/expected/sanity_check.out +++ b/src/test/regress/expected/sanity_check.out @@ -107,7 +107,6 @@ SELECT relname, relhasindex pg_language | t pg_largeobject | t pg_largeobject_metadata | t - pg_listener | f pg_namespace | t pg_opclass | t pg_operator | t @@ -154,7 +153,7 @@ SELECT relname, relhasindex timetz_tbl | f tinterval_tbl | f varchar_tbl | f -(143 rows) +(142 rows) -- -- another sanity check: every system catalog that has OIDs should have diff --git a/src/test/regress/sql/guc.sql b/src/test/regress/sql/guc.sql index a7b795af47d..21ed86f26ba 100644 --- a/src/test/regress/sql/guc.sql +++ b/src/test/regress/sql/guc.sql @@ -165,7 +165,7 @@ CREATE TEMP TABLE tmp_foo (data text) ON COMMIT DELETE ROWS; CREATE ROLE temp_reset_user; SET SESSION AUTHORIZATION temp_reset_user; -- look changes -SELECT relname FROM pg_listener; +SELECT pg_listening_channels(); SELECT name FROM pg_prepared_statements; SELECT name FROM pg_cursors; SHOW vacuum_cost_delay; @@ -174,7 +174,7 @@ SELECT current_user = 'temp_reset_user'; -- discard everything DISCARD ALL; -- look again -SELECT relname FROM pg_listener; +SELECT pg_listening_channels(); SELECT name FROM pg_prepared_statements; SELECT name FROM pg_cursors; SHOW vacuum_cost_delay;