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Implement pipeline mode in libpq

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Pipeline mode in libpq lets an application avoid the Sync messages in
the FE/BE protocol that are implicit in the old libpq API after each
query.  The application can then insert Sync at its leisure with a new
libpq function PQpipelineSync.  This can lead to substantial reductions
in query latency.

Co-authored-by: Craig Ringer <craig.ringer@enterprisedb.com>
Co-authored-by: Matthieu Garrigues <matthieu.garrigues@gmail.com>
Co-authored-by: Álvaro Herrera <alvherre@alvh.no-ip.org>
Reviewed-by: Andres Freund <andres@anarazel.de>
Reviewed-by: Aya Iwata <iwata.aya@jp.fujitsu.com>
Reviewed-by: Daniel Vérité <daniel@manitou-mail.org>
Reviewed-by: David G. Johnston <david.g.johnston@gmail.com>
Reviewed-by: Justin Pryzby <pryzby@telsasoft.com>
Reviewed-by: Kirk Jamison <k.jamison@fujitsu.com>
Reviewed-by: Michael Paquier <michael.paquier@gmail.com>
Reviewed-by: Nikhil Sontakke <nikhils@2ndquadrant.com>
Reviewed-by: Vaishnavi Prabakaran <VaishnaviP@fast.au.fujitsu.com>
Reviewed-by: Zhihong Yu <zyu@yugabyte.com>

Discussion: https://postgr.es/m/CAMsr+YFUjJytRyV4J-16bEoiZyH=4nj+sQ7JP9ajwz=B4dMMZw@mail.gmail.com
Discussion: https://postgr.es/m/CAJkzx4T5E-2cQe3dtv2R78dYFvz+in8PY7A8MArvLhs_pg75gg@mail.gmail.com
This commit is contained in:
Alvaro Herrera
2021-03-15 18:13:42 -03:00
parent 146cb3889c
commit acb7e4eb6b
18 changed files with 2706 additions and 113 deletions
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60
src/interfaces/libpq/libpq-int.h
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@@ -217,21 +217,16 @@ typedef enum
{
PGASYNC_IDLE, /* nothing's happening, dude */
PGASYNC_BUSY, /* query in progress */
PGASYNC_READY, /* result ready for PQgetResult */
PGASYNC_READY, /* query done, waiting for client to fetch
* result */
PGASYNC_READY_MORE, /* query done, waiting for client to fetch
* result, more results expected from this
* query */
PGASYNC_COPY_IN, /* Copy In data transfer in progress */
PGASYNC_COPY_OUT, /* Copy Out data transfer in progress */
PGASYNC_COPY_BOTH /* Copy In/Out data transfer in progress */
} PGAsyncStatusType;
/* PGQueryClass tracks which query protocol we are now executing */
typedef enum
{
PGQUERY_SIMPLE, /* simple Query protocol (PQexec) */
PGQUERY_EXTENDED, /* full Extended protocol (PQexecParams) */
PGQUERY_PREPARE, /* Parse only (PQprepare) */
PGQUERY_DESCRIBE /* Describe Statement or Portal */
} PGQueryClass;
/* Target server type (decoded value of target_session_attrs) */
typedef enum
{
@@ -305,6 +300,29 @@ typedef enum pg_conn_host_type
CHT_UNIX_SOCKET
} pg_conn_host_type;
/*
* PGQueryClass tracks which query protocol is in use for each command queue
* entry, or special operation in execution
*/
typedef enum
{
PGQUERY_SIMPLE, /* simple Query protocol (PQexec) */
PGQUERY_EXTENDED, /* full Extended protocol (PQexecParams) */
PGQUERY_PREPARE, /* Parse only (PQprepare) */
PGQUERY_DESCRIBE, /* Describe Statement or Portal */
PGQUERY_SYNC /* Sync (at end of a pipeline) */
} PGQueryClass;
/*
* An entry in the pending command queue.
*/
typedef struct PGcmdQueueEntry
{
PGQueryClass queryclass; /* Query type */
char *query; /* SQL command, or NULL if none/unknown/OOM */
struct PGcmdQueueEntry *next; /* list link */
} PGcmdQueueEntry;
/*
* pg_conn_host stores all information about each of possibly several hosts
* mentioned in the connection string. Most fields are derived by splitting
@@ -389,12 +407,11 @@ struct pg_conn
ConnStatusType status;
PGAsyncStatusType asyncStatus;
PGTransactionStatusType xactStatus; /* never changes to ACTIVE */
PGQueryClass queryclass;
char *last_query; /* last SQL command, or NULL if unknown */
char last_sqlstate[6]; /* last reported SQLSTATE */
bool options_valid; /* true if OK to attempt connection */
bool nonblocking; /* whether this connection is using nonblock
* sending semantics */
PGpipelineStatus pipelineStatus; /* status of pipeline mode */
bool singleRowMode; /* return current query result row-by-row? */
char copy_is_binary; /* 1 = copy binary, 0 = copy text */
int copy_already_done; /* # bytes already returned in COPY OUT */
@@ -407,6 +424,19 @@ struct pg_conn
pg_conn_host *connhost; /* details about each named host */
char *connip; /* IP address for current network connection */
/*
* The pending command queue as a singly-linked list. Head is the command
* currently in execution, tail is where new commands are added.
*/
PGcmdQueueEntry *cmd_queue_head;
PGcmdQueueEntry *cmd_queue_tail;
/*
* To save malloc traffic, we don't free entries right away; instead we
* save them in this list for possible reuse.
*/
PGcmdQueueEntry *cmd_queue_recycle;
/* Connection data */
pgsocket sock; /* FD for socket, PGINVALID_SOCKET if
* unconnected */
@@ -622,6 +652,7 @@ extern void pqSaveMessageField(PGresult *res, char code,
extern void pqSaveParameterStatus(PGconn *conn, const char *name,
const char *value);
extern int pqRowProcessor(PGconn *conn, const char **errmsgp);
extern void pqCommandQueueAdvance(PGconn *conn);
extern int PQsendQueryContinue(PGconn *conn, const char *query);
/* === in fe-protocol3.c === */
@@ -795,6 +826,11 @@ extern ssize_t pg_GSS_read(PGconn *conn, void *ptr, size_t len);
*/
#define pqIsnonblocking(conn) ((conn)->nonblocking)
/*
* Connection's outbuffer threshold, for pipeline mode.
*/
#define OUTBUFFER_THRESHOLD 65536
#ifdef ENABLE_NLS
extern char *libpq_gettext(const char *msgid) pg_attribute_format_arg(1);
extern char *libpq_ngettext(const char *msgid, const char *msgid_plural, unsigned long n) pg_attribute_format_arg(1) pg_attribute_format_arg(2);