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Refactor to split Apply and Tablesync Workers code.

Browse Source 
Both apply and tablesync workers were using ApplyWorkerMain() as entry
point. As the name implies, ApplyWorkerMain() should be considered as
the main function for apply workers. Tablesync worker's path was hidden
and does not have enough in common to share the same main function with
apply worker.

Also, most of the code shared by both worker types is already combined
in LogicalRepApplyLoop(). There is no need to combine the rest in
ApplyWorkerMain() anymore.

This patch introduces TablesyncWorkerMain() as a new entry point for
tablesync workers. This aims to increase code readability and would help
with future improvements like the reuse of tablesync workers in the
initial synchronization.

Author: Melih Mutlu based on suggestions by Melanie Plageman
Reviewed-by: Peter Smith, Kuroda Hayato, Amit Kapila
Discussion: http://postgr.es/m/CAGPVpCTq=rUDd4JUdaRc1XUWf4BrH2gdSNf3rtOMUGj9rPpfzQ@mail.gmail.com
This commit is contained in:
Amit Kapila 2023-08-03 08:59:50 +05:30
parent 0125c4e21d
commit 02c1b64fb1
7 changed files with 304 additions and 229 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
src/backend/postmaster/bgworker.c
View File

@ -131,6 +131,9 @@ static const struct
},
{
"ParallelApplyWorkerMain", ParallelApplyWorkerMain
},
{
"TablesyncWorkerMain", TablesyncWorkerMain
}
};

2
src/backend/replication/logical/applyparallelworker.c
View File

@ -942,7 +942,7 @@ ParallelApplyWorkerMain(Datum main_arg)
MyLogicalRepWorker->last_send_time = MyLogicalRepWorker->last_recv_time =
MyLogicalRepWorker->reply_time = 0;
InitializeApplyWorker();
InitializeLogRepWorker();
InitializingApplyWorker = false;

34
src/backend/replication/logical/launcher.c
View File

@ -459,24 +459,30 @@ retry:
snprintf(bgw.bgw_library_name, MAXPGPATH, "postgres");
if (is_parallel_apply_worker)
{
snprintf(bgw.bgw_function_name, BGW_MAXLEN, "ParallelApplyWorkerMain");
else
snprintf(bgw.bgw_function_name, BGW_MAXLEN, "ApplyWorkerMain");
if (OidIsValid(relid))
snprintf(bgw.bgw_name, BGW_MAXLEN,
"logical replication worker for subscription %u sync %u", subid, relid);
else if (is_parallel_apply_worker)
snprintf(bgw.bgw_name, BGW_MAXLEN,
"logical replication parallel apply worker for subscription %u", subid);
else
snprintf(bgw.bgw_name, BGW_MAXLEN,
"logical replication apply worker for subscription %u", subid);
if (is_parallel_apply_worker)
"logical replication parallel apply worker for subscription %u",
subid);
snprintf(bgw.bgw_type, BGW_MAXLEN, "logical replication parallel worker");
}
else if (OidIsValid(relid))
{
snprintf(bgw.bgw_function_name, BGW_MAXLEN, "TablesyncWorkerMain");
snprintf(bgw.bgw_name, BGW_MAXLEN,
"logical replication tablesync worker for subscription %u sync %u",
subid,
relid);
snprintf(bgw.bgw_type, BGW_MAXLEN, "logical replication tablesync worker");
}
else
snprintf(bgw.bgw_type, BGW_MAXLEN, "logical replication worker");
{
snprintf(bgw.bgw_function_name, BGW_MAXLEN, "ApplyWorkerMain");
snprintf(bgw.bgw_name, BGW_MAXLEN,
"logical replication apply worker for subscription %u",
subid);
snprintf(bgw.bgw_type, BGW_MAXLEN, "logical replication apply worker");
}
bgw.bgw_restart_time = BGW_NEVER_RESTART;
bgw.bgw_notify_pid = MyProcPid;

91
src/backend/replication/logical/tablesync.c
View File

@ -106,6 +106,7 @@
#include "pgstat.h"
#include "replication/logicallauncher.h"
#include "replication/logicalrelation.h"
#include "replication/logicalworker.h"
#include "replication/walreceiver.h"
#include "replication/worker_internal.h"
#include "replication/slot.h"
@ -1241,7 +1242,7 @@ ReplicationSlotNameForTablesync(Oid suboid, Oid relid,
*
* The returned slot name is palloc'ed in current memory context.
*/
char *
static char *
LogicalRepSyncTableStart(XLogRecPtr *origin_startpos)
{
char *slotname;
@ -1584,6 +1585,94 @@ FetchTableStates(bool *started_tx)
return has_subrels;
}
/*
* Execute the initial sync with error handling. Disable the subscription,
* if it's required.
*
* Allocate the slot name in long-lived context on return. Note that we don't
* handle FATAL errors which are probably because of system resource error and
* are not repeatable.
*/
static void
start_table_sync(XLogRecPtr *origin_startpos, char **slotname)
{
char *sync_slotname = NULL;
Assert(am_tablesync_worker());
PG_TRY();
{
/* Call initial sync. */
sync_slotname = LogicalRepSyncTableStart(origin_startpos);
}
PG_CATCH();
{
if (MySubscription->disableonerr)
DisableSubscriptionAndExit();
else
{
/*
* Report the worker failed during table synchronization. Abort
* the current transaction so that the stats message is sent in an
* idle state.
*/
AbortOutOfAnyTransaction();
pgstat_report_subscription_error(MySubscription->oid, false);
PG_RE_THROW();
}
}
PG_END_TRY();
/* allocate slot name in long-lived context */
*slotname = MemoryContextStrdup(ApplyContext, sync_slotname);
pfree(sync_slotname);
}
/*
* Runs the tablesync worker.
*
* It starts syncing tables. After a successful sync, sets streaming options
* and starts streaming to catchup with apply worker.
*/
static void
run_tablesync_worker()
{
char originname[NAMEDATALEN];
XLogRecPtr origin_startpos = InvalidXLogRecPtr;
char *slotname = NULL;
WalRcvStreamOptions options;
start_table_sync(&origin_startpos, &slotname);
ReplicationOriginNameForLogicalRep(MySubscription->oid,
MyLogicalRepWorker->relid,
originname,
sizeof(originname));
set_apply_error_context_origin(originname);
set_stream_options(&options, slotname, &origin_startpos);
walrcv_startstreaming(LogRepWorkerWalRcvConn, &options);
/* Apply the changes till we catchup with the apply worker. */
start_apply(origin_startpos);
}
/* Logical Replication Tablesync worker entry point */
void
TablesyncWorkerMain(Datum main_arg)
{
int worker_slot = DatumGetInt32(main_arg);
SetupApplyOrSyncWorker(worker_slot);
run_tablesync_worker();
finish_sync_worker();
}
/*
* If the subscription has no tables then return false.
*

388
src/backend/replication/logical/worker.c
View File

@ -396,8 +396,6 @@ static void stream_close_file(void);
static void send_feedback(XLogRecPtr recvpos, bool force, bool requestReply);
static void DisableSubscriptionAndExit(void);
static void apply_handle_commit_internal(LogicalRepCommitData *commit_data);
static void apply_handle_insert_internal(ApplyExecutionData *edata,
ResultRelInfo *relinfo,
@ -4327,6 +4325,57 @@ stream_open_and_write_change(TransactionId xid, char action, StringInfo s)
stream_stop_internal(xid);
}
/*
* Sets streaming options including replication slot name and origin start
* position. Workers need these options for logical replication.
*/
void
set_stream_options(WalRcvStreamOptions *options,
char *slotname,
XLogRecPtr *origin_startpos)
{
int server_version;
options->logical = true;
options->startpoint = *origin_startpos;
options->slotname = slotname;
server_version = walrcv_server_version(LogRepWorkerWalRcvConn);
options->proto.logical.proto_version =
server_version >= 160000 ? LOGICALREP_PROTO_STREAM_PARALLEL_VERSION_NUM :
server_version >= 150000 ? LOGICALREP_PROTO_TWOPHASE_VERSION_NUM :
server_version >= 140000 ? LOGICALREP_PROTO_STREAM_VERSION_NUM :
LOGICALREP_PROTO_VERSION_NUM;
options->proto.logical.publication_names = MySubscription->publications;
options->proto.logical.binary = MySubscription->binary;
/*
* Assign the appropriate option value for streaming option according to
* the 'streaming' mode and the publisher's ability to support that mode.
*/
if (server_version >= 160000 &&
MySubscription->stream == LOGICALREP_STREAM_PARALLEL)
{
options->proto.logical.streaming_str = "parallel";
MyLogicalRepWorker->parallel_apply = true;
}
else if (server_version >= 140000 &&
MySubscription->stream != LOGICALREP_STREAM_OFF)
{
options->proto.logical.streaming_str = "on";
MyLogicalRepWorker->parallel_apply = false;
}
else
{
options->proto.logical.streaming_str = NULL;
MyLogicalRepWorker->parallel_apply = false;
}
options->proto.logical.twophase = false;
options->proto.logical.origin = pstrdup(MySubscription->origin);
}
/*
* Cleanup the memory for subxacts and reset the related variables.
*/
@ -4361,57 +4410,13 @@ TwoPhaseTransactionGid(Oid subid, TransactionId xid, char *gid, int szgid)
}
/*
* Execute the initial sync with error handling. Disable the subscription,
* if it's required.
*
* Allocate the slot name in long-lived context on return. Note that we don't
* handle FATAL errors which are probably because of system resource error and
* are not repeatable.
*/
static void
start_table_sync(XLogRecPtr *origin_startpos, char **myslotname)
{
char *syncslotname = NULL;
Assert(am_tablesync_worker());
PG_TRY();
{
/* Call initial sync. */
syncslotname = LogicalRepSyncTableStart(origin_startpos);
}
PG_CATCH();
{
if (MySubscription->disableonerr)
DisableSubscriptionAndExit();
else
{
/*
* Report the worker failed during table synchronization. Abort
* the current transaction so that the stats message is sent in an
* idle state.
*/
AbortOutOfAnyTransaction();
pgstat_report_subscription_error(MySubscription->oid, false);
PG_RE_THROW();
}
}
PG_END_TRY();
/* allocate slot name in long-lived context */
*myslotname = MemoryContextStrdup(ApplyContext, syncslotname);
pfree(syncslotname);
}
/*
* Run the apply loop with error handling. Disable the subscription,
* if necessary.
* Common function to run the apply loop with error handling. Disable the
* subscription, if necessary.
*
* Note that we don't handle FATAL errors which are probably because
* of system resource error and are not repeatable.
*/
static void
void
start_apply(XLogRecPtr origin_startpos)
{
PG_TRY();
@ -4439,13 +4444,118 @@ start_apply(XLogRecPtr origin_startpos)
}
/*
* Common initialization for leader apply worker and parallel apply worker.
* Runs the leader apply worker.
*
* It sets up replication origin, streaming options and then starts streaming.
*/
static void
run_apply_worker()
{
char originname[NAMEDATALEN];
XLogRecPtr origin_startpos = InvalidXLogRecPtr;
char *slotname = NULL;
WalRcvStreamOptions options;
RepOriginId originid;
TimeLineID startpointTLI;
char *err;
bool must_use_password;
slotname = MySubscription->slotname;
/*
* This shouldn't happen if the subscription is enabled, but guard against
* DDL bugs or manual catalog changes. (libpqwalreceiver will crash if
* slot is NULL.)
*/
if (!slotname)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("subscription has no replication slot set")));
/* Setup replication origin tracking. */
ReplicationOriginNameForLogicalRep(MySubscription->oid, InvalidOid,
originname, sizeof(originname));
StartTransactionCommand();
originid = replorigin_by_name(originname, true);
if (!OidIsValid(originid))
originid = replorigin_create(originname);
replorigin_session_setup(originid, 0);
replorigin_session_origin = originid;
origin_startpos = replorigin_session_get_progress(false);
/* Is the use of a password mandatory? */
must_use_password = MySubscription->passwordrequired &&
!superuser_arg(MySubscription->owner);
/* Note that the superuser_arg call can access the DB */
CommitTransactionCommand();
LogRepWorkerWalRcvConn = walrcv_connect(MySubscription->conninfo, true,
must_use_password,
MySubscription->name, &err);
if (LogRepWorkerWalRcvConn == NULL)
ereport(ERROR,
(errcode(ERRCODE_CONNECTION_FAILURE),
errmsg("could not connect to the publisher: %s", err)));
/*
* We don't really use the output identify_system for anything but it does
* some initializations on the upstream so let's still call it.
*/
(void) walrcv_identify_system(LogRepWorkerWalRcvConn, &startpointTLI);
set_apply_error_context_origin(originname);
set_stream_options(&options, slotname, &origin_startpos);
/*
* Even when the two_phase mode is requested by the user, it remains as
* the tri-state PENDING until all tablesyncs have reached READY state.
* Only then, can it become ENABLED.
*
* Note: If the subscription has no tables then leave the state as
* PENDING, which allows ALTER SUBSCRIPTION ... REFRESH PUBLICATION to
* work.
*/
if (MySubscription->twophasestate == LOGICALREP_TWOPHASE_STATE_PENDING &&
AllTablesyncsReady())
{
/* Start streaming with two_phase enabled */
options.proto.logical.twophase = true;
walrcv_startstreaming(LogRepWorkerWalRcvConn, &options);
StartTransactionCommand();
UpdateTwoPhaseState(MySubscription->oid, LOGICALREP_TWOPHASE_STATE_ENABLED);
MySubscription->twophasestate = LOGICALREP_TWOPHASE_STATE_ENABLED;
CommitTransactionCommand();
}
else
{
walrcv_startstreaming(LogRepWorkerWalRcvConn, &options);
}
ereport(DEBUG1,
(errmsg_internal("logical replication apply worker for subscription \"%s\" two_phase is %s",
MySubscription->name,
MySubscription->twophasestate == LOGICALREP_TWOPHASE_STATE_DISABLED ? "DISABLED" :
MySubscription->twophasestate == LOGICALREP_TWOPHASE_STATE_PENDING ? "PENDING" :
MySubscription->twophasestate == LOGICALREP_TWOPHASE_STATE_ENABLED ? "ENABLED" :
"?")));
/* Run the main loop. */
start_apply(origin_startpos);
}
/*
* Common initialization for leader apply worker, parallel apply worker and
* tablesync worker.
*
* Initialize the database connection, in-memory subscription and necessary
* config options.
*/
void
InitializeApplyWorker(void)
InitializeLogRepWorker(void)
{
MemoryContext oldctx;
@ -4518,22 +4628,15 @@ InitializeApplyWorker(void)
CommitTransactionCommand();
}
/* Logical Replication Apply worker entry point */
/* Common function to setup the leader apply or tablesync worker. */
void
ApplyWorkerMain(Datum main_arg)
SetupApplyOrSyncWorker(int worker_slot)
{
int worker_slot = DatumGetInt32(main_arg);
char originname[NAMEDATALEN];
XLogRecPtr origin_startpos = InvalidXLogRecPtr;
char *myslotname = NULL;
WalRcvStreamOptions options;
int server_version;
InitializingApplyWorker = true;
/* Attach to slot */
logicalrep_worker_attach(worker_slot);
Assert(am_tablesync_worker() || am_leader_apply_worker());
/* Setup signal handling */
pqsignal(SIGHUP, SignalHandlerForConfigReload);
pqsignal(SIGTERM, die);
@ -4551,79 +4654,12 @@ ApplyWorkerMain(Datum main_arg)
/* Load the libpq-specific functions */
load_file("libpqwalreceiver", false);
InitializeApplyWorker();
InitializingApplyWorker = false;
InitializeLogRepWorker();
/* Connect to the origin and start the replication. */
elog(DEBUG1, "connecting to publisher using connection string \"%s\"",
MySubscription->conninfo);
if (am_tablesync_worker())
{
start_table_sync(&origin_startpos, &myslotname);
ReplicationOriginNameForLogicalRep(MySubscription->oid,
MyLogicalRepWorker->relid,
originname,
sizeof(originname));
set_apply_error_context_origin(originname);
}
else
{
/* This is the leader apply worker */
RepOriginId originid;
TimeLineID startpointTLI;
char *err;
bool must_use_password;
myslotname = MySubscription->slotname;
/*
* This shouldn't happen if the subscription is enabled, but guard
* against DDL bugs or manual catalog changes. (libpqwalreceiver will
* crash if slot is NULL.)
*/
if (!myslotname)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("subscription has no replication slot set")));
/* Setup replication origin tracking. */
StartTransactionCommand();
ReplicationOriginNameForLogicalRep(MySubscription->oid, InvalidOid,
originname, sizeof(originname));
originid = replorigin_by_name(originname, true);
if (!OidIsValid(originid))
originid = replorigin_create(originname);
replorigin_session_setup(originid, 0);
replorigin_session_origin = originid;
origin_startpos = replorigin_session_get_progress(false);
/* Is the use of a password mandatory? */
must_use_password = MySubscription->passwordrequired &&
!superuser_arg(MySubscription->owner);
/* Note that the superuser_arg call can access the DB */
CommitTransactionCommand();
LogRepWorkerWalRcvConn = walrcv_connect(MySubscription->conninfo, true,
must_use_password,
MySubscription->name, &err);
if (LogRepWorkerWalRcvConn == NULL)
ereport(ERROR,
(errcode(ERRCODE_CONNECTION_FAILURE),
errmsg("could not connect to the publisher: %s", err)));
/*
* We don't really use the output identify_system for anything but it
* does some initializations on the upstream so let's still call it.
*/
(void) walrcv_identify_system(LogRepWorkerWalRcvConn, &startpointTLI);
set_apply_error_context_origin(originname);
}
/*
* Setup callback for syscache so that we know when something changes in
* the subscription relation state.
@ -4631,91 +4667,21 @@ ApplyWorkerMain(Datum main_arg)
CacheRegisterSyscacheCallback(SUBSCRIPTIONRELMAP,
invalidate_syncing_table_states,
(Datum) 0);
}
/* Build logical replication streaming options. */
options.logical = true;
options.startpoint = origin_startpos;
options.slotname = myslotname;
/* Logical Replication Apply worker entry point */
void
ApplyWorkerMain(Datum main_arg)
{
int worker_slot = DatumGetInt32(main_arg);
server_version = walrcv_server_version(LogRepWorkerWalRcvConn);
options.proto.logical.proto_version =
server_version >= 160000 ? LOGICALREP_PROTO_STREAM_PARALLEL_VERSION_NUM :
server_version >= 150000 ? LOGICALREP_PROTO_TWOPHASE_VERSION_NUM :
server_version >= 140000 ? LOGICALREP_PROTO_STREAM_VERSION_NUM :
LOGICALREP_PROTO_VERSION_NUM;
InitializingApplyWorker = true;
options.proto.logical.publication_names = MySubscription->publications;
options.proto.logical.binary = MySubscription->binary;
SetupApplyOrSyncWorker(worker_slot);
/*
* Assign the appropriate option value for streaming option according to
* the 'streaming' mode and the publisher's ability to support that mode.
*/
if (server_version >= 160000 &&
MySubscription->stream == LOGICALREP_STREAM_PARALLEL)
{
options.proto.logical.streaming_str = "parallel";
MyLogicalRepWorker->parallel_apply = true;
}
else if (server_version >= 140000 &&
MySubscription->stream != LOGICALREP_STREAM_OFF)
{
options.proto.logical.streaming_str = "on";
MyLogicalRepWorker->parallel_apply = false;
}
else
{
options.proto.logical.streaming_str = NULL;
MyLogicalRepWorker->parallel_apply = false;
}
InitializingApplyWorker = false;
options.proto.logical.twophase = false;
options.proto.logical.origin = pstrdup(MySubscription->origin);
if (!am_tablesync_worker())
{
/*
* Even when the two_phase mode is requested by the user, it remains
* as the tri-state PENDING until all tablesyncs have reached READY
* state. Only then, can it become ENABLED.
*
* Note: If the subscription has no tables then leave the state as
* PENDING, which allows ALTER SUBSCRIPTION ... REFRESH PUBLICATION to
* work.
*/
if (MySubscription->twophasestate == LOGICALREP_TWOPHASE_STATE_PENDING &&
AllTablesyncsReady())
{
/* Start streaming with two_phase enabled */
options.proto.logical.twophase = true;
walrcv_startstreaming(LogRepWorkerWalRcvConn, &options);
StartTransactionCommand();
UpdateTwoPhaseState(MySubscription->oid, LOGICALREP_TWOPHASE_STATE_ENABLED);
MySubscription->twophasestate = LOGICALREP_TWOPHASE_STATE_ENABLED;
CommitTransactionCommand();
}
else
{
walrcv_startstreaming(LogRepWorkerWalRcvConn, &options);
}
ereport(DEBUG1,
(errmsg_internal("logical replication apply worker for subscription \"%s\" two_phase is %s",
MySubscription->name,
MySubscription->twophasestate == LOGICALREP_TWOPHASE_STATE_DISABLED ? "DISABLED" :
MySubscription->twophasestate == LOGICALREP_TWOPHASE_STATE_PENDING ? "PENDING" :
MySubscription->twophasestate == LOGICALREP_TWOPHASE_STATE_ENABLED ? "ENABLED" :
"?")));
}
else
{
/* Start normal logical streaming replication. */
walrcv_startstreaming(LogRepWorkerWalRcvConn, &options);
}
/* Run the main loop. */
start_apply(origin_startpos);
run_apply_worker();
proc_exit(0);
}
@ -4724,7 +4690,7 @@ ApplyWorkerMain(Datum main_arg)
* After error recovery, disable the subscription in a new transaction
* and exit cleanly.
*/
static void
void
DisableSubscriptionAndExit(void)
{
/*

1
src/include/replication/logicalworker.h
View File

@ -18,6 +18,7 @@ extern PGDLLIMPORT volatile sig_atomic_t ParallelApplyMessagePending;
extern void ApplyWorkerMain(Datum main_arg);
extern void ParallelApplyWorkerMain(Datum main_arg);
extern void TablesyncWorkerMain(Datum main_arg);
extern bool IsLogicalWorker(void);
extern bool IsLogicalParallelApplyWorker(void);

14
src/include/replication/worker_internal.h
View File

@ -19,6 +19,7 @@
#include "datatype/timestamp.h"
#include "miscadmin.h"
#include "replication/logicalrelation.h"
#include "replication/walreceiver.h"
#include "storage/buffile.h"
#include "storage/fileset.h"
#include "storage/lock.h"
@ -243,7 +244,6 @@ extern int logicalrep_sync_worker_count(Oid subid);
extern void ReplicationOriginNameForLogicalRep(Oid suboid, Oid relid,
char *originname, Size szoriginname);
extern char *LogicalRepSyncTableStart(XLogRecPtr *origin_startpos);
extern bool AllTablesyncsReady(void);
extern void UpdateTwoPhaseState(Oid suboid, char new_state);
@ -265,7 +265,17 @@ extern void maybe_reread_subscription(void);
extern void stream_cleanup_files(Oid subid, TransactionId xid);
extern void InitializeApplyWorker(void);
extern void set_stream_options(WalRcvStreamOptions *options,
char *slotname,
XLogRecPtr *origin_startpos);
extern void start_apply(XLogRecPtr origin_startpos);
extern void InitializeLogRepWorker(void);
extern void SetupApplyOrSyncWorker(int worker_slot);
extern void DisableSubscriptionAndExit(void);
extern void store_flush_position(XLogRecPtr remote_lsn, XLogRecPtr local_lsn);