#include "postgres.h"
#include "funcapi.h"
#include "miscadmin.h"
#include "pgstat.h"
#include "access/heapam.h"
#include "access/htup.h"
#include "access/htup_details.h"
#include "access/xact.h"
#include "catalog/pg_subscription.h"
#include "catalog/pg_subscription_rel.h"
#include "libpq/pqsignal.h"
#include "postmaster/bgworker.h"
#include "postmaster/fork_process.h"
#include "postmaster/postmaster.h"
#include "replication/logicallauncher.h"
#include "replication/logicalworker.h"
#include "replication/slot.h"
#include "replication/walreceiver.h"
#include "replication/worker_internal.h"
#include "storage/ipc.h"
#include "storage/proc.h"
#include "storage/procarray.h"
#include "storage/procsignal.h"
#include "tcop/tcopprot.h"
#include "utils/memutils.h"
#include "utils/pg_lsn.h"
#include "utils/ps_status.h"
#include "utils/timeout.h"
#include "utils/snapmgr.h"

Include dependency graph for launcher.c:

Data Structures
struct	LogicalRepCtxStruct

struct	LogicalRepWorkerId

Macros
#define	DEFAULT_NAPTIME_PER_CYCLE 180000L

#define	PG_STAT_GET_SUBSCRIPTION_COLS 8

Typedefs
typedef struct LogicalRepCtxStruct	LogicalRepCtxStruct

typedef struct LogicalRepWorkerId	LogicalRepWorkerId

Functions
static void	ApplyLauncherWakeup (void)

static void	logicalrep_launcher_onexit (int code, Datum arg)

static void	logicalrep_worker_onexit (int code, Datum arg)

static void	logicalrep_worker_detach (void)

static void	logicalrep_worker_cleanup (LogicalRepWorker *worker)

Datum	pg_stat_get_subscription (PG_FUNCTION_ARGS)

static List *	get_subscription_list (void)

static void	WaitForReplicationWorkerAttach (LogicalRepWorker worker, uint16 generation, BackgroundWorkerHandle handle)

LogicalRepWorker *	logicalrep_worker_find (Oid subid, Oid relid, bool only_running)

List *	logicalrep_workers_find (Oid subid, bool only_running)

void	logicalrep_worker_launch (Oid dbid, Oid subid, const char *subname, Oid userid, Oid relid)

void	logicalrep_worker_stop (Oid subid, Oid relid)

void	logicalrep_worker_stop_at_commit (Oid subid, Oid relid)

void	logicalrep_worker_wakeup (Oid subid, Oid relid)

void	logicalrep_worker_wakeup_ptr (LogicalRepWorker *worker)

void	logicalrep_worker_attach (int slot)

static void	logicalrep_launcher_sighup (SIGNAL_ARGS)

int	logicalrep_sync_worker_count (Oid subid)

Size	ApplyLauncherShmemSize (void)

void	ApplyLauncherRegister (void)

void	ApplyLauncherShmemInit (void)

bool	XactManipulatesLogicalReplicationWorkers (void)

void	AtEOXact_ApplyLauncher (bool isCommit)

void	ApplyLauncherWakeupAtCommit (void)

void	ApplyLauncherMain (Datum main_arg)

bool	IsLogicalLauncher (void)

Variables
int	max_logical_replication_workers = 4

int	max_sync_workers_per_subscription = 2

LogicalRepWorker *	MyLogicalRepWorker = NULL

LogicalRepCtxStruct *	LogicalRepCtx

static List *	on_commit_stop_workers = NIL

static volatile sig_atomic_t	got_SIGHUP = false

static bool	on_commit_launcher_wakeup = false

Macro Definition Documentation

#define DEFAULT_NAPTIME_PER_CYCLE 180000L

Definition at line 58 of file launcher.c.

Referenced by ApplyLauncherMain().

#define PG_STAT_GET_SUBSCRIPTION_COLS 8

Referenced by pg_stat_get_subscription().

Typedef Documentation

typedef struct LogicalRepCtxStruct LogicalRepCtxStruct

typedef struct LogicalRepWorkerId LogicalRepWorkerId

Function Documentation

void ApplyLauncherMain ( Datum main_arg )

Definition at line 880 of file launcher.c.

References ALLOCSET_DEFAULT_INITSIZE, ALLOCSET_DEFAULT_MAXSIZE, ALLOCSET_DEFAULT_MINSIZE, AllocSetContextCreate(), Assert, BackgroundWorkerInitializeConnection(), BackgroundWorkerUnblockSignals(), before_shmem_exit(), CHECK_FOR_INTERRUPTS, Subscription::dbid, DEBUG1, DEFAULT_NAPTIME_PER_CYCLE, die(), Subscription::enabled, ereport, errmsg(), get_subscription_list(), GetCurrentTimestamp(), got_SIGHUP, InvalidOid, LogicalRepCtxStruct::launcher_pid, lfirst, logicalrep_launcher_onexit(), logicalrep_launcher_sighup(), logicalrep_worker_find(), logicalrep_worker_launch(), LW_SHARED, LWLockAcquire(), LWLockRelease(), MemoryContextDelete(), MemoryContextSwitchTo(), MyLatch, MyProcPid, Subscription::name, now(), Subscription::oid, Subscription::owner, PGC_SIGHUP, pqsignal(), proc_exit(), ProcessConfigFile(), ResetLatch(), SIGHUP, TimestampDifferenceExceeds(), TopMemoryContext, WAIT_EVENT_LOGICAL_LAUNCHER_MAIN, WaitLatch(), wal_retrieve_retry_interval, WL_LATCH_SET, WL_POSTMASTER_DEATH, and WL_TIMEOUT.

 {
     TimestampTz last_start_time = 0;
 
     ereport(DEBUG1,
             (errmsg("logical replication launcher started")));
 
     before_shmem_exit(logicalrep_launcher_onexit, (Datum) 0);
 
     Assert(LogicalRepCtx->launcher_pid == 0);
     LogicalRepCtx->launcher_pid = MyProcPid;
 
     /* Establish signal handlers. */
     pqsignal(SIGHUP, logicalrep_launcher_sighup);
     pqsignal(SIGTERM, die);
     BackgroundWorkerUnblockSignals();
 
     /*
      * Establish connection to nailed catalogs (we only ever access
      * pg_subscription).
      */
     BackgroundWorkerInitializeConnection(NULL, NULL);
 
     /* Enter main loop */
     for (;;)
     {
         int         rc;
         List       *sublist;
         ListCell   *lc;
         MemoryContext subctx;
         MemoryContext oldctx;
         TimestampTz now;
         long        wait_time = DEFAULT_NAPTIME_PER_CYCLE;
 
         CHECK_FOR_INTERRUPTS();
 
         now = GetCurrentTimestamp();
 
         /* Limit the start retry to once a wal_retrieve_retry_interval */
         if (TimestampDifferenceExceeds(last_start_time, now,
                                        wal_retrieve_retry_interval))
         {
             /* Use temporary context for the database list and worker info. */
             subctx = AllocSetContextCreate(TopMemoryContext,
                                            "Logical Replication Launcher sublist",
                                            ALLOCSET_DEFAULT_MINSIZE,
                                            ALLOCSET_DEFAULT_INITSIZE,
                                            ALLOCSET_DEFAULT_MAXSIZE);
             oldctx = MemoryContextSwitchTo(subctx);
 
             /* search for subscriptions to start or stop. */
             sublist = get_subscription_list();
 
             /* Start the missing workers for enabled subscriptions. */
             foreach(lc, sublist)
             {
                 Subscription *sub = (Subscription *) lfirst(lc);
                 LogicalRepWorker *w;
 
                 if (!sub->enabled)
                     continue;
 
                 LWLockAcquire(LogicalRepWorkerLock, LW_SHARED);
                 w = logicalrep_worker_find(sub->oid, InvalidOid, false);
                 LWLockRelease(LogicalRepWorkerLock);
 
                 if (w == NULL)
                 {
                     last_start_time = now;
                     wait_time = wal_retrieve_retry_interval;
 
                     logicalrep_worker_launch(sub->dbid, sub->oid, sub->name,
                                              sub->owner, InvalidOid);
                 }
             }
 
             /* Switch back to original memory context. */
             MemoryContextSwitchTo(oldctx);
             /* Clean the temporary memory. */
             MemoryContextDelete(subctx);
         }
         else
         {
             /*
              * The wait in previous cycle was interrupted in less than
              * wal_retrieve_retry_interval since last worker was started, this
              * usually means crash of the worker, so we should retry in
              * wal_retrieve_retry_interval again.
              */
             wait_time = wal_retrieve_retry_interval;
         }
 
         /* Wait for more work. */
         rc = WaitLatch(MyLatch,
                        WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH,
                        wait_time,
                        WAIT_EVENT_LOGICAL_LAUNCHER_MAIN);
 
         /* emergency bailout if postmaster has died */
         if (rc & WL_POSTMASTER_DEATH)
             proc_exit(1);
 
         if (rc & WL_LATCH_SET)
         {
             ResetLatch(MyLatch);
             CHECK_FOR_INTERRUPTS();
         }
 
         if (got_SIGHUP)
         {
             got_SIGHUP = false;
             ProcessConfigFile(PGC_SIGHUP);
         }
     }
 
     /* Not reachable */
 }

void ApplyLauncherRegister ( void )

Definition at line 763 of file launcher.c.

References BackgroundWorker::bgw_flags, BackgroundWorker::bgw_function_name, BackgroundWorker::bgw_library_name, BackgroundWorker::bgw_main_arg, BGW_MAXLEN, BackgroundWorker::bgw_name, BackgroundWorker::bgw_notify_pid, BackgroundWorker::bgw_restart_time, BackgroundWorker::bgw_start_time, BGWORKER_BACKEND_DATABASE_CONNECTION, BGWORKER_SHMEM_ACCESS, BgWorkerStart_RecoveryFinished, max_logical_replication_workers, RegisterBackgroundWorker(), and snprintf().

Referenced by PostmasterMain().

 {
     BackgroundWorker bgw;
 
     if (max_logical_replication_workers == 0)
         return;
 
     memset(&bgw, 0, sizeof(bgw));
     bgw.bgw_flags = BGWORKER_SHMEM_ACCESS |
         BGWORKER_BACKEND_DATABASE_CONNECTION;
     bgw.bgw_start_time = BgWorkerStart_RecoveryFinished;
     snprintf(bgw.bgw_library_name, BGW_MAXLEN, "postgres");
     snprintf(bgw.bgw_function_name, BGW_MAXLEN, "ApplyLauncherMain");
     snprintf(bgw.bgw_name, BGW_MAXLEN,
              "logical replication launcher");
     bgw.bgw_restart_time = 5;
     bgw.bgw_notify_pid = 0;
     bgw.bgw_main_arg = (Datum) 0;
 
     RegisterBackgroundWorker(&bgw);
 }

void ApplyLauncherShmemInit ( void )

Definition at line 790 of file launcher.c.

References ApplyLauncherShmemSize(), max_logical_replication_workers, LogicalRepWorker::relmutex, ShmemInitStruct(), SpinLockInit, and LogicalRepCtxStruct::workers.

Referenced by CreateSharedMemoryAndSemaphores().

 {
     bool        found;
 
     LogicalRepCtx = (LogicalRepCtxStruct *)
         ShmemInitStruct("Logical Replication Launcher Data",
                         ApplyLauncherShmemSize(),
                         &found);
 
     if (!found)
     {
         int         slot;
 
         memset(LogicalRepCtx, 0, ApplyLauncherShmemSize());
 
         /* Initialize memory and spin locks for each worker slot. */
         for (slot = 0; slot < max_logical_replication_workers; slot++)
         {
             LogicalRepWorker *worker = &LogicalRepCtx->workers[slot];
 
             memset(worker, 0, sizeof(LogicalRepWorker));
             SpinLockInit(&worker->relmutex);
         }
     }
 }

Size ApplyLauncherShmemSize ( void )

Definition at line 744 of file launcher.c.

References add_size(), max_logical_replication_workers, MAXALIGN, and mul_size().

Referenced by ApplyLauncherShmemInit(), and CreateSharedMemoryAndSemaphores().

 {
     Size        size;
 
     /*
      * Need the fixed struct and the array of LogicalRepWorker.
      */
     size = sizeof(LogicalRepCtxStruct);
     size = MAXALIGN(size);
     size = add_size(size, mul_size(max_logical_replication_workers,
                                    sizeof(LogicalRepWorker)));
     return size;
 }

static void ApplyLauncherWakeup ( void )

static

Definition at line 870 of file launcher.c.

References LogicalRepCtxStruct::launcher_pid, and SIGUSR1.

Referenced by AtEOXact_ApplyLauncher(), and logicalrep_worker_onexit().

 {
     if (LogicalRepCtx->launcher_pid != 0)
         kill(LogicalRepCtx->launcher_pid, SIGUSR1);
 }

void ApplyLauncherWakeupAtCommit ( void )

Definition at line 863 of file launcher.c.

References on_commit_launcher_wakeup.

Referenced by AlterSubscription(), and CreateSubscription().

 {
     if (!on_commit_launcher_wakeup)
         on_commit_launcher_wakeup = true;
 }

void AtEOXact_ApplyLauncher ( bool isCommit )

Definition at line 830 of file launcher.c.

References ApplyLauncherWakeup(), lfirst, logicalrep_worker_stop(), NIL, on_commit_launcher_wakeup, LogicalRepWorkerId::relid, and LogicalRepWorkerId::subid.

Referenced by AbortTransaction(), and CommitTransaction().

 {
     if (isCommit)
     {
         ListCell   *lc;
 
         foreach(lc, on_commit_stop_workers)
         {
             LogicalRepWorkerId *wid = lfirst(lc);
 
             logicalrep_worker_stop(wid->subid, wid->relid);
         }
 
         if (on_commit_launcher_wakeup)
             ApplyLauncherWakeup();
     }
 
     /*
      * No need to pfree on_commit_stop_workers.  It was allocated in
      * transaction memory context, which is going to be cleaned soon.
      */
     on_commit_stop_workers = NIL;
     on_commit_launcher_wakeup = false;
 }

static List* get_subscription_list ( void )

static

Definition at line 105 of file launcher.c.

References AccessShareLock, CommitTransactionCommand(), CurrentMemoryContext, Subscription::dbid, Subscription::enabled, ForwardScanDirection, GETSTRUCT, GetTransactionSnapshot(), heap_beginscan_catalog(), heap_close, heap_endscan(), heap_getnext(), heap_open(), HeapTupleGetOid, HeapTupleIsValid, lappend(), MemoryContextSwitchTo(), Subscription::name, NameStr, NIL, Subscription::oid, Subscription::owner, palloc0(), pstrdup(), StartTransactionCommand(), and SubscriptionRelationId.

Referenced by ApplyLauncherMain().

 {
     List       *res = NIL;
     Relation    rel;
     HeapScanDesc scan;
     HeapTuple   tup;
     MemoryContext resultcxt;
 
     /* This is the context that we will allocate our output data in */
     resultcxt = CurrentMemoryContext;
 
     /*
      * Start a transaction so we can access pg_database, and get a snapshot.
      * We don't have a use for the snapshot itself, but we're interested in
      * the secondary effect that it sets RecentGlobalXmin.  (This is critical
      * for anything that reads heap pages, because HOT may decide to prune
      * them even if the process doesn't attempt to modify any tuples.)
      */
     StartTransactionCommand();
     (void) GetTransactionSnapshot();
 
     rel = heap_open(SubscriptionRelationId, AccessShareLock);
     scan = heap_beginscan_catalog(rel, 0, NULL);
 
     while (HeapTupleIsValid(tup = heap_getnext(scan, ForwardScanDirection)))
     {
         Form_pg_subscription subform = (Form_pg_subscription) GETSTRUCT(tup);
         Subscription *sub;
         MemoryContext oldcxt;
 
         /*
          * Allocate our results in the caller's context, not the
          * transaction's. We do this inside the loop, and restore the original
          * context at the end, so that leaky things like heap_getnext() are
          * not called in a potentially long-lived context.
          */
         oldcxt = MemoryContextSwitchTo(resultcxt);
 
         sub = (Subscription *) palloc0(sizeof(Subscription));
         sub->oid = HeapTupleGetOid(tup);
         sub->dbid = subform->subdbid;
         sub->owner = subform->subowner;
         sub->enabled = subform->subenabled;
         sub->name = pstrdup(NameStr(subform->subname));
         /* We don't fill fields we are not interested in. */
 
         res = lappend(res, sub);
         MemoryContextSwitchTo(oldcxt);
     }
 
     heap_endscan(scan);
     heap_close(rel, AccessShareLock);
 
     CommitTransactionCommand();
 
     return res;
 }

bool IsLogicalLauncher ( void )

Definition at line 1002 of file launcher.c.

References LogicalRepCtxStruct::launcher_pid, and MyProcPid.

Referenced by ProcessInterrupts().

 {
     return LogicalRepCtx->launcher_pid == MyProcPid;
 }

static void logicalrep_launcher_onexit	(	int	code,
		Datum	arg
	)

static

Definition at line 679 of file launcher.c.

References LogicalRepCtxStruct::launcher_pid.

Referenced by ApplyLauncherMain().

 {
     LogicalRepCtx->launcher_pid = 0;
 }

static void logicalrep_launcher_sighup ( SIGNAL_ARGS )

static

Definition at line 703 of file launcher.c.

References got_SIGHUP, MyLatch, and SetLatch().

Referenced by ApplyLauncherMain().

 {
     int         save_errno = errno;
 
     got_SIGHUP = true;
 
     /* Waken anything waiting on the process latch */
     SetLatch(MyLatch);
 
     errno = save_errno;
 }

int logicalrep_sync_worker_count ( Oid subid )

Definition at line 720 of file launcher.c.

References Assert, i, LWLockHeldByMe(), max_logical_replication_workers, OidIsValid, LogicalRepWorker::relid, LogicalRepWorker::subid, and LogicalRepCtxStruct::workers.

Referenced by logicalrep_worker_launch(), and process_syncing_tables_for_apply().

 {
     int         i;
     int         res = 0;
 
     Assert(LWLockHeldByMe(LogicalRepWorkerLock));
 
     /* Search for attached worker for a given subscription id. */
     for (i = 0; i < max_logical_replication_workers; i++)
     {
         LogicalRepWorker *w = &LogicalRepCtx->workers[i];
 
         if (w->subid == subid && OidIsValid(w->relid))
             res++;
     }
 
     return res;
 }

void logicalrep_worker_attach ( int slot )

Definition at line 611 of file launcher.c.

References Assert, before_shmem_exit(), ereport, errcode(), errmsg(), ERROR, LogicalRepWorker::in_use, logicalrep_worker_onexit(), LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), max_logical_replication_workers, MyProc, LogicalRepWorker::proc, and LogicalRepCtxStruct::workers.

Referenced by ApplyWorkerMain().

 {
     /* Block concurrent access. */
     LWLockAcquire(LogicalRepWorkerLock, LW_EXCLUSIVE);
 
     Assert(slot >= 0 && slot < max_logical_replication_workers);
     MyLogicalRepWorker = &LogicalRepCtx->workers[slot];
 
     if (!MyLogicalRepWorker->in_use)
     {
         LWLockRelease(LogicalRepWorkerLock);
         ereport(ERROR,
                 (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                  errmsg("logical replication worker slot %d is empty, cannot attach",
                         slot)));
     }
 
     if (MyLogicalRepWorker->proc)
     {
         LWLockRelease(LogicalRepWorkerLock);
         ereport(ERROR,
                 (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                  errmsg("logical replication worker slot %d is already used by "
                         "another worker, cannot attach", slot)));
     }
 
     MyLogicalRepWorker->proc = MyProc;
     before_shmem_exit(logicalrep_worker_onexit, (Datum) 0);
 
     LWLockRelease(LogicalRepWorkerLock);
 }

static void logicalrep_worker_cleanup ( LogicalRepWorker * worker )

static

Definition at line 661 of file launcher.c.

References Assert, LogicalRepWorker::dbid, LogicalRepWorker::in_use, InvalidOid, LW_EXCLUSIVE, LWLockHeldByMeInMode(), LogicalRepWorker::proc, LogicalRepWorker::relid, LogicalRepWorker::subid, and LogicalRepWorker::userid.

Referenced by logicalrep_worker_detach(), logicalrep_worker_launch(), and WaitForReplicationWorkerAttach().

 {
     Assert(LWLockHeldByMeInMode(LogicalRepWorkerLock, LW_EXCLUSIVE));
 
     worker->in_use = false;
     worker->proc = NULL;
     worker->dbid = InvalidOid;
     worker->userid = InvalidOid;
     worker->subid = InvalidOid;
     worker->relid = InvalidOid;
 }

static void logicalrep_worker_detach ( void )

static

Definition at line 647 of file launcher.c.

References logicalrep_worker_cleanup(), LW_EXCLUSIVE, LWLockAcquire(), and LWLockRelease().

Referenced by logicalrep_worker_onexit().

 {
     /* Block concurrent access. */
     LWLockAcquire(LogicalRepWorkerLock, LW_EXCLUSIVE);
 
     logicalrep_worker_cleanup(MyLogicalRepWorker);
 
     LWLockRelease(LogicalRepWorkerLock);
 }

LogicalRepWorker* logicalrep_worker_find	(	Oid	subid,
		Oid	relid,
		bool	only_running
	)

Definition at line 234 of file launcher.c.

References Assert, i, LogicalRepWorker::in_use, LWLockHeldByMe(), max_logical_replication_workers, LogicalRepWorker::proc, LogicalRepWorker::relid, LogicalRepWorker::subid, and LogicalRepCtxStruct::workers.

Referenced by ApplyLauncherMain(), logicalrep_worker_stop(), logicalrep_worker_wakeup(), process_syncing_tables_for_apply(), wait_for_relation_state_change(), and wait_for_worker_state_change().

 {
     int         i;
     LogicalRepWorker *res = NULL;
 
     Assert(LWLockHeldByMe(LogicalRepWorkerLock));
 
     /* Search for attached worker for a given subscription id. */
     for (i = 0; i < max_logical_replication_workers; i++)
     {
         LogicalRepWorker *w = &LogicalRepCtx->workers[i];
 
         if (w->in_use && w->subid == subid && w->relid == relid &&
             (!only_running || w->proc))
         {
             res = w;
             break;
         }
     }
 
     return res;
 }

void logicalrep_worker_launch	(	Oid	dbid,
		Oid	subid,
		const char *	subname,
		Oid	userid,
		Oid	relid
	)

Definition at line 285 of file launcher.c.

Referenced by ApplyLauncherMain(), and process_syncing_tables_for_apply().

 {
     BackgroundWorker bgw;
     BackgroundWorkerHandle *bgw_handle;
     uint16      generation;
     int         i;
     int         slot = 0;
     LogicalRepWorker *worker = NULL;
     int         nsyncworkers;
     TimestampTz now;
 
     ereport(DEBUG1,
             (errmsg("starting logical replication worker for subscription \"%s\"",
                     subname)));
 
     /* Report this after the initial starting message for consistency. */
     if (max_replication_slots == 0)
         ereport(ERROR,
                 (errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
                  errmsg("cannot start logical replication workers when max_replication_slots = 0")));
 
     /*
      * We need to do the modification of the shared memory under lock so that
      * we have consistent view.
      */
     LWLockAcquire(LogicalRepWorkerLock, LW_EXCLUSIVE);
 
 retry:
     /* Find unused worker slot. */
     for (i = 0; i < max_logical_replication_workers; i++)
     {
         LogicalRepWorker *w = &LogicalRepCtx->workers[i];
 
         if (!w->in_use)
         {
             worker = w;
             slot = i;
             break;
         }
     }
 
     nsyncworkers = logicalrep_sync_worker_count(subid);
 
     now = GetCurrentTimestamp();
 
     /*
      * If we didn't find a free slot, try to do garbage collection.  The
      * reason we do this is because if some worker failed to start up and its
      * parent has crashed while waiting, the in_use state was never cleared.
      */
     if (worker == NULL || nsyncworkers >= max_sync_workers_per_subscription)
     {
         bool        did_cleanup = false;
 
         for (i = 0; i < max_logical_replication_workers; i++)
         {
             LogicalRepWorker *w = &LogicalRepCtx->workers[i];
 
             /*
              * If the worker was marked in use but didn't manage to attach in
              * time, clean it up.
              */
             if (w->in_use && !w->proc &&
                 TimestampDifferenceExceeds(w->launch_time, now,
                                            wal_receiver_timeout))
             {
                 elog(WARNING,
                      "logical replication worker for subscription %u took too long to start; canceled",
                      w->subid);
 
                 logicalrep_worker_cleanup(w);
                 did_cleanup = true;
             }
         }
 
         if (did_cleanup)
             goto retry;
     }
 
     /*
      * If we reached the sync worker limit per subscription, just exit
      * silently as we might get here because of an otherwise harmless race
      * condition.
      */
     if (nsyncworkers >= max_sync_workers_per_subscription)
     {
         LWLockRelease(LogicalRepWorkerLock);
         return;
     }
 
     /*
      * However if there are no more free worker slots, inform user about it
      * before exiting.
      */
     if (worker == NULL)
     {
         LWLockRelease(LogicalRepWorkerLock);
         ereport(WARNING,
                 (errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
                  errmsg("out of logical replication worker slots"),
                  errhint("You might need to increase max_logical_replication_workers.")));
         return;
     }
 
     /* Prepare the worker slot. */
     worker->launch_time = now;
     worker->in_use = true;
     worker->generation++;
     worker->proc = NULL;
     worker->dbid = dbid;
     worker->userid = userid;
     worker->subid = subid;
     worker->relid = relid;
     worker->relstate = SUBREL_STATE_UNKNOWN;
     worker->relstate_lsn = InvalidXLogRecPtr;
     worker->last_lsn = InvalidXLogRecPtr;
     TIMESTAMP_NOBEGIN(worker->last_send_time);
     TIMESTAMP_NOBEGIN(worker->last_recv_time);
     worker->reply_lsn = InvalidXLogRecPtr;
     TIMESTAMP_NOBEGIN(worker->reply_time);
 
     /* Before releasing lock, remember generation for future identification. */
     generation = worker->generation;
 
     LWLockRelease(LogicalRepWorkerLock);
 
     /* Register the new dynamic worker. */
     memset(&bgw, 0, sizeof(bgw));
     bgw.bgw_flags = BGWORKER_SHMEM_ACCESS |
         BGWORKER_BACKEND_DATABASE_CONNECTION;
     bgw.bgw_start_time = BgWorkerStart_RecoveryFinished;
     snprintf(bgw.bgw_library_name, BGW_MAXLEN, "postgres");
     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
         snprintf(bgw.bgw_name, BGW_MAXLEN,
                  "logical replication worker for subscription %u", subid);
 
     bgw.bgw_restart_time = BGW_NEVER_RESTART;
     bgw.bgw_notify_pid = MyProcPid;
     bgw.bgw_main_arg = Int32GetDatum(slot);
 
     if (!RegisterDynamicBackgroundWorker(&bgw, &bgw_handle))
     {
         /* Failed to start worker, so clean up the worker slot. */
         LWLockAcquire(LogicalRepWorkerLock, LW_EXCLUSIVE);
         Assert(generation == worker->generation);
         logicalrep_worker_cleanup(worker);
         LWLockRelease(LogicalRepWorkerLock);
 
         ereport(WARNING,
                 (errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
                  errmsg("out of background worker slots"),
                  errhint("You might need to increase max_worker_processes.")));
         return;
     }
 
     /* Now wait until it attaches. */
     WaitForReplicationWorkerAttach(worker, generation, bgw_handle);
 }

static void logicalrep_worker_onexit	(	int	code,
		Datum	arg
	)

static

Definition at line 690 of file launcher.c.

References ApplyLauncherWakeup(), logicalrep_worker_detach(), walrcv_disconnect, and wrconn.

Referenced by logicalrep_worker_attach().

 {
     /* Disconnect gracefully from the remote side. */
     if (wrconn)
         walrcv_disconnect(wrconn);
 
     logicalrep_worker_detach();
 
     ApplyLauncherWakeup();
 }

void logicalrep_worker_stop	(	Oid	subid,
		Oid	relid
	)

Definition at line 454 of file launcher.c.

References CHECK_FOR_INTERRUPTS, LogicalRepWorker::generation, LogicalRepWorker::in_use, logicalrep_worker_find(), LW_SHARED, LWLockAcquire(), LWLockRelease(), MyLatch, PGPROC::pid, LogicalRepWorker::proc, proc_exit(), ResetLatch(), WAIT_EVENT_BGWORKER_SHUTDOWN, WAIT_EVENT_BGWORKER_STARTUP, WaitLatch(), WL_LATCH_SET, WL_POSTMASTER_DEATH, and WL_TIMEOUT.

Referenced by AtEOXact_ApplyLauncher(), and DropSubscription().

 {
     LogicalRepWorker *worker;
     uint16      generation;
 
     LWLockAcquire(LogicalRepWorkerLock, LW_SHARED);
 
     worker = logicalrep_worker_find(subid, relid, false);
 
     /* No worker, nothing to do. */
     if (!worker)
     {
         LWLockRelease(LogicalRepWorkerLock);
         return;
     }
 
     /*
      * Remember which generation was our worker so we can check if what we see
      * is still the same one.
      */
     generation = worker->generation;
 
     /*
      * If we found a worker but it does not have proc set then it is still
      * starting up; wait for it to finish starting and then kill it.
      */
     while (worker->in_use && !worker->proc)
     {
         int         rc;
 
         LWLockRelease(LogicalRepWorkerLock);
 
         /* Wait a bit --- we don't expect to have to wait long. */
         rc = WaitLatch(MyLatch,
                        WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH,
                        10L, WAIT_EVENT_BGWORKER_STARTUP);
 
         /* emergency bailout if postmaster has died */
         if (rc & WL_POSTMASTER_DEATH)
             proc_exit(1);
 
         if (rc & WL_LATCH_SET)
         {
             ResetLatch(MyLatch);
             CHECK_FOR_INTERRUPTS();
         }
 
         /* Recheck worker status. */
         LWLockAcquire(LogicalRepWorkerLock, LW_SHARED);
 
         /*
          * Check whether the worker slot is no longer used, which would mean
          * that the worker has exited, or whether the worker generation is
          * different, meaning that a different worker has taken the slot.
          */
         if (!worker->in_use || worker->generation != generation)
         {
             LWLockRelease(LogicalRepWorkerLock);
             return;
         }
 
         /* Worker has assigned proc, so it has started. */
         if (worker->proc)
             break;
     }
 
     /* Now terminate the worker ... */
     kill(worker->proc->pid, SIGTERM);
 
     /* ... and wait for it to die. */
     for (;;)
     {
         int         rc;
 
         /* is it gone? */
         if (!worker->proc || worker->generation != generation)
             break;
 
         LWLockRelease(LogicalRepWorkerLock);
 
         /* Wait a bit --- we don't expect to have to wait long. */
         rc = WaitLatch(MyLatch,
                        WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH,
                        10L, WAIT_EVENT_BGWORKER_SHUTDOWN);
 
         /* emergency bailout if postmaster has died */
         if (rc & WL_POSTMASTER_DEATH)
             proc_exit(1);
 
         if (rc & WL_LATCH_SET)
         {
             ResetLatch(MyLatch);
             CHECK_FOR_INTERRUPTS();
         }
 
         LWLockAcquire(LogicalRepWorkerLock, LW_SHARED);
     }
 
     LWLockRelease(LogicalRepWorkerLock);
 }

void logicalrep_worker_stop_at_commit	(	Oid	subid,
		Oid	relid
	)

Definition at line 559 of file launcher.c.

References lappend(), MemoryContextSwitchTo(), palloc(), LogicalRepWorkerId::relid, LogicalRepWorkerId::subid, and TopTransactionContext.

Referenced by AlterSubscription_refresh().

 {
     LogicalRepWorkerId *wid;
     MemoryContext oldctx;
 
     /* Make sure we store the info in context that survives until commit. */
     oldctx = MemoryContextSwitchTo(TopTransactionContext);
 
     wid = palloc(sizeof(LogicalRepWorkerId));
     wid->subid = subid;
     wid->relid = relid;
 
     on_commit_stop_workers = lappend(on_commit_stop_workers, wid);
 
     MemoryContextSwitchTo(oldctx);
 }

void logicalrep_worker_wakeup	(	Oid	subid,
		Oid	relid
	)

Definition at line 580 of file launcher.c.

References logicalrep_worker_find(), logicalrep_worker_wakeup_ptr(), LW_SHARED, LWLockAcquire(), and LWLockRelease().

Referenced by pg_attribute_noreturn().

 {
     LogicalRepWorker *worker;
 
     LWLockAcquire(LogicalRepWorkerLock, LW_SHARED);
 
     worker = logicalrep_worker_find(subid, relid, true);
 
     if (worker)
         logicalrep_worker_wakeup_ptr(worker);
 
     LWLockRelease(LogicalRepWorkerLock);
 }

void logicalrep_worker_wakeup_ptr ( LogicalRepWorker * worker )

Definition at line 600 of file launcher.c.

References Assert, LWLockHeldByMe(), LogicalRepWorker::proc, PGPROC::procLatch, and SetLatch().

Referenced by logicalrep_worker_wakeup(), process_syncing_tables_for_apply(), and wait_for_worker_state_change().

 {
     Assert(LWLockHeldByMe(LogicalRepWorkerLock));
 
     SetLatch(&worker->proc->procLatch);
 }

List* logicalrep_workers_find	(	Oid	subid,
		bool	only_running
	)

Definition at line 262 of file launcher.c.

References Assert, i, LogicalRepWorker::in_use, lappend(), LWLockHeldByMe(), max_logical_replication_workers, NIL, LogicalRepWorker::proc, LogicalRepWorker::subid, and LogicalRepCtxStruct::workers.

Referenced by DropSubscription().

 {
     int         i;
     List       *res = NIL;
 
     Assert(LWLockHeldByMe(LogicalRepWorkerLock));
 
     /* Search for attached worker for a given subscription id. */
     for (i = 0; i < max_logical_replication_workers; i++)
     {
         LogicalRepWorker *w = &LogicalRepCtx->workers[i];
 
         if (w->in_use && w->subid == subid && (!only_running || w->proc))
             res = lappend(res, w);
     }
 
     return res;
 }

Datum pg_stat_get_subscription ( PG_FUNCTION_ARGS )

Definition at line 1011 of file launcher.c.

References ReturnSetInfo::allowedModes, ReturnSetInfo::econtext, ExprContext::ecxt_per_query_memory, elog, ereport, errcode(), errmsg(), ERROR, get_call_result_type(), i, Int32GetDatum, InvalidOid, IsA, IsBackendPid(), LogicalRepWorker::last_lsn, LogicalRepWorker::last_recv_time, LogicalRepWorker::last_send_time, LSNGetDatum, LW_SHARED, LWLockAcquire(), LWLockRelease(), max_logical_replication_workers, MemoryContextSwitchTo(), MemSet, ObjectIdGetDatum, OidIsValid, PG_ARGISNULL, PG_GETARG_OID, PG_STAT_GET_SUBSCRIPTION_COLS, PGPROC::pid, LogicalRepWorker::proc, LogicalRepWorker::relid, LogicalRepWorker::reply_lsn, LogicalRepWorker::reply_time, ReturnSetInfo::returnMode, ReturnSetInfo::setDesc, ReturnSetInfo::setResult, SFRM_Materialize, LogicalRepWorker::subid, TimestampTzGetDatum, tuplestore_begin_heap(), tuplestore_donestoring, tuplestore_putvalues(), TYPEFUNC_COMPOSITE, values, work_mem, LogicalRepCtxStruct::workers, and XLogRecPtrIsInvalid.

 {
 #define PG_STAT_GET_SUBSCRIPTION_COLS   8
     Oid         subid = PG_ARGISNULL(0) ? InvalidOid : PG_GETARG_OID(0);
     int         i;
     ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
     TupleDesc   tupdesc;
     Tuplestorestate *tupstore;
     MemoryContext per_query_ctx;
     MemoryContext oldcontext;
 
     /* check to see if caller supports us returning a tuplestore */
     if (rsinfo == NULL || !IsA(rsinfo, ReturnSetInfo))
         ereport(ERROR,
                 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                  errmsg("set-valued function called in context that cannot accept a set")));
     if (!(rsinfo->allowedModes & SFRM_Materialize))
         ereport(ERROR,
                 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                  errmsg("materialize mode required, but it is not " \
                         "allowed in this context")));
 
     /* Build a tuple descriptor for our result type */
     if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
         elog(ERROR, "return type must be a row type");
 
     per_query_ctx = rsinfo->econtext->ecxt_per_query_memory;
     oldcontext = MemoryContextSwitchTo(per_query_ctx);
 
     tupstore = tuplestore_begin_heap(true, false, work_mem);
     rsinfo->returnMode = SFRM_Materialize;
     rsinfo->setResult = tupstore;
     rsinfo->setDesc = tupdesc;
 
     MemoryContextSwitchTo(oldcontext);
 
     /* Make sure we get consistent view of the workers. */
     LWLockAcquire(LogicalRepWorkerLock, LW_SHARED);
 
     for (i = 0; i <= max_logical_replication_workers; i++)
     {
         /* for each row */
         Datum       values[PG_STAT_GET_SUBSCRIPTION_COLS];
         bool        nulls[PG_STAT_GET_SUBSCRIPTION_COLS];
         int         worker_pid;
         LogicalRepWorker worker;
 
         memcpy(&worker, &LogicalRepCtx->workers[i],
                sizeof(LogicalRepWorker));
         if (!worker.proc || !IsBackendPid(worker.proc->pid))
             continue;
 
         if (OidIsValid(subid) && worker.subid != subid)
             continue;
 
         worker_pid = worker.proc->pid;
 
         MemSet(values, 0, sizeof(values));
         MemSet(nulls, 0, sizeof(nulls));
 
         values[0] = ObjectIdGetDatum(worker.subid);
         if (OidIsValid(worker.relid))
             values[1] = ObjectIdGetDatum(worker.relid);
         else
             nulls[1] = true;
         values[2] = Int32GetDatum(worker_pid);
         if (XLogRecPtrIsInvalid(worker.last_lsn))
             nulls[3] = true;
         else
             values[3] = LSNGetDatum(worker.last_lsn);
         if (worker.last_send_time == 0)
             nulls[4] = true;
         else
             values[4] = TimestampTzGetDatum(worker.last_send_time);
         if (worker.last_recv_time == 0)
             nulls[5] = true;
         else
             values[5] = TimestampTzGetDatum(worker.last_recv_time);
         if (XLogRecPtrIsInvalid(worker.reply_lsn))
             nulls[6] = true;
         else
             values[6] = LSNGetDatum(worker.reply_lsn);
         if (worker.reply_time == 0)
             nulls[7] = true;
         else
             values[7] = TimestampTzGetDatum(worker.reply_time);
 
         tuplestore_putvalues(tupstore, tupdesc, values, nulls);
 
         /*
          * If only a single subscription was requested, and we found it,
          * break.
          */
         if (OidIsValid(subid))
             break;
     }
 
     LWLockRelease(LogicalRepWorkerLock);
 
     /* clean up and return the tuplestore */
     tuplestore_donestoring(tupstore);
 
     return (Datum) 0;
 }

static void WaitForReplicationWorkerAttach	(	LogicalRepWorker *	worker,
		uint16	generation,
		BackgroundWorkerHandle *	handle
	)

static

Definition at line 170 of file launcher.c.

References BGWH_STOPPED, CHECK_FOR_INTERRUPTS, LogicalRepWorker::generation, GetBackgroundWorkerPid(), LogicalRepWorker::in_use, logicalrep_worker_cleanup(), LW_EXCLUSIVE, LW_SHARED, LWLockAcquire(), LWLockRelease(), MyLatch, LogicalRepWorker::proc, proc_exit(), ResetLatch(), status(), WAIT_EVENT_BGWORKER_STARTUP, WaitLatch(), WL_LATCH_SET, WL_POSTMASTER_DEATH, and WL_TIMEOUT.

Referenced by logicalrep_worker_launch().

 {
     BgwHandleStatus status;
     int         rc;
 
     for (;;)
     {
         pid_t       pid;
 
         CHECK_FOR_INTERRUPTS();
 
         LWLockAcquire(LogicalRepWorkerLock, LW_SHARED);
 
         /* Worker either died or has started; no need to do anything. */
         if (!worker->in_use || worker->proc)
         {
             LWLockRelease(LogicalRepWorkerLock);
             return;
         }
 
         LWLockRelease(LogicalRepWorkerLock);
 
         /* Check if worker has died before attaching, and clean up after it. */
         status = GetBackgroundWorkerPid(handle, &pid);
 
         if (status == BGWH_STOPPED)
         {
             LWLockAcquire(LogicalRepWorkerLock, LW_EXCLUSIVE);
             /* Ensure that this was indeed the worker we waited for. */
             if (generation == worker->generation)
                 logicalrep_worker_cleanup(worker);
             LWLockRelease(LogicalRepWorkerLock);
             return;
         }
 
         /*
          * We need timeout because we generally don't get notified via latch
          * about the worker attach.  But we don't expect to have to wait long.
          */
         rc = WaitLatch(MyLatch,
                        WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH,
                        10L, WAIT_EVENT_BGWORKER_STARTUP);
 
         /* emergency bailout if postmaster has died */
         if (rc & WL_POSTMASTER_DEATH)
             proc_exit(1);
 
         if (rc & WL_LATCH_SET)
         {
             ResetLatch(MyLatch);
             CHECK_FOR_INTERRUPTS();
         }
     }
 
     return;
 }

bool XactManipulatesLogicalReplicationWorkers ( void )

Definition at line 821 of file launcher.c.

References NIL.

Referenced by PrepareTransaction().

 {
     return (on_commit_stop_workers != NIL);
 }

Variable Documentation

volatile sig_atomic_t got_SIGHUP = false

static

Definition at line 91 of file launcher.c.

Referenced by ApplyLauncherMain(), and logicalrep_launcher_sighup().

LogicalRepCtxStruct* LogicalRepCtx

Definition at line 74 of file launcher.c.

int max_logical_replication_workers = 4

Definition at line 60 of file launcher.c.

Referenced by ApplyLauncherRegister(), ApplyLauncherShmemInit(), ApplyLauncherShmemSize(), logicalrep_sync_worker_count(), logicalrep_worker_attach(), logicalrep_worker_find(), logicalrep_worker_launch(), logicalrep_workers_find(), and pg_stat_get_subscription().

int max_sync_workers_per_subscription = 2

Definition at line 61 of file launcher.c.

Referenced by logicalrep_worker_launch(), and process_syncing_tables_for_apply().

LogicalRepWorker* MyLogicalRepWorker = NULL

Definition at line 63 of file launcher.c.

Referenced by ApplyWorkerMain(), IsLogicalWorker(), LogicalRepSyncTableStart(), maybe_reread_subscription(), pg_attribute_noreturn(), process_syncing_tables_for_apply(), process_syncing_tables_for_sync(), should_apply_changes_for_rel(), UpdateWorkerStats(), wait_for_relation_state_change(), and wait_for_worker_state_change().

bool on_commit_launcher_wakeup = false

static

Definition at line 93 of file launcher.c.

Referenced by ApplyLauncherWakeupAtCommit(), and AtEOXact_ApplyLauncher().

List* on_commit_stop_workers = NIL

static

Definition at line 82 of file launcher.c.

Data Structures

Macros

Typedefs

Functions

Variables

Macro Definition Documentation

Typedef Documentation

Function Documentation

Variable Documentation