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Simplify determining logical replication worker types.

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We deduce a LogicalRepWorker's type from the values of several different
fields ('relid' and 'leader_pid') whenever logic needs to know it.

In fact, the logical replication worker type is already known at the time
of launching the LogicalRepWorker and it never changes for the lifetime of
that process. Instead of deducing the type, it is simpler to just store it
one time, and access it directly thereafter.

Author: Peter Smith
Reviewed-by: Amit Kapila, Bharath Rupireddy
Discussion: http://postgr.es/m/CAHut+PttPSuP0yoZ=9zLDXKqTJ=d0bhxwKaEaNcaym1XqcvDEg@mail.gmail.com
This commit is contained in:
Amit Kapila
2023-08-14 08:38:03 +05:30
parent 3d8d217450
commit 2a8b40e368
5 changed files with 42 additions and 16 deletions
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29
src/backend/replication/logical/launcher.c
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@@ -303,7 +303,8 @@ logicalrep_workers_find(Oid subid, bool only_running)
* Returns true on success, false on failure.
*/
bool
logicalrep_worker_launch(Oid dbid, Oid subid, const char *subname, Oid userid,
logicalrep_worker_launch(LogicalRepWorkerType wtype,
Oid dbid, Oid subid, const char *subname, Oid userid,
Oid relid, dsm_handle subworker_dsm)
{
BackgroundWorker bgw;
@@ -315,10 +316,18 @@ logicalrep_worker_launch(Oid dbid, Oid subid, const char *subname, Oid userid,
int nsyncworkers;
int nparallelapplyworkers;
TimestampTz now;
bool is_parallel_apply_worker = (subworker_dsm != DSM_HANDLE_INVALID);
bool is_tablesync_worker = (wtype == WORKERTYPE_TABLESYNC);
bool is_parallel_apply_worker = (wtype == WORKERTYPE_PARALLEL_APPLY);
/* Sanity check - tablesync worker cannot be a subworker */
Assert(!(is_parallel_apply_worker && OidIsValid(relid)));
/*----------
* Sanity checks:
* - must be valid worker type
* - tablesync workers are only ones to have relid
* - parallel apply worker is the only kind of subworker
*/
Assert(wtype != WORKERTYPE_UNKNOWN);
Assert(is_tablesync_worker == OidIsValid(relid));
Assert(is_parallel_apply_worker == (subworker_dsm != DSM_HANDLE_INVALID));
ereport(DEBUG1,
(errmsg_internal("starting logical replication worker for subscription \"%s\"",
@@ -393,7 +402,7 @@ retry:
* sync worker limit per subscription. So, just return silently as we
* might get here because of an otherwise harmless race condition.
*/
if (OidIsValid(relid) && nsyncworkers >= max_sync_workers_per_subscription)
if (is_tablesync_worker && nsyncworkers >= max_sync_workers_per_subscription)
{
LWLockRelease(LogicalRepWorkerLock);
return false;
@@ -427,6 +436,7 @@ retry:
}
/* Prepare the worker slot. */
worker->type = wtype;
worker->launch_time = now;
worker->in_use = true;
worker->generation++;
@@ -466,7 +476,7 @@ retry:
subid);
snprintf(bgw.bgw_type, BGW_MAXLEN, "logical replication parallel worker");
}
else if (OidIsValid(relid))
else if (is_tablesync_worker)
{
snprintf(bgw.bgw_function_name, BGW_MAXLEN, "TablesyncWorkerMain");
snprintf(bgw.bgw_name, BGW_MAXLEN,
@@ -847,7 +857,7 @@ logicalrep_sync_worker_count(Oid subid)
{
LogicalRepWorker *w = &LogicalRepCtx->workers[i];
if (w->subid == subid && OidIsValid(w->relid))
if (w->subid == subid && isTablesyncWorker(w))
res++;
}
@@ -1180,7 +1190,8 @@ ApplyLauncherMain(Datum main_arg)
(elapsed = TimestampDifferenceMilliseconds(last_start, now)) >= wal_retrieve_retry_interval)
{
ApplyLauncherSetWorkerStartTime(sub->oid, now);
logicalrep_worker_launch(sub->dbid, sub->oid, sub->name,
logicalrep_worker_launch(WORKERTYPE_APPLY,
sub->dbid, sub->oid, sub->name,
sub->owner, InvalidOid,
DSM_HANDLE_INVALID);
}
@@ -1290,7 +1301,7 @@ pg_stat_get_subscription(PG_FUNCTION_ARGS)
worker_pid = worker.proc->pid;
values[0] = ObjectIdGetDatum(worker.subid);
if (OidIsValid(worker.relid))
if (isTablesyncWorker(&worker))
values[1] = ObjectIdGetDatum(worker.relid);
else
nulls[1] = true;