Refactor job cancellation logic in background job processing for improved clarity and maintainability

m3hm3t/issue_7896
Mehmet Yilmaz 2025-04-04 11:02:32 +00:00
parent 3c23f897e4
commit 85a1c730ce
1 changed files with 101 additions and 98 deletions

View File

@ -256,95 +256,99 @@ citus_task_wait(PG_FUNCTION_ARGS)
void
citus_job_wait_internal(int64 jobid, BackgroundJobStatus *desiredStatus)
{
PG_TRY();
{
/*
* Since we are wait polling, we actually allocate memory on every poll. To avoid
* putting unneeded pressure on memory, we create a context that we reset
* every iteration.
*/
MemoryContext waitContext = AllocSetContextCreate(CurrentMemoryContext,
"JobsWaitContext",
ALLOCSET_DEFAULT_MINSIZE,
ALLOCSET_DEFAULT_INITSIZE,
ALLOCSET_DEFAULT_MAXSIZE);
MemoryContext oldContext = MemoryContextSwitchTo(waitContext);
PG_TRY();
{
/*
* Since we are wait polling, we actually allocate memory on every poll. To avoid
* putting unneeded pressure on memory, we create a context that we reset
* every iteration.
*/
MemoryContext waitContext = AllocSetContextCreate(CurrentMemoryContext,
"JobsWaitContext",
ALLOCSET_DEFAULT_MINSIZE,
ALLOCSET_DEFAULT_INITSIZE,
ALLOCSET_DEFAULT_MAXSIZE);
MemoryContext oldContext = MemoryContextSwitchTo(waitContext);
while (true)
{
MemoryContextReset(waitContext);
while (true)
{
MemoryContextReset(waitContext);
BackgroundJob *job = GetBackgroundJobByJobId(jobid);
if (!job)
{
ereport(ERROR,
(errmsg("no job found for job with jobid: %ld", jobid)));
}
BackgroundJob *job = GetBackgroundJobByJobId(jobid);
if (!job)
{
ereport(ERROR,
(errmsg("no job found for job with jobid: %ld", jobid)));
}
/* If we have a desiredStatus and we've reached it, we're done */
if (desiredStatus && job->state == *desiredStatus)
{
break;
}
/* If we have a desiredStatus and we've reached it, we're done */
if (desiredStatus && job->state == *desiredStatus)
{
break;
}
/* If the job is in a terminal state (e.g. SUCCEEDED, FAILED, or CANCELED),
* but not the desired state, throw an error or stop waiting.
*/
if (IsBackgroundJobStatusTerminal(job->state))
{
if (desiredStatus)
{
Oid reachedStatusOid = BackgroundJobStatusOid(job->state);
Datum reachedStatusNameDatum = DirectFunctionCall1(enum_out, reachedStatusOid);
char *reachedStatusName = DatumGetCString(reachedStatusNameDatum);
/* If the job is in a terminal state (e.g. SUCCEEDED, FAILED, or CANCELED),
* but not the desired state, throw an error or stop waiting.
*/
if (IsBackgroundJobStatusTerminal(job->state))
{
if (desiredStatus)
{
Oid reachedStatusOid = BackgroundJobStatusOid(job->state);
Datum reachedStatusNameDatum = DirectFunctionCall1(enum_out,
reachedStatusOid);
char *reachedStatusName = DatumGetCString(reachedStatusNameDatum);
Oid desiredStatusOid = BackgroundJobStatusOid(*desiredStatus);
Datum desiredStatusNameDatum = DirectFunctionCall1(enum_out, desiredStatusOid);
char *desiredStatusName = DatumGetCString(desiredStatusNameDatum);
Oid desiredStatusOid = BackgroundJobStatusOid(*desiredStatus);
Datum desiredStatusNameDatum = DirectFunctionCall1(enum_out,
desiredStatusOid);
char *desiredStatusName = DatumGetCString(desiredStatusNameDatum);
ereport(ERROR,
(errmsg("Job reached terminal state \"%s\" instead of desired "
"state \"%s\"", reachedStatusName, desiredStatusName)));
}
ereport(ERROR,
(errmsg(
"Job reached terminal state \"%s\" instead of desired "
"state \"%s\"", reachedStatusName,
desiredStatusName)));
}
/* Otherwise, if no desiredStatus was given, we accept this terminal state. */
break;
}
/* Otherwise, if no desiredStatus was given, we accept this terminal state. */
break;
}
/* Before sleeping, check for user interrupts (Ctrl+C, statement_timeout, etc.) */
CHECK_FOR_INTERRUPTS();
/* Before sleeping, check for user interrupts (Ctrl+C, statement_timeout, etc.) */
CHECK_FOR_INTERRUPTS();
/* Sleep 1 second before re-checking the job status */
const long delay_ms = 1000;
(void) WaitLatch(MyLatch,
WL_LATCH_SET | WL_TIMEOUT | WL_EXIT_ON_PM_DEATH,
delay_ms,
WAIT_EVENT_PG_SLEEP);
/* Sleep 1 second before re-checking the job status */
const long delay_ms = 1000;
(void) WaitLatch(MyLatch,
WL_LATCH_SET | WL_TIMEOUT | WL_EXIT_ON_PM_DEATH,
delay_ms,
WAIT_EVENT_PG_SLEEP);
ResetLatch(MyLatch);
}
ResetLatch(MyLatch);
}
MemoryContextSwitchTo(oldContext);
MemoryContextDelete(waitContext);
}
PG_CATCH();
{
/*
* If we get here, the user canceled the statement or an ERROR occurred.
* We forcibly cancel the job so that it doesn't remain running in background.
* This ensures no "zombie" shard moves or leftover replication slots.
*/
MemoryContextSwitchTo(oldContext);
MemoryContextDelete(waitContext);
}
PG_CATCH();
{
/*
* If we get here, the user canceled the statement or an ERROR occurred.
* We forcibly cancel the job so that it doesn't remain running in background.
* This ensures no "zombie" shard moves or leftover replication slots.
*/
/* Switch out of the waitContext so we can safely do cleanup in TopMemoryContext. */
MemoryContextSwitchTo(TopMemoryContext);
/* Switch out of the waitContext so we can safely do cleanup in TopMemoryContext. */
MemoryContextSwitchTo(TopMemoryContext);
/* Attempt to cancel the job; if it's already in a terminal state, that's okay. */
citus_cancel_job(jobid);
/* Attempt to cancel the job; if it's already in a terminal state, that's okay. */
citus_cancel_job(jobid);
/* Re-throw the original error so Postgres knows this statement was canceled. */
PG_RE_THROW();
}
PG_END_TRY();
/* Re-throw the original error so Postgres knows this statement was canceled. */
PG_RE_THROW();
}
PG_END_TRY();
}
@ -356,36 +360,35 @@ citus_job_wait_internal(int64 jobid, BackgroundJobStatus *desiredStatus)
bool
citus_cancel_job(int64 jobId)
{
BackgroundJob *job = GetBackgroundJobByJobId(jobId);
if (!job)
{
/* No such job ID */
return false;
}
BackgroundJob *job = GetBackgroundJobByJobId(jobId);
if (!job)
{
/* No such job ID */
return false;
}
/*
* If the job is already in a terminal state, or is scheduled,
* decide if you want to do anything special.
* But typically you just check if it is still "running" or "cancelling".
*/
if (IsBackgroundJobStatusTerminal(job->state))
{
return false;
}
/*
* If the job is already in a terminal state, or is scheduled,
* decide if you want to do anything special.
* But typically you just check if it is still "running" or "cancelling".
*/
if (IsBackgroundJobStatusTerminal(job->state))
{
return false;
}
/* Mark job as canceled, then update the catalog */
job->state = BACKGROUND_JOB_STATUS_CANCELLED;
/* Mark job as canceled, then update the catalog */
job->state = BACKGROUND_JOB_STATUS_CANCELLED;
/* This projects the tasks states into the job's new state,
* and updates the row in pg_dist_background_job.
*/
UpdateBackgroundJob(job->jobid);
/* This projects the tasks states into the job's new state,
* and updates the row in pg_dist_background_job.
*/
UpdateBackgroundJob(job->jobid);
return true;
return true;
}
/*
* citus_task_wait_internal implements the waiting on a task for reuse in other areas where
* we want to wait on tasks.