/*
* We get here when a session has been idle for a while (waiting for the
* client to send us SQL to execute). The idea is to consume less resources while sitting idle,
* so we can support more sessions being logged on.
*
* The expectation is that if the session is logged on, but nobody is sending us work to do,
* we want to free up whatever resources we can. Usually it means there is a human being at the
* other end of the connection, and that person has walked away from their terminal, or just hasn't
* decided what to do next. We could be idle for a very long time (many hours).
*
* Of course, freeing gangs means that the next time the user does send in an SQL statement,
* we need to allocate gangs (at least the writer gang) to do anything. This entails extra work,
* so we don't want to do this if we don't think the session has gone idle.
*
* We can call cleanupIdleReaderGangs() to just free some resources, or cleanupAllIdleGangs() to
* free up everything possible on the segDB side. At the moment, I can't find a reason to
* use cleanupIdleReaderGangs(), but it we wanted to, we would have two timeouts: The first
* when we free the reader gangs, and the second later time free the writer gang.
* My current thinking is that it is better to free all the gangs as soon as we decide
* the session is idle.
*
* P.s: Is there anything we can free up on the master (QD) side? I can't think of anything.
*
*/
static void
HandleClientWaitTimeout(void)
{
elog(DEBUG2,"HandleClientWaitTimeout");
/*
* cancel the timer, as there is no reason we need it to go off again.
*/
disable_sig_alarm(false);
/*
* Free gangs to free up resources on the segDBs.
*/
if (gangsExist())
{
cleanupAllIdleGangs();
}
}
/*
* FtsHandleGangConnectionFailure is called by createGang during
* creating connections return true if error need to be thrown
*/
bool
FtsHandleGangConnectionFailure(SegmentDatabaseDescriptor * segdbDesc, int size)
{
int i;
bool dtx_active;
bool reportError = false;
bool realFaultFound = false;
bool forceRescan=true;
for (i = 0; i < size; i++)
{
if (PQstatus(segdbDesc[i].conn) != CONNECTION_OK)
{
CdbComponentDatabaseInfo *segInfo = segdbDesc[i].segment_database_info;
elog(DEBUG2, "FtsHandleGangConnectionFailure: looking for real fault on segment dbid %d", segInfo->dbid);
if (!FtsTestConnection(segInfo, forceRescan))
{
elog(DEBUG2, "found fault with segment dbid %d", segInfo->dbid);
realFaultFound = true;
/* that at least one fault exists is enough, for now */
break;
}
forceRescan = false; /* only force the rescan on the first call. */
}
}
if (!realFaultFound)
{
/* If we successfully tested the gang and didn't notice a
* failure, our caller must've seen some kind of transient
* failure when the gang was originally constructed ... */
elog(DEBUG2, "FtsHandleGangConnectionFailure: no real fault found!");
return false;
}
if (!isFTSEnabled())
{
return false;
}
ereport(LOG, (errmsg_internal("FTS: reconfiguration is in progress")));
forceRescan = true;
for (i = 0; i < size; i++)
{
CdbComponentDatabaseInfo *segInfo = segdbDesc[i].segment_database_info;
if (PQstatus(segdbDesc[i].conn) != CONNECTION_OK)
{
if (!FtsTestConnection(segInfo, forceRescan))
{
ereport(LOG, (errmsg_internal("FTS: found bad segment with dbid %d", segInfo->dbid),
errSendAlert(true)));
/* probe process has already marked segment down. */
}
forceRescan = false; /* only force rescan on first call. */
}
}
if (gangsExist())
{
reportError = true;
disconnectAndDestroyAllGangs();
}
/*
* KLUDGE: Do not error out if we are attempting a DTM protocol retry
*/
if (DistributedTransactionContext == DTX_CONTEXT_QD_RETRY_PHASE_2)
{
return false;
}
/* is there a transaction active ? */
dtx_active = isCurrentDtxActive();
/* When the error is raised, it will abort the current DTM transaction */
if (dtx_active)
{
elog((Debug_print_full_dtm ? LOG : DEBUG5),
"FtsHandleGangConnectionFailure found an active DTM transaction (returning true).");
return true;
}
/*
* error out if this sets read only flag, at this stage the read only
* transaction checking has passed, so error out, but do not error out if
* tm is in recovery
*/
if ((*ftsReadOnlyFlag && !isTMInRecovery()) || reportError)
return true;
elog((Debug_print_full_dtm ? LOG : DEBUG5),
"FtsHandleGangConnectionFailure returning false.");
return false;
}
