static void
thread_DispatchOut(DispatchCommandParms * pParms)
{
CdbDispatchResult *dispatchResult;
int i,
db_count = pParms->db_count;
/*
* The pParms contains an array of SegmentDatabaseDescriptors
* to send commands through to.
*/
for (i = 0; i < db_count; i++)
{
dispatchResult = pParms->dispatchResultPtrArray[i];
/*
* Don't use elog, it's not thread-safe
*/
if (DEBUG5 >= log_min_messages)
{
if (dispatchResult->segdbDesc->conn)
{
write_log
("thread_DispatchCommand working on %d of %d commands. asyncStatus %d",
i + 1, db_count,
dispatchResult->segdbDesc->conn->asyncStatus);
}
}
dispatchResult->hasDispatched = false;
dispatchResult->sentSignal = DISPATCH_WAIT_NONE;
dispatchResult->wasCanceled = false;
if (!shouldStillDispatchCommand(pParms, dispatchResult))
{
/*
* Don't dispatch if cancellation pending or no connection.
*/
dispatchResult->stillRunning = false;
if (PQisBusy(dispatchResult->segdbDesc->conn))
write_log
(" We thought we were done, because !shouldStillDispatchCommand(), but libpq says we are still busy");
if (PQstatus(dispatchResult->segdbDesc->conn) == CONNECTION_BAD)
write_log
(" We thought we were done, because !shouldStillDispatchCommand(), but libpq says the connection died?");
}
else
{
/*
* Kick off the command over the libpq connection.
* * If unsuccessful, proceed anyway, and check for lost connection below.
*/
if (PQisBusy(dispatchResult->segdbDesc->conn))
{
write_log
("Trying to send to busy connection %s %d %d asyncStatus %d",
dispatchResult->segdbDesc->whoami, i, db_count,
dispatchResult->segdbDesc->conn->asyncStatus);
}
if (PQstatus(dispatchResult->segdbDesc->conn) == CONNECTION_BAD)
{
char *msg;
msg = PQerrorMessage(dispatchResult->segdbDesc->conn);
write_log
("Dispatcher noticed a problem before query transmit: %s (%s)",
msg ? msg : "unknown error",
dispatchResult->segdbDesc->whoami);
/*
* Save error info for later.
*/
cdbdisp_appendMessage(dispatchResult, LOG,
ERRCODE_GP_INTERCONNECTION_ERROR,
"Error before transmit from %s: %s",
dispatchResult->segdbDesc->whoami,
msg ? msg : "unknown error");
PQfinish(dispatchResult->segdbDesc->conn);
dispatchResult->segdbDesc->conn = NULL;
dispatchResult->stillRunning = false;
continue;
}
#ifdef USE_NONBLOCKING
/*
* In 2000, Tom Lane said:
* "I believe that the nonblocking-mode code is pretty buggy, and don't
* recommend using it unless you really need it and want to help debug
* it.."
*
* Reading through the code, I'm not convinced the situation has
* improved in 2007... I still see some very questionable things
* about nonblocking mode, so for now, I'm disabling it.
*/
PQsetnonblocking(dispatchResult->segdbDesc->conn, TRUE);
#endif
dispatchCommand(dispatchResult, pParms->query_text,
pParms->query_text_len);
}
}
#ifdef USE_NONBLOCKING
/*
* Is everything sent? Well, if the network stack was too busy, and we are using
* nonblocking mode, some of the sends
* might not have completed. We can't use SELECT to wait unless they have
* received their work, or we will wait forever. Make sure they do.
*/
{
bool allsent = true;
/*
* debug loop to check to see if this really is needed
*/
for (i = 0; i < db_count; i++)
{
dispatchResult = pParms->dispatchResultPtrArray[i];
if (!dispatchResult->stillRunning
|| !dispatchResult->hasDispatched)
continue;
if (PQstatus(dispatchResult->segdbDesc->conn) == CONNECTION_BAD)
continue;
if (dispatchResult->segdbDesc->conn->outCount > 0)
{
write_log("Yes, extra flushing is necessary %d", i);
break;
}
}
/*
* Check to see if any needed extra flushing.
*/
for (i = 0; i < db_count; i++)
{
int flushResult;
dispatchResult = pParms->dispatchResultPtrArray[i];
if (!dispatchResult->stillRunning
|| !dispatchResult->hasDispatched)
continue;
if (PQstatus(dispatchResult->segdbDesc->conn) == CONNECTION_BAD)
continue;
/*
* If data remains unsent, send it. Else we might be waiting for the
* result of a command the backend hasn't even got yet.
*/
flushResult = PQflush(dispatchResult->segdbDesc->conn);
/*
* First time, go through the loop without waiting if we can't
* flush, in case we are using multiple network adapters, and
* other connections might be able to flush
*/
if (flushResult > 0)
{
allsent = false;
write_log("flushing didn't finish the work %d", i);
}
}
/*
* our first attempt at doing more flushes didn't get everything out,
* so we need to continue to try.
*/
for (i = 0; i < db_count; i++)
{
dispatchResult = pParms->dispatchResultPtrArray[i];
while (PQisnonblocking(dispatchResult->segdbDesc->conn))
{
PQflush(dispatchResult->segdbDesc->conn);
PQsetnonblocking(dispatchResult->segdbDesc->conn, FALSE);
}
}
}
#endif
}
/********************************************************************************
* Returns the blocking status of the database connection
int PQisnonblocking(const PGconn *conn)
Returns TRUE if the connection is set to non-blocking mode, FALSE if
blocking.
********************************************************************************/
int
dbi_isnonblocking(const DBI_conn *conn)
{
return PQisnonblocking(conn);
}
