static void
StartupProcSigUsr1Handler(SIGNAL_ARGS)
{
+ int save_errno = errno;
+
latch_sigusr1_handler();
+
+ errno = save_errno;
}
/* SIGUSR2: set flag to finish recovery */
static void
StartupProcTriggerHandler(SIGNAL_ARGS)
{
+ int save_errno = errno;
+
promote_triggered = true;
WakeupRecovery();
+
+ errno = save_errno;
}
/* SIGHUP: set flag to re-read config file at next convenient time */
static void
StartupProcSigHupHandler(SIGNAL_ARGS)
{
+ int save_errno = errno;
+
got_SIGHUP = true;
WakeupRecovery();
+
+ errno = save_errno;
}
/* SIGTERM: set flag to abort redo and exit */
static void
StartupProcShutdownHandler(SIGNAL_ARGS)
{
+ int save_errno = errno;
+
if (in_restore_command)
proc_exit(1);
else
shutdown_requested = true;
WakeupRecovery();
+
+ errno = save_errno;
}
/* Handle SIGHUP and SIGTERM signals of startup process */
* If the latch is already set, the function returns immediately.
*
* The 'timeout' is given in milliseconds, and -1 means wait forever.
- * On some platforms, signals cause the timeout to be restarted, so beware
- * that the function can sleep for several times longer than the specified
- * timeout.
+ * On some platforms, signals do not interrupt the wait, or even
+ * cause the timeout to be restarted, so beware that the function can sleep
+ * for several times longer than the requested timeout. However, this
+ * difficulty is not so great as it seems, because the signal handlers for any
+ * signals that the caller should respond to ought to be programmed to end the
+ * wait by calling SetLatch. Ideally, the timeout parameter is vestigial.
*
* The latch must be owned by the current process, ie. it must be a
* backend-local latch initialized with InitLatch, or a shared latch
{
if (errno == EINTR)
continue;
+ waiting = false;
ereport(ERROR,
(errcode_for_socket_access(),
errmsg("select() failed: %m")));
* Sets a latch and wakes up anyone waiting on it.
*
* This is cheap if the latch is already set, otherwise not so much.
+ *
+ * NB: when calling this in a signal handler, be sure to save and restore
+ * errno around it. (That's standard practice in most signal handlers, of
+ * course, but we used to omit it in handlers that only set a flag.)
*/
void
SetLatch(volatile Latch *latch)
if (owner_pid == 0)
return;
else if (owner_pid == MyProcPid)
- sendSelfPipeByte();
+ {
+ if (waiting)
+ sendSelfPipeByte();
+ }
else
kill(owner_pid, SIGUSR1);
}
* SetLatch uses SIGUSR1 to wake up the process waiting on the latch.
*
* Wake up WaitLatch, if we're waiting. (We might not be, since SIGUSR1 is
- * overloaded for multiple purposes.)
+ * overloaded for multiple purposes; or we might not have reached WaitLatch
+ * yet, in which case we don't need to fill the pipe either.)
+ *
+ * NB: when calling this in a signal handler, be sure to save and restore
+ * errno around it.
*/
void
latch_sigusr1_handler(void)
}
}
-/* Read all available data from the self-pipe */
+/*
+ * Read all available data from the self-pipe
+ *
+ * Note: this is only called when waiting = true. If it fails and doesn't
+ * return, it must reset that flag first (though ideally, this will never
+ * happen).
+ */
static void
drainSelfPipe(void)
{
/*
* There shouldn't normally be more than one byte in the pipe, or maybe a
- * few more if multiple processes run SetLatch at the same instant.
+ * few bytes if multiple processes run SetLatch at the same instant.
*/
char buf[16];
int rc;
else if (errno == EINTR)
continue; /* retry */
else
+ {
+ waiting = false;
elog(ERROR, "read() on self-pipe failed: %m");
+ }
}
else if (rc == 0)
+ {
+ waiting = false;
elog(ERROR, "unexpected EOF on self-pipe");
+ }
+ else if (rc < sizeof(buf))
+ {
+ /* we successfully drained the pipe; no need to read() again */
+ break;
+ }
+ /* else buffer wasn't big enough, so read again */
}
}
Assert(SHMQueueIsDetached(&(MyProc->syncRepLinks)));
Assert(WalSndCtl != NULL);
- /* Reset the latch before adding ourselves to the queue. */
- ResetLatch(&MyProc->waitLatch);
-
LWLockAcquire(SyncRepLock, LW_EXCLUSIVE);
Assert(MyProc->syncRepState == SYNC_REP_NOT_WAITING);
int syncRepState;
/* Must reset the latch before testing state. */
- ResetLatch(&MyProc->waitLatch);
+ ResetLatch(&MyProc->procLatch);
/*
* Try checking the state without the lock first. There's no
}
/*
- * Wait on latch for up to 60 seconds. This allows us to check for
+ * Wait on latch for up to 10 seconds. This allows us to check for
* cancel/die signal or postmaster death regularly while waiting. Note
* that timeout here does not necessarily release from loop.
*/
- WaitLatch(&MyProc->waitLatch, 60000L);
+ WaitLatch(&MyProc->procLatch, 10000L);
}
/*
}
void
-SyncRepCleanupAtProcExit(int code, Datum arg)
+SyncRepCleanupAtProcExit(void)
{
if (!SHMQueueIsDetached(&(MyProc->syncRepLinks)))
{
SHMQueueDelete(&(MyProc->syncRepLinks));
LWLockRelease(SyncRepLock);
}
-
- DisownLatch(&MyProc->waitLatch);
}
/*
/*
* Wake only when we have set state and removed from queue.
*/
- Assert(SHMQueueIsDetached(&(thisproc->syncRepLinks)));
- Assert(thisproc->syncRepState == SYNC_REP_WAIT_COMPLETE);
- SetLatch(&(thisproc->waitLatch));
+ SetLatch(&(thisproc->procLatch));
numprocs++;
}
static void
WalRcvShutdownHandler(SIGNAL_ARGS)
{
+ int save_errno = errno;
+
got_SIGTERM = true;
/* Don't joggle the elbow of proc_exit */
if (!proc_exit_inprogress && WalRcvImmediateInterruptOK)
ProcessWalRcvInterrupts();
+
+ errno = save_errno;
}
/*
static void
WalSndSigHupHandler(SIGNAL_ARGS)
{
+ int save_errno = errno;
+
got_SIGHUP = true;
if (MyWalSnd)
SetLatch(&MyWalSnd->latch);
+
+ errno = save_errno;
}
/* SIGTERM: set flag to shut down */
static void
WalSndShutdownHandler(SIGNAL_ARGS)
{
+ int save_errno = errno;
+
walsender_shutdown_requested = true;
if (MyWalSnd)
SetLatch(&MyWalSnd->latch);
+
+ errno = save_errno;
}
/*
static void
WalSndXLogSendHandler(SIGNAL_ARGS)
{
+ int save_errno = errno;
+
latch_sigusr1_handler();
+
+ errno = save_errno;
}
/* SIGUSR2: set flag to do a last cycle and shut down afterwards */
static void
WalSndLastCycleHandler(SIGNAL_ARGS)
{
+ int save_errno = errno;
+
walsender_ready_to_stop = true;
if (MyWalSnd)
SetLatch(&MyWalSnd->latch);
+
+ errno = save_errno;
}
/* Set up signal handlers */
ProcGlobal->spins_per_delay = DEFAULT_SPINS_PER_DELAY;
/*
- * Pre-create the PGPROC structures and create a semaphore for each.
+ * Pre-create the PGPROC structures and create a semaphore and latch
+ * for each.
*/
procs = (PGPROC *) ShmemAlloc((MaxConnections) * sizeof(PGPROC));
if (!procs)
for (i = 0; i < MaxConnections; i++)
{
PGSemaphoreCreate(&(procs[i].sem));
+ InitSharedLatch(&procs[i].procLatch);
procs[i].links.next = (SHM_QUEUE *) ProcGlobal->freeProcs;
ProcGlobal->freeProcs = &procs[i];
- InitSharedLatch(&procs[i].waitLatch);
}
/*
for (i = 0; i < autovacuum_max_workers + 1; i++)
{
PGSemaphoreCreate(&(procs[i].sem));
+ InitSharedLatch(&procs[i].procLatch);
procs[i].links.next = (SHM_QUEUE *) ProcGlobal->autovacFreeProcs;
ProcGlobal->autovacFreeProcs = &procs[i];
- InitSharedLatch(&procs[i].waitLatch);
}
/*
{
AuxiliaryProcs[i].pid = 0; /* marks auxiliary proc as not in use */
PGSemaphoreCreate(&(AuxiliaryProcs[i].sem));
- InitSharedLatch(&procs[i].waitLatch);
+ InitSharedLatch(&AuxiliaryProcs[i].procLatch);
}
/* Create ProcStructLock spinlock, too */
MarkPostmasterChildActive();
/*
- * Initialize all fields of MyProc, except for the semaphore which was
- * prepared for us by InitProcGlobal.
+ * Initialize all fields of MyProc, except for the semaphore and latch,
+ * which were prepared for us by InitProcGlobal.
*/
SHMQueueElemInit(&(MyProc->links));
MyProc->waitStatus = STATUS_OK;
SHMQueueInit(&(MyProc->myProcLocks[i]));
MyProc->recoveryConflictPending = false;
- /* Initialise for sync rep */
+ /* Initialize fields for sync rep */
MyProc->waitLSN.xlogid = 0;
MyProc->waitLSN.xrecoff = 0;
MyProc->syncRepState = SYNC_REP_NOT_WAITING;
SHMQueueElemInit(&(MyProc->syncRepLinks));
- OwnLatch(&MyProc->waitLatch);
+
+ /*
+ * Acquire ownership of the PGPROC's latch, so that we can use WaitLatch.
+ * Note that there's no particular need to do ResetLatch here.
+ */
+ OwnLatch(&MyProc->procLatch);
/*
* We might be reusing a semaphore that belonged to a failed process. So
/*
* Arrange to clean that up at backend exit.
*/
- on_shmem_exit(SyncRepCleanupAtProcExit, 0);
on_shmem_exit(RemoveProcFromArray, 0);
}
SpinLockRelease(ProcStructLock);
/*
- * Initialize all fields of MyProc, except for the semaphore which was
- * prepared for us by InitProcGlobal.
+ * Initialize all fields of MyProc, except for the semaphore and latch,
+ * which were prepared for us by InitProcGlobal.
*/
SHMQueueElemInit(&(MyProc->links));
MyProc->waitStatus = STATUS_OK;
for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
SHMQueueInit(&(MyProc->myProcLocks[i]));
+ /*
+ * Acquire ownership of the PGPROC's latch, so that we can use WaitLatch.
+ * Note that there's no particular need to do ResetLatch here.
+ */
+ OwnLatch(&MyProc->procLatch);
+
/*
* We might be reusing a semaphore that belonged to a failed process. So
* be careful and reinitialize its value here. (This is not strictly
Assert(MyProc != NULL);
+ /* Make sure we're out of the sync rep lists */
+ SyncRepCleanupAtProcExit();
+
/*
* Release any LW locks I am holding. There really shouldn't be any, but
* it's cheap to check again before we cut the knees off the LWLock
*/
LWLockReleaseAll();
+ /* Release ownership of the process's latch, too */
+ DisownLatch(&MyProc->procLatch);
+
SpinLockAcquire(ProcStructLock);
/* Return PGPROC structure (and semaphore) to appropriate freelist */
/* Release any LW locks I am holding (see notes above) */
LWLockReleaseAll();
+ /* Release ownership of the process's latch, too */
+ DisownLatch(&MyProc->procLatch);
+
SpinLockAcquire(ProcStructLock);
/* Mark auxiliary proc no longer in use */
InterruptHoldoffCount--;
ProcessInterrupts();
}
-
- /* Interrupt any sync rep wait which is currently in progress. */
- SetLatch(&(MyProc->waitLatch));
}
+ /* If we're still here, waken anything waiting on the process latch */
+ if (MyProc)
+ SetLatch(&MyProc->procLatch);
+
errno = save_errno;
}
InterruptHoldoffCount--;
ProcessInterrupts();
}
-
- /* Interrupt any sync rep wait which is currently in progress. */
- SetLatch(&(MyProc->waitLatch));
}
+ /* If we're still here, waken anything waiting on the process latch */
+ if (MyProc)
+ SetLatch(&MyProc->procLatch);
+
errno = save_errno;
}
/* called by user backend */
extern void SyncRepWaitForLSN(XLogRecPtr XactCommitLSN);
-/* callback at backend exit */
-extern void SyncRepCleanupAtProcExit(int code, Datum arg);
+/* called at backend exit */
+extern void SyncRepCleanupAtProcExit(void);
/* called by wal sender */
extern void SyncRepInitConfig(void);
LOCKMASK heldLocks; /* bitmask for lock types already held on this
* lock object by this backend */
+ Latch procLatch; /* generic latch for process */
+
/*
* Info to allow us to wait for synchronous replication, if needed.
* waitLSN is InvalidXLogRecPtr if not waiting; set only by user backend.
* syncRepState must not be touched except by owning process or WALSender.
* syncRepLinks used only while holding SyncRepLock.
*/
- Latch waitLatch; /* allow us to wait for sync rep */
XLogRecPtr waitLSN; /* waiting for this LSN or higher */
int syncRepState; /* wait state for sync rep */
SHM_QUEUE syncRepLinks; /* list link if process is in syncrep queue */
projects / postgresql / commitdiff