diff options
Diffstat (limited to 'src/backend/port/unix_latch.c')
| -rw-r--r-- | src/backend/port/unix_latch.c | 72 |
1 files changed, 38 insertions, 34 deletions
diff --git a/src/backend/port/unix_latch.c b/src/backend/port/unix_latch.c index 335e9f66afb..bbd1810ea53 100644 --- a/src/backend/port/unix_latch.c +++ b/src/backend/port/unix_latch.c @@ -60,11 +60,41 @@ static volatile sig_atomic_t waiting = false; static int selfpipe_readfd = -1; static int selfpipe_writefd = -1; -/* private function prototypes */ -static void initSelfPipe(void); -static void drainSelfPipe(void); +/* Private function prototypes */ static void sendSelfPipeByte(void); +static void drainSelfPipe(void); + + +/* + * Initialize the process-local latch infrastructure. + * + * This must be called once during startup of any process that can wait on + * latches, before it issues any InitLatch() or OwnLatch() calls. + */ +void +InitializeLatchSupport(void) +{ + int pipefd[2]; + + Assert(selfpipe_readfd == -1); + + /* + * Set up the self-pipe that allows a signal handler to wake up the + * select() in WaitLatch. Make the write-end non-blocking, so that + * SetLatch won't block if the event has already been set many times + * filling the kernel buffer. Make the read-end non-blocking too, so that + * we can easily clear the pipe by reading until EAGAIN or EWOULDBLOCK. + */ + if (pipe(pipefd) < 0) + elog(FATAL, "pipe() failed: %m"); + if (fcntl(pipefd[0], F_SETFL, O_NONBLOCK) < 0) + elog(FATAL, "fcntl() failed on read-end of self-pipe: %m"); + if (fcntl(pipefd[1], F_SETFL, O_NONBLOCK) < 0) + elog(FATAL, "fcntl() failed on write-end of self-pipe: %m"); + selfpipe_readfd = pipefd[0]; + selfpipe_writefd = pipefd[1]; +} /* * Initialize a backend-local latch. @@ -72,9 +102,8 @@ static void sendSelfPipeByte(void); void InitLatch(volatile Latch *latch) { - /* Initialize the self-pipe if this is our first latch in the process */ - if (selfpipe_readfd == -1) - initSelfPipe(); + /* Assert InitializeLatchSupport has been called in this process */ + Assert(selfpipe_readfd >= 0); latch->is_set = false; latch->owner_pid = MyProcPid; @@ -116,11 +145,10 @@ InitSharedLatch(volatile Latch *latch) void OwnLatch(volatile Latch *latch) { - Assert(latch->is_shared); + /* Assert InitializeLatchSupport has been called in this process */ + Assert(selfpipe_readfd >= 0); - /* Initialize the self-pipe if this is our first latch in this process */ - if (selfpipe_readfd == -1) - initSelfPipe(); + Assert(latch->is_shared); /* sanity check */ if (latch->owner_pid != 0) @@ -514,30 +542,6 @@ latch_sigusr1_handler(void) sendSelfPipeByte(); } -/* initialize the self-pipe */ -static void -initSelfPipe(void) -{ - int pipefd[2]; - - /* - * Set up the self-pipe that allows a signal handler to wake up the - * select() in WaitLatch. Make the write-end non-blocking, so that - * SetLatch won't block if the event has already been set many times - * filling the kernel buffer. Make the read-end non-blocking too, so that - * we can easily clear the pipe by reading until EAGAIN or EWOULDBLOCK. - */ - if (pipe(pipefd) < 0) - elog(FATAL, "pipe() failed: %m"); - if (fcntl(pipefd[0], F_SETFL, O_NONBLOCK) < 0) - elog(FATAL, "fcntl() failed on read-end of self-pipe: %m"); - if (fcntl(pipefd[1], F_SETFL, O_NONBLOCK) < 0) - elog(FATAL, "fcntl() failed on write-end of self-pipe: %m"); - - selfpipe_readfd = pipefd[0]; - selfpipe_writefd = pipefd[1]; -} - /* Send one byte to the self-pipe, to wake up WaitLatch */ static void sendSelfPipeByte(void) |