From 7d7cc7fd6fbdfca68fe144476078c03d3c36e158 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Fri, 9 Feb 2024 11:11:39 -0500 Subject: Clean up Windows-specific mutex code in libpq and ecpglib. Fix pthread-win32.h and pthread-win32.c to provide a more complete emulation of POSIX pthread mutexes: define PTHREAD_MUTEX_INITIALIZER and make sure that pthread_mutex_lock() can operate on a mutex object that's been initialized that way. Then we don't need the duplicative platform-specific logic in default_threadlock() and pgtls_init(), which we'd otherwise need yet a third copy of for an upcoming bug fix. Also, since default_threadlock() supposes that pthread_mutex_lock() cannot fail, try to ensure that that's actually true, by getting rid of the malloc call that was formerly involved in initializing an emulated mutex. We can define an extra state for the spinlock field instead. Also, replace the similar code in ecpglib/misc.c with this version. While ecpglib's version at least had a POSIX-compliant API, it also had the potential of failing during mutex init (but here, because of CreateMutex failure rather than malloc failure). Since all of misc.c's callers ignore failures, it seems like a wise idea to avoid failures here too. A further improvement in this area could be to unify libpq's and ecpglib's implementations into a src/port/pthread-win32.c file. But that doesn't seem like a bug fix, so I'll desist for now. In preparation for the aforementioned bug fix, back-patch to all supported branches. Discussion: https://postgr.es/m/264860.1707163416@sss.pgh.pa.us --- src/interfaces/libpq/fe-connect.c | 16 ---------------- 1 file changed, 16 deletions(-) (limited to 'src/interfaces/libpq/fe-connect.c') diff --git a/src/interfaces/libpq/fe-connect.c b/src/interfaces/libpq/fe-connect.c index 0278f1c6496..d7945375d33 100644 --- a/src/interfaces/libpq/fe-connect.c +++ b/src/interfaces/libpq/fe-connect.c @@ -7327,24 +7327,8 @@ static void default_threadlock(int acquire) { #ifdef ENABLE_THREAD_SAFETY -#ifndef WIN32 static pthread_mutex_t singlethread_lock = PTHREAD_MUTEX_INITIALIZER; -#else - static pthread_mutex_t singlethread_lock = NULL; - static long mutex_initlock = 0; - if (singlethread_lock == NULL) - { - while (InterlockedExchange(&mutex_initlock, 1) == 1) - /* loop, another thread own the lock */ ; - if (singlethread_lock == NULL) - { - if (pthread_mutex_init(&singlethread_lock, NULL)) - PGTHREAD_ERROR("failed to initialize mutex"); - } - InterlockedExchange(&mutex_initlock, 0); - } -#endif if (acquire) { if (pthread_mutex_lock(&singlethread_lock)) -- cgit v1.2.3