diff options
Diffstat (limited to 'lib/windows-timedmutex.c')
| -rw-r--r-- | lib/windows-timedmutex.c | 227 |
1 files changed, 227 insertions, 0 deletions
diff --git a/lib/windows-timedmutex.c b/lib/windows-timedmutex.c new file mode 100644 index 0000000..301c80e --- /dev/null +++ b/lib/windows-timedmutex.c @@ -0,0 +1,227 @@ +/* Timed mutexes (native Windows implementation). + Copyright (C) 2005-2023 Free Software Foundation, Inc. + + This file is free software: you can redistribute it and/or modify + it under the terms of the GNU Lesser General Public License as + published by the Free Software Foundation; either version 2.1 of the + License, or (at your option) any later version. + + This file is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public License + along with this program. If not, see <https://www.gnu.org/licenses/>. */ + +/* Written by Bruno Haible <bruno@clisp.org>, 2005, 2019. + Based on GCC's gthr-win32.h. */ + +#include <config.h> + +/* Specification. */ +#include "windows-timedmutex.h" + +#include <errno.h> +#include <stdlib.h> +#include <sys/time.h> + +/* Don't assume that UNICODE is not defined. */ +#undef CreateEvent +#define CreateEvent CreateEventA + +int +glwthread_timedmutex_init (glwthread_timedmutex_t *mutex) +{ + /* Attempt to allocate an auto-reset event object. */ + /* CreateEvent + <https://docs.microsoft.com/en-us/windows/desktop/api/synchapi/nf-synchapi-createeventa> */ + HANDLE event = CreateEvent (NULL, FALSE, FALSE, NULL); + if (event == INVALID_HANDLE_VALUE) + return EAGAIN; + mutex->event = event; + InitializeCriticalSection (&mutex->lock); + mutex->guard.done = 1; + return 0; +} + +int +glwthread_timedmutex_lock (glwthread_timedmutex_t *mutex) +{ + if (!mutex->guard.done) + { + if (InterlockedIncrement (&mutex->guard.started) == 0) + { + /* This thread is the first one to need this mutex. + Initialize it. */ + int err = glwthread_timedmutex_init (mutex); + if (err != 0) + { + /* Undo increment. */ + InterlockedDecrement (&mutex->guard.started); + return err; + } + } + else + { + /* Don't let mutex->guard.started grow and wrap around. */ + InterlockedDecrement (&mutex->guard.started); + /* Yield the CPU while waiting for another thread to finish + initializing this mutex. */ + while (!mutex->guard.done) + Sleep (0); + } + } + EnterCriticalSection (&mutex->lock); + return 0; +} + +int +glwthread_timedmutex_trylock (glwthread_timedmutex_t *mutex) +{ + if (!mutex->guard.done) + { + if (InterlockedIncrement (&mutex->guard.started) == 0) + { + /* This thread is the first one to need this mutex. + Initialize it. */ + int err = glwthread_timedmutex_init (mutex); + if (err != 0) + { + /* Undo increment. */ + InterlockedDecrement (&mutex->guard.started); + return err; + } + } + else + { + /* Don't let mutex->guard.started grow and wrap around. */ + InterlockedDecrement (&mutex->guard.started); + /* Let another thread finish initializing this mutex, and let it also + lock this mutex. */ + return EBUSY; + } + } + if (!TryEnterCriticalSection (&mutex->lock)) + return EBUSY; + return 0; +} + +int +glwthread_timedmutex_timedlock (glwthread_timedmutex_t *mutex, + const struct timespec *abstime) +{ + if (!mutex->guard.done) + { + if (InterlockedIncrement (&mutex->guard.started) == 0) + { + /* This thread is the first one to need this mutex. + Initialize it. */ + int err = glwthread_timedmutex_init (mutex); + if (err != 0) + { + /* Undo increment. */ + InterlockedDecrement (&mutex->guard.started); + return err; + } + } + else + { + /* Don't let mutex->guard.started grow and wrap around. */ + InterlockedDecrement (&mutex->guard.started); + /* Yield the CPU while waiting for another thread to finish + initializing this mutex. */ + while (!mutex->guard.done) + Sleep (0); + } + } + + /* POSIX says: + "Under no circumstance shall the function fail with a timeout if + the mutex can be locked immediately. The validity of the abstime + parameter need not be checked if the mutex can be locked + immediately." + Therefore start the loop with a TryEnterCriticalSection call. */ + for (;;) + { + if (TryEnterCriticalSection (&mutex->lock)) + break; + + { + struct timeval currtime; + DWORD timeout; + DWORD result; + + gettimeofday (&currtime, NULL); + + /* Wait until another thread signals the event or until the + abstime passes. */ + if (currtime.tv_sec > abstime->tv_sec) + timeout = 0; + else + { + unsigned long seconds = abstime->tv_sec - currtime.tv_sec; + timeout = seconds * 1000; + if (timeout / 1000 != seconds) /* overflow? */ + timeout = INFINITE; + else + { + long milliseconds = + abstime->tv_nsec / 1000000 - currtime.tv_usec / 1000; + if (milliseconds >= 0) + { + timeout += milliseconds; + if (timeout < milliseconds) /* overflow? */ + timeout = INFINITE; + } + else + { + if (timeout >= - milliseconds) + timeout -= (- milliseconds); + else + timeout = 0; + } + } + } + if (timeout == 0) + return ETIMEDOUT; + + /* WaitForSingleObject + <https://docs.microsoft.com/en-us/windows/desktop/api/synchapi/nf-synchapi-waitforsingleobject> */ + result = WaitForSingleObject (mutex->event, timeout); + if (result == WAIT_FAILED) + abort (); + if (result == WAIT_TIMEOUT) + return ETIMEDOUT; + /* Another thread has just unlocked the mutex. We have good chances at + locking it now. */ + } + } + return 0; +} + +int +glwthread_timedmutex_unlock (glwthread_timedmutex_t *mutex) +{ + if (!mutex->guard.done) + return EINVAL; + LeaveCriticalSection (&mutex->lock); + /* Notify one of the threads that were waiting with a timeout. */ + /* SetEvent + <https://docs.microsoft.com/en-us/windows/desktop/api/synchapi/nf-synchapi-setevent> */ + SetEvent (mutex->event); + return 0; +} + +int +glwthread_timedmutex_destroy (glwthread_timedmutex_t *mutex) +{ + if (!mutex->guard.done) + return EINVAL; + DeleteCriticalSection (&mutex->lock); + /* CloseHandle + <https://docs.microsoft.com/en-us/windows/desktop/api/handleapi/nf-handleapi-closehandle> */ + CloseHandle (mutex->event); + mutex->guard.done = 0; + return 0; +} |