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Diffstat (limited to 'liblo/pthreads.2/pthread_once.x')
| -rw-r--r-- | liblo/pthreads.2/pthread_once.x | 204 |
1 files changed, 204 insertions, 0 deletions
diff --git a/liblo/pthreads.2/pthread_once.x b/liblo/pthreads.2/pthread_once.x new file mode 100644 index 0000000..1d9197d --- /dev/null +++ b/liblo/pthreads.2/pthread_once.x @@ -0,0 +1,204 @@ +/*
+ * pthread_once.c
+ *
+ * Description:
+ * This translation unit implements miscellaneous thread functions.
+ *
+ * --------------------------------------------------------------------------
+ *
+ * Pthreads-win32 - POSIX Threads Library for Win32
+ * Copyright(C) 1998 John E. Bossom
+ * Copyright(C) 1999,2005 Pthreads-win32 contributors
+ *
+ * Contact Email: rpj@callisto.canberra.edu.au
+ *
+ * The current list of contributors is contained
+ * in the file CONTRIBUTORS included with the source
+ * code distribution. The list can also be seen at the
+ * following World Wide Web location:
+ * http://sources.redhat.com/pthreads-win32/contributors.html
+ *
+ * This library 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 of the License, or (at your option) any later version.
+ *
+ * This library 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 library in the file COPYING.LIB;
+ * if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
+ */
+
+#include "pthread.h"
+#include "implement.h"
+
+
+static void PTW32_CDECL
+ptw32_once_init_routine_cleanup(void * arg)
+{
+ pthread_once_t * once_control = (pthread_once_t *) arg;
+
+ /*
+ * Continue to direct new threads into the wait path until the waiter that we
+ * release can reset state to INIT.
+ */
+ (void) PTW32_INTERLOCKED_EXCHANGE((LPLONG)&once_control->state, (LONG)PTW32_ONCE_CANCELLED);
+
+ if (InterlockedExchangeAdd((LPLONG)&once_control->semaphore, 0L)) /* MBR fence */
+ {
+ ReleaseSemaphore(once_control->semaphore, 1, NULL);
+ }
+}
+
+int
+pthread_once (pthread_once_t * once_control, void (*init_routine) (void))
+ /*
+ * ------------------------------------------------------
+ * DOCPUBLIC
+ * If any thread in a process with a once_control parameter
+ * makes a call to pthread_once(), the first call will summon
+ * the init_routine(), but subsequent calls will not. The
+ * once_control parameter determines whether the associated
+ * initialization routine has been called. The init_routine()
+ * is complete upon return of pthread_once().
+ * This function guarantees that one and only one thread
+ * executes the initialization routine, init_routine when
+ * access is controlled by the pthread_once_t control
+ * key.
+ *
+ * pthread_once() is not a cancelation point, but the init_routine
+ * can be. If it's cancelled then the effect on the once_control is
+ * as if pthread_once had never been entered.
+ *
+ *
+ * PARAMETERS
+ * once_control
+ * pointer to an instance of pthread_once_t
+ *
+ * init_routine
+ * pointer to an initialization routine
+ *
+ *
+ * DESCRIPTION
+ * See above.
+ *
+ * RESULTS
+ * 0 success,
+ * EINVAL once_control or init_routine is NULL
+ *
+ * ------------------------------------------------------
+ */
+{
+ int result;
+ int state;
+ HANDLE sema;
+
+ if (once_control == NULL || init_routine == NULL)
+ {
+ result = EINVAL;
+ goto FAIL0;
+ }
+ else
+ {
+ result = 0;
+ }
+
+ while ((state = (int)
+ PTW32_INTERLOCKED_COMPARE_EXCHANGE((PTW32_INTERLOCKED_LPLONG)&once_control->state,
+ (PTW32_INTERLOCKED_LONG)PTW32_ONCE_STARTED,
+ (PTW32_INTERLOCKED_LONG)PTW32_ONCE_INIT))
+ != PTW32_ONCE_DONE)
+ {
+ if (PTW32_ONCE_INIT == state)
+ {
+
+#ifdef _MSC_VER
+#pragma inline_depth(0)
+#endif
+
+ pthread_cleanup_push(ptw32_once_init_routine_cleanup, (void *) once_control);
+ (*init_routine)();
+ pthread_cleanup_pop(0);
+
+#ifdef _MSC_VER
+#pragma inline_depth()
+#endif
+
+ (void) PTW32_INTERLOCKED_EXCHANGE((LPLONG)&once_control->state,
+ (LONG)PTW32_ONCE_DONE);
+
+ /*
+ * we didn't create the semaphore.
+ * it is only there if there is someone waiting.
+ */
+ if (InterlockedExchangeAdd((LPLONG)&once_control->semaphore, 0L)) /* MBR fence */
+ {
+ ReleaseSemaphore(once_control->semaphore,
+ once_control->numSemaphoreUsers, NULL);
+ }
+ }
+ else
+ {
+ if (1 == InterlockedIncrement((LPLONG)&once_control->numSemaphoreUsers))
+
+// if (!InterlockedExchangeAdd((LPLONG)&once_control->semaphore, 0L)) /* MBR fence */
+ {
+ sema = CreateSemaphore(NULL, 0, INT_MAX, NULL);
+
+ if (PTW32_INTERLOCKED_COMPARE_EXCHANGE((PTW32_INTERLOCKED_LPLONG)&once_control->semaphore,
+ (PTW32_INTERLOCKED_LONG)sema,
+ (PTW32_INTERLOCKED_LONG)0))
+ {
+ CloseHandle(sema);
+ }
+ }
+
+ /*
+ * If initter was cancelled then state is CANCELLED.
+ * Until state is reset to INIT, all new threads will enter the wait path.
+ * The woken waiter, if it exists, will also re-enter the wait path, but + * either it or a new thread will reset state = INIT here, continue around the Wait, + * and become the new initter. Any thread that is suspended in the wait path before + * this point will hit this check. Any thread suspended between this check and + * the Wait will wait on a valid semaphore, and possibly continue through it + * if the cancellation handler has incremented (released) it and there were + * no waiters. + */
+ (void) PTW32_INTERLOCKED_COMPARE_EXCHANGE((PTW32_INTERLOCKED_LPLONG)&once_control->state,
+ (PTW32_INTERLOCKED_LONG)PTW32_ONCE_INIT,
+ (PTW32_INTERLOCKED_LONG)PTW32_ONCE_CANCELLED);
+
+ /*
+ * Check 'state' again in case the initting thread has finished
+ * and left before seeing that there was a semaphore.
+ */
+ if (InterlockedExchangeAdd((LPLONG)&once_control->state, 0L) >= PTW32_ONCE_STARTED)
+ {
+ WaitForSingleObject(once_control->semaphore, INFINITE);
+ }
+
+ if (0 == InterlockedDecrement((LPLONG)&once_control->numSemaphoreUsers))
+ {
+ /* we were last */
+ if ((sema =
+ (HANDLE) PTW32_INTERLOCKED_EXCHANGE((LPLONG)&once_control->semaphore, (LONG)0)))
+ {
+ CloseHandle(sema);
+ }
+ }
+ }
+ }
+
+ /*
+ * ------------
+ * Failure Code
+ * ------------
+ */
+FAIL0:
+ return (result);
+} /* pthread_once */
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