diff options
| author | Guenter Bartsch <guenter@users.sourceforge.net> | 2003-04-20 16:42:06 +0000 |
|---|---|---|
| committer | Guenter Bartsch <guenter@users.sourceforge.net> | 2003-04-20 16:42:06 +0000 |
| commit | ce4f3efd78c110c015c54eab05f201d1caac5f8d (patch) | |
| tree | 668c555d5de70518b93426f45fe3e44d7f06663c /win32/contrib/pthreads/condvar.c | |
| parent | 80f6215b607f0ed76f7f75deaf4e4668bc6f244d (diff) | |
| download | xine-lib-ce4f3efd78c110c015c54eab05f201d1caac5f8d.tar.gz xine-lib-ce4f3efd78c110c015c54eab05f201d1caac5f8d.tar.bz2 | |
importing win32 contrib sources and msvc build environment
CVS patchset: 4641
CVS date: 2003/04/20 16:42:06
Diffstat (limited to 'win32/contrib/pthreads/condvar.c')
| -rw-r--r-- | win32/contrib/pthreads/condvar.c | 1219 |
1 files changed, 1219 insertions, 0 deletions
diff --git a/win32/contrib/pthreads/condvar.c b/win32/contrib/pthreads/condvar.c new file mode 100644 index 000000000..c8876c4f2 --- /dev/null +++ b/win32/contrib/pthreads/condvar.c @@ -0,0 +1,1219 @@ +/*
+ * condvar.c
+ *
+ * Description:
+ * This translation unit implements condition variables and their primitives.
+ *
+ * Algorithm:
+ * The algorithm used in this implementation is that developed by
+ * Alexander Terekhov in colaboration with Louis Thomas. The bulk
+ * of the discussion is recorded in the file README.CV, which contains
+ * several generations of both colaborators original algorithms. The final
+ * algorithm used here is the one referred to as
+ *
+ * Algorithm 8a / IMPL_SEM,UNBLOCK_STRATEGY == UNBLOCK_ALL
+ *
+ * presented below in pseudo-code as it appeared:
+ *
+ *
+ * given:
+ * semBlockLock - bin.semaphore
+ * semBlockQueue - semaphore
+ * mtxExternal - mutex or CS
+ * mtxUnblockLock - mutex or CS
+ * nWaitersGone - int
+ * nWaitersBlocked - int
+ * nWaitersToUnblock - int
+ *
+ * wait( timeout ) {
+ *
+ * [auto: register int result ] // error checking omitted
+ * [auto: register int nSignalsWasLeft ]
+ * [auto: register int nWaitersWasGone ]
+ *
+ * sem_wait( semBlockLock );
+ * nWaitersBlocked++;
+ * sem_post( semBlockLock );
+ *
+ * unlock( mtxExternal );
+ * bTimedOut = sem_wait( semBlockQueue,timeout );
+ *
+ * lock( mtxUnblockLock );
+ * if ( 0 != (nSignalsWasLeft = nWaitersToUnblock) ) {
+ * if ( bTimeout ) { // timeout (or canceled)
+ * if ( 0 != nWaitersBlocked ) {
+ * nWaitersBlocked--;
+ * }
+ * else {
+ * nWaitersGone++; // count spurious wakeups.
+ * }
+ * }
+ * if ( 0 == --nWaitersToUnblock ) {
+ * if ( 0 != nWaitersBlocked ) {
+ * sem_post( semBlockLock ); // open the gate.
+ * nSignalsWasLeft = 0; // do not open the gate
+ * // below again.
+ * }
+ * else if ( 0 != (nWaitersWasGone = nWaitersGone) ) {
+ * nWaitersGone = 0;
+ * }
+ * }
+ * }
+ * else if ( INT_MAX/2 == ++nWaitersGone ) { // timeout/canceled or
+ * // spurious semaphore :-)
+ * sem_wait( semBlockLock );
+ * nWaitersBlocked -= nWaitersGone; // something is going on here
+ * // - test of timeouts? :-)
+ * sem_post( semBlockLock );
+ * nWaitersGone = 0;
+ * }
+ * unlock( mtxUnblockLock );
+ *
+ * if ( 1 == nSignalsWasLeft ) {
+ * if ( 0 != nWaitersWasGone ) {
+ * // sem_adjust( semBlockQueue,-nWaitersWasGone );
+ * while ( nWaitersWasGone-- ) {
+ * sem_wait( semBlockQueue ); // better now than spurious later
+ * }
+ * } sem_post( semBlockLock ); // open the gate
+ * }
+ *
+ * lock( mtxExternal );
+ *
+ * return ( bTimedOut ) ? ETIMEOUT : 0;
+ * }
+ *
+ * signal(bAll) {
+ *
+ * [auto: register int result ]
+ * [auto: register int nSignalsToIssue]
+ *
+ * lock( mtxUnblockLock );
+ *
+ * if ( 0 != nWaitersToUnblock ) { // the gate is closed!!!
+ * if ( 0 == nWaitersBlocked ) { // NO-OP
+ * return unlock( mtxUnblockLock );
+ * }
+ * if (bAll) {
+ * nWaitersToUnblock += nSignalsToIssue=nWaitersBlocked;
+ * nWaitersBlocked = 0;
+ * }
+ * else {
+ * nSignalsToIssue = 1;
+ * nWaitersToUnblock++;
+ * nWaitersBlocked--;
+ * }
+ * }
+ * else if ( nWaitersBlocked > nWaitersGone ) { // HARMLESS RACE CONDITION!
+ * sem_wait( semBlockLock ); // close the gate
+ * if ( 0 != nWaitersGone ) {
+ * nWaitersBlocked -= nWaitersGone;
+ * nWaitersGone = 0;
+ * }
+ * if (bAll) {
+ * nSignalsToIssue = nWaitersToUnblock = nWaitersBlocked;
+ * nWaitersBlocked = 0;
+ * }
+ * else {
+ * nSignalsToIssue = nWaitersToUnblock = 1;
+ * nWaitersBlocked--;
+ * }
+ * }
+ * else { // NO-OP
+ * return unlock( mtxUnblockLock );
+ * }
+ *
+ * unlock( mtxUnblockLock );
+ * sem_post( semBlockQueue,nSignalsToIssue );
+ * return result;
+ * }
+ *
+ * -------------------------------------------------------------
+ *
+ * Pthreads-win32 - POSIX Threads Library for Win32
+ * Copyright (C) 1998
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library 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
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; 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 INLINE int
+ptw32_cond_check_need_init (pthread_cond_t *cond)
+{
+ int result = 0;
+
+ /*
+ * The following guarded test is specifically for statically
+ * initialised condition variables (via PTHREAD_OBJECT_INITIALIZER).
+ *
+ * Note that by not providing this synchronisation we risk
+ * introducing race conditions into applications which are
+ * correctly written.
+ *
+ * Approach
+ * --------
+ * We know that static condition variables will not be PROCESS_SHARED
+ * so we can serialise access to internal state using
+ * Win32 Critical Sections rather than Win32 Mutexes.
+ *
+ * If using a single global lock slows applications down too much,
+ * multiple global locks could be created and hashed on some random
+ * value associated with each mutex, the pointer perhaps. At a guess,
+ * a good value for the optimal number of global locks might be
+ * the number of processors + 1.
+ *
+ */
+ EnterCriticalSection(&ptw32_cond_test_init_lock);
+
+ /*
+ * We got here possibly under race
+ * conditions. Check again inside the critical section.
+ * If a static cv has been destroyed, the application can
+ * re-initialise it only by calling pthread_cond_init()
+ * explicitly.
+ */
+ if (*cond == PTHREAD_COND_INITIALIZER)
+ {
+ result = pthread_cond_init(cond, NULL);
+ }
+ else if (*cond == NULL)
+ {
+ /*
+ * The cv has been destroyed while we were waiting to
+ * initialise it, so the operation that caused the
+ * auto-initialisation should fail.
+ */
+ result = EINVAL;
+ }
+
+ LeaveCriticalSection(&ptw32_cond_test_init_lock);
+
+ return result;
+}
+
+
+int
+pthread_condattr_init (pthread_condattr_t * attr)
+ /*
+ * ------------------------------------------------------
+ * DOCPUBLIC
+ * Initializes a condition variable attributes object
+ * with default attributes.
+ *
+ * PARAMETERS
+ * attr
+ * pointer to an instance of pthread_condattr_t
+ *
+ *
+ * DESCRIPTION
+ * Initializes a condition variable attributes object
+ * with default attributes.
+ *
+ * NOTES:
+ * 1) Use to define condition variable types
+ * 2) It is up to the application to ensure
+ * that it doesn't re-init an attribute
+ * without destroying it first. Otherwise
+ * a memory leak is created.
+ *
+ * RESULTS
+ * 0 successfully initialized attr,
+ * ENOMEM insufficient memory for attr.
+ *
+ * ------------------------------------------------------
+ */
+{
+ pthread_condattr_t attr_result;
+ int result = 0;
+
+ attr_result = (pthread_condattr_t) calloc (1, sizeof (*attr_result));
+
+ if (attr_result == NULL)
+ {
+ result = ENOMEM;
+ }
+
+ *attr = attr_result;
+
+ return result;
+
+} /* pthread_condattr_init */
+
+
+int
+pthread_condattr_destroy (pthread_condattr_t * attr)
+ /*
+ * ------------------------------------------------------
+ * DOCPUBLIC
+ * Destroys a condition variable attributes object.
+ * The object can no longer be used.
+ *
+ * PARAMETERS
+ * attr
+ * pointer to an instance of pthread_condattr_t
+ *
+ *
+ * DESCRIPTION
+ * Destroys a condition variable attributes object.
+ * The object can no longer be used.
+ *
+ * NOTES:
+ * 1) Does not affect condition variables created
+ * using 'attr'
+ *
+ * RESULTS
+ * 0 successfully released attr,
+ * EINVAL 'attr' is invalid.
+ *
+ * ------------------------------------------------------
+ */
+{
+ int result = 0;
+
+ if (attr == NULL || *attr == NULL)
+ {
+ result = EINVAL;
+ }
+ else
+ {
+ (void) free (*attr);
+
+ *attr = NULL;
+ result = 0;
+ }
+
+ return result;
+
+} /* pthread_condattr_destroy */
+
+
+int
+pthread_condattr_getpshared (const pthread_condattr_t * attr, int *pshared)
+ /*
+ * ------------------------------------------------------
+ * DOCPUBLIC
+ * Determine whether condition variables created with 'attr'
+ * can be shared between processes.
+ *
+ * PARAMETERS
+ * attr
+ * pointer to an instance of pthread_condattr_t
+ *
+ * pshared
+ * will be set to one of:
+ *
+ * PTHREAD_PROCESS_SHARED
+ * May be shared if in shared memory
+ *
+ * PTHREAD_PROCESS_PRIVATE
+ * Cannot be shared.
+ *
+ *
+ * DESCRIPTION
+ * Condition Variables created with 'attr' can be shared
+ * between processes if pthread_cond_t variable is allocated
+ * in memory shared by these processes.
+ * NOTES:
+ * 1) pshared condition variables MUST be allocated in
+ * shared memory.
+ *
+ * 2) The following macro is defined if shared mutexes
+ * are supported:
+ * _POSIX_THREAD_PROCESS_SHARED
+ *
+ * RESULTS
+ * 0 successfully retrieved attribute,
+ * EINVAL 'attr' is invalid,
+ *
+ * ------------------------------------------------------
+ */
+{
+ int result;
+
+ if ((attr != NULL && *attr != NULL) && (pshared != NULL))
+ {
+ *pshared = (*attr)->pshared;
+ result = 0;
+ }
+ else
+ {
+ *pshared = PTHREAD_PROCESS_PRIVATE;
+ result = EINVAL;
+ }
+
+ return result;
+
+} /* pthread_condattr_getpshared */
+
+
+int
+pthread_condattr_setpshared (pthread_condattr_t * attr, int pshared)
+ /*
+ * ------------------------------------------------------
+ * DOCPUBLIC
+ * Mutexes created with 'attr' can be shared between
+ * processes if pthread_mutex_t variable is allocated
+ * in memory shared by these processes.
+ *
+ * PARAMETERS
+ * attr
+ * pointer to an instance of pthread_mutexattr_t
+ *
+ * pshared
+ * must be one of:
+ *
+ * PTHREAD_PROCESS_SHARED
+ * May be shared if in shared memory
+ *
+ * PTHREAD_PROCESS_PRIVATE
+ * Cannot be shared.
+ *
+ * DESCRIPTION
+ * Mutexes creatd with 'attr' can be shared between
+ * processes if pthread_mutex_t variable is allocated
+ * in memory shared by these processes.
+ *
+ * NOTES:
+ * 1) pshared mutexes MUST be allocated in shared
+ * memory.
+ *
+ * 2) The following macro is defined if shared mutexes
+ * are supported:
+ * _POSIX_THREAD_PROCESS_SHARED
+ *
+ * RESULTS
+ * 0 successfully set attribute,
+ * EINVAL 'attr' or pshared is invalid,
+ * ENOSYS PTHREAD_PROCESS_SHARED not supported,
+ *
+ * ------------------------------------------------------
+ */
+{
+ int result;
+
+ if ((attr != NULL && *attr != NULL)
+ && ((pshared == PTHREAD_PROCESS_SHARED)
+ || (pshared == PTHREAD_PROCESS_PRIVATE)))
+ {
+ if (pshared == PTHREAD_PROCESS_SHARED)
+ {
+
+#if !defined( _POSIX_THREAD_PROCESS_SHARED )
+ result = ENOSYS;
+ pshared = PTHREAD_PROCESS_PRIVATE;
+#else
+ result = 0;
+
+#endif /* _POSIX_THREAD_PROCESS_SHARED */
+
+ }
+ else
+ {
+ result = 0;
+ }
+
+ (*attr)->pshared = pshared;
+ }
+ else
+ {
+ result = EINVAL;
+ }
+
+ return result;
+
+} /* pthread_condattr_setpshared */
+
+
+int
+pthread_cond_init (pthread_cond_t * cond, const pthread_condattr_t * attr)
+ /*
+ * ------------------------------------------------------
+ * DOCPUBLIC
+ * This function initializes a condition variable.
+ *
+ * PARAMETERS
+ * cond
+ * pointer to an instance of pthread_cond_t
+ *
+ * attr
+ * specifies optional creation attributes.
+ *
+ *
+ * DESCRIPTION
+ * This function initializes a condition variable.
+ *
+ * RESULTS
+ * 0 successfully created condition variable,
+ * EINVAL 'attr' is invalid,
+ * EAGAIN insufficient resources (other than
+ * memory,
+ * ENOMEM insufficient memory,
+ * EBUSY 'cond' is already initialized,
+ *
+ * ------------------------------------------------------
+ */
+{
+ int result;
+ pthread_cond_t cv = NULL;
+
+ if (cond == NULL)
+ {
+ return EINVAL;
+ }
+
+ if ((attr != NULL && *attr != NULL) &&
+ ((*attr)->pshared == PTHREAD_PROCESS_SHARED))
+ {
+ /*
+ * Creating condition variable that can be shared between
+ * processes.
+ */
+ result = ENOSYS;
+ goto DONE;
+ }
+
+ cv = (pthread_cond_t) calloc(1, sizeof (*cv));
+
+ if (cv == NULL)
+ {
+ result = ENOMEM;
+ goto DONE;
+ }
+
+ cv->nWaitersBlocked = 0;
+ cv->nWaitersUnblocked = 0;
+ cv->nWaitersToUnblock = 0;
+ cv->nWaitersGone = 0;
+
+ if (sem_init(&(cv->semBlockLock), 0, 1) != 0)
+ {
+ result = errno;
+ goto FAIL0;
+ }
+
+ if (sem_init(&(cv->semBlockQueue), 0, 0) != 0)
+ {
+ result = errno;
+ goto FAIL1;
+ }
+
+ if ((result = pthread_mutex_init(&(cv->mtxUnblockLock), 0)) != 0)
+ {
+ goto FAIL2;
+ }
+
+ result = 0;
+
+ goto DONE;
+
+ /*
+ * -------------
+ * Failed...
+ * -------------
+ */
+FAIL2:
+ (void) sem_destroy(&(cv->semBlockQueue));
+
+FAIL1:
+ (void) sem_destroy(&(cv->semBlockLock));
+
+FAIL0:
+ (void) free(cv);
+ cv = NULL;
+
+DONE:
+ *cond = cv;
+
+ return result;
+
+} /* pthread_cond_init */
+
+
+int
+pthread_cond_destroy (pthread_cond_t * cond)
+ /*
+ * ------------------------------------------------------
+ * DOCPUBLIC
+ * This function destroys a condition variable
+ *
+ *
+ * PARAMETERS
+ * cond
+ * pointer to an instance of pthread_cond_t
+ *
+ *
+ * DESCRIPTION
+ * This function destroys a condition variable.
+ *
+ * NOTES:
+ * 1) Safest after wakeup from 'cond', when
+ * no other threads will wait.
+ *
+ * RESULTS
+ * 0 successfully released condition variable,
+ * EINVAL 'cond' is invalid,
+ * EBUSY 'cond' is in use,
+ *
+ * ------------------------------------------------------
+ */
+{
+ pthread_cond_t cv;
+ int result = 0, result1 = 0, result2 = 0;
+
+ /*
+ * Assuming any race condition here is harmless.
+ */
+ if (cond == NULL
+ || *cond == NULL)
+ {
+ return EINVAL;
+ }
+
+ if (*cond != PTHREAD_COND_INITIALIZER)
+ {
+ cv = *cond;
+
+ /*
+ * Synchronize access to waiters blocked count (LEVEL-1)
+ */
+ if (sem_wait(&(cv->semBlockLock)) != 0)
+ {
+ return errno;
+ }
+
+ /*
+ * Synchronize access to waiters (to)unblock(ed) counts (LEVEL-2)
+ */
+ if ((result = pthread_mutex_lock(&(cv->mtxUnblockLock))) != 0)
+ {
+ (void) sem_post(&(cv->semBlockLock));
+ return result;
+ }
+
+ /*
+ * Check whether cv is still busy (still has waiters)
+ */
+ if (cv->nWaitersBlocked - cv->nWaitersGone - cv->nWaitersUnblocked > 0)
+ {
+ if (sem_post(&(cv->semBlockLock)) != 0)
+ {
+ result = errno;
+ }
+ result1 = pthread_mutex_unlock(&(cv->mtxUnblockLock));
+ result2 = EBUSY;
+ }
+ else
+ {
+ /*
+ * Now it is safe to destroy
+ */
+ *cond = NULL;
+ if (sem_destroy(&(cv->semBlockLock)) != 0)
+ {
+ result = errno;
+ }
+ if (sem_destroy(&(cv->semBlockQueue)) != 0)
+ {
+ result1 = errno;
+ }
+ if ((result2 = pthread_mutex_unlock(&(cv->mtxUnblockLock))) == 0)
+ {
+ result2 = pthread_mutex_destroy(&(cv->mtxUnblockLock));
+ }
+
+ (void) free(cv);
+ }
+ }
+ else
+ {
+ /*
+ * See notes in ptw32_cond_check_need_init() above also.
+ */
+ EnterCriticalSection(&ptw32_cond_test_init_lock);
+
+ /*
+ * Check again.
+ */
+ if (*cond == PTHREAD_COND_INITIALIZER)
+ {
+ /*
+ * This is all we need to do to destroy a statically
+ * initialised cond that has not yet been used (initialised).
+ * If we get to here, another thread
+ * waiting to initialise this cond will get an EINVAL.
+ */
+ *cond = NULL;
+ }
+ else
+ {
+ /*
+ * The cv has been initialised while we were waiting
+ * so assume it's in use.
+ */
+ result = EBUSY;
+ }
+
+ LeaveCriticalSection(&ptw32_cond_test_init_lock);
+ }
+
+ return ((result != 0) ? result : ((result1 != 0) ? result1 : result2));
+
+}
+
+/*
+ * Arguments for cond_wait_cleanup, since we can only pass a
+ * single void * to it.
+ */
+typedef struct {
+ pthread_mutex_t * mutexPtr;
+ pthread_cond_t cv;
+ int * resultPtr;
+ int signaled;
+} ptw32_cond_wait_cleanup_args_t;
+
+static void
+ptw32_cond_wait_cleanup(void * args)
+{
+ ptw32_cond_wait_cleanup_args_t * cleanup_args = (ptw32_cond_wait_cleanup_args_t *) args;
+ pthread_cond_t cv = cleanup_args->cv;
+ int * resultPtr = cleanup_args->resultPtr;
+ int nSignalsWasLeft;
+ int nWaitersWasGone = 0; /* Initialised to quell warnings. */
+ int result;
+
+ /*
+ * Whether we got here as a result of signal/broadcast or because of
+ * timeout on wait or thread cancellation we indicate that we are no
+ * longer waiting. The waiter is responsible for adjusting waiters
+ * (to)unblock(ed) counts (protected by unblock lock).
+ */
+ if ((result = pthread_mutex_lock(&(cv->mtxUnblockLock))) != 0)
+ {
+ *resultPtr = result;
+ return;
+ }
+
+ if ( 0 != (nSignalsWasLeft = cv->nWaitersToUnblock) )
+ {
+ if ( !cleanup_args->signaled )
+ {
+ if ( 0 != cv->nWaitersBlocked )
+ {
+ (cv->nWaitersBlocked)--;
+ }
+ else
+ {
+ (cv->nWaitersGone)++;
+ }
+ }
+ if ( 0 == --(cv->nWaitersToUnblock) )
+ {
+ if ( 0 != cv->nWaitersBlocked )
+ {
+ if (sem_post( &(cv->semBlockLock) ) != 0)
+ {
+ *resultPtr = errno;
+ /*
+ * This is a fatal error for this CV,
+ * so we deliberately don't unlock
+ * cv->mtxUnblockLock before returning.
+ */
+ return;
+ }
+ nSignalsWasLeft = 0;
+ }
+ else if ( 0 != (nWaitersWasGone = cv->nWaitersGone) )
+ {
+ cv->nWaitersGone = 0;
+ }
+ }
+ }
+ else if ( INT_MAX/2 == ++(cv->nWaitersGone) )
+ {
+ if (sem_wait( &(cv->semBlockLock) ) != 0)
+ {
+ *resultPtr = errno;
+ /*
+ * This is a fatal error for this CV,
+ * so we deliberately don't unlock
+ * cv->mtxUnblockLock before returning.
+ */
+ return;
+ }
+ cv->nWaitersBlocked -= cv->nWaitersGone;
+ if (sem_post( &(cv->semBlockLock) ) != 0)
+ {
+ *resultPtr = errno;
+ /*
+ * This is a fatal error for this CV,
+ * so we deliberately don't unlock
+ * cv->mtxUnblockLock before returning.
+ */
+ return;
+ }
+ cv->nWaitersGone = 0;
+ }
+
+ if ((result = pthread_mutex_unlock(&(cv->mtxUnblockLock))) != 0)
+ {
+ *resultPtr = result;
+ return;
+ }
+
+ if ( 1 == nSignalsWasLeft )
+ {
+ if ( 0 != nWaitersWasGone )
+ {
+ // sem_adjust( &(cv->semBlockQueue), -nWaitersWasGone );
+ while ( nWaitersWasGone-- )
+ {
+ if (sem_wait( &(cv->semBlockQueue)) != 0 )
+ {
+ *resultPtr = errno;
+ return;
+ }
+ }
+ }
+ if (sem_post(&(cv->semBlockLock)) != 0)
+ {
+ *resultPtr = errno;
+ return;
+ }
+ }
+
+ /*
+ * XSH: Upon successful return, the mutex has been locked and is owned
+ * by the calling thread
+ */
+ if ((result = pthread_mutex_lock(cleanup_args->mutexPtr)) != 0)
+ {
+ *resultPtr = result;
+ }
+
+} /* ptw32_cond_wait_cleanup */
+
+static INLINE int
+ptw32_cond_timedwait (pthread_cond_t * cond,
+ pthread_mutex_t * mutex,
+ const struct timespec *abstime)
+{
+ int result = 0;
+ pthread_cond_t cv;
+ ptw32_cond_wait_cleanup_args_t cleanup_args;
+
+ if (cond == NULL || *cond == NULL)
+ {
+ return EINVAL;
+ }
+
+ /*
+ * We do a quick check to see if we need to do more work
+ * to initialise a static condition variable. We check
+ * again inside the guarded section of ptw32_cond_check_need_init()
+ * to avoid race conditions.
+ */
+ if (*cond == PTHREAD_COND_INITIALIZER)
+ {
+ result = ptw32_cond_check_need_init(cond);
+ }
+
+ if (result != 0 && result != EBUSY)
+ {
+ return result;
+ }
+
+ cv = *cond;
+
+ if (sem_wait(&(cv->semBlockLock)) != 0)
+ {
+ return errno;
+ }
+
+ cv->nWaitersBlocked++;
+
+ if (sem_post(&(cv->semBlockLock)) != 0)
+ {
+ return errno;
+ }
+
+ /*
+ * Setup this waiter cleanup handler
+ */
+ cleanup_args.mutexPtr = mutex;
+ cleanup_args.cv = cv;
+ cleanup_args.resultPtr = &result;
+ /*
+ * If we're canceled, or the cancelable wait fails for any reason,
+ * including a timeout, then tell the cleanup routine that we
+ * have not been signaled.
+ */
+ cleanup_args.signaled = 0;
+
+ pthread_cleanup_push(ptw32_cond_wait_cleanup, (void *) &cleanup_args);
+
+ /*
+ * Now we can release 'mutex' and...
+ */
+ if ((result = pthread_mutex_unlock(mutex)) == 0)
+ {
+
+ /*
+ * ...wait to be awakened by
+ * pthread_cond_signal, or
+ * pthread_cond_broadcast, or
+ * timeout, or
+ * thread cancellation
+ *
+ * Note:
+ *
+ * ptw32_sem_timedwait is a cancellation point,
+ * hence providing the mechanism for making
+ * pthread_cond_wait a cancellation point.
+ * We use the cleanup mechanism to ensure we
+ * re-lock the mutex and adjust (to)unblock(ed) waiters
+ * counts if we are cancelled, timed out or signalled.
+ */
+ if (ptw32_sem_timedwait(&(cv->semBlockQueue), abstime) != 0)
+ {
+ result = errno;
+ }
+ }
+
+ /*
+ * Not executed if we're canceled. Signaled is false if we timed out.
+ */
+ cleanup_args.signaled = (result == 0);
+
+ /*
+ * Always cleanup
+ */
+ pthread_cleanup_pop(1);
+
+ /*
+ * "result" can be modified by the cleanup handler.
+ */
+ return result;
+
+} /* ptw32_cond_timedwait */
+
+
+static INLINE int
+ptw32_cond_unblock (pthread_cond_t * cond,
+ int unblockAll)
+ /*
+ * Notes.
+ *
+ * Does not use the external mutex for synchronisation,
+ * therefore semBlockLock is needed.
+ * mtxUnblockLock is for LEVEL-2 synch. LEVEL-2 is the
+ * state where the external mutex is not necessarily locked by
+ * any thread, ie. between cond_wait unlocking and re-acquiring
+ * the lock after having been signaled or a timeout or
+ * cancellation.
+ *
+ * Uses the following CV elements:
+ * nWaitersBlocked
+ * nWaitersToUnblock
+ * nWaitersGone
+ * mtxUnblockLock
+ * semBlockLock
+ * semBlockQueue
+ */
+{
+ int result;
+ pthread_cond_t cv;
+ int nSignalsToIssue;
+
+ if (cond == NULL || *cond == NULL)
+ {
+ return EINVAL;
+ }
+
+ cv = *cond;
+
+ /*
+ * No-op if the CV is static and hasn't been initialised yet.
+ * Assuming that any race condition is harmless.
+ */
+ if (cv == PTHREAD_COND_INITIALIZER)
+ {
+ return 0;
+ }
+
+ if ((result = pthread_mutex_lock(&(cv->mtxUnblockLock))) != 0)
+ {
+ return result;
+ }
+
+ if ( 0 != cv->nWaitersToUnblock )
+ {
+ if ( 0 == cv->nWaitersBlocked )
+ {
+ return pthread_mutex_unlock( &(cv->mtxUnblockLock) );
+ }
+ if (unblockAll)
+ {
+ cv->nWaitersToUnblock += (nSignalsToIssue = cv->nWaitersBlocked);
+ cv->nWaitersBlocked = 0;
+ }
+ else
+ {
+ nSignalsToIssue = 1;
+ cv->nWaitersToUnblock++;
+ cv->nWaitersBlocked--;
+ }
+ }
+ else if ( cv->nWaitersBlocked > cv->nWaitersGone )
+ {
+ if (sem_wait( &(cv->semBlockLock) ) != 0)
+ {
+ result = errno;
+ (void) pthread_mutex_unlock( &(cv->mtxUnblockLock) );
+ return result;
+ }
+ if ( 0 != cv->nWaitersGone )
+ {
+ cv->nWaitersBlocked -= cv->nWaitersGone;
+ cv->nWaitersGone = 0;
+ }
+ if (unblockAll)
+ {
+ nSignalsToIssue = cv->nWaitersToUnblock = cv->nWaitersBlocked;
+ cv->nWaitersBlocked = 0;
+ }
+ else
+ {
+ nSignalsToIssue = cv->nWaitersToUnblock = 1;
+ cv->nWaitersBlocked--;
+ }
+ }
+ else
+ {
+ return pthread_mutex_unlock( &(cv->mtxUnblockLock) );
+ }
+
+ if ((result = pthread_mutex_unlock( &(cv->mtxUnblockLock) )) == 0)
+ {
+ if (sem_post_multiple( &(cv->semBlockQueue), nSignalsToIssue ) != 0)
+ {
+ result = errno;
+ }
+ }
+
+ return result;
+
+} /* ptw32_cond_unblock */
+
+int
+pthread_cond_wait (pthread_cond_t * cond,
+ pthread_mutex_t * mutex)
+ /*
+ * ------------------------------------------------------
+ * DOCPUBLIC
+ * This function waits on a condition variable until
+ * awakened by a signal or broadcast.
+ *
+ * Caller MUST be holding the mutex lock; the
+ * lock is released and the caller is blocked waiting
+ * on 'cond'. When 'cond' is signaled, the mutex
+ * is re-acquired before returning to the caller.
+ *
+ * PARAMETERS
+ * cond
+ * pointer to an instance of pthread_cond_t
+ *
+ * mutex
+ * pointer to an instance of pthread_mutex_t
+ *
+ *
+ * DESCRIPTION
+ * This function waits on a condition variable until
+ * awakened by a signal or broadcast.
+ *
+ * NOTES:
+ *
+ * 1) The function must be called with 'mutex' LOCKED
+ * by the calling thread, or undefined behaviour
+ * will result.
+ *
+ * 2) This routine atomically releases 'mutex' and causes
+ * the calling thread to block on the condition variable.
+ * The blocked thread may be awakened by
+ * pthread_cond_signal or
+ * pthread_cond_broadcast.
+ *
+ * Upon successful completion, the 'mutex' has been locked and
+ * is owned by the calling thread.
+ *
+ *
+ * RESULTS
+ * 0 caught condition; mutex released,
+ * EINVAL 'cond' or 'mutex' is invalid,
+ * EINVAL different mutexes for concurrent waits,
+ * EINVAL mutex is not held by the calling thread,
+ *
+ * ------------------------------------------------------
+ */
+{
+ /*
+ * The NULL abstime arg means INFINITE waiting.
+ */
+ return (ptw32_cond_timedwait(cond, mutex, NULL));
+
+} /* pthread_cond_wait */
+
+
+int
+pthread_cond_timedwait (pthread_cond_t * cond,
+ pthread_mutex_t * mutex,
+ const struct timespec *abstime)
+ /*
+ * ------------------------------------------------------
+ * DOCPUBLIC
+ * This function waits on a condition variable either until
+ * awakened by a signal or broadcast; or until the time
+ * specified by abstime passes.
+ *
+ * PARAMETERS
+ * cond
+ * pointer to an instance of pthread_cond_t
+ *
+ * mutex
+ * pointer to an instance of pthread_mutex_t
+ *
+ * abstime
+ * pointer to an instance of (const struct timespec)
+ *
+ *
+ * DESCRIPTION
+ * This function waits on a condition variable either until
+ * awakened by a signal or broadcast; or until the time
+ * specified by abstime passes.
+ *
+ * NOTES:
+ * 1) The function must be called with 'mutex' LOCKED
+ * by the calling thread, or undefined behaviour
+ * will result.
+ *
+ * 2) This routine atomically releases 'mutex' and causes
+ * the calling thread to block on the condition variable.
+ * The blocked thread may be awakened by
+ * pthread_cond_signal or
+ * pthread_cond_broadcast.
+ *
+ *
+ * RESULTS
+ * 0 caught condition; mutex released,
+ * EINVAL 'cond', 'mutex', or abstime is invalid,
+ * EINVAL different mutexes for concurrent waits,
+ * EINVAL mutex is not held by the calling thread,
+ * ETIMEDOUT abstime ellapsed before cond was signaled.
+ *
+ * ------------------------------------------------------
+ */
+{
+ if (abstime == NULL)
+ {
+ return EINVAL;
+ }
+
+ return (ptw32_cond_timedwait(cond, mutex, abstime));
+
+} /* pthread_cond_timedwait */
+
+
+int
+pthread_cond_signal (pthread_cond_t * cond)
+ /*
+ * ------------------------------------------------------
+ * DOCPUBLIC
+ * This function signals a condition variable, waking
+ * one waiting thread.
+ * If SCHED_FIFO or SCHED_RR policy threads are waiting
+ * the highest priority waiter is awakened; otherwise,
+ * an unspecified waiter is awakened.
+ *
+ * PARAMETERS
+ * cond
+ * pointer to an instance of pthread_cond_t
+ *
+ *
+ * DESCRIPTION
+ * This function signals a condition variable, waking
+ * one waiting thread.
+ * If SCHED_FIFO or SCHED_RR policy threads are waiting
+ * the highest priority waiter is awakened; otherwise,
+ * an unspecified waiter is awakened.
+ *
+ * NOTES:
+ *
+ * 1) Use when any waiter can respond and only one need
+ * respond (all waiters being equal).
+ *
+ * RESULTS
+ * 0 successfully signaled condition,
+ * EINVAL 'cond' is invalid,
+ *
+ * ------------------------------------------------------
+ */
+{
+ /*
+ * The '0'(FALSE) unblockAll arg means unblock ONE waiter.
+ */
+ return (ptw32_cond_unblock(cond, 0));
+
+} /* pthread_cond_signal */
+
+int
+pthread_cond_broadcast (pthread_cond_t * cond)
+ /*
+ * ------------------------------------------------------
+ * DOCPUBLIC
+ * This function broadcasts the condition variable,
+ * waking all current waiters.
+ *
+ * PARAMETERS
+ * cond
+ * pointer to an instance of pthread_cond_t
+ *
+ *
+ * DESCRIPTION
+ * This function signals a condition variable, waking
+ * all waiting threads.
+ *
+ * NOTES:
+ *
+ * 1) Use when more than one waiter may respond to
+ * predicate change or if any waiting thread may
+ * not be able to respond
+ *
+ * RESULTS
+ * 0 successfully signalled condition to all
+ * waiting threads,
+ * EINVAL 'cond' is invalid
+ * ENOSPC a required resource has been exhausted,
+ *
+ * ------------------------------------------------------
+ */
+{
+ /*
+ * The '1'(TRUE) unblockAll arg means unblock ALL waiters.
+ */
+ return (ptw32_cond_unblock(cond, 1));
+
+} /* pthread_cond_broadcast */
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