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authorrpj <rpj>2002-02-18 03:16:52 +0000
committerrpj <rpj>2002-02-18 03:16:52 +0000
commita416ab17ecf9f2cb0f1e3f7bd645a8d1ce690ca2 (patch)
tree72f776cd64e48824a5578ff7a523bc69097143b4 /rwlock.c
parente6f1797e9e9925ae7f9dda54806ef8f52ae3ed07 (diff)
Major reorganisation of source code; new routine and tests added.
Diffstat (limited to 'rwlock.c')
-rw-r--r--rwlock.c826
1 files changed, 12 insertions, 814 deletions
diff --git a/rwlock.c b/rwlock.c
index 96a85e4..381a2ad 100644
--- a/rwlock.c
+++ b/rwlock.c
@@ -34,817 +34,15 @@
* 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
-#include <errno.h>
-#include <limits.h>
-
-#include "pthread.h"
-#include "implement.h"
-
-static INLINE int
-ptw32_rwlock_check_need_init(pthread_rwlock_t *rwlock)
-{
- int result = 0;
-
- /*
- * The following guarded test is specifically for statically
- * initialised rwlocks (via PTHREAD_RWLOCK_INITIALIZER).
- *
- * Note that by not providing this synchronisation we risk
- * introducing race conditions into applications which are
- * correctly written.
- *
- * Approach
- * --------
- * We know that static rwlocks 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_rwlock_test_init_lock);
-
- /*
- * We got here possibly under race
- * conditions. Check again inside the critical section
- * and only initialise if the rwlock is valid (not been destroyed).
- * If a static rwlock has been destroyed, the application can
- * re-initialise it only by calling pthread_rwlock_init()
- * explicitly.
- */
- if (*rwlock == PTHREAD_RWLOCK_INITIALIZER)
- {
- result = pthread_rwlock_init(rwlock, NULL);
- }
- else if (*rwlock == NULL)
- {
- /*
- * The rwlock has been destroyed while we were waiting to
- * initialise it, so the operation that caused the
- * auto-initialisation should fail.
- */
- result = EINVAL;
- }
-
- LeaveCriticalSection(&ptw32_rwlock_test_init_lock);
-
- return result;
-}
-
-int
-pthread_rwlock_init(pthread_rwlock_t *rwlock, const pthread_rwlockattr_t *attr)
-{
- int result;
- pthread_rwlock_t rwl = 0;
-
- if (rwlock == NULL)
- {
- return EINVAL;
- }
-
- if (attr != NULL && *attr != NULL)
- {
- result = EINVAL; /* Not supported */
- goto DONE;
- }
-
- rwl = (pthread_rwlock_t) calloc(1, sizeof(*rwl));
-
- if (rwl == NULL)
- {
- result = ENOMEM;
- goto DONE;
- }
-
- rwl->nSharedAccessCount = 0;
- rwl->nExclusiveAccessCount = 0;
- rwl->nCompletedSharedAccessCount = 0;
-
- result = pthread_mutex_init(&rwl->mtxExclusiveAccess, NULL);
- if (result != 0)
- {
- goto FAIL0;
- }
-
- result = pthread_mutex_init(&rwl->mtxSharedAccessCompleted, NULL);
- if (result != 0)
- {
- goto FAIL1;
- }
-
- result = pthread_cond_init(&rwl->cndSharedAccessCompleted, NULL);
- if (result != 0)
- {
- goto FAIL2;
- }
-
- rwl->nMagic = PTW32_RWLOCK_MAGIC;
-
- result = 0;
- goto DONE;
-
-FAIL2:
- (void) pthread_mutex_destroy(&(rwl->mtxSharedAccessCompleted));
-
-FAIL1:
- (void) pthread_mutex_destroy(&(rwl->mtxExclusiveAccess));
-
-FAIL0:
- (void) free(rwl);
- rwl = NULL;
-
-DONE:
- *rwlock = rwl;
-
- return result;
-}
-
-int
-pthread_rwlock_destroy(pthread_rwlock_t *rwlock)
-{
- pthread_rwlock_t rwl;
- int result = 0, result1 = 0, result2 = 0;
-
- if (rwlock == NULL || *rwlock == NULL)
- {
- return EINVAL;
- }
-
- if (*rwlock != PTHREAD_RWLOCK_INITIALIZER)
- {
- rwl = *rwlock;
-
- if (rwl->nMagic != PTW32_RWLOCK_MAGIC)
- {
- return EINVAL;
- }
-
- if ((result = pthread_mutex_lock(&(rwl->mtxExclusiveAccess))) != 0)
- {
- return result;
- }
-
- if ((result = pthread_mutex_lock(&(rwl->mtxSharedAccessCompleted))) != 0)
- {
- (void) pthread_mutex_unlock(&(rwl->mtxExclusiveAccess));
- return result;
- }
-
- /*
- * Check whether any threads own/wait for the lock (wait for ex.access);
- * report "BUSY" if so.
- */
- if (rwl->nExclusiveAccessCount > 0
- || rwl->nSharedAccessCount > rwl->nCompletedSharedAccessCount)
- {
- result = pthread_mutex_unlock(&(rwl->mtxSharedAccessCompleted));
- result1 = pthread_mutex_unlock(&(rwl->mtxExclusiveAccess));
- result2 = EBUSY;
- }
- else
- {
- rwl->nMagic = 0;
-
- if ((result = pthread_mutex_unlock(&(rwl->mtxSharedAccessCompleted))) != 0)
- {
- pthread_mutex_unlock(&rwl->mtxExclusiveAccess);
- return result;
- }
-
- if ((result = pthread_mutex_unlock(&(rwl->mtxExclusiveAccess))) != 0)
- {
- return result;
- }
-
- *rwlock = NULL; /* Invalidate rwlock before anything else */
- result = pthread_cond_destroy(&(rwl->cndSharedAccessCompleted));
- result1 = pthread_mutex_destroy(&(rwl->mtxSharedAccessCompleted));
- result2 = pthread_mutex_destroy(&(rwl->mtxExclusiveAccess));
- (void) free(rwl);
- }
- }
- else
- {
- /*
- * See notes in ptw32_rwlock_check_need_init() above also.
- */
- EnterCriticalSection(&ptw32_rwlock_test_init_lock);
-
- /*
- * Check again.
- */
- if (*rwlock == PTHREAD_RWLOCK_INITIALIZER)
- {
- /*
- * This is all we need to do to destroy a statically
- * initialised rwlock that has not yet been used (initialised).
- * If we get to here, another thread
- * waiting to initialise this rwlock will get an EINVAL.
- */
- *rwlock = NULL;
- }
- else
- {
- /*
- * The rwlock has been initialised while we were waiting
- * so assume it's in use.
- */
- result = EBUSY;
- }
-
- LeaveCriticalSection(&ptw32_rwlock_test_init_lock);
- }
-
- return ((result != 0) ? result : ((result1 != 0) ? result1 : result2));
-}
-
-
-int
-pthread_rwlockattr_init (pthread_rwlockattr_t * attr)
- /*
- * ------------------------------------------------------
- * DOCPUBLIC
- * Initializes a rwlock attributes object with default
- * attributes.
- *
- * PARAMETERS
- * attr
- * pointer to an instance of pthread_rwlockattr_t
- *
- *
- * DESCRIPTION
- * Initializes a rwlock attributes object with default
- * attributes.
- *
- * RESULTS
- * 0 successfully initialized attr,
- * ENOMEM insufficient memory for attr.
- *
- * ------------------------------------------------------
- */
-{
- int result = 0;
- pthread_rwlockattr_t rwa;
-
- rwa = (pthread_rwlockattr_t) calloc (1, sizeof (*rwa));
-
- if (rwa == NULL)
- {
- result = ENOMEM;
- }
- else
- {
- rwa->pshared = PTHREAD_PROCESS_PRIVATE;
- }
-
- *attr = rwa;
-
- return(result);
-} /* pthread_rwlockattr_init */
-
-
-int
-pthread_rwlockattr_destroy (pthread_rwlockattr_t * attr)
- /*
- * ------------------------------------------------------
- * DOCPUBLIC
- * Destroys a rwlock attributes object. The object can
- * no longer be used.
- *
- * PARAMETERS
- * attr
- * pointer to an instance of pthread_rwlockattr_t
- *
- *
- * DESCRIPTION
- * Destroys a rwlock attributes object. The object can
- * no longer be used.
- *
- * NOTES:
- * 1) Does not affect rwlockss created using 'attr'
- *
- * RESULTS
- * 0 successfully released attr,
- * EINVAL 'attr' is invalid.
- *
- * ------------------------------------------------------
- */
-{
- int result = 0;
-
- if (attr == NULL || *attr == NULL)
- {
- result = EINVAL;
- }
- else
- {
- pthread_rwlockattr_t rwa = *attr;
-
- *attr = NULL;
- free (rwa);
- }
-
- return(result);
-} /* pthread_rwlockattr_destroy */
-
-
-int
-pthread_rwlockattr_getpshared (const pthread_rwlockattr_t * attr,
- int *pshared)
- /*
- * ------------------------------------------------------
- * DOCPUBLIC
- * Determine whether rwlocks created with 'attr' can be
- * shared between processes.
- *
- * PARAMETERS
- * attr
- * pointer to an instance of pthread_rwlockattr_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
- * Rwlocks creatd with 'attr' can be shared between
- * processes if pthread_rwlock_t variable is allocated
- * in memory shared by these processes.
- * NOTES:
- * 1) pshared rwlocks MUST be allocated in shared
- * memory.
- * 2) The following macro is defined if shared rwlocks
- * 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
- {
- result = EINVAL;
- }
-
- return (result);
-
-} /* pthread_rwlockattr_getpshared */
-
-
-int
-pthread_rwlockattr_setpshared (pthread_rwlockattr_t * attr,
- int pshared)
- /*
- * ------------------------------------------------------
- * DOCPUBLIC
- * Rwlocks created with 'attr' can be shared between
- * processes if pthread_rwlock_t variable is allocated
- * in memory shared by these processes.
- *
- * PARAMETERS
- * attr
- * pointer to an instance of pthread_rwlockattr_t
- *
- * pshared
- * must be one of:
- *
- * PTHREAD_PROCESS_SHARED
- * May be shared if in shared memory
- *
- * PTHREAD_PROCESS_PRIVATE
- * Cannot be shared.
- *
- * DESCRIPTION
- * Rwlocks creatd with 'attr' can be shared between
- * processes if pthread_rwlock_t variable is allocated
- * in memory shared by these processes.
- *
- * NOTES:
- * 1) pshared rwlocks MUST be allocated in shared
- * memory.
- *
- * 2) The following macro is defined if shared rwlocks
- * 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_rwlockattr_setpshared */
-
-
-int
-pthread_rwlock_rdlock(pthread_rwlock_t *rwlock)
-{
- int result;
- pthread_rwlock_t rwl;
-
- if (rwlock == NULL || *rwlock == NULL)
- {
- return EINVAL;
- }
-
- /*
- * We do a quick check to see if we need to do more work
- * to initialise a static rwlock. We check
- * again inside the guarded section of ptw32_rwlock_check_need_init()
- * to avoid race conditions.
- */
- if (*rwlock == PTHREAD_RWLOCK_INITIALIZER)
- {
- result = ptw32_rwlock_check_need_init(rwlock);
-
- if (result != 0 && result != EBUSY)
- {
- return result;
- }
- }
-
- rwl = *rwlock;
-
- if (rwl->nMagic != PTW32_RWLOCK_MAGIC)
- {
- return EINVAL;
- }
-
- if ((result = pthread_mutex_lock(&(rwl->mtxExclusiveAccess))) != 0)
- {
- return result;
- }
-
- if (++rwl->nSharedAccessCount == INT_MAX)
- {
- if ((result = pthread_mutex_lock(&(rwl->mtxSharedAccessCompleted))) != 0)
- {
- (void) pthread_mutex_unlock(&(rwl->mtxExclusiveAccess));
- return result;
- }
-
- rwl->nSharedAccessCount -= rwl->nCompletedSharedAccessCount;
- rwl->nCompletedSharedAccessCount = 0;
-
- if ((result = pthread_mutex_unlock(&(rwl->mtxSharedAccessCompleted))) != 0)
- {
- (void) pthread_mutex_unlock(&(rwl->mtxExclusiveAccess));
- return result;
- }
- }
-
- return (pthread_mutex_unlock(&(rwl->mtxExclusiveAccess)));
-}
-
-static void
-ptw32_rwlock_cancelwrwait(void * arg)
-{
- pthread_rwlock_t rwl = (pthread_rwlock_t) arg;
-
- rwl->nSharedAccessCount = -rwl->nCompletedSharedAccessCount;
- rwl->nCompletedSharedAccessCount = 0;
-
- (void) pthread_mutex_unlock(&(rwl->mtxSharedAccessCompleted));
- (void) pthread_mutex_unlock(&(rwl->mtxExclusiveAccess));
-}
-
-int
-pthread_rwlock_wrlock(pthread_rwlock_t * rwlock)
-{
- int result;
- pthread_rwlock_t rwl;
-
- if (rwlock == NULL || *rwlock == NULL)
- {
- return EINVAL;
- }
-
- /*
- * We do a quick check to see if we need to do more work
- * to initialise a static rwlock. We check
- * again inside the guarded section of ptw32_rwlock_check_need_init()
- * to avoid race conditions.
- */
- if (*rwlock == PTHREAD_RWLOCK_INITIALIZER)
- {
- result = ptw32_rwlock_check_need_init(rwlock);
-
- if (result != 0 && result != EBUSY)
- {
- return result;
- }
- }
-
- rwl = *rwlock;
-
- if (rwl->nMagic != PTW32_RWLOCK_MAGIC)
- {
- return EINVAL;
- }
-
- if ((result = pthread_mutex_lock(&(rwl->mtxExclusiveAccess))) != 0)
- {
- return result;
- }
-
- if ((result = pthread_mutex_lock(&(rwl->mtxSharedAccessCompleted))) != 0)
- {
- (void) pthread_mutex_unlock(&(rwl->mtxExclusiveAccess));
- return result;
- }
-
- if (rwl->nExclusiveAccessCount == 0)
- {
- if (rwl->nCompletedSharedAccessCount > 0)
- {
- rwl->nSharedAccessCount -= rwl->nCompletedSharedAccessCount;
- rwl->nCompletedSharedAccessCount = 0;
- }
-
- if (rwl->nSharedAccessCount > 0)
- {
- rwl->nCompletedSharedAccessCount = -rwl->nSharedAccessCount;
-
- /*
- * This routine may be a cancelation point
- * according to POSIX 1003.1j section 18.1.2.
- */
-#ifdef _MSC_VER
-#pragma inline_depth(0)
-#endif
- pthread_cleanup_push(ptw32_rwlock_cancelwrwait, (void*)rwl);
-
- do
- {
- result = pthread_cond_wait(&(rwl->cndSharedAccessCompleted),
- &(rwl->mtxSharedAccessCompleted));
- }
- while (result == 0 && rwl->nCompletedSharedAccessCount < 0);
-
- pthread_cleanup_pop ((result != 0) ? 1 : 0);
-#ifdef _MSC_VER
-#pragma inline_depth()
-#endif
-
- if (result == 0)
- {
- rwl->nSharedAccessCount = 0;
- }
- }
- }
-
- if (result == 0)
- {
- rwl->nExclusiveAccessCount++;
- }
-
- return result;
-}
-
-int
-pthread_rwlock_unlock(pthread_rwlock_t * rwlock)
-{
- int result, result1;
- pthread_rwlock_t rwl;
-
- if (rwlock == NULL || *rwlock == NULL)
- {
- return(EINVAL);
- }
-
- if (*rwlock == PTHREAD_RWLOCK_INITIALIZER)
- {
- /*
- * Assume any race condition here is harmless.
- */
- return 0;
- }
-
- rwl = *rwlock;
-
- if (rwl->nMagic != PTW32_RWLOCK_MAGIC)
- {
- return EINVAL;
- }
-
- if (rwl->nExclusiveAccessCount == 0)
- {
- if ((result = pthread_mutex_lock(&(rwl->mtxSharedAccessCompleted))) != 0)
- {
- return result;
- }
-
- if (++rwl->nCompletedSharedAccessCount == 0)
- {
- result = pthread_cond_signal(&(rwl->cndSharedAccessCompleted));
- }
-
- result1 = pthread_mutex_unlock(&(rwl->mtxSharedAccessCompleted));
- }
- else
- {
- rwl->nExclusiveAccessCount--;
-
- result = pthread_mutex_unlock(&(rwl->mtxSharedAccessCompleted));
- result1 = pthread_mutex_unlock(&(rwl->mtxExclusiveAccess));
-
- }
-
- return ((result != 0) ? result : result1);
-}
-
-int
-pthread_rwlock_tryrdlock(pthread_rwlock_t * rwlock)
-{
- int result;
- pthread_rwlock_t rwl;
-
- if (rwlock == NULL || *rwlock == NULL)
- {
- return EINVAL;
- }
-
- /*
- * We do a quick check to see if we need to do more work
- * to initialise a static rwlock. We check
- * again inside the guarded section of ptw32_rwlock_check_need_init()
- * to avoid race conditions.
- */
- if (*rwlock == PTHREAD_RWLOCK_INITIALIZER)
- {
- result = ptw32_rwlock_check_need_init(rwlock);
-
- if (result != 0 && result != EBUSY)
- {
- return result;
- }
- }
-
- rwl = *rwlock;
-
- if (rwl->nMagic != PTW32_RWLOCK_MAGIC)
- {
- return EINVAL;
- }
-
- if ((result = pthread_mutex_trylock(&(rwl->mtxExclusiveAccess))) != 0)
- {
- return result;
- }
-
- if (++rwl->nSharedAccessCount == INT_MAX)
- {
- if ((result = pthread_mutex_lock(&(rwl->mtxSharedAccessCompleted))) != 0)
- {
- (void) pthread_mutex_unlock(&(rwl->mtxExclusiveAccess));
- return result;
- }
-
- rwl->nSharedAccessCount -= rwl->nCompletedSharedAccessCount;
- rwl->nCompletedSharedAccessCount = 0;
-
- if ((result = pthread_mutex_unlock(&(rwl->mtxSharedAccessCompleted))) != 0)
- {
- (void) pthread_mutex_unlock(&(rwl->mtxExclusiveAccess));
- return result;
- }
- }
-
- return (pthread_mutex_unlock(&rwl->mtxExclusiveAccess));
-}
-
-int
-pthread_rwlock_trywrlock(pthread_rwlock_t * rwlock)
-{
- int result, result1;
- pthread_rwlock_t rwl;
-
- if (rwlock == NULL || *rwlock == NULL)
- {
- return EINVAL;
- }
-
- /*
- * We do a quick check to see if we need to do more work
- * to initialise a static rwlock. We check
- * again inside the guarded section of ptw32_rwlock_check_need_init()
- * to avoid race conditions.
- */
- if (*rwlock == PTHREAD_RWLOCK_INITIALIZER)
- {
- result = ptw32_rwlock_check_need_init(rwlock);
-
- if (result != 0 && result != EBUSY)
- {
- return result;
- }
- }
-
- rwl = *rwlock;
-
- if (rwl->nMagic != PTW32_RWLOCK_MAGIC)
- {
- return EINVAL;
- }
-
- if ((result = pthread_mutex_trylock(&(rwl->mtxExclusiveAccess))) != 0)
- {
- return result;
- }
-
- if ((result = pthread_mutex_trylock(&(rwl->mtxSharedAccessCompleted))) != 0)
- {
- result1 = pthread_mutex_unlock(&(rwl->mtxExclusiveAccess));
- return ((result1 != 0) ? result1 : result);
- }
-
- if (rwl->nExclusiveAccessCount == 0)
- {
- if (rwl->nCompletedSharedAccessCount > 0)
- {
- rwl->nSharedAccessCount -= rwl->nCompletedSharedAccessCount;
- rwl->nCompletedSharedAccessCount = 0;
- }
-
- if (rwl->nSharedAccessCount > 0)
- {
- if ((result = pthread_mutex_unlock(&(rwl->mtxSharedAccessCompleted))) != 0)
- {
- (void) pthread_mutex_unlock(&(rwl->mtxExclusiveAccess));
- return result;
- }
-
- if ((result = pthread_mutex_unlock(&(rwl->mtxExclusiveAccess))) == 0)
- {
- result = EBUSY;
- }
- }
- else
- {
- rwl->nExclusiveAccessCount = 1;
- }
- }
- else
- {
- result = EBUSY;
- }
-
- return result;
-}
+#include "ptw32_rwlock_check_need_init.c"
+#include "pthread_rwlock_init.c"
+#include "pthread_rwlock_destroy.c"
+#include "pthread_rwlockattr_init.c"
+#include "pthread_rwlockattr_destroy.c"
+#include "pthread_rwlockattr_getpshared.c"
+#include "pthread_rwlockattr_setpshared.c"
+#include "pthread_rwlock_rdlock.c"
+#include "pthread_rwlock_wrlock.c"
+#include "pthread_rwlock_unlock.c"
+#include "pthread_rwlock_tryrdlock.c"
+#include "pthread_rwlock_trywrlock.c"