Apache Portable Runtime
Typedefs | Functions
Reader/Writer Lock Routines
Apache Portability Runtime library

Typedefs

typedef struct apr_thread_rwlock_t apr_thread_rwlock_t

Functions

apr_status_t apr_thread_rwlock_create (apr_thread_rwlock_t **rwlock, apr_pool_t *pool)
apr_status_t apr_thread_rwlock_rdlock (apr_thread_rwlock_t *rwlock)
apr_status_t apr_thread_rwlock_tryrdlock (apr_thread_rwlock_t *rwlock)
apr_status_t apr_thread_rwlock_wrlock (apr_thread_rwlock_t *rwlock)
apr_status_t apr_thread_rwlock_trywrlock (apr_thread_rwlock_t *rwlock)
apr_status_t apr_thread_rwlock_unlock (apr_thread_rwlock_t *rwlock)
apr_status_t apr_thread_rwlock_destroy (apr_thread_rwlock_t *rwlock)
apr_pool_tapr_thread_rwlock_pool_get (const apr_thread_rwlock_t *thethread_rwlock)

Typedef Documentation

Opaque read-write thread-safe lock.


Function Documentation

apr_status_t apr_thread_rwlock_create ( apr_thread_rwlock_t **  rwlock,
apr_pool_t pool 
)

Note: The following operations have undefined results: unlocking a read-write lock which is not locked in the calling thread; write locking a read-write lock which is already locked by the calling thread; destroying a read-write lock more than once; clearing or destroying the pool from which a locked read-write lock is allocated. Create and initialize a read-write lock that can be used to synchronize threads.

Parameters:
rwlockthe memory address where the newly created readwrite lock will be stored.
poolthe pool from which to allocate the mutex.
apr_status_t apr_thread_rwlock_destroy ( apr_thread_rwlock_t rwlock)

Destroy the read-write lock and free the associated memory.

Parameters:
rwlockthe rwlock to destroy.
apr_pool_t* apr_thread_rwlock_pool_get ( const apr_thread_rwlock_t thethread_rwlock)

Get the pool used by this thread_rwlock.

Returns:
apr_pool_t the pool
apr_status_t apr_thread_rwlock_rdlock ( apr_thread_rwlock_t rwlock)

Acquire a shared-read lock on the given read-write lock. This will allow multiple threads to enter the same critical section while they have acquired the read lock.

Parameters:
rwlockthe read-write lock on which to acquire the shared read.
apr_status_t apr_thread_rwlock_tryrdlock ( apr_thread_rwlock_t rwlock)

Attempt to acquire the shared-read lock on the given read-write lock. This is the same as apr_thread_rwlock_rdlock(), only that the function fails if there is another thread holding the write lock, or if there are any write threads blocking on the lock. If the function fails for this case, APR_EBUSY will be returned. Note: it is important that the APR_STATUS_IS_EBUSY(s) macro be used to determine if the return value was APR_EBUSY, for portability reasons.

Parameters:
rwlockthe rwlock on which to attempt the shared read.
apr_status_t apr_thread_rwlock_trywrlock ( apr_thread_rwlock_t rwlock)

Attempt to acquire the exclusive-write lock on the given read-write lock. This is the same as apr_thread_rwlock_wrlock(), only that the function fails if there is any other thread holding the lock (for reading or writing), in which case the function will return APR_EBUSY. Note: it is important that the APR_STATUS_IS_EBUSY(s) macro be used to determine if the return value was APR_EBUSY, for portability reasons.

Parameters:
rwlockthe rwlock on which to attempt the exclusive write.
apr_status_t apr_thread_rwlock_unlock ( apr_thread_rwlock_t rwlock)

Release either the read or write lock currently held by the calling thread associated with the given read-write lock.

Parameters:
rwlockthe read-write lock to be released (unlocked).
apr_status_t apr_thread_rwlock_wrlock ( apr_thread_rwlock_t rwlock)

Acquire an exclusive-write lock on the given read-write lock. This will allow only one single thread to enter the critical sections. If there are any threads currently holding the read-lock, this thread is put to sleep until it can have exclusive access to the lock.

Parameters:
rwlockthe read-write lock on which to acquire the exclusive write.
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