pthread_rwlock_destroy(3c) [sunos man page]
pthread_rwlock_init(3C) pthread_rwlock_init(3C) NAME
pthread_rwlock_init, pthread_rwlock_destroy - initialize or destroy read-write lock object SYNOPSIS
cc -mt [ flag... ] file... -lpthread [ library... ] #include <pthread.h> int pthread_rwlock_init(pthread_rwlock_t *restrict rwlock, const pthread_rwlockattr_t *restrict attr); int pthread_rwlock_destroy(pthread_rwlock_t **rwlock); pthread_rwlock_t rwlock=PTHREAD_RWLOCK_INITIALIZER; The pthread_rwlock_init() function initializes the read-write lock referenced by rwlock with the attributes referenced by attr. If attr is NULL, the default read-write lock attributes are used; the effect is the same as passing the address of a default read-write lock attributes object. Once initialized, the lock can be used any number of times without being re-initialized. Upon successful initializa- tion, the state of the read-write lock becomes initialized and unlocked. Results are undefined if pthread_rwlock_init() is called speci- fying an already initialized read-write lock. Results are undefined if a read-write lock is used without first being initialized. If the pthread_rwlock_init() function fails, rwlock is not initialized and the contents of rwlock are undefined. The pthread_rwlock_destroy() function destroys the read-write lock object referenced by rwlock and releases any resources used by the lock. The effect of subsequent use of the lock is undefined until the lock is re-initialized by another call to pthread_rwlock_init(). An implementation may cause pthread_rwlock_destroy() to set the object referenced by rwlock to an invalid value. Results are undefined if pthread_rwlock_destroy() is called when any thread holds rwlock. Attempting to destroy an uninitialized read-write lock results in unde- fined behaviour. A destroyed read-write lock object can be re-initialized using pthread_rwlock_init(); the results of otherwise referenc- ing the read-write lock object after it has been destroyed are undefined. In cases where default read-write lock attributes are appropriate, the macro PTHREAD_RWLOCK_INITIALIZER can be used to initialize read- write locks that are statically allocated. The effect is equivalent to dynamic initialization by a call to pthread_rwlock_init() with the parameter attr specified as NULL, except that no error checks are performed. If successful, the pthread_rwlock_init() and pthread_rwlock_destroy() functions return 0. Otherwise, an error number is returned to indicate the error. The pthread_rwlock_init() and pthread_rwlock_destroy() functions will fail if: EINVAL The value specified by attr is invalid. EINVAL The value specified by rwlock is invalid. See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ |MT-Level |MT-Safe | +-----------------------------+-----------------------------+ pthread_rwlock_rdlock(3C), pthread_rwlock_unlock(3C), pthread_rwlock_wrlock(3C), pthread_rwlockattr_init(3C), attributes(5), standards(5) 23 mar 2005 pthread_rwlock_init(3C)
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pthread_rwlock_init(3T) pthread_rwlock_init(3T) NAME
pthread_rwlock_init(), pthread_rwlock_destroy() - initialize or destroy a read-write lock SYNOPSIS
PARAMETERS
rwlock Pointer to the read-write lock to be initialized or destroyed. attr Pointer to the attributes object that defines the characteristics of the read-write lock to be initialized. If the pointer is NULL, default attributes are used. DESCRIPTION
initializes the read-write lock referenced by rwlock with the attributes attr. If attr is NULL, the default read-write lock attributes are used. Upon successful initialization, the state of the read-write lock becomes initialized and unlocked. Attempting to initialize an already initialized read-write lock object results in undefined behavior. The macro can be used to initialize read-write locks which are statically allocated. The effect is equivalent to dynamic initialization by a call to with the attr parameter specified as NULL, except that no error checks are performed. The read-write lock will be initialized with default attributes. If the process-shared attribute in the read-write lock attributes object referenced by attr is defined as the read-write lock must be allo- cated such that the processes sharing the read-write lock has access to it. This may be done through the memory-mapping functions (see mmap(2)) or shared memory functions (see shmget(2)). destroys the read-write referenced by rwlock. This function may set rwlock to an invalid value. The destroyed read-write lock can be reinitialized using the function If the read-write lock is referenced after destruction in any read-write lock call, the resulting behavior is undefined. A read-write lock should be destroyed only when no threads are currently using it. Destroying a read-write lock which is currently in use results in undefined behavior. RETURN VALUE
Upon successful completion, and returns zero. Otherwise, an error number is returned to indicate the error (the variable is not set). ERRORS
If any of the following occur, the function returns the corresponding error number: The necessary resources (other than memory) to initialize rwlock are not available. rwlock is an already initialized read-write lock. However, getting for reinitializing the rwlock cannot be expected all the time since the behavior of reinitializing the rwlock is undefined. The value specified by rwlock or attr is invalid. There is insufficient memory available in which to initialize the read-write lock rwlock. The caller does not have the privilege to perform the operation. If any of the following occur, the function returns the corresponding error number: rwlock is currently locked or being used by other threads. The value specified by rwlock is invalid. WARNINGS
The space for the read-write lock must to be allocated before calling Undefined behavior may result if the process-shared attribute of attr is and the space allocated for the read-write lock is not accessible to cooperating threads. AUTHOR
and were developed by X/Open. SEE ALSO
pthread_rwlock_rdlock(3T), pthread_rwlock_tryrdlock(3T), pthread_rwlock_trywrlock(3T), pthread_rwlock_unlock(3T), pthread_rwlock_wrlock(3T). STANDARDS CONFORMANCE
Pthread Library pthread_rwlock_init(3T)