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pthread(3)

NAME

     pthread -- POSIX thread functions

LIBRARY

     POSIX Threads Library (libpthread, -lpthread)
     1:1 Threading Library (libthr, -lthr)
     Reentrant C Library (libc_r, -lc_r)

SYNOPSIS

     #include <pthread.h>

DESCRIPTION

     POSIX threads are a set of functions that support applications with
     requirements for multiple flows of control, called threads, within a
     process.  Multithreading is used to improve the performance of a program.

     The POSIX thread functions are summarized in this section in the follow-
     ing groups:

	   o   Thread Routines
	   o   Attribute Object Routines
	   o   Mutex Routines
	   o   Condition Variable Routines
	   o   Read/Write Lock Routines
	   o   Per-Thread Context Routines
	   o   Cleanup Routines

   Thread Routines
     int pthread_create(pthread_t *thread, const pthread_attr_t *attr,
	     void *(*start_routine)(void *), void *arg)
	     Creates a new thread of execution.

     int pthread_cancel(pthread_t thread)
	     Cancels execution of a thread.

     int pthread_detach(pthread_t thread)
	     Marks a thread for deletion.

     int pthread_equal(pthread_t t1, pthread_t t2)
	     Compares two thread IDs.

     void pthread_exit(void *value_ptr)
	     Terminates the calling thread.

     int pthread_join(pthread_t thread, void **value_ptr)
	     Causes the calling thread to wait for the termination of the
	     specified thread.

     int pthread_kill(pthread_t thread, int sig)
	     Delivers a signal to a specified thread.

     int pthread_once(pthread_once_t *once_control, void
	     (*init_routine)(void))
	     Calls an initialization routine once.

     pthread_t pthread_self(void)
	     Returns the thread ID of the calling thread.
	     Creates a cancellation point in the calling thread.

     void pthread_yield(void)
	     Allows the scheduler to run another thread instead of the current
	     one.

   Attribute Object Routines
     int pthread_attr_destroy(pthread_attr_t *attr)
	     Destroy a thread attributes object.

     int pthread_attr_getinheritsched(const pthread_attr_t *attr,
	     int *inheritsched)
	     Get the inherit scheduling attribute from a thread attributes
	     object.

     int pthread_attr_getschedparam(const pthread_attr_t *attr,
	     struct sched_param *param)
	     Get the scheduling parameter attribute from a thread attributes
	     object.

     int pthread_attr_getschedpolicy(const pthread_attr_t *attr, int *policy)
	     Get the scheduling policy attribute from a thread attributes
	     object.

     int pthread_attr_getscope(const pthread_attr_t *attr, int
	     *contentionscope)
	     Get the contention scope attribute from a thread attributes
	     object.

     int pthread_attr_getstacksize(const pthread_attr_t *attr, size_t
	     *stacksize)
	     Get the stack size attribute from a thread attributes object.

     int pthread_attr_getstackaddr(const pthread_attr_t *attr, void
	     **stackaddr)
	     Get the stack address attribute from a thread attributes object.

     int pthread_attr_getdetachstate(const pthread_attr_t *attr, int
	     *detachstate)
	     Get the detach state attribute from a thread attributes object.

     int pthread_attr_init(pthread_attr_t *attr)
	     Initialize a thread attributes object with default values.

     int pthread_attr_setinheritsched(pthread_attr_t *attr, int inheritsched)
	     Set the inherit scheduling attribute in a thread attributes
	     object.

     int pthread_attr_setschedparam(pthread_attr_t *attr,
	     const struct sched_param *param)
	     Set the scheduling parameter attribute in a thread attributes
	     object.

     int pthread_attr_setschedpolicy(pthread_attr_t *attr, int policy)
	     Set the scheduling policy attribute in a thread attributes
	     object.

     int pthread_attr_setscope(pthread_attr_t *attr, int contentionscope)
     int pthread_attr_setdetachstate(pthread_attr_t *attr, int detachstate)
	     Set the detach state in a thread attributes object.

   Mutex Routines
     int pthread_mutexattr_destroy(pthread_mutexattr_t *attr)
	     Destroy a mutex attributes object.

     int pthread_mutexattr_getprioceiling(pthread_mutexattr_t *attr, int
	     *ceiling)
	     Obtain priority ceiling attribute of mutex attribute object.

     int pthread_mutexattr_getprotocol(pthread_mutexattr_t *attr, int
	     *protocol)
	     Obtain protocol attribute of mutex attribute object.

     int pthread_mutexattr_gettype(pthread_mutexattr_t *attr, int *type)
	     Obtain the mutex type attribute in the specified mutex attributes
	     object.

     int pthread_mutexattr_init(pthread_mutexattr_t *attr)
	     Initialize a mutex attributes object with default values.

     int pthread_mutexattr_setprioceiling(pthread_mutexattr_t *attr, int
	     ceiling)
	     Set priority ceiling attribute of mutex attribute object.

     int pthread_mutexattr_setprotocol(pthread_mutexattr_t *attr, int
	     protocol)
	     Set protocol attribute of mutex attribute object.

     int pthread_mutexattr_settype(pthread_mutexattr_t *attr, int type)
	     Set the mutex type attribute that is used when a mutex is cre-
	     ated.

     int pthread_mutex_destroy(pthread_mutex_t *mutex)
	     Destroy a mutex.

     int pthread_mutex_init(pthread_mutex_t *mutex,
	     const pthread_mutexattr_t *attr)
	     Initialize a mutex with specified attributes.

     int pthread_mutex_lock(pthread_mutex_t *mutex)
	     Lock a mutex and block until it becomes available.

     int pthread_mutex_timedlock(pthread_mutex_t *mutex,
	     const struct timespec *abstime)
	     Lock a mutex and block until it becomes available or until the
	     timeout expires.

     int pthread_mutex_trylock(pthread_mutex_t *mutex)
	     Try to lock a mutex, but don't block if the mutex is locked by
	     another thread, including the current thread.

     int pthread_mutex_unlock(pthread_mutex_t *mutex)
	     Unlock a mutex.

   Condition Variable Routines
     int pthread_condattr_destroy(pthread_condattr_t *attr)
	     variable.

     int pthread_cond_destroy(pthread_cond_t *cond)
	     Destroy a condition variable.

     int pthread_cond_init(pthread_cond_t *cond, const pthread_condattr_t
	     *attr)
	     Initialize a condition variable with specified attributes.

     int pthread_cond_signal(pthread_cond_t *cond)
	     Unblock at least one of the threads blocked on the specified con-
	     dition variable.

     int pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex,
	     const struct timespec *abstime)
	     Wait no longer than the specified time for a condition and lock
	     the specified mutex.

     int pthread_cond_wait(pthread_cond_t *, pthread_mutex_t *mutex)
	     Wait for a condition and lock the specified mutex.

   Read/Write Lock Routines
     int pthread_rwlock_destroy(pthread_rwlock_t *lock)
	     Destroy a read/write lock object.

     int pthread_rwlock_init(pthread_rwlock_t *lock,
	     const pthread_rwlockattr_t *attr)
	     Initialize a read/write lock object.

     int pthread_rwlock_rdlock(pthread_rwlock_t *lock)
	     Lock a read/write lock for reading, blocking until the lock can
	     be acquired.

     int pthread_rwlock_tryrdlock(pthread_rwlock_t *lock)
	     Attempt to lock a read/write lock for reading, without blocking
	     if the lock is unavailable.

     int pthread_rwlock_trywrlock(pthread_rwlock_t *lock)
	     Attempt to lock a read/write lock for writing, without blocking
	     if the lock is unavailable.

     int pthread_rwlock_unlock(pthread_rwlock_t *lock)
	     Unlock a read/write lock.

     int pthread_rwlock_wrlock(pthread_rwlock_t *lock)
	     Lock a read/write lock for writing, blocking until the lock can
	     be acquired.

     int pthread_rwlockattr_destroy(pthread_rwlockattr_t *attr)
	     Destroy a read/write lock attribute object.

     int pthread_rwlockattr_getpshared(const pthread_rwlockattr_t *attr,
	     int *pshared)
	     Retrieve the process shared setting for the read/write lock
	     attribute object.

     int pthread_rwlockattr_init(pthread_rwlockattr_t *attr)
	     Initialize a read/write lock attribute object.
	     Create a thread-specific data key.

     int pthread_key_delete(pthread_key_t key)
	     Delete a thread-specific data key.

     void * pthread_getspecific(pthread_key_t key)
	     Get the thread-specific value for the specified key.

     int pthread_setspecific(pthread_key_t key, const void *value_ptr)
	     Set the thread-specific value for the specified key.

   Cleanup Routines
     void pthread_cleanup_pop(int execute)
	     Remove the routine at the top of the calling thread's cancella-
	     tion cleanup stack and optionally invoke it.

     void pthread_cleanup_push(void (*routine)(void *), void *routine_arg)
	     Push the specified cancellation cleanup handler onto the calling
	     thread's cancellation stack.

INSTALLATION

     The current FreeBSD POSIX thread implementation is built in three
     libraries, Reentrant C Library (libc_r, -lc_r), POSIX Threads Library
     (libpthread, -lpthread), and 1:1 Threading Library (libthr, -lthr).  They
     contain both thread-safe versions of Standard C Library (libc, -lc) func-
     tions and the thread functions.  Threaded applications are linked with
     one of these libraries.

SEE ALSO

     pthread_cleanup_pop(3), pthread_cleanup_push(3),
     pthread_condattr_destroy(3), pthread_condattr_init(3),
     pthread_cond_broadcast(3), pthread_cond_destroy(3), pthread_cond_init(3),
     pthread_cond_signal(3), pthread_cond_timedwait(3), pthread_cond_wait(3),
     pthread_create(3), pthread_detach(3), pthread_equal(3), pthread_exit(3),
     pthread_getspecific(3), pthread_join(3), pthread_key_delete(3),
     pthread_kill(3), pthread_mutexattr_destroy(3),
     pthread_mutexattr_getprioceiling(3), pthread_mutexattr_getprotocol(3),
     pthread_mutexattr_gettype(3), pthread_mutexattr_init(3),
     pthread_mutexattr_setprioceiling(3), pthread_mutexattr_setprotocol(3),
     pthread_mutexattr_settype(3), pthread_mutex_destroy(3),
     pthread_mutex_init(3), pthread_mutex_lock(3), pthread_mutex_trylock(3),
     pthread_mutex_unlock(3), pthread_once(3), pthread_rwlockattr_destroy(3),
     pthread_rwlockattr_getpshared(3), pthread_rwlockattr_init(3),
     pthread_rwlockattr_setpshared(3), pthread_rwlock_destroy(3),
     pthread_rwlock_init(3), pthread_rwlock_rdlock(3),
     pthread_rwlock_unlock(3), pthread_rwlock_wrlock(3), pthread_self(3),
     pthread_setcancelstate(3), pthread_setcanceltype(3),
     pthread_setspecific(3), pthread_testcancel(3)

STANDARDS

     The functions with the pthread_ prefix and not _np suffix or
     pthread_rwlock prefix conform to ISO/IEC 9945-1:1996 (``POSIX.1'').

     The functions with the pthread_ prefix and _np suffix are non-portable
     extensions to POSIX threads.

     The functions with the pthread_rwlock prefix are extensions created by
     The Open Group as part of the Version 2 of the Single UNIX Specification

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