PTHREAD(3)

NAME
pthread - POSIX thread functions

LIBRARY
libpthread

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 following groups:

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

FreeBSD extensions to the POSIX thread functions are summarized in pthread_np(3).

  Thread Routines

    int pthread_create(pthread_t *thread, const pthread_attr_t *attr, void **start_routinevoid *, 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_routinevoid) Calls an initialization routine once.

    pthread_t pthread_self(void) Returns the thread ID of the calling thread.

    int pthread_setcancelstate(int state, int *oldstate) Sets the current thread's cancelability state.

    int pthread_setcanceltype(int type, int *oldtype) Sets the current thread's cancelability type.

    void pthread_testcancel(void) 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) Set the contention scope attribute in a thread attributes object.

    int pthread_attr_setstacksize(pthread_attr_t *attr, size_t stacksize) Set the stack size attribute in a thread attributes object.

    int pthread_attr_setstackaddr(pthread_attr_t *attr, void *stackaddr) Set the stack address attribute in a thread attributes object.

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

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

    int pthread_mutexattr_gettype(const pthread_mutexattr_t *restrict attr, int *restrict 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 created.

    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 do not 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) Destroy a condition variable attributes object.

    int pthread_condattr_init(pthread_condattr_t *attr) Initialize a condition variable attributes object with default values.

    int pthread_cond_broadcast(pthread_cond_t *cond) Unblock all threads currently blocked on the specified condition 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 condition variable.

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

    int pthread_cond_wait(pthread_cond_t *, pthread_mutex_t *mutex) Unlock the specified mutex, wait for a condition, and relock the 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.

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

  Per-Thread Context Routines

    int pthread_key_create(pthread_key_t *key, void *routinevoid *) 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

    int pthread_atfork(void *preparevoid, void *parentvoid, void *childvoid) Register fork handlers.

    void pthread_cleanup_pop(int execute) Remove the routine at the top of the calling thread's cancellation cleanup stack and optionally invoke it.

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

IMPLEMENTATION NOTES
The current FreeBSD POSIX thread implementation is built into the libthr library. It contains thread-safe versions of libc functions and the thread functions. Threaded applications are linked with this library.

SEE ALSO
libthr(3), pthread_atfork(3), pthread_attr(3), pthread_cancel(3), pthread_cleanup_pop(3), pthread_cleanup_push(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_condattr_destroy(3), pthread_condattr_init(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_mutex_destroy(3), pthread_mutex_init(3), pthread_mutex_lock(3), pthread_mutex_trylock(3), pthread_mutex_unlock(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_np(3), pthread_once(3), pthread_rwlock_destroy(3), pthread_rwlock_init(3), pthread_rwlock_rdlock(3), pthread_rwlock_unlock(3), pthread_rwlock_wrlock(3), pthread_rwlockattr_destroy(3), pthread_rwlockattr_getpshared(3), pthread_rwlockattr_init(3), pthread_rwlockattr_setpshared(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 p1003.1-96.

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 susv2.