Linux C并发控制

Linux线程接口也称为pthread或POSIX线程，Linux2.6以后，采用Native POSIX线程库的新线程实现。

1，互斥量

头文件<pthread.h> pthread_mutex_t mtx = PTHREAD_MUTEX_INITIALIZER;

静态分配：

pthread_mutex_t mtx = PTHREAD_MUTEX_INITIALIZER;

int pthread_mutex_init(pthread_mutex_t *mutex, const pthread_mutexattr_t *attr)

int pthread_mutex_destroy(pthread_mutex_t *mutex)

操作函数：

int pthread_mutex_lock(pthread_mutex_t *mutex)

int pthread_mutex_trylock(pthread_mutex_t *mutex)

int pthread_mutex_unlock(pthread_mutex_t *mutex)

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互斥量类型：

PTHREAD_MUTEX_NORMAL：不具有死锁检测功能，如线程试图对已由自己锁定的互斥量加锁，则发生死锁，互斥量处于未锁定状态，或者已由其他线程锁定，对其解锁会导致不确定的结果（在Linux上，对这类互斥量的上述两种操作都会成功）。

PTHREAD_MUTEX_ERRORCHECK：所有操作会执行错误检查，所有上述3种情况都会导致相关的函数返回错误，运行起来比一般要慢。

PTHREAD_MUTEX_RECURSIVE：递归互斥量维护一个计数器，加锁递增计数器，解锁递减计数器，为0时，释放该互斥量。

2，读写锁

<pthread.h>

int pthread_rwlock_init(pthread_rwlock_t *restict rwlock, const pthread_rwlockattr_t *restrict attr);

int pthread_rwlock_destroy(pthread_rwlock_t *restict rwlock);

int pthread_rwlock_rdlock(pthread_rwlock_t *restict rwlock);

int pthread_rwlock_wrlock(pthread_rwlock_t *restict rwlock);

int pthread_rwlock_unlock(pthread_rwlock_t *restict rwlock);
3，条件变量

<pthread.h>

int pthread_cond_init(pthread_cond_t *restict cond, const pthread_condattr_t *restrict attr);

int pthread_cond_destroy(pthread_cond_t *cond);

int pthread_cond_wait(pthread_cond_t *restict cond, pthread_mutex_t *restrict cond);

int pthread_cond_timedwait(pthread_cond_t *restict cond, pthread_mutex_t *restrict mutex, const struct timespec *restrict tsptr);

int pthread_cond_signal(pthread_cond_t *cond);

int pthread_cond_broadcast(pthread_cond_t *cond);

4，自旋锁

<pthread.h>

int pthread_spin_init(pthread_spinlock_t *lock,int pshared);

int pthread_spin_destroy(pthread_spinlock_t *lock);

int pthread_spin_lock(pthread_spinlock_t *lock);

int pthread_spin_trylock(pthread_spinlock_t *lock);

int pthread_spin_unlock(pthread_spinlock_t *lock);

5，屏障

屏障是用户协调多个线程并行工作的同步机制，允许每个线程等待，直到有合作的线程都到达某一点，然后从该点继续执行。

int pthread_barrier_init(pthread_barrier_t *restrict barrier, const pthread_barrierattr_t *restrict attr, unsigned int count)

int pthread_barrier_destroy(pthread_barrier_t *barrier)

int pthread_barrier_wait(pthread_barrier_t *barrier)