4. API 比较细节

4.3 交互锁函数

pthreads定义使用交互锁同步变量。从Solaris到pthreads的改变是微小的，仅增加前缀pthread_ 。所有的交互锁函数由相似的参数，除了交互锁初始化。

• Solaris API

#include <synch.h>

int mutex_init (mutex_t *mp, int type, void *arg)

int mutex_destroy (mutex_t *mp)

int mutex_lock (mutex_t *mp)

int mutex_unlock (mutex_t *mp)

int mutex_trylock (mutex_t *mp)

• pthreads API

#include <pthread.h>

int pthread_mutex_init (pthread_mutex_t *mp, pthread_mutexattr_t *attr)

int pthread_mutex_destroy (pthread_mutex_t *mp)

int pthread_mutex_lock (pthread_mutex_t *mp)

int pthread_mutex_unlock (pthread_mutex_t *mp)

int pthread_mutex_trylock (pthread_mutex_t *mp)

• 用进程内部的范围初始化交互锁

在Solaris 中

mutex_t mp;

int ret;

ret = mutex_init (&mp, USYNC_THREAD, 0); /* to be used within this process only */

在pthreads 中

如果一个交互锁变量在一个进程内共享，它可以用两种方式初始化。一种方式是用attr为NULL调用初始化函数。另一种是用一个属性对象mattr，用pshare属性的缺省值初始化此对象（PTHREAD_PROCESS_PRIVATE）。

在前一个已初始化的mattr中,也可能明显地将pshare属性设置为PTHREAD_PROCESS_PRIVATE。这些状态等价于在Solaris线索中的USYNC_THREAD状态。

pthread_mutex_t mp;

int ret;

pthread_mutexattr_t mattr;

ret = pthread_ mutex_init (&mp, NULL); /* Using a NULL argument to specify the default creation state */

或者

ret = pthread_mutexattr_init (&mattr);

ret = pthread_ mutex_init (&mp, &mattr); /* Using an attribute object initialized and left in the default state */

或者

ret = pthread_mutexattr_setpshared (&mattr, PTHREAD_PROCESS_PRIVATE);

ret = pthread_mutex_init (&mp, &mattr); /* Explicitly setting the attribute object to indicate PTHREAD_PROCESS_PRIVATE */

• 用进程间的范围初始化交互锁

在Solaris 中

mutex_t mp;

int ret;

ret = mutex_init (&mp, USYNC_PROCESS, 0); /* to be used among all processes */

在pthreads 中

如果一个交互锁变量在进程中共享，用属性对象mattr对它初始化，此属性对象已用值PTHREAD_PROCESS_PROCESS设置。这等价于在Solaris线索中的USYNC_PROCESS状态。

mutex_t mp;

int ret;

pthread_mutexattr_t mattr;

ret = pthread_mutexattr_init (&mattr);

ret = pthread_mutexattr_setpshared (&mattr, PTHREAD_PROCESS_SHARED);

ret = pthread_mutex_init (&mp, &mattr); /* to be used among all processes */

• 释放一个交互锁

在Solaris 中

mutex_t mp;

int ret;

ret = mutex_destroy(&mp); /* Mutex is destroyed */

在pthreads 中

mutex_t mp;

int ret;

ret = pthread_ mutex_destroy(&mp); /* Mutex is destroyed */

• 交互锁上锁

在Solaris 中

mutex_t mp;

int ret;

ret = mutex_lock (&mp); /* acquire the Mutex */

在pthreads 中

pthread_mutex_t mp;

int ret;

ret = pthread_ mutex_lock (&mp); /* acquire the Mutex */

• 交互锁解锁

在Solaris 中

mutex_t mp;

int ret;

ret = mutex_unlock (&mp); /* release the Mutex */

在pthreads 中

pthread_mutex_t mp;

int ret;

ret = pthread_ mutex_unlock (&mp); /* release the Mutex */

• 交互锁尝试上锁

在Solaris 中

mutex_t mp;

int ret;

ret = mutex_trylock (&mp); /* try to grab Mutex */

在pthreads 中

pthread_mutex_t mp;

int ret;

ret = pthread_ mutex_trylock (&mp); /* try to grab Mutex */

Copyright: NPACT