怎么基于linuxthreads2.0.1线程源码分析specific.c

   
     
 
    
    //* Thread-specific data */#include <errno.h>#include <stddef.h>#include "pthread.h"#include "internals.h"typedef void (*destr_function)(void *);/* Table of keys. */struct pthread_key_struct {  int in_use;                   /* already allocated? */  destr_function destr;         /* destruction routine */};static struct pthread_key_struct pthread_keys[PTHREAD_KEYS_MAX] =  { { 0, NULL } };/* Mutex to protect access to pthread_keys */static pthread_mutex_t pthread_keys_mutex = PTHREAD_MUTEX_INITIALIZER;/* Create a new key */// 创建一个keyint __pthread_key_create(pthread_key_t * key, destr_function destr){  int i;  // 加锁  pthread_mutex_lock(&pthread_keys_mutex);  // 从列表中找一项空闲的  for (i = 0; i < PTHREAD_KEYS_MAX; i++) {    if (! pthread_keys[i].in_use) {      pthread_keys[i].in_use = 1;      pthread_keys[i].destr = destr;      // 找到则解锁并返回键值      pthread_mutex_unlock(&pthread_keys_mutex);      *key = i;      return 0;    }  }  // 找不到则解锁  pthread_mutex_unlock(&pthread_keys_mutex);  return EAGAIN;}weak_alias (__pthread_key_create, pthread_key_create)/* Delete a key */// 删除一个键对应的项int pthread_key_delete(pthread_key_t key){  pthread_mutex_lock(&pthread_keys_mutex);  if (key >= PTHREAD_KEYS_MAX || !pthread_keys[key].in_use) {    pthread_mutex_unlock(&pthread_keys_mutex);    return EINVAL;  }  pthread_keys[key].in_use = 0;  pthread_keys[key].destr = NULL;  pthread_mutex_unlock(&pthread_keys_mutex);  return 0;}/* Set the value of a key */// 关联键对应的值int __pthread_setspecific(pthread_key_t key, const void * pointer){  pthread_t self = thread_self();  if (key >= PTHREAD_KEYS_MAX) return EINVAL;  self->p_specific[key] = (void *) pointer;  return 0;}weak_alias (__pthread_setspecific, pthread_setspecific)/* Get the value of a key */void * __pthread_getspecific(pthread_key_t key){  pthread_t self = thread_self();  if (key >= PTHREAD_KEYS_MAX)    return NULL;  else    return self->p_specific[key];}weak_alias (__pthread_getspecific, pthread_getspecific)/* Call the destruction routines on all keys */// 逐个调用pthread_keys数组中的destr函数，并以线程关联的value为参数void __pthread_destroy_specifics(){  int i;  pthread_t self = thread_self();  destr_function destr;  void * data;  for (i = 0; i < PTHREAD_KEYS_MAX; i++) {    // 销毁时执行的函数    destr = pthread_keys[i].destr;    // 获取键对应的值    data = self->p_specific[i];    // 执行    if (destr != NULL && data != NULL) destr(data);  }}
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