memcache扩展(0.2版本)源代码讲解(memcache_delete)

最新推荐文章于 2021-11-07 17:27:00 发布

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最新推荐文章于 2021-11-07 17:27:00 发布

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本文链接：https://blog.youkuaiyun.com/jjcaijjcai/article/details/8501293

本文详细介绍了PHP中Memcache删除数据的方法，包括memcache_delete函数的实现原理与mmc_delete的具体步骤，展示了如何通过PHP操作Memcache来删除指定的缓存项。

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从ＭＣ中删除数据的代码如下：

PHP_FUNCTION(memcache_delete)
{
zval *id, **key, **time;

注：当前MＣ对象在内存中的地址，要删除的key，及时间
mmc_t *mmc;

　注：连接对象
int inx, result, real_time;

　注：连接id
   int ac = ZEND_NUM_ARGS();
　注：参数个数
   if ((id = getThis()) != 0) {
       if ((inx = mmc_get_connection(id, &mmc TSRMLS_CC)) == 0) {
           RETURN_FALSE;
       }

　　注：没建立连接，返回false
       if (ac < 1 || ac > 2 || zend_get_parameters_ex(ac, &key, &time) == FAILURE) {
           WRONG_PARAM_COUNT;
       }
        注：参数个不是一个或两个，返回参数个数错误
       convert_to_string_ex(key);

　　注：key转成字符串
       real_time = 0;

       if (ac > 1) {
           convert_to_long_ex(time);
           real_time = Z_LVAL_PP(time);
       }
        注：如果传递了time参数，使用传递的time值，否则使用默认0
       result = mmc_delete(mmc, Z_STRVAL_PP(key), real_time);
        注：调用　mmc_delete方法删除数据，mmc_delete参考后续代码
       if (result > 0) {
           RETURN_TRUE;
       }

       注：删除成功
       else if (result == 0) {
           php_error_docref(NULL TSRMLS_CC, E_NOTICE, "such key doesn't exist");
           RETURN_FALSE;
       }

　　注：key不存在
       else {
           php_error_docref(NULL TSRMLS_CC, E_NOTICE, "error while deleting item");
       }

　　注：删除失败
       RETURN_FALSE;
   }
   php_error_docref(NULL TSRMLS_CC, E_NOTICE, "memcache_delete() should not be called like this. Use $memcache->delete($key,$timeout) to delete item");
   RETURN_FALSE;
}

mmc_delete方法代码如下：

两个参数，一个是要删除的key，一个是时间

static int mmc_delete(mmc_t *mmc, char *key, int time)
{
   char *real_command, *time_tmp;
   int size, response_buf_size;

   time_tmp = emalloc(MAX_LENGTH_OF_LONG + 1);

注：分配内存MAX_LENGTH_OF_LONG宏，32位系统是11 64位系统是20
   size = sprintf(time_tmp, "%d", time);
   time_tmp[size] = '\0';
    注：把time写入time_tmp缓存区，在最后追加一个结束符
   real_command = emalloc(
                              6               /* strlen(delete) */
                           + 1               /* space */
                           + strlen(key)
                           + 1               /* space */
                           + size
                           + 1
                           );
　注：命令字符串的大小，举例 delete key1 time
   PREPARE_KEY(key, strlen(key));

注：替换宏，走的这个方法php_strtr(key, key_len, "\t\r\n ", "____", 4);　把key中\t\r\n 这４个字符（后面有个空格）全部替换为"_"字符

    size = sprintf(real_command, "%s ", "delete");
   size += sprintf(real_command + size, "%s ", key);
   size += sprintf(real_command + size, "%s", time_tmp);

   real_command [size] = '\0';
注：把命令写入real_command缓冲中，追加结束符
   efree(time_tmp);
　注：释放资源
   mmc_debug("mmc_delete: trying to delete '%s'", key);

   /* drop it! =) */
   if (mmc_sendcmd(mmc, real_command, size) < 0) {
       efree(real_command);
       return -1;
   }
   efree(real_command);

   /* get server's response */
   if ((response_buf_size = mmc_readline(mmc)) < 0){
       return -1;
   }
    注：删除失败返回-1
   mmc_debug("mmc_delete: server's response is '%s'", mmc->inbuf);

   /* ok? */
   if(mmc_str_left(mmc->inbuf,"DELETED", response_buf_size, 7)) {
       return 1;
   }
    注：删除成功返回１
   if(mmc_str_left(mmc->inbuf,"NOT_FOUND", response_buf_size, 9)) {
       /* return 0, if such wasn't found */
       return 0;
   }
    注：删除的key不存在，返回0
   /* hmm.. */
   return -1;
}