microtime
Description ¶
microtime ([ bool
$get_as_float= FALSE ] ) : mixedmicrotime() returns the current Unix timestamp with microseconds. This function is only available on operating systems that support the gettimeofday() system call.
source file:** /php-src/ext/standard/microtime.c**
Part-1 : 内核抛出定义
1.1 源码
185 /* {{{ proto mixed microtime([bool get_as_float])
286 Returns either a string or a float containing the current time in seconds and microseconds */
387 PHP_FUNCTION(microtime)
488 {
589 _php_gettimeofday(INTERNAL_FUNCTION_PARAM_PASSTHRU, 0);
690 }
791 /* }}} */
Part-2 : 源码分析
2.1 源码
149 static void _php_gettimeofday(INTERNAL_FUNCTION_PARAMETERS, int mode)
250 {
351 zend_bool get_as_float = 0;
452 struct timeval tp = {0};
553
654 ZEND_PARSE_PARAMETERS_START(0, 1)
755 Z_PARAM_OPTIONAL
856 Z_PARAM_BOOL(get_as_float)
957 ZEND_PARSE_PARAMETERS_END();
1058
1159 if (gettimeofday(&tp, NULL)) {
1260 RETURN_FALSE;
1361 }
1462
1563 if (get_as_float) {
1664 RETURN_DOUBLE((double)(tp.tv_sec + tp.tv_usec / MICRO_IN_SEC));
1765 }
1866
1967 if (mode) {
2068 timelib_time_offset *offset;
2169
2270 offset = timelib_get_time_zone_info(tp.tv_sec, get_timezone_info());
2371
2472 array_init(return_value);
2573 add_assoc_long(return_value, "sec", tp.tv_sec);
2674 add_assoc_long(return_value, "usec", tp.tv_usec);
2775
2876 add_assoc_long(return_value, "minuteswest", -offset->offset / SEC_IN_MIN);
2977 add_assoc_long(return_value, "dsttime", offset->is_dst);
3078
3179 timelib_time_offset_dtor(offset);
3280 } else {
3381 RETURN_NEW_STR(zend_strpprintf(0, "%.8F %ld", tp.tv_usec / MICRO_IN_SEC, (long)tp.tv_sec));
3482 }
3583 }
3684
3785 /* {{{ proto mixed microtime([bool get_as_float])
3886 Returns either a string or a float containing the current time in seconds and microseconds */
3987 PHP_FUNCTION(microtime)
4088 {
4189 _php_gettimeofday(INTERNAL_FUNCTION_PARAM_PASSTHRU, 0);
4290 }
4391 /* }}} */
2.2 源码详解
首先在87行是Part-1部分提到的PHP引擎对外抛出函数,此处通过PHP_FUNCTION宏定义让PHP引擎拥有过的内核函数microtime .
从49行开始是_php_gettimeofday函数的具体实现函数,具体解析如下:
- 54-57行: 从PHP函数调用处解析可选参数get_as_float
- 59-61行: 调用操作系统内核函数gettimeofday获取时间信息 (链接)
- 63-65行: 如果get_as_float为true则返回double给用户(此处需要注意编译器的bit数量,32和64位精度不一样)
- 67-82行: 如果mode为false则构造字符串数据并返回,如果为true则构造数组并返回.
Part-2 : 注意
牵扯到64浮点数据 , 一定要注意编译器的位数 , 精度的不同会造成意想不到的BUG. 你函数能够返回Double类型,要注意.