我应该用什么来替换 Windows 上的 gettimeofday()? [英] What should I use to replace gettimeofday() on Windows?

问题描述

我正在编写一个可移植的 Socket 类，它支持发送和接收超时...要实现这些超时，我使用 select().... 但是，我有时需要知道我在 select() 中被阻塞了多长时间，当然在 Linux 上我会通过在调用 select() 之前和之后调用 gettimeofday() 来实现code> 然后使用 timersub() 计算增量...

I'm writing a portable Socket class that supports timeouts for both sending and receiving... To implement these timeouts I'm using select().... But, I sometimes need to know how long I was blocked inside select() which of course on Linux I would implement by calling gettimeofday() before and after I call select() and then using timersub() to calculate the delta...

鉴于 select() 在 Windows 上接受 struct timeval 因为它的超时，我应该使用什么方法来替换 Windows 上的 gettimeofday()?

Given that select() on Windows accepts struct timeval for it's timeout, what method should I used to replace gettimeofday() on Windows?

推荐答案

我最终找到了这个页面:gettimeofday() Windows 函数(现在通过 Wayback Machine)gettimeofday() 在 Windows 上的一个方便、花哨的实现.它使用 GetSystemTimeAsFileTime() 方法来获得准确的时钟.

I ended up finding this page: gettimeofday() function for Windows (now via the Wayback Machine) which has a handy, dandy implementation of gettimeofday() on Windows. It uses the GetSystemTimeAsFileTime() method to get an accurate clock.

更新:这是用于 HPC 的 Unix 到 Windows 移植词典"的备用活动链接gettimeofday()(现在通过 Wayback Machine)指向 OP 所指的实现.另请注意，链接的实现中有一个错字:

Update: Here's an alternative active link from the 'Unix to Windows Porting Dictionary for HPC' gettimeofday() (now via the Wayback Machine) that points to the implementation the OP referred to. Note also that there's a typo in the linked implementation:

#if defined(_MSC_VER) || defined(_MSC_EXTENSIONS)
  #define DELTA_EPOCH_IN_MICROSECS  11644473600000000Ui64 // WRONG
#else
  #define DELTA_EPOCH_IN_MICROSECS  11644473600000000ULL // WRONG
#endif

显示的值在末尾缺少一个额外的 0(它们假定为微秒，而不是 100 纳秒间隔的数量).这个错字是通过此评论发现的谷歌代码项目页面.要使用的正确值如下所示:

The values shown are missing an extra 0 at the end (they assumed microseconds, not the number of 100-nanosecond intervals). This typo was found via this comment on a Google code project page. The correct values to use are shown below:

#if defined(_MSC_VER) || defined(_MSC_EXTENSIONS)
  #define DELTA_EPOCH_IN_MICROSECS  116444736000000000Ui64 // CORRECT
#else
  #define DELTA_EPOCH_IN_MICROSECS  116444736000000000ULL // CORRECT
#endif

<小时>

PostgreSQL 对 Windows 的 gettimeofday 的实现:

/*
 * gettimeofday.c
 *    Win32 gettimeofday() replacement
 *
 * src/port/gettimeofday.c
 *
 * Copyright (c) 2003 SRA, Inc.
 * Copyright (c) 2003 SKC, Inc.
 *
 * Permission to use, copy, modify, and distribute this software and
 * its documentation for any purpose, without fee, and without a
 * written agreement is hereby granted, provided that the above
 * copyright notice and this paragraph and the following two
 * paragraphs appear in all copies.
 *
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE TO ANY PARTY FOR DIRECT,
 * INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING
 * LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
 * DOCUMENTATION, EVEN IF THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * THE AUTHOR SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS ON AN "AS
 * IS" BASIS, AND THE AUTHOR HAS NO OBLIGATIONS TO PROVIDE MAINTENANCE,
 * SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
 */

#include "c.h"

#include <sys/time.h>


/* FILETIME of Jan 1 1970 00:00:00. */
static const unsigned __int64 epoch = ((unsigned __int64) 116444736000000000ULL);

/*
 * timezone information is stored outside the kernel so tzp isn't used anymore.
 *
 * Note: this function is not for Win32 high precision timing purpose. See
 * elapsed_time().
 */
int
gettimeofday(struct timeval * tp, struct timezone * tzp)
{
    FILETIME    file_time;
    SYSTEMTIME  system_time;
    ULARGE_INTEGER ularge;

    GetSystemTime(&system_time);
    SystemTimeToFileTime(&system_time, &file_time);
    ularge.LowPart = file_time.dwLowDateTime;
    ularge.HighPart = file_time.dwHighDateTime;

    tp->tv_sec = (long) ((ularge.QuadPart - epoch) / 10000000L);
    tp->tv_usec = (long) (system_time.wMilliseconds * 1000);

    return 0;
}

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