curl/lib/timeval.c

   1 /***************************************************************************
   2  *                                  _   _ ____  _
   3  *  Project                     ___| | | |  _ \| |
   4  *                             / __| | | | |_) | |
   5  *                            | (__| |_| |  _ <| |___
   6  *                             \___|\___/|_| \_\_____|
   7  *
   8  * Copyright (C) 1998 - 2008, Daniel Stenberg, <daniel@haxx.se>, et al.
   9  *
  10  * This software is licensed as described in the file COPYING, which
  11  * you should have received as part of this distribution. The terms
  12  * are also available at http://curl.haxx.se/docs/copyright.html.
  13  *
  14  * You may opt to use, copy, modify, merge, publish, distribute and/or sell
  15  * copies of the Software, and permit persons to whom the Software is
  16  * furnished to do so, under the terms of the COPYING file.
  17  *
  18  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  19  * KIND, either express or implied.
  20  *
  21  * $Id: timeval.c,v 1.32 2008-07-02 03:04:56 yangtse Exp $
  22  ***************************************************************************/
  23
  24 #include "timeval.h"
  25
  26 #if defined(WIN32) && !defined(MSDOS)
  27
  28 struct timeval curlx_tvnow(void)
  29 {
  30   /*
  31   ** GetTickCount() is available on _all_ Windows versions from W95 up
  32   ** to nowadays. Returns milliseconds elapsed since last system boot,
  33   ** increases monotonically and wraps once 49.7 days have elapsed.
  34   */
  35   struct timeval now;
  36   DWORD milliseconds = GetTickCount();
  37   now.tv_sec = milliseconds / 1000;
  38   now.tv_usec = (milliseconds % 1000) * 1000;
  39   return now;
  40 }
  41
  42 #elif defined(HAVE_CLOCK_GETTIME_MONOTONIC)
  43
  44 struct timeval curlx_tvnow(void)
  45 {
  46   /*
  47   ** clock_gettime() is granted to be increased monotonically when the
  48   ** monotonic clock is queried. Time starting point is unspecified, it
  49   ** could be the system start-up time, the Epoch, or something else,
  50   ** in any case the time starting point does not change once that the
  51   ** system has started up.
  52   */
  53   struct timeval now;
  54   struct timespec tsnow;
  55   if(0 == clock_gettime(CLOCK_MONOTONIC, &tsnow)) {
  56     now.tv_sec = tsnow.tv_sec;
  57     now.tv_usec = tsnow.tv_nsec / 1000;
  58   }
  59   /*
  60   ** Even when the configure process has truly detected monotonic clock
  61   ** availability, it might happen that it is not actually available at
  62   ** run-time. When this occurs simply fallback to other time source.
  63   */
  64 #ifdef HAVE_GETTIMEOFDAY
  65   else
  66     (void)gettimeofday(&now, NULL);
  67 #else
  68   else {
  69     now.tv_sec = (long)time(NULL);
  70     now.tv_usec = 0;
  71   }
  72 #endif
  73   return now;
  74 }
  75
  76 #elif defined(HAVE_GETTIMEOFDAY)
  77
  78 struct timeval curlx_tvnow(void)
  79 {
  80   /*
  81   ** gettimeofday() is not granted to be increased monotonically, due to
  82   ** clock drifting and external source time synchronization it can jump
  83   ** forward or backward in time.
  84   */
  85   struct timeval now;
  86   (void)gettimeofday(&now, NULL);
  87   return now;
  88 }
  89
  90 #else
  91
  92 struct timeval curlx_tvnow(void)
  93 {
  94   /*
  95   ** time() returns the value of time in seconds since the Epoch.
  96   */
  97   struct timeval now;
  98   now.tv_sec = (long)time(NULL);
  99   now.tv_usec = 0;
 100   return now;
 101 }
 102
 103 #endif
 104
 105 /*
 106  * Make sure that the first argument is the more recent time, as otherwise
 107  * we'll get a weird negative time-diff back...
 108  *
 109  * Returns: the time difference in number of milliseconds.
 110  */
 111 long curlx_tvdiff(struct timeval newer, struct timeval older)
 112 {
 113   return (newer.tv_sec-older.tv_sec)*1000+
 114     (newer.tv_usec-older.tv_usec)/1000;
 115 }
 116
 117 /*
 118  * Same as curlx_tvdiff but with full usec resolution.
 119  *
 120  * Returns: the time difference in seconds with subsecond resolution.
 121  */
 122 double curlx_tvdiff_secs(struct timeval newer, struct timeval older)
 123 {
 124   return (double)(newer.tv_sec-older.tv_sec)+
 125     (double)(newer.tv_usec-older.tv_usec)/1000000.0;
 126 }
 127
 128 /* return the number of seconds in the given input timeval struct */
 129 long Curl_tvlong(struct timeval t1)
 130 {
 131   return t1.tv_sec;
 132 }