Home | History | Annotate | Download | only in base 
      1 /*
      2  * libjingle
      3  * Copyright 2004--2005, Google Inc.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions are met:
      7  *
      8  *  1. Redistributions of source code must retain the above copyright notice,
      9  *     this list of conditions and the following disclaimer.
     10  *  2. Redistributions in binary form must reproduce the above copyright notice,
     11  *     this list of conditions and the following disclaimer in the documentation
     12  *     and/or other materials provided with the distribution.
     13  *  3. The name of the author may not be used to endorse or promote products
     14  *     derived from this software without specific prior written permission.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
     17  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
     18  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
     19  * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     20  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     21  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
     22  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
     23  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
     24  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
     25  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     26  */
     27 
     28 #ifdef POSIX
     29 #include <sys/time.h>
     30 #if defined(OSX) || defined(IOS)
     31 #include <mach/mach_time.h>
     32 #endif
     33 #endif
     34 
     35 #ifdef WIN32
     36 #define WIN32_LEAN_AND_MEAN
     37 #include <windows.h>
     38 #include <mmsystem.h>
     39 #endif
     40 
     41 #include "talk/base/common.h"
     42 #include "talk/base/timeutils.h"
     43 
     44 #define EFFICIENT_IMPLEMENTATION 1
     45 
     46 namespace talk_base {
     47 
     48 const uint32 LAST = 0xFFFFFFFF;
     49 const uint32 HALF = 0x80000000;
     50 
     51 uint64 TimeNanos() {
     52   int64 ticks = 0;
     53 #if defined(OSX) || defined(IOS)
     54   static mach_timebase_info_data_t timebase;
     55   if (timebase.denom == 0) {
     56     // Get the timebase if this is the first time we run.
     57     // Recommended by Apple's QA1398.
     58     VERIFY(KERN_SUCCESS == mach_timebase_info(&timebase));
     59   }
     60   // Use timebase to convert absolute time tick units into nanoseconds.
     61   ticks = mach_absolute_time() * timebase.numer / timebase.denom;
     62 #elif defined(POSIX)
     63   struct timespec ts;
     64   // TODO: Do we need to handle the case when CLOCK_MONOTONIC
     65   // is not supported?
     66   clock_gettime(CLOCK_MONOTONIC, &ts);
     67   ticks = kNumNanosecsPerSec * static_cast<int64>(ts.tv_sec) +
     68       static_cast<int64>(ts.tv_nsec);
     69 #elif defined(WIN32)
     70   static volatile LONG last_timegettime = 0;
     71   static volatile int64 num_wrap_timegettime = 0;
     72   volatile LONG* last_timegettime_ptr = &last_timegettime;
     73   DWORD now = timeGetTime();
     74   // Atomically update the last gotten time
     75   DWORD old = InterlockedExchange(last_timegettime_ptr, now);
     76   if (now < old) {
     77     // If now is earlier than old, there may have been a race between
     78     // threads.
     79     // 0x0fffffff ~3.1 days, the code will not take that long to execute
     80     // so it must have been a wrap around.
     81     if (old > 0xf0000000 && now < 0x0fffffff) {
     82       num_wrap_timegettime++;
     83     }
     84   }
     85   ticks = now + (num_wrap_timegettime << 32);
     86   // TODO: Calculate with nanosecond precision.  Otherwise, we're just
     87   // wasting a multiply and divide when doing Time() on Windows.
     88   ticks = ticks * kNumNanosecsPerMillisec;
     89 #endif
     90   return ticks;
     91 }
     92 
     93 uint32 Time() {
     94   return static_cast<uint32>(TimeNanos() / kNumNanosecsPerMillisec);
     95 }
     96 
     97 #if defined(WIN32)
     98 static const uint64 kFileTimeToUnixTimeEpochOffset = 116444736000000000ULL;
     99 
    100 struct timeval {
    101   long tv_sec, tv_usec;  // NOLINT
    102 };
    103 
    104 // Emulate POSIX gettimeofday().
    105 // Based on breakpad/src/third_party/glog/src/utilities.cc
    106 static int gettimeofday(struct timeval *tv, void *tz) {
    107   // FILETIME is measured in tens of microseconds since 1601-01-01 UTC.
    108   FILETIME ft;
    109   GetSystemTimeAsFileTime(&ft);
    110 
    111   LARGE_INTEGER li;
    112   li.LowPart = ft.dwLowDateTime;
    113   li.HighPart = ft.dwHighDateTime;
    114 
    115   // Convert to seconds and microseconds since Unix time Epoch.
    116   int64 micros = (li.QuadPart - kFileTimeToUnixTimeEpochOffset) / 10;
    117   tv->tv_sec = static_cast<long>(micros / kNumMicrosecsPerSec);  // NOLINT
    118   tv->tv_usec = static_cast<long>(micros % kNumMicrosecsPerSec); // NOLINT
    119 
    120   return 0;
    121 }
    122 
    123 // Emulate POSIX gmtime_r().
    124 static struct tm *gmtime_r(const time_t *timep, struct tm *result) {
    125   // On Windows, gmtime is thread safe.
    126   struct tm *tm = gmtime(timep);  // NOLINT
    127   if (tm == NULL) {
    128     return NULL;
    129   }
    130   *result = *tm;
    131   return result;
    132 }
    133 #endif  // WIN32
    134 
    135 void CurrentTmTime(struct tm *tm, int *microseconds) {
    136   struct timeval timeval;
    137   if (gettimeofday(&timeval, NULL) < 0) {
    138     // Incredibly unlikely code path.
    139     timeval.tv_sec = timeval.tv_usec = 0;
    140   }
    141   time_t secs = timeval.tv_sec;
    142   gmtime_r(&secs, tm);
    143   *microseconds = timeval.tv_usec;
    144 }
    145 
    146 uint32 TimeAfter(int32 elapsed) {
    147   ASSERT(elapsed >= 0);
    148   ASSERT(static_cast<uint32>(elapsed) < HALF);
    149   return Time() + elapsed;
    150 }
    151 
    152 bool TimeIsBetween(uint32 earlier, uint32 middle, uint32 later) {
    153   if (earlier <= later) {
    154     return ((earlier <= middle) && (middle <= later));
    155   } else {
    156     return !((later < middle) && (middle < earlier));
    157   }
    158 }
    159 
    160 bool TimeIsLaterOrEqual(uint32 earlier, uint32 later) {
    161 #if EFFICIENT_IMPLEMENTATION
    162   int32 diff = later - earlier;
    163   return (diff >= 0 && static_cast<uint32>(diff) < HALF);
    164 #else
    165   const bool later_or_equal = TimeIsBetween(earlier, later, earlier + HALF);
    166   return later_or_equal;
    167 #endif
    168 }
    169 
    170 bool TimeIsLater(uint32 earlier, uint32 later) {
    171 #if EFFICIENT_IMPLEMENTATION
    172   int32 diff = later - earlier;
    173   return (diff > 0 && static_cast<uint32>(diff) < HALF);
    174 #else
    175   const bool earlier_or_equal = TimeIsBetween(later, earlier, later + HALF);
    176   return !earlier_or_equal;
    177 #endif
    178 }
    179 
    180 int32 TimeDiff(uint32 later, uint32 earlier) {
    181 #if EFFICIENT_IMPLEMENTATION
    182   return later - earlier;
    183 #else
    184   const bool later_or_equal = TimeIsBetween(earlier, later, earlier + HALF);
    185   if (later_or_equal) {
    186     if (earlier <= later) {
    187       return static_cast<long>(later - earlier);
    188     } else {
    189       return static_cast<long>(later + (LAST - earlier) + 1);
    190     }
    191   } else {
    192     if (later <= earlier) {
    193       return -static_cast<long>(earlier - later);
    194     } else {
    195       return -static_cast<long>(earlier + (LAST - later) + 1);
    196     }
    197   }
    198 #endif
    199 }
    200 
    201 } // namespace talk_base
    202