1 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #include "base/time.h" 6 7 #include <sys/time.h> 8 #include <time.h> 9 10 #include <limits> 11 12 #include "base/basictypes.h" 13 #include "base/logging.h" 14 15 namespace base { 16 17 #if !defined(OS_MACOSX) 18 // The Time routines in this file use standard POSIX routines, or almost- 19 // standard routines in the case of timegm. We need to use a Mach-specific 20 // function for TimeTicks::Now() on Mac OS X. 21 22 // Time ----------------------------------------------------------------------- 23 24 // Windows uses a Gregorian epoch of 1601. We need to match this internally 25 // so that our time representations match across all platforms. See bug 14734. 26 // irb(main):010:0> Time.at(0).getutc() 27 // => Thu Jan 01 00:00:00 UTC 1970 28 // irb(main):011:0> Time.at(-11644473600).getutc() 29 // => Mon Jan 01 00:00:00 UTC 1601 30 static const int64 kWindowsEpochDeltaSeconds = GG_INT64_C(11644473600); 31 static const int64 kWindowsEpochDeltaMilliseconds = 32 kWindowsEpochDeltaSeconds * Time::kMillisecondsPerSecond; 33 34 // static 35 const int64 Time::kWindowsEpochDeltaMicroseconds = 36 kWindowsEpochDeltaSeconds * Time::kMicrosecondsPerSecond; 37 38 // Some functions in time.cc use time_t directly, so we provide an offset 39 // to convert from time_t (Unix epoch) and internal (Windows epoch). 40 // static 41 const int64 Time::kTimeTToMicrosecondsOffset = kWindowsEpochDeltaMicroseconds; 42 43 // static 44 Time Time::Now() { 45 struct timeval tv; 46 struct timezone tz = { 0, 0 }; // UTC 47 if (gettimeofday(&tv, &tz) != 0) { 48 DCHECK(0) << "Could not determine time of day"; 49 } 50 // Combine seconds and microseconds in a 64-bit field containing microseconds 51 // since the epoch. That's enough for nearly 600 centuries. Adjust from 52 // Unix (1970) to Windows (1601) epoch. 53 return Time((tv.tv_sec * kMicrosecondsPerSecond + tv.tv_usec) + 54 kWindowsEpochDeltaMicroseconds); 55 } 56 57 // static 58 Time Time::NowFromSystemTime() { 59 // Just use Now() because Now() returns the system time. 60 return Now(); 61 } 62 63 // static 64 Time Time::FromExploded(bool is_local, const Exploded& exploded) { 65 struct tm timestruct; 66 timestruct.tm_sec = exploded.second; 67 timestruct.tm_min = exploded.minute; 68 timestruct.tm_hour = exploded.hour; 69 timestruct.tm_mday = exploded.day_of_month; 70 timestruct.tm_mon = exploded.month - 1; 71 timestruct.tm_year = exploded.year - 1900; 72 timestruct.tm_wday = exploded.day_of_week; // mktime/timegm ignore this 73 timestruct.tm_yday = 0; // mktime/timegm ignore this 74 timestruct.tm_isdst = -1; // attempt to figure it out 75 timestruct.tm_gmtoff = 0; // not a POSIX field, so mktime/timegm ignore 76 timestruct.tm_zone = NULL; // not a POSIX field, so mktime/timegm ignore 77 78 time_t seconds; 79 if (is_local) 80 seconds = mktime(×truct); 81 else 82 seconds = timegm(×truct); 83 84 int64 milliseconds; 85 // Handle overflow. Clamping the range to what mktime and timegm might 86 // return is the best that can be done here. It's not ideal, but it's better 87 // than failing here or ignoring the overflow case and treating each time 88 // overflow as one second prior to the epoch. 89 if (seconds == -1 && 90 (exploded.year < 1969 || exploded.year > 1970)) { 91 // If exploded.year is 1969 or 1970, take -1 as correct, with the 92 // time indicating 1 second prior to the epoch. (1970 is allowed to handle 93 // time zone and DST offsets.) Otherwise, return the most future or past 94 // time representable. Assumes the time_t epoch is 1970-01-01 00:00:00 UTC. 95 // 96 // The minimum and maximum representible times that mktime and timegm could 97 // return are used here instead of values outside that range to allow for 98 // proper round-tripping between exploded and counter-type time 99 // representations in the presence of possible truncation to time_t by 100 // division and use with other functions that accept time_t. 101 // 102 // When representing the most distant time in the future, add in an extra 103 // 999ms to avoid the time being less than any other possible value that 104 // this function can return. 105 if (exploded.year < 1969) { 106 milliseconds = std::numeric_limits<time_t>::min() * 107 kMillisecondsPerSecond; 108 } else { 109 milliseconds = (std::numeric_limits<time_t>::max() * 110 kMillisecondsPerSecond) + 111 kMillisecondsPerSecond - 1; 112 } 113 } else { 114 milliseconds = seconds * kMillisecondsPerSecond + exploded.millisecond; 115 } 116 117 // Adjust from Unix (1970) to Windows (1601) epoch. 118 return Time((milliseconds * kMicrosecondsPerMillisecond) + 119 kWindowsEpochDeltaMicroseconds); 120 } 121 122 void Time::Explode(bool is_local, Exploded* exploded) const { 123 // Time stores times with microsecond resolution, but Exploded only carries 124 // millisecond resolution, so begin by being lossy. Adjust from Windows 125 // epoch (1601) to Unix epoch (1970); 126 int64 milliseconds = (us_ - kWindowsEpochDeltaMicroseconds) / 127 kMicrosecondsPerMillisecond; 128 time_t seconds = milliseconds / kMillisecondsPerSecond; 129 130 struct tm timestruct; 131 if (is_local) 132 localtime_r(&seconds, ×truct); 133 else 134 gmtime_r(&seconds, ×truct); 135 136 exploded->year = timestruct.tm_year + 1900; 137 exploded->month = timestruct.tm_mon + 1; 138 exploded->day_of_week = timestruct.tm_wday; 139 exploded->day_of_month = timestruct.tm_mday; 140 exploded->hour = timestruct.tm_hour; 141 exploded->minute = timestruct.tm_min; 142 exploded->second = timestruct.tm_sec; 143 exploded->millisecond = milliseconds % kMillisecondsPerSecond; 144 } 145 146 // TimeTicks ------------------------------------------------------------------ 147 // FreeBSD 6 has CLOCK_MONOLITHIC but defines _POSIX_MONOTONIC_CLOCK to -1. 148 #if (defined(OS_POSIX) && \ 149 defined(_POSIX_MONOTONIC_CLOCK) && _POSIX_MONOTONIC_CLOCK >= 0) || \ 150 defined(OS_FREEBSD) 151 152 // static 153 TimeTicks TimeTicks::Now() { 154 uint64_t absolute_micro; 155 156 struct timespec ts; 157 if (clock_gettime(CLOCK_MONOTONIC, &ts) != 0) { 158 NOTREACHED() << "clock_gettime(CLOCK_MONOTONIC) failed."; 159 return TimeTicks(); 160 } 161 162 absolute_micro = 163 (static_cast<int64>(ts.tv_sec) * Time::kMicrosecondsPerSecond) + 164 (static_cast<int64>(ts.tv_nsec) / Time::kNanosecondsPerMicrosecond); 165 166 return TimeTicks(absolute_micro); 167 } 168 169 #else // _POSIX_MONOTONIC_CLOCK 170 #error No usable tick clock function on this platform. 171 #endif // _POSIX_MONOTONIC_CLOCK 172 173 // static 174 TimeTicks TimeTicks::HighResNow() { 175 return Now(); 176 } 177 178 #endif // !OS_MACOSX 179 180 struct timespec TimeDelta::ToTimeSpec() const { 181 int64 microseconds = InMicroseconds(); 182 time_t seconds = 0; 183 if (microseconds >= Time::kMicrosecondsPerSecond) { 184 seconds = InSeconds(); 185 microseconds -= seconds * Time::kMicrosecondsPerSecond; 186 } 187 struct timespec result = 188 {seconds, 189 microseconds * Time::kNanosecondsPerMicrosecond}; 190 return result; 191 } 192 193 } // namespace base 194
