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// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/time.h"
#include <sys/time.h>
#include <time.h>
#include <limits>
#include "base/basictypes.h"
#include "base/logging.h"
namespace base {
// The Time routines in this file use standard POSIX routines, or almost-
// standard routines in the case of timegm. We need to use a Mach-specific
// function for TimeTicks::Now() on Mac OS X.
// Time -----------------------------------------------------------------------
// Windows uses a Gregorian epoch of 1601. We need to match this internally
// so that our time representations match across all platforms. See bug 14734.
// irb(main):010:0> Time.at(0).getutc()
// => Thu Jan 01 00:00:00 UTC 1970
// irb(main):011:0> Time.at(-11644473600).getutc()
// => Mon Jan 01 00:00:00 UTC 1601
static const int64 kWindowsEpochDeltaSeconds = GG_INT64_C(11644473600);
static const int64 kWindowsEpochDeltaMilliseconds =
kWindowsEpochDeltaSeconds * Time::kMillisecondsPerSecond;
// static
const int64 Time::kWindowsEpochDeltaMicroseconds =
kWindowsEpochDeltaSeconds * Time::kMicrosecondsPerSecond;
// Some functions in time.cc use time_t directly, so we provide an offset
// to convert from time_t (Unix epoch) and internal (Windows epoch).
// static
const int64 Time::kTimeTToMicrosecondsOffset = kWindowsEpochDeltaMicroseconds;
// static
Time Time::Now() {
struct timeval tv;
struct timezone tz = { 0, 0 }; // UTC
if (gettimeofday(&tv, &tz) != 0) {
DCHECK(0) << "Could not determine time of day";
}
// Combine seconds and microseconds in a 64-bit field containing microseconds
// since the epoch. That's enough for nearly 600 centuries. Adjust from
// Unix (1970) to Windows (1601) epoch.
return Time((tv.tv_sec * kMicrosecondsPerSecond + tv.tv_usec) +
kWindowsEpochDeltaMicroseconds);
}
// static
Time Time::NowFromSystemTime() {
// Just use Now() because Now() returns the system time.
return Now();
}
// static
Time Time::FromExploded(bool is_local, const Exploded& exploded) {
struct tm timestruct;
timestruct.tm_sec = exploded.second;
timestruct.tm_min = exploded.minute;
timestruct.tm_hour = exploded.hour;
timestruct.tm_mday = exploded.day_of_month;
timestruct.tm_mon = exploded.month - 1;
timestruct.tm_year = exploded.year - 1900;
timestruct.tm_wday = exploded.day_of_week; // mktime/timegm ignore this
timestruct.tm_yday = 0; // mktime/timegm ignore this
timestruct.tm_isdst = -1; // attempt to figure it out
timestruct.tm_gmtoff = 0; // not a POSIX field, so mktime/timegm ignore
timestruct.tm_zone = NULL; // not a POSIX field, so mktime/timegm ignore
time_t seconds;
if (is_local)
seconds = mktime(×truct);
else
seconds = timegm(×truct);
int64 milliseconds;
// Handle overflow. Clamping the range to what mktime and timegm might
// return is the best that can be done here. It's not ideal, but it's better
// than failing here or ignoring the overflow case and treating each time
// overflow as one second prior to the epoch.
if (seconds == -1 &&
(exploded.year < 1969 || exploded.year > 1970)) {
// If exploded.year is 1969 or 1970, take -1 as correct, with the
// time indicating 1 second prior to the epoch. (1970 is allowed to handle
// time zone and DST offsets.) Otherwise, return the most future or past
// time representable. Assumes the time_t epoch is 1970-01-01 00:00:00 UTC.
//
// The minimum and maximum representible times that mktime and timegm could
// return are used here instead of values outside that range to allow for
// proper round-tripping between exploded and counter-type time
// representations in the presence of possible truncation to time_t by
// division and use with other functions that accept time_t.
//
// When representing the most distant time in the future, add in an extra
// 999ms to avoid the time being less than any other possible value that
// this function can return.
if (exploded.year < 1969) {
milliseconds = std::numeric_limits<time_t>::min() *
kMillisecondsPerSecond;
} else {
milliseconds = (std::numeric_limits<time_t>::max() *
kMillisecondsPerSecond) +
kMillisecondsPerSecond - 1;
}
} else {
milliseconds = seconds * kMillisecondsPerSecond + exploded.millisecond;
}
// Adjust from Unix (1970) to Windows (1601) epoch.
return Time((milliseconds * kMicrosecondsPerMillisecond) +
kWindowsEpochDeltaMicroseconds);
}
void Time::Explode(bool is_local, Exploded* exploded) const {
// Time stores times with microsecond resolution, but Exploded only carries
// millisecond resolution, so begin by being lossy. Adjust from Windows
// epoch (1601) to Unix epoch (1970);
int64 milliseconds = (us_ - kWindowsEpochDeltaMicroseconds) /
kMicrosecondsPerMillisecond;
time_t seconds = milliseconds / kMillisecondsPerSecond;
struct tm timestruct;
if (is_local)
localtime_r(&seconds, ×truct);
else
gmtime_r(&seconds, ×truct);
exploded->year = timestruct.tm_year + 1900;
exploded->month = timestruct.tm_mon + 1;
exploded->day_of_week = timestruct.tm_wday;
exploded->day_of_month = timestruct.tm_mday;
exploded->hour = timestruct.tm_hour;
exploded->minute = timestruct.tm_min;
exploded->second = timestruct.tm_sec;
exploded->millisecond = milliseconds % kMillisecondsPerSecond;
}
// TimeTicks ------------------------------------------------------------------
// FreeBSD 6 has CLOCK_MONOLITHIC but defines _POSIX_MONOTONIC_CLOCK to -1.
#if (defined(OS_POSIX) && \
defined(_POSIX_MONOTONIC_CLOCK) && _POSIX_MONOTONIC_CLOCK >= 0) || \
defined(OS_FREEBSD)
// static
TimeTicks TimeTicks::Now() {
uint64_t absolute_micro;
struct timespec ts;
if (clock_gettime(CLOCK_MONOTONIC, &ts) != 0) {
NOTREACHED() << "clock_gettime(CLOCK_MONOTONIC) failed.";
return TimeTicks();
}
absolute_micro =
(static_cast<int64>(ts.tv_sec) * Time::kMicrosecondsPerSecond) +
(static_cast<int64>(ts.tv_nsec) / Time::kNanosecondsPerMicrosecond);
return TimeTicks(absolute_micro);
}
#else // _POSIX_MONOTONIC_CLOCK
#error No usable tick clock function on this platform.
#endif // _POSIX_MONOTONIC_CLOCK
// static
TimeTicks TimeTicks::HighResNow() {
return Now();
}
} // namespace base
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