Make POSIX time routines work on Linux by providing a POSIX-conformant version of TimeTicks::Now() to replace the Mach-specific one used on the Mac.

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@664 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 162 insertions, 0 deletions

diff --git a/base/time_posix.cc b/base/time_posix.cc
new file mode 100644
index 0000000..de08c90
--- /dev/null
+++ b/base/time_posix.cc
@@ -0,0 +1,162 @@
+// Copyright 2008, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//    * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//    * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//    * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "base/time.h"
+
+#ifdef OS_MACOSX
+#include <mach/mach_time.h>
+#endif
+#include <sys/time.h>
+#include <time.h>
+
+#include "base/basictypes.h"
+#include "base/logging.h"
+
+// 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 -----------------------------------------------------------------------
+
+// The internal representation of Time uses time_t directly, so there is no
+// offset.  The epoch is 1970-01-01 00:00:00 UTC.
+// static
+const int64 Time::kTimeTToMicrosecondsOffset = GG_INT64_C(0);
+
+// static
+int64 Time::CurrentWallclockMicroseconds() {
+  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.
+  return tv.tv_sec * kMicrosecondsPerSecond + tv.tv_usec;
+}
+
+// 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(&timestruct);
+  else
+    seconds = timegm(&timestruct);
+  DCHECK(seconds >= 0) << "mktime/timegm could not convert from exploded";
+
+  uint64 milliseconds = seconds * kMillisecondsPerSecond + exploded.millisecond;
+  return Time(milliseconds * kMicrosecondsPerMillisecond);
+}
+
+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.
+  uint64 milliseconds = us_ / kMicrosecondsPerMillisecond;
+  time_t seconds = milliseconds / kMillisecondsPerSecond;
+
+  struct tm timestruct;
+  if (is_local)
+    localtime_r(&seconds, &timestruct);
+  else
+    gmtime_r(&seconds, &timestruct);
+
+  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 ------------------------------------------------------------------
+
+// static
+TimeTicks TimeTicks::Now() {
+  uint64_t absolute_micro;
+
+#if defined(OS_MACOSX)
+
+  static bool has_timebase_info = false;
+  static mach_timebase_info_data_t timebase_info = {1, 1};
+  if (!has_timebase_info) {
+    has_timebase_info = mach_timebase_info(&timebase_info) == KERN_SUCCESS;
+  }
+  DCHECK(has_timebase_info) << "Could not determine system tick rate";
+
+  // mach_absolute_time is it when it comes to ticks on the Mac.  Other calls
+  // with less precision (such as TickCount) just call through to
+  // mach_absolute_time.
+
+  // timebase_info converts absolute time tick units into nanoseconds.  Convert
+  // to microseconds up front to stave off overflows.
+  absolute_micro = mach_absolute_time() / Time::kNanosecondsPerMicrosecond *
+                   timebase_info.numer / timebase_info.denom;
+
+  // Don't bother with the rollover handling that the Windows version does.
+  // With numer and denom = 1 (the expected case), the 64-bit absolute time
+  // reported in nanoseconds is enough to last nearly 585 years.
+
+#elif defined(OS_POSIX) && \
+      defined(_POSIX_MONOTONIC_CLOCK) && _POSIX_MONOTONIC_CLOCK >= 0
+  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);
+
+#else  // _POSIX_MONOTONIC_CLOCK
+#error No usable tick clock function on this platform.
+#endif  // _POSIX_MONOTONIC_CLOCK
+
+  return TimeTicks(absolute_micro);
+}
+
+// static
+TimeTicks TimeTicks::UnreliableHighResNow() {
+  return Now();
+}