Fuchsia port of base/time, with some refactoring of POSIX time modules.

base/time/time_now_posix.cc

+// Copyright (c) 2012 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/time.h"
+
+#include <stdint.h>
+#include <sys/time.h>
+#include <time.h>
+#if defined(OS_ANDROID) && !defined(__LP64__)
+#include <time64.h>
+#endif
+#include <unistd.h>
+
+#include "base/logging.h"
+#include "base/numerics/safe_math.h"
+#include "build/build_config.h"
+
+// Ensure the Fuchsia and Mac builds do not include this module. Instead,
+// non-POSIX implementation is used for sampling the system clocks.
+#if defined(OS_FUCHSIA) || defined(OS_MACOSX)
+#error "This implementation is for POSIX platforms other than Fuchsia or Mac."
+#endif
+
+namespace {
+
+int64_t ConvertTimespecToMicros(const struct timespec& ts) {
+  // On 32-bit systems, the calculation cannot overflow int64_t.
+  // 2**32 * 1000000 + 2**64 / 1000 < 2**63
+  if (sizeof(ts.tv_sec) <= 4 && sizeof(ts.tv_nsec) <= 8) {
+    int64_t result = ts.tv_sec;
+    result *= base::Time::kMicrosecondsPerSecond;
+    result += (ts.tv_nsec / base::Time::kNanosecondsPerMicrosecond);
+    return result;
+  } else {
+    base::CheckedNumeric<int64_t> result(ts.tv_sec);
+    result *= base::Time::kMicrosecondsPerSecond;
+    result += (ts.tv_nsec / base::Time::kNanosecondsPerMicrosecond);
+    return result.ValueOrDie();
+  }
+}
+
+// Helper function to get results from clock_gettime() and convert to a
+// microsecond timebase. Minimum requirement is MONOTONIC_CLOCK to be supported
+// on the system. FreeBSD 6 has CLOCK_MONOTONIC but defines
+// _POSIX_MONOTONIC_CLOCK to -1.
+#if (defined(OS_POSIX) && defined(_POSIX_MONOTONIC_CLOCK) && \
+     _POSIX_MONOTONIC_CLOCK >= 0) ||                         \
+    defined(OS_BSD) || defined(OS_ANDROID)
+int64_t ClockNow(clockid_t clk_id) {
+  struct timespec ts;
+  CHECK(clock_gettime(clk_id, &ts) == 0);
+  return ConvertTimespecToMicros(ts);
+}
+#else  // _POSIX_MONOTONIC_CLOCK
+#error No usable tick clock function on this platform.
+#endif  // _POSIX_MONOTONIC_CLOCK
+
+}  // namespace
+
+namespace base {
+
+// Time -----------------------------------------------------------------------
+
+// static
+Time Time::Now() {
+  struct timeval tv;
+  struct timezone tz = {0, 0};  // UTC
+  CHECK(gettimeofday(&tv, &tz) == 0);
+  // 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) +
+              kTimeTToMicrosecondsOffset);
+}
+
+// static
+Time Time::NowFromSystemTime() {
+  // Just use Now() because Now() returns the system time.
+  return Now();
+}
+
+// TimeTicks ------------------------------------------------------------------
+
+// static
+TimeTicks TimeTicks::Now() {
+  return TimeTicks(ClockNow(CLOCK_MONOTONIC));
+}
+
+// static
+TimeTicks::Clock TimeTicks::GetClock() {
+  return Clock::LINUX_CLOCK_MONOTONIC;
+}
+
+// static
+bool TimeTicks::IsHighResolution() {
+  return true;
+}
+
+// static
+bool TimeTicks::IsConsistentAcrossProcesses() {
+  return true;
+}
+
+// static
+ThreadTicks ThreadTicks::Now() {
+#if (defined(_POSIX_THREAD_CPUTIME) && (_POSIX_THREAD_CPUTIME >= 0)) || \
+    defined(OS_ANDROID)
+  return ThreadTicks(ClockNow(CLOCK_THREAD_CPUTIME_ID));
+#else
+  NOTREACHED();
+  return ThreadTicks();
+#endif
+}
+
+}  // namespace base