1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465 |
- // Copyright 2018 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"
- namespace base {
- // static
- TimeTicks TimeTicks::FromUptimeMillis(int64_t uptime_millis_value) {
- // The implementation of the SystemClock.uptimeMillis() in AOSP uses the same
- // clock as base::TimeTicks::Now(): clock_gettime(CLOCK_MONOTONIC), see in
- // platform/system/code:
- // 1. libutils/SystemClock.cpp
- // 2. libutils/Timers.cpp
- //
- // We are not aware of any motivations for Android OEMs to modify the AOSP
- // implementation of either uptimeMillis() or clock_gettime(CLOCK_MONOTONIC),
- // so we assume that there are no such customizations.
- //
- // Under these assumptions the conversion is as safe as copying the value of
- // base::TimeTicks::Now() with a loss of sub-millisecond precision.
- return TimeTicks(uptime_millis_value * Time::kMicrosecondsPerMillisecond);
- }
- // This file is included on chromeos_ash because it needs to interpret
- // UptimeMillis values from the Android container.
- #if BUILDFLAG(IS_ANDROID)
- // static
- TimeTicks TimeTicks::FromJavaNanoTime(int64_t nano_time_value) {
- // The implementation of the System.nanoTime() in AOSP uses the same
- // clock as UptimeMillis() and base::TimeTicks::Now():
- // clock_gettime(CLOCK_MONOTONIC), see ojluni/src/main/native/System.c in
- // AOSP.
- //
- // From Android documentation on android.os.SystemClock:
- // [uptimeMillis()] is the basis for most interval timing such as
- // Thread.sleep(millls), Object.wait(millis), and System.nanoTime().
- //
- // We are not aware of any motivations for Android OEMs to modify the AOSP
- // implementation of either uptimeMillis(), nanoTime, or
- // clock_gettime(CLOCK_MONOTONIC), so we assume that there are no such
- // customizations.
- //
- // Under these assumptions the conversion is as safe as copying the value of
- // base::TimeTicks::Now() without the (theoretical) sub-microsecond
- // resolution.
- return TimeTicks(nano_time_value / Time::kNanosecondsPerMicrosecond);
- }
- jlong TimeTicks::ToUptimeMillis() const {
- // See FromUptimeMillis. UptimeMillis and TimeTicks use the same clock source,
- // and only differ in resolution.
- return us_ / Time::kMicrosecondsPerMillisecond;
- }
- jlong TimeTicks::ToUptimeMicros() const {
- // Same as ToUptimeMillis but maintains sub-millisecond precision.
- return us_;
- }
- #endif // BUILDFLAG(IS_ANDROID)
- } // namespace base
|