75 lines
2.9 KiB
C
75 lines
2.9 KiB
C
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// Copyright 2018 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef BASE_TIME_TIME_OVERRIDE_H_
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#define BASE_TIME_TIME_OVERRIDE_H_
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#include "base/base_export.h"
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#include "base/time/time.h"
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namespace base {
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using TimeNowFunction = decltype(&Time::Now);
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using TimeTicksNowFunction = decltype(&TimeTicks::Now);
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using ThreadTicksNowFunction = decltype(&ThreadTicks::Now);
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// Time overrides should be used with extreme caution. Discuss with //base/time
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// OWNERS before adding a new one.
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namespace subtle {
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// Override the return value of Time::Now and Time::NowFromSystemTime /
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// TimeTicks::Now / ThreadTicks::Now to emulate time, e.g. for tests or to
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// modify progression of time. Note that the override should be set while
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// single-threaded and before the first call to Now() to avoid threading issues
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// and inconsistencies in returned values. Nested overrides are not allowed.
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class BASE_EXPORT ScopedTimeClockOverrides {
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public:
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// Pass |nullptr| for any override if it shouldn't be overriden.
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ScopedTimeClockOverrides(TimeNowFunction time_override,
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TimeTicksNowFunction time_ticks_override,
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ThreadTicksNowFunction thread_ticks_override);
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// Restores the platform default Now() functions.
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~ScopedTimeClockOverrides();
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static bool overrides_active() { return overrides_active_; }
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private:
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static bool overrides_active_;
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DISALLOW_COPY_AND_ASSIGN(ScopedTimeClockOverrides);
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};
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// These methods return the platform default Time::Now / TimeTicks::Now /
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// ThreadTicks::Now values even while an override is in place. These methods
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// should only be used in places where emulated time should be disregarded. For
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// example, they can be used to implement test timeouts for tests that may
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// override time.
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BASE_EXPORT Time TimeNowIgnoringOverride();
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BASE_EXPORT Time TimeNowFromSystemTimeIgnoringOverride();
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BASE_EXPORT TimeTicks TimeTicksNowIgnoringOverride();
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BASE_EXPORT ThreadTicks ThreadTicksNowIgnoringOverride();
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} // namespace subtle
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namespace internal {
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// These function pointers are used by platform-independent implementations of
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// the Now() methods and ScopedTimeClockOverrides. They are set to point to the
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// respective NowIgnoringOverride functions by default, but can also be set by
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// platform-specific code to select a default implementation at runtime, thereby
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// avoiding the indirection via the NowIgnoringOverride functions. Note that the
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// pointers can be overridden and later reset to the NowIgnoringOverride
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// functions by ScopedTimeClockOverrides.
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extern TimeNowFunction g_time_now_function;
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extern TimeNowFunction g_time_now_from_system_time_function;
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extern TimeTicksNowFunction g_time_ticks_now_function;
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extern ThreadTicksNowFunction g_thread_ticks_now_function;
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} // namespace internal
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} // namespace base
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#endif // BASE_TIME_TIME_OVERRIDE_H_
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