// Copyright 2016 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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#include "base/task_scheduler/task.h"
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#include <utility>
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#include "base/atomic_sequence_num.h"
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#include "base/critical_closure.h"
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namespace base {
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namespace internal {
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namespace {
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AtomicSequenceNumber g_sequence_nums_for_tracing;
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} // namespace
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Task::Task(const Location& posted_from,
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OnceClosure task,
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const TaskTraits& traits,
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TimeDelta delay)
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: PendingTask(
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posted_from,
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traits.shutdown_behavior() == TaskShutdownBehavior::BLOCK_SHUTDOWN
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? MakeCriticalClosure(std::move(task))
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: std::move(task),
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delay.is_zero() ? TimeTicks() : TimeTicks::Now() + delay,
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Nestable::kNonNestable),
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// Prevent a delayed BLOCK_SHUTDOWN task from blocking shutdown before it
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// starts running by changing its shutdown behavior to SKIP_ON_SHUTDOWN.
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traits(
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(!delay.is_zero() &&
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traits.shutdown_behavior() == TaskShutdownBehavior::BLOCK_SHUTDOWN)
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? TaskTraits::Override(traits,
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{TaskShutdownBehavior::SKIP_ON_SHUTDOWN})
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: traits),
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delay(delay) {
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// TaskScheduler doesn't use |sequence_num| but tracing (toplevel.flow) relies
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// on it being unique. While this subtle dependency is a bit overreaching,
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// TaskScheduler is the only task system that doesn't use |sequence_num| and
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// the dependent code rarely changes so this isn't worth a big change and
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// faking it here isn't too bad for now (posting tasks is full of atomic ops
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// already).
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this->sequence_num = g_sequence_nums_for_tracing.GetNext();
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}
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// This should be "= default but MSVC has trouble with "noexcept = default" in
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// this case.
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Task::Task(Task&& other) noexcept
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: PendingTask(std::move(other)),
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traits(other.traits),
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delay(other.delay),
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sequenced_time(other.sequenced_time),
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sequenced_task_runner_ref(std::move(other.sequenced_task_runner_ref)),
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single_thread_task_runner_ref(
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std::move(other.single_thread_task_runner_ref)) {}
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Task::~Task() = default;
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Task& Task::operator=(Task&& other) = default;
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} // namespace internal
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} // namespace base
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