naiveproxy/base/task/task_scheduler/task.cc
2018-12-09 21:59:24 -05:00

67 lines
2.3 KiB
C++

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