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// Copyright (c) 2011 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 <array>
#include "base/base_export.h"
#include "base/callback.h"
#include "base/containers/queue.h"
#include "base/location.h"
#include "base/optional.h"
#include "base/time/time.h"
namespace base {
enum class Nestable : uint8_t {
// Contains data about a pending task. Stored in TaskQueue and DelayedTaskQueue
// for use by classes that queue and execute tasks.
struct BASE_EXPORT PendingTask {
PendingTask(const Location& posted_from,
OnceClosure task,
TimeTicks delayed_run_time = TimeTicks(),
Nestable nestable = Nestable::kNestable);
PendingTask(PendingTask&& other);
PendingTask& operator=(PendingTask&& other);
// Used to support sorting.
bool operator<(const PendingTask& other) const;
// The task to run.
OnceClosure task;
// The site this PendingTask was posted from.
Location posted_from;
// The time when the task should be run.
base::TimeTicks delayed_run_time;
// The time at which the task was queued. For SequenceManager tasks and
// ThreadPool non-delayed tasks, this happens at post time. For
// ThreadPool delayed tasks, this happens some time after the task's delay
// has expired. This is not set for SequenceManager tasks if
// SetAddQueueTimeToTasks(true) wasn't call. This defaults to a null TimeTicks
// if the task hasn't been inserted in a sequence yet.
TimeTicks queue_time;
// Chain of symbols of the parent tasks which led to this one being posted.
static constexpr size_t kTaskBacktraceLength = 4;
std::array<const void*, kTaskBacktraceLength> task_backtrace = {};
// The context of the IPC message that was being handled when this task was
// posted. This is a hash of the IPC message name that is set within the scope
// of an IPC handler and when symbolized uniquely identifies the message being
// processed. This property is also propagated from one PendingTask to the
// next. For example, if pending task A was posted while handling an IPC,
// and pending task B was posted from within pending task A, then pending task
// B will inherit the |ipc_hash| of pending task A. In some sense this can be
// interpreted as a "root" task backtrace frame.
uint32_t ipc_hash = 0;
// Secondary sort key for run time.
int sequence_num = 0;
bool task_backtrace_overflow = false;
// OK to dispatch from a nested loop.
Nestable nestable;
// Needs high resolution timers.
bool is_high_res = false;
using TaskQueue = base::queue<PendingTask>;
// PendingTasks are sorted by their |delayed_run_time| property.
using DelayedTaskQueue = std::priority_queue<base::PendingTask>;
} // namespace base