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// Copyright 2018 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef BASE_TASK_SEQUENCE_MANAGER_SEQUENCED_TASK_SOURCE_H_
#define BASE_TASK_SEQUENCE_MANAGER_SEQUENCED_TASK_SOURCE_H_
#include <optional>
#include "base/base_export.h"
#include "base/functional/callback_helpers.h"
#include "base/memory/raw_ptr_exclusion.h"
#include "base/pending_task.h"
#include "base/task/common/lazy_now.h"
#include "base/task/sequence_manager/task_queue.h"
#include "base/task/sequence_manager/tasks.h"
#include "build/build_config.h"
namespace perfetto {
class EventContext;
}
namespace base {
namespace sequence_manager {
namespace internal {
// Interface to pass tasks to ThreadController.
class SequencedTaskSource {
public:
enum class SelectTaskOption { kDefault, kSkipDelayedTask };
using TaskExecutionTraceLogger =
RepeatingCallback<void(perfetto::EventContext&, const Task&)>;
struct BASE_EXPORT SelectedTask {
SelectedTask(const SelectedTask&);
SelectedTask(Task& task,
TaskExecutionTraceLogger task_execution_trace_logger,
TaskQueue::QueuePriority priority,
QueueName task_queue_name);
~SelectedTask();
// RAW_PTR_EXCLUSION: Performance reasons: based on this sampling profiler
// result on Mac. go/brp-mac-prof-diff-20230403
RAW_PTR_EXCLUSION Task& task;
// Callback to fill trace event arguments associated with the task
// execution. Can be null
TaskExecutionTraceLogger task_execution_trace_logger =
TaskExecutionTraceLogger();
TaskQueue::QueuePriority priority;
QueueName task_queue_name;
};
virtual ~SequencedTaskSource() = default;
// Controls whether a `SequencedTaskRunner` associated with this source can
// run a task synchronously in `RunOrPostTask`. Enable this to indicate that
// there isn't any pending or running work that has mutual exclusion or
// ordering expectations with tasks from this source, outside of
// `SelectNextTask()` or `OnBeginWork()` -> `OnIdle()` (those prevent tasks
// from running synchronously, irrespective of the state set here).
virtual void SetRunTaskSynchronouslyAllowed(
bool can_run_tasks_synchronously) = 0;
// Returns the next task to run from this source or nullopt if
// there're no more tasks ready to run. If a task is returned,
// DidRunTask() must be invoked before the next call to SelectNextTask().
// |option| allows control on which kind of tasks can be selected.
virtual std::optional<SelectedTask> SelectNextTask(
LazyNow& lazy_now,
SelectTaskOption option) = 0;
std::optional<SelectedTask> SelectNextTask(LazyNow& lazy_now) {
return SelectNextTask(lazy_now, SelectTaskOption::kDefault);
}
// Notifies this source that the task previously obtained
// from SelectNextTask() has been completed.
virtual void DidRunTask(LazyNow& lazy_now) = 0;
// Returns a WakeUp for the next pending task, is_immediate() if the
// next task can run immediately, or nullopt if there are no more immediate or
// delayed tasks. |option| allows control on which kind of tasks can be
// selected. May delete canceled tasks.
virtual std::optional<WakeUp> GetPendingWakeUp(LazyNow* lazy_now,
SelectTaskOption option) = 0;
std::optional<WakeUp> GetPendingWakeUp(LazyNow* lazy_now) {
return GetPendingWakeUp(lazy_now, SelectTaskOption::kDefault);
}
#if BUILDFLAG(IS_WIN)
// Return true if the next wakeup requires Windows' high-resolution timer to
// be enabled.
virtual bool NextWakeUpNeedsHighRes() = 0;
#endif
// Indicates that work that has mutual exclusion expectations with tasks from
// this `SequencedTaskSource` will start running.
virtual void OnBeginWork() = 0;
// Called when we have run out of immediate work. If more immediate work
// becomes available as a result of any processing done by this callback,
// return true to schedule a future DoWork.
virtual bool OnIdle() = 0;
// Called prior to running `selected_task` to emit trace event data for it.
virtual void MaybeEmitTaskDetails(
perfetto::EventContext& ctx,
const SelectedTask& selected_task) const = 0;
};
} // namespace internal
} // namespace sequence_manager
} // namespace base
#endif // BASE_TASK_SEQUENCE_MANAGER_SEQUENCED_TASK_SOURCE_H_
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