blob: 4c2951bf7b3d44d2f3d31985cd33151b6b5cd99c [file] [log] [blame]
// Copyright 2018 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/base_export.h"
#include "base/macros.h"
#include "base/threading/thread.h"
#include "base/time/time.h"
#include "base/timer/timer.h"
namespace base {
namespace internal {
class TaskTracker;
// The TaskScheduler's ServiceThread is a mostly idle thread that is responsible
// for handling async events (e.g. delayed tasks and async I/O). Its role is to
// merely forward such events to their destination (hence staying mostly idle
// and highly responsive).
// It aliases Thread::Run() to enforce that ServiceThread::Run() be on the stack
// and make it easier to identify the service thread in stack traces.
class BASE_EXPORT ServiceThread : public Thread {
// Constructs a ServiceThread which will record heartbeat metrics. This
// includes metrics recorded through |report_heartbeat_metrics_callback|,
// in addition to latency metrics through |task_tracker| if non-null. In that
// case, this ServiceThread will assume a registered TaskScheduler instance
// and that |task_tracker| will outlive this ServiceThread.
explicit ServiceThread(const TaskTracker* task_tracker
,RepeatingClosure report_heartbeat_metrics_callback);
~ServiceThread() override;
// Overrides the default interval at which |heartbeat_latency_timer_| fires.
// Call this with a |heartbeat| of zero to undo the override.
// Must not be called while the ServiceThread is running.
static void SetHeartbeatIntervalForTesting(TimeDelta heartbeat);
// Thread:
void Init() override;
void Run(RunLoop* run_loop) override;
void ReportHeartbeatMetrics() const;
// Kicks off a single async task which will record a histogram on the latency
// of a randomly chosen set of TaskTraits.
void PerformHeartbeatLatencyReport() const;
const TaskTracker* const task_tracker_;
// Fires a recurring heartbeat task to record metrics which are independent
// from any execution sequence. This is done on the service thread to avoid
// all external dependencies (even main thread).
base::RepeatingTimer heartbeat_metrics_timer_;
RepeatingClosure report_heartbeat_metrics_callback_;
} // namespace internal
} // namespace base