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// Copyright (c) 2012 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.
#ifndef COMPONENTS_METRICS_PROFILER_TRACKING_SYNCHRONIZER_H_
#define COMPONENTS_METRICS_PROFILER_TRACKING_SYNCHRONIZER_H_
#include <map>
#include <memory>
#include <string>
#include <vector>
#include "base/callback_forward.h"
#include "base/lazy_instance.h"
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/memory/weak_ptr.h"
#include "base/threading/thread_checker.h"
#include "base/time/tick_clock.h"
#include "base/time/time.h"
#include "base/tracked_objects.h"
#include "components/metrics/profiler/tracking_synchronizer_delegate.h"
#include "components/metrics/proto/chrome_user_metrics_extension.pb.h"
// This class maintains state that is used to upload profiler data from the
// various processes, into the browser process. Such transactions are usually
// instigated by the browser. In general, a process will respond by gathering
// profiler data, and transmitting the pickled profiler data. We collect the
// data in asynchronous mode that doesn't block the UI thread.
//
// To assure that all the processes have responded, a counter is maintained
// to indicate the number of pending (not yet responsive) processes. We tag
// each group of requests with a sequence number. For each group of requests, we
// create RequestContext object which stores the sequence number, pending
// processes and the callback_object that needs to be notified when we receive
// an update from processes. When an update arrives we find the RequestContext
// associated with sequence number and send the unpickled profiler data to the
// |callback_object_|.
namespace metrics {
class TrackingSynchronizerObserver;
typedef base::Callback<std::unique_ptr<TrackingSynchronizerDelegate>(
TrackingSynchronizer*)>
TrackingSynchronizerDelegateFactory;
class TrackingSynchronizer
: public base::RefCountedThreadSafe<TrackingSynchronizer> {
public:
// Construction also sets up the global singleton instance. This instance is
// used to communicate between the IO and UI thread, and is destroyed only as
// the main thread (browser_main) terminates, which means the IO thread has
// already completed, and will not need this instance any further.
// |clock| is a clock used for durations of profiling phases.
// |delegate| is used to abstract platform-specific profiling functionality.
TrackingSynchronizer(
std::unique_ptr<base::TickClock> clock,
const TrackingSynchronizerDelegateFactory& delegate_factory);
// Contact all processes, and get them to upload to the browser any/all
// changes to profiler data. It calls |callback_object|'s SetData method with
// the data received from each sub-process.
// This method is accessible on the UI thread.
static void FetchProfilerDataAsynchronously(
const base::WeakPtr<TrackingSynchronizerObserver>& callback_object);
// Called when a profiling phase completes. |profiling_event| is the event
// that triggered the completion of the current phase, and begins a new phase.
// This method is accessible on the UI thread.
static void OnProfilingPhaseCompleted(
ProfilerEventProto::ProfilerEvent profiling_event);
// Send profiler_data back to |callback_object_| by calling
// DecrementPendingProcessesAndSendData which records that we are waiting
// for one less profiler data from renderer or browser child process for the
// given sequence number. This method is accessible on UI thread.
void OnProfilerDataCollected(
int sequence_number,
const tracked_objects::ProcessDataSnapshot& profiler_data,
ProfilerEventProto::TrackedObject::ProcessType process_type);
// Update the number of pending processes for the given |sequence_number|.
// This is called on UI thread.
void OnPendingProcesses(int sequence_number, int pending_processes, bool end);
protected:
virtual ~TrackingSynchronizer();
// Update the sequence of completed phases with a new phase completion info.
void RegisterPhaseCompletion(
ProfilerEventProto::ProfilerEvent profiling_event);
// Notify |observer| about |profiler_data| received from process of type
// |process_type|.
void SendData(const tracked_objects::ProcessDataSnapshot& profiler_data,
ProfilerEventProto::TrackedObject::ProcessType process_type,
TrackingSynchronizerObserver* observer) const;
private:
friend class base::RefCountedThreadSafe<TrackingSynchronizer>;
class RequestContext;
// Establish a new sequence_number_, and use it to notify all the processes of
// the need to supply, to the browser, their tracking data. It also registers
// |callback_object| in |outstanding_requests_| map. Return the
// sequence_number_ that was used. This method is accessible on UI thread.
int RegisterAndNotifyAllProcesses(
const base::WeakPtr<TrackingSynchronizerObserver>& callback_object);
// Notifies all processes of a completion of a profiling phase.
// |profiling_event| is the event associated with the phase change.
void NotifyAllProcessesOfProfilingPhaseCompletion(
ProfilerEventProto::ProfilerEvent profiling_event);
// It finds the RequestContext for the given |sequence_number| and notifies
// the RequestContext's |callback_object_| about the |value|. This is called
// whenever we receive profiler data from processes. It also records that we
// are waiting for one less profiler data from a process for the given
// sequence number. If we have received a response from all renderers and
// browser processes, then it calls RequestContext's DeleteIfAllDone to delete
// the entry for sequence_number. This method is accessible on UI thread.
void DecrementPendingProcessesAndSendData(
int sequence_number,
const tracked_objects::ProcessDataSnapshot& profiler_data,
ProfilerEventProto::TrackedObject::ProcessType process_type);
// Get a new sequence number to be sent to processes from browser process.
// This method is accessible on UI thread.
int GetNextAvailableSequenceNumber();
// Used to verify that certain methods are called on the UI thread (the thread
// on which this object was created).
base::ThreadChecker thread_checker_;
// We don't track the actual processes that are contacted for an update, only
// the count of the number of processes, and we can sometimes time-out and
// give up on a "slow to respond" process. We use a sequence_number to be
// sure a response from a process is associated with the current round of
// requests. All sequence numbers used are non-negative.
// last_used_sequence_number_ is the most recently used number (used to avoid
// reuse for a long time).
int last_used_sequence_number_;
// Sequence of events associated with already completed profiling phases. The
// index in the vector is the phase number. The current phase is not included.
std::vector<ProfilerEventProto::ProfilerEvent>
phase_completion_events_sequence_;
// Clock for profiling phase durations.
const std::unique_ptr<base::TickClock> clock_;
// Times of starts of all profiling phases, including the current phase. The
// index in the vector is the phase number.
std::vector<base::TimeTicks> phase_start_times_;
// This object's delegate.
// NOTE: Leave this ivar last so that the delegate is torn down first at
// destruction, as it has a reference to this object.
std::unique_ptr<TrackingSynchronizerDelegate> delegate_;
DISALLOW_COPY_AND_ASSIGN(TrackingSynchronizer);
};
} // namespace metrics
#endif // COMPONENTS_METRICS_PROFILER_TRACKING_SYNCHRONIZER_H_
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