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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.
#ifndef CHROME_BROWSER_METRICS_TRACKING_SYNCHRONIZER_H_
#define CHROME_BROWSER_METRICS_TRACKING_SYNCHRONIZER_H_
#pragma once
#include <map>
#include <string>
#include <vector>
#include "base/basictypes.h"
#include "base/memory/ref_counted.h"
#include "base/memory/weak_ptr.h"
#include "base/time.h"
#include "base/values.h"
#include "chrome/browser/ui/webui/tracking_ui.h"
#include "content/common/child_process_info.h"
#include "content/public/browser/browser_thread.h"
// This class maintains state that is used to upload tracking 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
// tracking data, and transmitting the pickled tracking 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 tracking data to the
// |callback_object_|.
namespace chrome_browser_metrics {
class TrackingSynchronizer : public
base::RefCountedThreadSafe<TrackingSynchronizer> {
public:
// The "RequestContext" structure describes an individual request received
// from the UI.
struct RequestContext {
RequestContext(const base::WeakPtr<TrackingUI>& callback_object,
int sequence_number,
int processes_pending,
base::TimeTicks callback_start_time)
: callback_object_(callback_object),
sequence_number_(sequence_number),
processes_pending_(processes_pending),
request_start_time_(callback_start_time) {
}
~RequestContext() {}
// Requests are made to asynchronously send data to the |callback_object_|.
base::WeakPtr<TrackingUI> callback_object_;
// The sequence number used by the most recent update request to contact all
// processes.
int sequence_number_;
// The number of processes that have not yet responded to requests.
int processes_pending_;
// The time when we were told to start the fetching of data from processes.
base::TimeTicks request_start_time_;
};
// A map from sequence_number_ to the actual RequestContexts.
typedef std::map<int, RequestContext*> RequestContextMap;
// 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.
TrackingSynchronizer();
// Return pointer to the singleton instance, which is allocated and
// deallocated on the main UI thread (during system startup and teardown).
static TrackingSynchronizer* CurrentSynchronizer();
// Contact all processes, and get them to upload to the browser any/all
// changes to tracking data. It calls |callback_object|'s SetData method with
// the data received from each sub-process.
// This method is accessible on UI thread.
static void FetchTrackingDataAsynchronously(
const base::WeakPtr<TrackingUI>& callback_object);
// Contact all processes and set tracking status to |enable|.
// This method is accessible on UI thread.
static void SetTrackingStatus(bool enable);
// Respond to this message from the renderer by setting the tracking status
// (SetTrackingStatusInProcess) in that renderer process.
// |process_id| is used to find the renderer process.
// This method is accessible on IO thread.
static void IsTrackingEnabled(int process_id);
// Get the current tracking status from the browser process and set it in the
// renderer process. |process_id| is used to find the renderer process.
// This method is accessible on UI thread.
static void SetTrackingStatusInProcess(int process_id);
// Deserialize the tracking data and record that we have received tracking
// data from a process. This method posts a task to call
// DeserializeTrackingListOnUI on UI thread to send the |tracking_data| to
// callback_object_. This method is accessible on IO thread.
static void DeserializeTrackingList(
int sequence_number,
const std::string& tracking_data,
ChildProcessInfo::ProcessType process_type);
// Deserialize the tracking data and record that we have received tracking
// data from a process. This method is accessible on UI thread.
static void DeserializeTrackingListOnUI(
int sequence_number,
const std::string& tracking_data,
ChildProcessInfo::ProcessType process_type);
private:
friend class base::RefCountedThreadSafe<TrackingSynchronizer>;
virtual ~TrackingSynchronizer();
// 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<TrackingUI>& callback_object);
// It finds the |callback_object_| in |outstanding_requests_| map for the
// given |sequence_number| and notifies the |callback_object_| about the
// |value|. This is called whenever we receive tracked data from processes. It
// also records that we are waiting for one less tracking data from a process
// for the given sequence number. If we have received a response from all
// renderers, then it deletes the entry for sequence_number from
// |outstanding_requests_| map. This method is accessible on UI thread.
void DecrementPendingProcessesAndSendData(int sequence_number,
base::DictionaryValue* value);
// Records that we are waiting for one less tracking data from a process for
// the given sequence number.
// This method is accessible on UI thread.
void DecrementPendingProcesses(int sequence_number);
// When all changes have been acquired, or when the wait time expires
// (whichever is sooner), this method is called. This method deletes the entry
// for the given sequence_number from |outstanding_requests_| map.
// This method is accessible on UI thread.
void ForceTrackingSynchronizationDoneCallback(int sequence_number);
// Get a new sequence number to be sent to processes from browser process.
// This method is accessible on UI thread.
int GetNextAvailableSequenceNumber();
// Map of all outstanding RequestContexts, from sequence_number_ to
// RequestContext.
RequestContextMap outstanding_requests_;
// 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_;
// This singleton instance should be started during the single threaded
// portion of main(). It initializes globals to provide support for all future
// calls. This object is created on the UI thread, and it is destroyed after
// all the other threads have gone away. As a result, it is ok to call it
// from the UI thread, or for about:tracking.
static TrackingSynchronizer* tracking_synchronizer_;
DISALLOW_COPY_AND_ASSIGN(TrackingSynchronizer);
};
} // namespace chrome_browser_metrics
#endif // CHROME_BROWSER_METRICS_TRACKING_SYNCHRONIZER_H_
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