Collect profiler stats from browser child processes.

chrome/browser/metrics/tracking_synchronizer.h

 // 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/lazy_instance.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/profiler_ui.h"
-#include "content/common/child_process_info.h"
-#include "content/public/browser/browser_thread.h"
+#include "content/public/browser/profiler_subscriber.h"
 
-// This class maintains state that is used to upload tracking data from the
+// 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
-// tracking data, and transmitting the pickled tracking data. We collect the
+// 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 tracking data to the
+// associated with sequence number and send the unpickled profiler data to the
 // |callback_object_|.
 
 namespace chrome_browser_metrics {
 
-class TrackingSynchronizer : public
-    base::RefCountedThreadSafe<TrackingSynchronizer> {
+class RequestContext;
+
+class TrackingSynchronizer
+    : public content::ProfilerSubscriber,
+      public base::RefCountedThreadSafe<TrackingSynchronizer> {
  public:
-  // The "RequestContext" structure describes an individual request received
-  // from the UI.
-  struct RequestContext {
-    RequestContext(const base::WeakPtr<ProfilerUI>& 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<ProfilerUI> 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
+  // changes to profiler 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(
+  static void FetchProfilerDataAsynchronously(
       const base::WeakPtr<ProfilerUI>& callback_object);
 
-  // Contact all processes and set tracking status to |enable|.
-  // This method is accessible on UI thread.
-  static void SetTrackingStatus(bool enable);
+  // ------------------------------------------------------
+  // ProfilerSubscriber methods for browser child processes
+  // ------------------------------------------------------
 
-  // 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);
+  // Update the number of pending processes for the given |sequence_number|.
+  // This is called on UI thread.
+  virtual void OnPendingProcesses(int sequence_number,
+                                  int pending_processes) OVERRIDE;
 
-  // 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(
+  // 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.
+  virtual void OnProfilerDataCollected(
       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);
+      base::DictionaryValue* profiler_data) OVERRIDE;
 
  private:
   friend class base::RefCountedThreadSafe<TrackingSynchronizer>;
+  friend class RequestContext;
 
   virtual ~TrackingSynchronizer();
 
+  // Send profiler_data back to callback_object_. It 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 OnProfilerDataCollectedOnUI(int sequence_number,
+                                   base::DictionaryValue* profiler_data);
+
   // 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<ProfilerUI>& 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.
+  // 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,
                                             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_;
+  // Return pointer to the singleton instance, which is allocated and
+  // deallocated on the main UI thread (during system startup and teardown).
+  // This method is accessible on UI thread.
+  static TrackingSynchronizer* CurrentSynchronizer();
 
   // 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.
+  // from the UI thread, or for about:profiler.
   static TrackingSynchronizer* tracking_synchronizer_;
 
   DISALLOW_COPY_AND_ASSIGN(TrackingSynchronizer);
 };
 
 }  // namespace chrome_browser_metrics
 
 #endif  // CHROME_BROWSER_METRICS_TRACKING_SYNCHRONIZER_H_