content/browser/histogram_controller.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CONTENT_BROWSER_HISTOGRAM_CONTROLLER_H_
   6 #define CONTENT_BROWSER_HISTOGRAM_CONTROLLER_H_
   7
   8 #include <string>
   9 #include <vector>
  10
  11 #include "base/memory/singleton.h"
  12
  13 namespace content {
  14
  15 class HistogramSubscriber;
  16
  17 // HistogramController is used on the browser process to collect histogram data.
  18 // Only the browser UI thread is allowed to interact with the
  19 // HistogramController object.
  20 class HistogramController {
  21  public:
  22   // Returns the HistogramController object for the current process, or NULL if
  23   // none.
  24   static HistogramController* GetInstance();
  25
  26   // Normally instantiated when the child process is launched. Only one instance
  27   // should be created per process.
  28   HistogramController();
  29   virtual ~HistogramController();
  30
  31   // Register the subscriber so that it will be called when for example
  32   // OnHistogramDataCollected is returning histogram data from a child process.
  33   // This is called on UI thread.
  34   void Register(HistogramSubscriber* subscriber);
  35
  36   // Unregister the subscriber so that it will not be called when for example
  37   // OnHistogramDataCollected is returning histogram data from a child process.
  38   // Safe to call even if caller is not the current subscriber.
  39   void Unregister(const HistogramSubscriber* subscriber);
  40
  41   // Contact all processes and get their histogram data.
  42   void GetHistogramData(int sequence_number);
  43
  44   // Notify the |subscriber_| that it should expect at least |pending_processes|
  45   // additional calls to OnHistogramDataCollected().  OnPendingProcess() may be
  46   // called repeatedly; the last call will have |end| set to true, indicating
  47   // that there is no longer a possibility for the count of pending processes to
  48   // increase.  This is called on the UI thread.
  49   void OnPendingProcesses(int sequence_number, int pending_processes, bool end);
  50
  51   // Send the |histogram| back to the |subscriber_|.
  52   // This can be called from any thread.
  53   void OnHistogramDataCollected(
  54       int sequence_number,
  55       const std::vector<std::string>& pickled_histograms);
  56
  57  private:
  58   friend struct DefaultSingletonTraits<HistogramController>;
  59
  60   // Contact PLUGIN and GPU child processes and get their histogram data.
  61   // TODO(rtenneti): Enable getting histogram data for other processes like
  62   // PPAPI and NACL.
  63   void GetHistogramDataFromChildProcesses(int sequence_number);
  64
  65   HistogramSubscriber* subscriber_;
  66
  67   DISALLOW_COPY_AND_ASSIGN(HistogramController);
  68 };
  69
  70 }  // namespace content
  71
  72 #endif  // CONTENT_BROWSER_HISTOGRAM_CONTROLLER_H_