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_ 73