chrome/browser/hang_monitor/hung_window_detector.h

   1 // Copyright (c) 2010 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 CHROME_BROWSER_HANG_MONITOR_HUNG_WINDOW_DETECTOR_H__
   6 #define CHROME_BROWSER_HANG_MONITOR_HUNG_WINDOW_DETECTOR_H__
   7
   8 #include "base/synchronization/lock.h"
   9 #include "chrome/common/worker_thread_ticker.h"
  10
  11 // This class provides the following functionality:
  12 // Given a top-level window handle, it enumerates all descendant windows
  13 // of that window and, on finding a window that belongs to a different
  14 // thread from that of the top-level window, it tests to see if that window
  15 // is responding to messages. It does this test by first calling the
  16 // IsHungAppWindow API and, additionally (since the IsHungAppWindow API
  17 // does not deal correctly with suspended threads), send a dummy message
  18 // (WM_NULL) to the window and verifies that the call does not timeout.
  19 // This class is typically used in conjunction with the WorkerThreadTicker
  20 // class so that the checking can happen on a periodic basis.
  21 // If a hung window is detected it calls back the specified implementation of
  22 // the HungWindowNotification interface. Currently this class only supports
  23 // a single callback but it can be extended later to support multiple
  24 // callbacks.
  25 class HungWindowDetector : public WorkerThreadTicker::Callback {
  26  public:
  27   // This property specifies the message timeout for a child window.
  28   static const wchar_t kHungChildWindowTimeout[];
  29   // This is the notification callback interface that is used to notify
  30   // callers about a non-responsive window
  31   class HungWindowNotification  {
  32    public:
  33     enum ActionOnHungWindow {
  34       HUNG_WINDOW_IGNORE,
  35       HUNG_WINDOW_TERMINATE_PROCESS,
  36     };
  37
  38     // This callback method is invoked when a hung window is detected.
  39     // A return value of false indicates that we should stop enumerating the
  40     // child windows of the browser window to check if they are hung.
  41     virtual bool OnHungWindowDetected(HWND hung_window, HWND top_level_window,
  42                                       ActionOnHungWindow* action) = 0;
  43   };
  44
  45   // The notification object is not owned by this class. It is assumed that
  46   // this pointer will be valid throughout the lifetime of this class.
  47   // Ownership of this pointer is not transferred to this class.
  48   // Note that the Initialize method needs to be called to initiate monitoring
  49   // of hung windows.
  50   explicit HungWindowDetector(HungWindowNotification* notification);
  51   ~HungWindowDetector();
  52
  53   // This method initialized the monitoring of hung windows. All descendant
  54   // windows of the passed-in top-level window which belong to a thread
  55   // different from that of the top-level window are monitored. The
  56   // message_response_timeout parameter indicates how long this class must
  57   // wait for a window to respond to a sent message before it is considered
  58   // to be non-responsive.
  59   // Initialize can be called multiple times to change the actual window to
  60   // be monitored as well as the message response timeout
  61   bool Initialize(HWND top_level_window,
  62                   int message_response_timeout);
  63
  64   // Implementation of the WorkerThreadTicker::Callback interface
  65   virtual void OnTick();
  66
  67  private:
  68   // Helper function that checks whether the specified child window is hung.
  69   // If so, it invokes the HungWindowNotification interface implementation
  70   bool CheckChildWindow(HWND child_window);
  71
  72   static BOOL CALLBACK ChildWndEnumProc(HWND child_window, LPARAM param);
  73
  74   // Pointer to the HungWindowNotification callback interface. This class does
  75   // not RefCount this pointer and it is assumed that the pointer will be valid
  76   // throughout the lifetime of this class.
  77   HungWindowNotification* notification_;
  78   HWND top_level_window_;
  79
  80   // How long do we wait before we consider a window hung (in ms)
  81   int message_response_timeout_;
  82   base::Lock hang_detection_lock_;
  83   // Indicates if this object is currently enumerating hung windows
  84   bool enumerating_;
  85
  86   DISALLOW_COPY_AND_ASSIGN(HungWindowDetector);
  87 };
  88
  89
  90 #endif  // CHROME_BROWSER_HANG_MONITOR_HUNG_WINDOW_DETECTOR_H__