components/browser_watcher/window_hang_monitor_win.h

   1 // Copyright 2015 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 #ifndef COMPONENTS_BROWSER_WATCHER_WINDOW_HANG_MONITOR_WIN_H_
   5 #define COMPONENTS_BROWSER_WATCHER_WINDOW_HANG_MONITOR_WIN_H_
   6
   7 #include <windows.h>
   8
   9 #include "base/callback_forward.h"
  10 #include "base/macros.h"
  11 #include "base/process/process.h"
  12 #include "base/strings/string16.h"
  13 #include "base/time/time.h"
  14 #include "base/timer/timer.h"
  15
  16 namespace browser_watcher {
  17
  18 // Monitors a window for hanging by periodically sending it a WM_NULL message
  19 // and timing the response.
  20 class WindowHangMonitor {
  21  public:
  22   enum WindowEvent {
  23     WINDOW_HUNG,
  24     WINDOW_VANISHED,
  25   };
  26   // Called when a hang is detected or when the window has gone away.
  27   // Called precisely zero or one time(s).
  28   typedef base::Callback<void(WindowEvent)> WindowEventCallback;
  29
  30   // Initialize the monitor with an event callback.
  31   explicit WindowHangMonitor(const WindowEventCallback& callback);
  32   ~WindowHangMonitor();
  33
  34   // Initializes the watcher to monitor the window answering to |window_name|.
  35   // Returns true on success.
  36   bool Initialize(const base::string16& window_name);
  37
  38   // Testing accessors.
  39   bool IsIdleForTesting() const { return !timer_.IsRunning(); }
  40   void SetPingIntervalForTesting(base::TimeDelta ping_interval);
  41   void SetHangTimeoutForTesting(base::TimeDelta hang_timeout);
  42
  43   HWND window() const { return window_; }
  44   const base::Process& window_process() const { return window_process_; }
  45
  46  private:
  47   struct OutstandingPing {
  48     WindowHangMonitor* monitor;
  49   };
  50
  51   static void CALLBACK
  52   OnPongReceived(HWND window, UINT msg, ULONG_PTR data, LRESULT lresult);
  53
  54   // Checks that |window_| is still valid, and sends it a ping.
  55   // Issues a |WINDOW_VANISHED| callback if the window's no longer valid.
  56   // Schedules OnHangTimeout in case of success.
  57   // Returns true on success, false if the window is no longer valid or other
  58   // failure.
  59   bool MaybeSendPing();
  60
  61   // Runs after a |hang_timeout_| delay after sending a ping. Checks whether
  62   // a pong was received. Either issues a callback or schedules OnRetryTimeout.
  63   void OnHangTimeout();
  64
  65   // Runs periodically at |ping_interval_| interval, as long as the window is
  66   // still valid and not hung.
  67   void OnRetryTimeout();
  68
  69   // Invoked on significant window events.
  70   WindowEventCallback callback_;
  71
  72   // The name of the (message) window to monitor.
  73   base::string16 window_name_;
  74
  75   // The monitored window handle.
  76   HWND window_;
  77
  78   // The process that owned |window_| when Initialize was called.
  79   base::Process window_process_;
  80
  81   // The time the last message was sent.
  82   base::Time last_ping_;
  83
  84   // The ping interval, must be larger than |hang_timeout_|.
  85   base::TimeDelta ping_interval_;
  86
  87   // The time after which |window_| is assumed hung.
  88   base::TimeDelta hang_timeout_;
  89
  90   // The timer used to schedule polls.
  91   base::Timer timer_;
  92
  93   // Non-null when there is an outstanding ping.
  94   // This is intentionally leaked when a hang is detected.
  95   OutstandingPing* outstanding_ping_;
  96
  97   DISALLOW_COPY_AND_ASSIGN(WindowHangMonitor);
  98 };
  99
 100 }  // namespace browser_watcher
 101
 102 #endif  // COMPONENTS_BROWSER_WATCHER_WINDOW_HANG_MONITOR_WIN_H_