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// Copyright 2015 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 COMPONENTS_BROWSER_WATCHER_WINDOW_HANG_MONITOR_WIN_H_
#define COMPONENTS_BROWSER_WATCHER_WINDOW_HANG_MONITOR_WIN_H_
#include <windows.h>
#include "base/callback_forward.h"
#include "base/macros.h"
#include "base/process/process.h"
#include "base/strings/string16.h"
#include "base/time/time.h"
#include "base/timer/timer.h"
namespace browser_watcher {
// Monitors a window for hanging by periodically sending it a WM_NULL message
// and timing the response.
class WindowHangMonitor {
public:
// Represents a detected window event.
enum WindowEvent {
// The target process exited before the window was detected.
WINDOW_NOT_FOUND,
// The window failed to respond to a ping within the configured timeout.
WINDOW_HUNG,
// The window disappeared.
WINDOW_VANISHED,
};
// Called when a window event is detected. Called precisely zero or one
// time(s).
typedef base::Callback<void(WindowEvent)> WindowEventCallback;
// Initialize the monitor with |callback|. The callback is guaranteed
// to be called no more than once, and never after the WindowHangMonitor is
// destroyed. The monitor will be configured to issue pings according to
// |ping_interval|. A failure to respond within |timeout| will be interpreted
// as a hang.
WindowHangMonitor(base::TimeDelta ping_interval,
base::TimeDelta timeout,
const WindowEventCallback& callback);
~WindowHangMonitor();
// Initializes the watcher to monitor a window named |window_name| and owned
// by |process|. May be invoked prior to the appearance of the window.
void Initialize(base::Process process, const base::string16& window_name);
private:
struct OutstandingPing {
WindowHangMonitor* monitor;
};
// Schedules a delayed task to poll for the appearance of the target window.
void ScheduleFindWindow();
// Checks for the appearance of the target window. If found, initiates the
// ping cycle. Otherwise, calls ScheduleFindWindow.
void PollForWindow();
static void CALLBACK
OnPongReceived(HWND window, UINT msg, ULONG_PTR data, LRESULT lresult);
// Sends a ping to |hwnd|. Issues a |WINDOW_VANISHED| callback if the
// operation fails. Schedules OnHangTimeout otherwise.
void SendPing(HWND hwnd);
// Runs after a |hang_timeout_| delay after sending a ping to |hwnd|. Checks
// whether a pong was received. Either issues a callback or schedules
// OnRetryTimeout.
void OnHangTimeout(HWND hwnd);
// Runs periodically at |ping_interval_| interval, as long as the window is
// still valid and not hung. Verifies that the target window still exists. If
// so, invokes SendPing. Otherwise, issues a |WINDOW_VANISHED| callback.
void OnRetryTimeout();
// Invoked when a window event is detected.
WindowEventCallback callback_;
// The name of the (message) window to monitor.
base::string16 window_name_;
// The target process in which the monitored window is expected to exist.
base::Process window_process_;
// The time the last message was sent.
base::Time last_ping_;
// The ping interval, must be larger than |hang_timeout_|.
base::TimeDelta ping_interval_;
// The time after which |window_| is assumed hung.
base::TimeDelta hang_timeout_;
// The timer used to schedule polls.
base::Timer timer_;
// Non-null when there is an outstanding ping.
// This is intentionally leaked when a hang is detected.
OutstandingPing* outstanding_ping_;
DISALLOW_COPY_AND_ASSIGN(WindowHangMonitor);
};
} // namespace browser_watcher
#endif // COMPONENTS_BROWSER_WATCHER_WINDOW_HANG_MONITOR_WIN_H_
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