Restart the host when the third party auth certificate changes

remoting/host/linux/certificate_watcher.h

+// Copyright 2016 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 REMOTING_HOST_LINUX_CERTIFICATE_WATCHER_H_
+#define REMOTING_HOST_LINUX_CERTIFICATE_WATCHER_H_
+
+#include "base/files/file_path.h"
+#include "base/files/file_path_watcher.h"
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
+#include "base/timer/timer.h"
+#include "remoting/host/host_status_monitor.h"
+#include "remoting/host/host_status_observer.h"
+
+namespace remoting {
+
+// This class watches the cert database and kills the host when a change of the

[Sergey Ulanov, 2016/04/06 21:04:06]

Suggest rewording the first sentence:
 // This class watches the cert database and notifies when the
 // host needs to be restarted.

This class doesn't stop the host itself. It also doesn't notify about changes
immediately.

[Yuwei, 2016/04/07 00:35:41]

Done.

+// database is detected. The runner script will restart the host when the host
+// is killed then the new host will capture any new changes of the database.
+//
+// Acceptable false positives will be caused by desktop sessions and other
+// external programs.
+//
+// Implements HostStatusObserver to defer restart action when the host is
+// connected to a client.
+class CertificateWatcher : public remoting::HostStatusObserver {
+ public:
+  CertificateWatcher(
+      const base::Closure& restart_action,
+      scoped_refptr<base::SingleThreadTaskRunner> io_task_runner);
+
+  // The message loop of io_task_runner MUST be running after the destructor is
+  // called, otherwise there will be memory leaks.
+  ~CertificateWatcher() override;
+
+  // Starts watching file changes
+  // calling |restart_action_| when the host need to restart.
+  void Start();
+
+  // Sets the monitor to observe connection/disconnection events to toggle
+  // the inhibit mode. Should be called after the watcher starts.
+  // Adds |this| as an observer to the monitor.
+  // Removes |this| as an observer from the old monitor if it is not null.
+  void SetMonitor(base::WeakPtr<HostStatusMonitor> monitor);
+
+  // HostStatusObserver interface.
+  void OnClientConnected(const std::string& jid) override;
+  void OnClientDisconnected(const std::string& jid) override;
+
+  // Will only work before the watcher starts.
+  void SetDelayForTests(const base::TimeDelta& delay);
+  void SetWatchPathForTests(const base::FilePath& watch_path);
+
+ private:
+  // Returns true if the watcher has started.
+  bool is_started() const;
+
+  // Callback passed to |file_watcher_|. Runs in IO thread.
+  static void OnCertDirectoryChanged(
+      scoped_refptr<base::SingleThreadTaskRunner> network_task_runner,
+      base::WeakPtr<CertificateWatcher> watcher_, const base::FilePath& path,
+      bool error);
+
+  // Runs in the caller's thread.
+  void DirectoryChanged(const base::FilePath& path, bool error);
+
+  // Called by |restart_timer_| when it's time to reset the host.
+  // It will defer restart if |inhibit_restart_scheduled_| flag is set to true.
+  void OnTimer();
+
+  // Reference to the monitor
+  base::WeakPtr<HostStatusMonitor> monitor_;
+
+  // Called when a restart is scheduled.
+  base::Closure restart_action_;
+
+  // The runner that runs everything other than the file watcher.
+  scoped_refptr<base::SingleThreadTaskRunner> caller_task_runner_;
+
+  // The runner that runs the file watcher.
+  scoped_refptr<base::SingleThreadTaskRunner> io_task_runner_;
+
+  bool inhibit_mode_ = false;
+
+  bool restart_pending_ = false;
+
+  // Path of the certificate files/directories.
+  base::FilePath cert_watch_path_;
+
+  // The file watcher to watch changes inside the certificate folder.
+  scoped_ptr<base::FilePathWatcher> file_watcher_;
+
+  // The time to wait to restart when it is scheduled.
+  base::TimeDelta delay_;
+
+  // Timer to delay the restart action.
+  scoped_ptr<base::DelayTimer> restart_timer_;
+
+  base::WeakPtrFactory<CertificateWatcher> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(CertificateWatcher);
+};
+
+}  // namespace remoting
+
+#endif  // REMOTING_HOST_LINUX_CERTIFICATE_WATCHER_H_