[Chromoting] The daemon process now starts the networking process and passes the host configuration…

remoting/host/daemon_config_watcher.h

+// Copyright (c) 2012 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_DAEMON_CONFIG_WATCHER_H_
+#define REMOTING_HOST_DAEMON_CONFIG_WATCHER_H_
+
+#include "base/basictypes.h"
+#include "base/compiler_specific.h"
+#include "base/file_path.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
+#include "base/timer.h"
+
+namespace base {
+class SingleThreadTaskRunner;
+class Thread;
+
+namespace files {
+class FilePathWatcher;
+}  // namespace files
+}  // namespace base
+
+namespace remoting {
+
+extern const char kHostConfigSwitchName[];
+extern const FilePath::CharType kDefaultHostConfigFile[];
+
+class DaemonConfigWatcher {

[Wez, 2012/08/24 22:20:38]

I realise that we're only going to use this for reading the host configuration
in the Daemon, but this class just watches a file and dispatches a callback
every time it changes, with the file's contents; rename it ConfigFileReader?

[alexeypa (please no reviews), 2012/08/27 23:16:41]

Done. ConfigFileWatcher.

+ public:
+  class Delegate {
+   public:
+    virtual ~Delegate();
+
+    // Called once after starting watching the configuration file and every time
+    // the file changes.
+    virtual void OnConfigUpdated(const std::string& config) = 0;
+
+    // Called when the configuration file watcher encountered an error.
+    virtual void OnConfigWatcherError() = 0;
+  };
+
+  // Creates a configuration file watcher that lives at the |io_task_runner|
+  // thread but posts config file updates on on |main_task_runner|.

[Wez, 2012/08/24 22:20:38]

nit: Clarify that this means |delegate| must be created & destroyed on
|main_task_runner|

[alexeypa (please no reviews), 2012/08/27 23:16:41]

It does not mean that. |delegate| can be created and destroyed on any thread as
long as it can receive calls in |main_task_runner| for as long as
|DaemonConfigWatcher| is alive.

+  DaemonConfigWatcher(
+      scoped_refptr<base::SingleThreadTaskRunner> main_task_runner,
+      scoped_refptr<base::SingleThreadTaskRunner> io_task_runner,
+      const base::WeakPtr<Delegate>& delegate);
+
+  virtual ~DaemonConfigWatcher();
+
+  // Starts watching |config_path|.
+  void Watch(const FilePath& config_path);
+
+  // Stops watching the configuration file.
+  void Stop(scoped_ptr<DaemonConfigWatcher> self);

[Wez, 2012/08/24 22:20:38]

Why does the caller need to pass in a scoped_ptr to the Watcher?

[alexeypa (please no reviews), 2012/08/27 23:16:41]

It is needed to delete the object once the last task completes. It does not look
nice so I renamed it to StopAdnDelete().

+
+ private:
+  // Called every time the host configuration file is updated.
+  void OnConfigUpdated(const FilePath& path, bool error);
+
+  // Reads the configuration file and passes it to the delegate.
+  void ReloadConfig();
+
+  FilePath config_path_;
+
+  scoped_ptr<base::DelayTimer<DaemonConfigWatcher> > config_updated_timer_;
+
+  // Monitors the host configuration file changes.
+  scoped_ptr<base::files::FilePathWatcher> config_watcher_;
+
+  base::WeakPtr<Delegate> delegate_;
+
+  scoped_refptr<base::SingleThreadTaskRunner> main_task_runner_;
+  scoped_refptr<base::SingleThreadTaskRunner> io_task_runner_;
+
+  DISALLOW_COPY_AND_ASSIGN(DaemonConfigWatcher);
+};
+
+}  // namespace remoting
+
+#endif  // REMOTING_HOST_DAEMON_CONFIG_WATCHER_H_