Add a DirectoryWatcher class, allowing objects to be notified whenever...

base/directory_watcher_win.cc

+// Copyright (c) 2006-2008 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.
+
+#include "base/directory_watcher.h"
+
+#include "base/file_path.h"
+#include "base/object_watcher.h"
+
+// Private implementation class implementing the behavior of DirectoryWatcher.
+class DirectoryWatcher::Impl : public base::RefCounted<DirectoryWatcher::Impl>,
+                               public base::ObjectWatcher::Delegate {
+ public:
+  Impl(DirectoryWatcher::Delegate* delegate)
+      : delegate_(delegate), handle_(INVALID_HANDLE_VALUE) {}
+  ~Impl();
+
+  // Register interest in any changes in |path|.
+  // Returns false on error.
+  bool Watch(const FilePath& path);
+
+  // Callback from MessageLoopForIO.
+  virtual void OnObjectSignaled(HANDLE object);
+
+ private:
+  // Delegate to notify upon changes.
+  DirectoryWatcher::Delegate* delegate_;
+  // Path we're watching (passed to delegate).
+  FilePath path_;
+  // Handle for FindFirstChangeNotification.
+  HANDLE handle_;
+  // ObjectWatcher to watch handle_ for events.
+  base::ObjectWatcher watcher_;
+};
+
+DirectoryWatcher::Impl::~Impl() {
+  if (handle_ != INVALID_HANDLE_VALUE) {
+    watcher_.StopWatching();
+    FindCloseChangeNotification(handle_);
+  }
+}
+
+bool DirectoryWatcher::Impl::Watch(const FilePath& path) {
+  DCHECK(path_.value().empty());  // Can only watch one path.
+
+  handle_ = FindFirstChangeNotification(
+      path.value().c_str(),
+      FALSE,  // Don't watch subtree.
+      FILE_NOTIFY_CHANGE_FILE_NAME | FILE_NOTIFY_CHANGE_SIZE |
+      FILE_NOTIFY_CHANGE_LAST_WRITE);
+  if (handle_ == INVALID_HANDLE_VALUE) {
+    NOTREACHED();
+    return false;
+  }
+
+  path_ = path;
+  watcher_.StartWatching(handle_, this);
+
+  return true;
+}
+
+void DirectoryWatcher::Impl::OnObjectSignaled(HANDLE object) {
+  DCHECK(object == handle_);
+  // Make sure we stay alive through the body of this function.
+  scoped_refptr<DirectoryWatcher::Impl> keep_alive(this);
+
+  delegate_->OnDirectoryChanged(path_);
+
+  // Register for more notifications on file change.
+  BOOL ok = FindNextChangeNotification(object);
+  DCHECK(ok);
+  watcher_.StartWatching(object, this);
+}
+
+DirectoryWatcher::DirectoryWatcher() {
+}
+
+DirectoryWatcher::~DirectoryWatcher() {
+  // Declared in .cc file for access to ~DirectoryWatcher::Impl.
+}
+
+bool DirectoryWatcher::Watch(const FilePath& path,
+                             Delegate* delegate) {
+  impl_ = new DirectoryWatcher::Impl(delegate);
+  return impl_->Watch(path);
+}