Getting service process on Mac to handle having things moved/changed underneath it.

base/file_path_component_watcher.h

Index: base/file_path_component_watcher.h
diff --git a/base/file_path_component_watcher.h b/base/file_path_component_watcher.h
new file mode 100644
index 0000000000000000000000000000000000000000..03b3240bcc0730f6ef6ea6bb5951ac3ad55b5afb
--- /dev/null
+++ b/base/file_path_component_watcher.h
@@ -0,0 +1,69 @@
+// Copyright (c) 2010 The Chromium Authors. All rights reserved.

[Mark Mentovai, 2011/03/11 20:13:52]

What year is it?

Throughout the entire change, the added files should say 2011. I don’t care if
you don’t touch modified files. In fact, I prefer if you don’t.

+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// This module provides a way to monitor a filepath for changes in the path.

[TVL, 2011/03/11 14:03:54]

chrome/browser/file_path_watcher/file_path_watcher.h...

[Mark Mentovai, 2011/03/11 20:13:52]

TVL wrote:
I think dmac’s comment below covers that.

[Mark Mentovai, 2011/03/11 20:13:52]

filepath is two words.

+
+#ifndef BASE_FILE_PATH_COMPONENT_WATCHER_H_
+#define BASE_FILE_PATH_COMPONENT_WATCHER_H_
+#pragma once
+
+#include "base/basictypes.h"
+#include "base/file_path.h"
+#include "base/ref_counted.h"
+
+namespace base {
+// This class lets you register interest in changes on a FilePath.
+// The delegate will get called whenever any components of a FilePath are
+// changed (moved, deleted, attributes changed). This is different from
+// FilePathWatcher, in that FilePathWatcher watches a single file, and it's

[Mark Mentovai, 2011/03/11 20:13:52]

"single file, and it's" -> "single file and its"

+// parent directory for changes, whereas this watches each component in a file's
+// path for changes.
+class FilePathComponentWatcher {
+ public:
+  // Declares the callback client code implements to receive notifications. Note
+  // that implementations of this interface should not keep a reference to the
+  // corresponding FileWatcher object to prevent a reference cycle.

[Mark Mentovai, 2011/03/11 20:13:52]

What’s a FileWatcher object?

+  class Delegate : public base::RefCountedThreadSafe<Delegate> {
+   public:
+    virtual ~Delegate() {}
+    virtual void OnFilePathComponentsChanged(FilePathComponentWatcher* watcher,
+                                             const FilePath& old_path,
+                                             const FilePath& new_path) = 0;
+    // Called when platform specific code detected an error. The watcher will

[Mark Mentovai, 2011/03/11 20:13:52]

Blank line before.

+    // not call OnFilePathChanged for future changes.
+    virtual void OnError(FilePathComponentWatcher* watcher) {}
+  };
+
+  FilePathComponentWatcher();
+  ~FilePathComponentWatcher();
+
+  // Register interest in any changes on |path|. OnPathChanged will be called
+  // back for each change. Returns true on success.
+  bool Watch(const FilePath& path, Delegate* delegate) WARN_UNUSED_RESULT;

[Mark Mentovai, 2011/03/11 20:13:52]

Are you supposed to be able to call Watch twice on the same object? Probably
not, but nothing in the code seems to check this or care.

+
+  // Used internally to encapsulate different members on different platforms.

[Mark Mentovai, 2011/03/11 20:13:52]

I’m going to hold off on a thorough review of the interface-implementation
separation until you combine things into a single implementation-only thing as
Brett mentioned, or explain why you’d prefer not to do so. No point in reviewing
this aspect now if it’s going to change.

+  class PlatformDelegate
+      : public base::RefCountedThreadSafe<PlatformDelegate> {

[Mark Mentovai, 2011/03/11 20:13:52]

What I just said notwithstanding…

Why is the platform delegate reference-counted? And is the Cancel thing really
necessary? (Maybe it’s not if you didn’t have this be reference-counted.)

+   public:
+    virtual ~PlatformDelegate() {}
+
+    // Start watching for the given |path| and notify |delegate| about changes.
+    virtual bool Watch(const FilePath& path, Delegate* delegate)
+        WARN_UNUSED_RESULT = 0;
+
+    // Stop watching. This is called from FilePathComponentWatcher's dtor

[Mark Mentovai, 2011/03/11 20:13:52]

Spell things out. Destructor, not dtor.

+    // in order to allow it to shut down properly while the object is still
+    // alive.
+    virtual void Cancel() {}
+  };
+
+ private:
+  scoped_refptr<PlatformDelegate> impl_;
+
+  DISALLOW_COPY_AND_ASSIGN(FilePathComponentWatcher);
+};
+
+}  // namespace

[Mark Mentovai, 2011/03/11 20:13:52]

}  // namespace base

+
+#endif  // BASE_FILE_PATH_COMPONENT_WATCHER_H_