Only update watches when directories change.

base/files/file_path_watcher_linux.cc

 // 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.
 
 #include "base/files/file_path_watcher.h"
 
 #include <errno.h>
 #include <stddef.h>
 #include <string.h>
 #include <sys/inotify.h>
@@ skipping 494 matching lines @@
       g_inotify_reader.Get().RemoveWatch(old_watch, this);
     path = path.Append(watch_entry.subdir);
   }
 
   UpdateRecursiveWatches(InotifyReader::kInvalidWatch,
                          false /* is directory? */);
 }
 
 void FilePathWatcherImpl::UpdateRecursiveWatches(
     InotifyReader::Watch fired_watch,
     bool is_dir) {

[Shuhei Takahashi, 2016/09/08 05:10:52]

Could you insert DCHECK(HasValidWatchVector()); here?

[dspaid, 2016/09/09 02:00:55]

Done.

   if (!recursive_)
     return;
 
   if (!DirectoryExists(target_)) {
     RemoveRecursiveWatches();
     return;
   }
 
+  // Underneath |target_|, only directory changes trigger watch updates.
+  if (!is_dir && fired_watch != InotifyReader::kInvalidWatch)
+    return;
+
   // Check to see if this is a forced update or if some component of |target_|
   // has changed. For these cases, redo the watches for |target_| and below.
   if (!ContainsKey(recursive_paths_by_watch_, fired_watch)) {

[Shuhei Takahashi, 2016/09/08 05:10:52]

Hmm, reordering the checks is fragile and I'm afraid future changes may cause
regression unexpectedly. I prefer proper fix here:

if (!ContainsKey(recursive_paths_by_watch_, fired_watch) &&
    fired_watch != watches_.back().watch)

[dspaid, 2016/09/09 02:00:55]

Done.

     UpdateRecursiveWatchesForPath(target_);
     return;
   }
 
-  // Underneath |target_|, only directory changes trigger watch updates.
-  if (!is_dir)
-    return;
-
   const FilePath& changed_dir = recursive_paths_by_watch_[fired_watch];
 
   std::map<FilePath, InotifyReader::Watch>::iterator start_it =
       recursive_watches_by_path_.lower_bound(changed_dir);
   std::map<FilePath, InotifyReader::Watch>::iterator end_it = start_it;
   for (; end_it != recursive_watches_by_path_.end(); ++end_it) {
     const FilePath& cur_path = end_it->first;
     if (!changed_dir.IsParent(cur_path))
       break;
     if (!DirectoryExists(cur_path))
@@ skipping 107 matching lines @@
   return watches_.back().subdir.empty();
 }
 
 }  // namespace
 
 FilePathWatcher::FilePathWatcher() {
   impl_ = new FilePathWatcherImpl();
 }
 
 }  // namespace base