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chrome/browser/file_path_watcher_mac.cc

Index: chrome/browser/file_path_watcher_mac.cc
===================================================================
--- chrome/browser/file_path_watcher_mac.cc	(revision 68044)
+++ chrome/browser/file_path_watcher_mac.cc	(working copy)
@@ -1,232 +0,0 @@
-// Copyright (c) 2009 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 "chrome/browser/file_path_watcher.h"
-
-#include <CoreServices/CoreServices.h>
-#include <set>
-
-#include "base/file_path.h"
-#include "base/file_util.h"
-#include "base/logging.h"
-#include "base/mac/scoped_cftyperef.h"
-#include "base/singleton.h"
-#include "base/time.h"
-
-namespace {
-
-// The latency parameter passed to FSEventsStreamCreate().
-const CFAbsoluteTime kEventLatencySeconds = 0.3;
-
-// Mac-specific file watcher implementation based on the FSEvents API.
-class FilePathWatcherImpl : public FilePathWatcher::PlatformDelegate {
- public:
-  FilePathWatcherImpl();
-  virtual ~FilePathWatcherImpl() {}
-
-  // Called from the FSEvents callback whenever there is a change to the paths
-  void OnFilePathChanged();
-
-  // (Re-)Initialize the event stream to start reporting events from
-  // |start_event|.
-  void UpdateEventStream(FSEventStreamEventId start_event);
-
-  // FilePathWatcher::PlatformDelegate overrides.
-  virtual bool Watch(const FilePath& path, FilePathWatcher::Delegate* delegate);
-  virtual void Cancel();
-
- private:
-  // Destroy the event stream.
-  void DestroyEventStream();
-
-  // Delegate to notify upon changes.
-  scoped_refptr<FilePathWatcher::Delegate> delegate_;
-
-  // Target path to watch (passed to delegate).
-  FilePath target_;
-
-  // Keep track of the last modified time of the file.  We use nulltime
-  // to represent the file not existing.
-  base::Time last_modified_;
-
-  // The time at which we processed the first notification with the
-  // |last_modified_| time stamp.
-  base::Time first_notification_;
-
-  // Backend stream we receive event callbacks from (strong reference).
-  FSEventStreamRef fsevent_stream_;
-
-  // Used to detect early cancellation.
-  bool canceled_;
-
-  DISALLOW_COPY_AND_ASSIGN(FilePathWatcherImpl);
-};
-
-// The callback passed to FSEventStreamCreate().
-void FSEventsCallback(ConstFSEventStreamRef stream,
-                      void* event_watcher, size_t num_events,
-                      void* event_paths, const FSEventStreamEventFlags flags[],
-                      const FSEventStreamEventId event_ids[]) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-
-  FilePathWatcherImpl* watcher =
-      reinterpret_cast<FilePathWatcherImpl*>(event_watcher);
-  bool root_changed = false;
-  FSEventStreamEventId root_change_at = FSEventStreamGetLatestEventId(stream);
-  for (size_t i = 0; i < num_events; i++) {
-    if (flags[i] & kFSEventStreamEventFlagRootChanged)
-      root_changed = true;
-    if (event_ids[i])
-      root_change_at = std::min(root_change_at, event_ids[i]);
-  }
-
-  // Reinitialize the event stream if we find changes to the root. This is
-  // necessary since FSEvents doesn't report any events for the subtree after
-  // the directory to be watched gets created.
-  if (root_changed) {
-    // Resetting the event stream from within the callback fails (FSEvents spews
-    // bad file descriptor errors), so post a task to do the reset.
-    BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
-        NewRunnableMethod(watcher, &FilePathWatcherImpl::UpdateEventStream,
-                          root_change_at));
-  }
-
-  BrowserThread::PostTask(BrowserThread::FILE, FROM_HERE,
-      NewRunnableMethod(watcher, &FilePathWatcherImpl::OnFilePathChanged));
-}
-
-// FilePathWatcherImpl implementation:
-
-FilePathWatcherImpl::FilePathWatcherImpl()
-    : fsevent_stream_(NULL),
-      canceled_(false) {
-}
-
-void FilePathWatcherImpl::OnFilePathChanged() {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
-  DCHECK(!target_.empty());
-
-  base::PlatformFileInfo file_info;
-  bool file_exists = file_util::GetFileInfo(target_, &file_info);
-  if (file_exists && (last_modified_.is_null() ||
-      last_modified_ != file_info.last_modified)) {
-    last_modified_ = file_info.last_modified;
-    first_notification_ = base::Time::Now();
-    delegate_->OnFilePathChanged(target_);
-  } else if (file_exists && !first_notification_.is_null()) {
-    // The target's last modification time is equal to what's on record. This
-    // means that either an unrelated event occurred, or the target changed
-    // again (file modification times only have a resolution of 1s). Comparing
-    // file modification times against the wall clock is not reliable to find
-    // out whether the change is recent, since this code might just run too
-    // late. Moreover, there's no guarantee that file modification time and wall
-    // clock times come from the same source.
-    //
-    // Instead, the time at which the first notification carrying the current
-    // |last_notified_| time stamp is recorded. Later notifications that find
-    // the same file modification time only need to be forwarded until wall
-    // clock has advanced one second from the initial notification. After that
-    // interval, client code is guaranteed to having seen the current revision
-    // of the file.
-    if (base::Time::Now() - first_notification_ >
-        base::TimeDelta::FromSeconds(1)) {
-      // Stop further notifications for this |last_modification_| time stamp.
-      first_notification_ = base::Time();
-    }
-    delegate_->OnFilePathChanged(target_);
-  } else if (!file_exists && !last_modified_.is_null()) {
-    last_modified_ = base::Time();
-    delegate_->OnFilePathChanged(target_);
-  }
-}
-
-bool FilePathWatcherImpl::Watch(const FilePath& path,
-                                FilePathWatcher::Delegate* delegate) {
-  DCHECK(target_.value().empty());
-
-  target_ = path;
-  delegate_ = delegate;
-
-  FSEventStreamEventId start_event = FSEventsGetCurrentEventId();
-
-  base::PlatformFileInfo file_info;
-  if (file_util::GetFileInfo(target_, &file_info)) {
-    last_modified_ = file_info.last_modified;
-    first_notification_ = base::Time::Now();
-  }
-
-  BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
-      NewRunnableMethod(this, &FilePathWatcherImpl::UpdateEventStream,
-                        start_event));
-
-  return true;
-}
-
-void FilePathWatcherImpl::Cancel() {
-  // Switch to the UI thread if necessary, so we can tear down the event stream.
-  if (!BrowserThread::CurrentlyOn(BrowserThread::UI)) {
-    BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
-        NewRunnableMethod(this, &FilePathWatcherImpl::Cancel));
-    return;
-  }
-
-  canceled_ = true;
-  if (fsevent_stream_)
-    DestroyEventStream();
-}
-
-void FilePathWatcherImpl::UpdateEventStream(FSEventStreamEventId start_event) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-
-  // It can happen that the watcher gets canceled while tasks that call this
-  // function are still in flight, so abort if this situation is detected.
-  if (canceled_)
-    return;
-
-  if (fsevent_stream_)
-    DestroyEventStream();
-
-  base::mac::ScopedCFTypeRef<CFStringRef> cf_path(CFStringCreateWithCString(
-      NULL, target_.value().c_str(), kCFStringEncodingMacHFS));
-  base::mac::ScopedCFTypeRef<CFStringRef> cf_dir_path(CFStringCreateWithCString(
-      NULL, target_.DirName().value().c_str(), kCFStringEncodingMacHFS));
-  CFStringRef paths_array[] = { cf_path.get(), cf_dir_path.get() };
-  base::mac::ScopedCFTypeRef<CFArrayRef> watched_paths(CFArrayCreate(
-      NULL, reinterpret_cast<const void**>(paths_array), arraysize(paths_array),
-      &kCFTypeArrayCallBacks));
-
-  FSEventStreamContext context;
-  context.version = 0;
-  context.info = this;
-  context.retain = NULL;
-  context.release = NULL;
-  context.copyDescription = NULL;
-
-  fsevent_stream_ = FSEventStreamCreate(NULL, &FSEventsCallback, &context,
-                                        watched_paths,
-                                        start_event,
-                                        kEventLatencySeconds,
-                                        kFSEventStreamCreateFlagWatchRoot);
-  FSEventStreamScheduleWithRunLoop(fsevent_stream_, CFRunLoopGetCurrent(),
-                                   kCFRunLoopDefaultMode);
-  if (!FSEventStreamStart(fsevent_stream_)) {
-    BrowserThread::PostTask(BrowserThread::FILE, FROM_HERE,
-        NewRunnableMethod(delegate_.get(),
-                          &FilePathWatcher::Delegate::OnError));
-  }
-}
-
-void FilePathWatcherImpl::DestroyEventStream() {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-  FSEventStreamStop(fsevent_stream_);
-  FSEventStreamInvalidate(fsevent_stream_);
-  FSEventStreamRelease(fsevent_stream_);
-  fsevent_stream_ = NULL;
-}
-
-}  // namespace
-
-FilePathWatcher::FilePathWatcher() {
-  impl_ = new FilePathWatcherImpl();
-}