Revert 274735 "Use FSEvents for recursive file watch on Mac"

trunk/src/base/files/file_path_watcher_kqueue.cc

Index: trunk/src/base/files/file_path_watcher_kqueue.cc
===================================================================
--- trunk/src/base/files/file_path_watcher_kqueue.cc	(revision 274756)
+++ trunk/src/base/files/file_path_watcher_kqueue.cc	(working copy)
@@ -2,14 +2,19 @@
 // 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_kqueue.h"
+#include "base/files/file_path_watcher.h"
 
 #include <fcntl.h>
+#include <sys/event.h>
 #include <sys/param.h>
 
+#include <vector>
+
 #include "base/bind.h"
 #include "base/file_util.h"
 #include "base/logging.h"
+#include "base/message_loop/message_loop.h"
+#include "base/message_loop/message_loop_proxy.h"
 #include "base/strings/stringprintf.h"
 
 // On some platforms these are not defined.
@@ -22,18 +27,136 @@
 
 namespace base {
 
-FilePathWatcherKQueue::FilePathWatcherKQueue() : kqueue_(-1) {}
+namespace {
 
-FilePathWatcherKQueue::~FilePathWatcherKQueue() {}
+// Mac-specific file watcher implementation based on kqueue.
+// Originally it was based on FSEvents so that the semantics were equivalent
+// on Linux, OSX and Windows where it was able to detect:
+// - file creation/deletion/modification in a watched directory
+// - file creation/deletion/modification for a watched file
+// - modifications to the paths to a watched object that would affect the
+//   object such as renaming/attibute changes etc.
+// The FSEvents version did all of the above except handling attribute changes
+// to path components. Unfortunately FSEvents appears to have an issue where the
+// current implementation (Mac OS X 10.6.7) sometimes drops events and doesn't
+// send notifications. See
+// http://code.google.com/p/chromium/issues/detail?id=54822#c31 for source that
+// will reproduce the problem. FSEvents also required having a CFRunLoop
+// backing the thread that it was running on, that caused added complexity
+// in the interfaces.
+// The kqueue implementation will handle all of the items in the list above
+// except for detecting modifications to files in a watched directory. It will
+// detect the creation and deletion of files, just not the modification of
+// files. It does however detect the attribute changes that the FSEvents impl
+// would miss.
+class FilePathWatcherImpl : public FilePathWatcher::PlatformDelegate,
+                            public MessageLoopForIO::Watcher,
+                            public MessageLoop::DestructionObserver {
+ public:
+  FilePathWatcherImpl() : kqueue_(-1) {}
 
-void FilePathWatcherKQueue::ReleaseEvent(struct kevent& event) {
+  // MessageLoopForIO::Watcher overrides.
+  virtual void OnFileCanReadWithoutBlocking(int fd) OVERRIDE;
+  virtual void OnFileCanWriteWithoutBlocking(int fd) OVERRIDE;
+
+  // MessageLoop::DestructionObserver overrides.
+  virtual void WillDestroyCurrentMessageLoop() OVERRIDE;
+
+  // FilePathWatcher::PlatformDelegate overrides.
+  virtual bool Watch(const FilePath& path,
+                     bool recursive,
+                     const FilePathWatcher::Callback& callback) OVERRIDE;
+  virtual void Cancel() OVERRIDE;
+
+ protected:
+  virtual ~FilePathWatcherImpl() {}
+
+ private:
+  class EventData {
+   public:
+    EventData(const FilePath& path, const FilePath::StringType& subdir)
+        : path_(path), subdir_(subdir) { }
+    FilePath path_;  // Full path to this item.
+    FilePath::StringType subdir_;  // Path to any sub item.
+  };
+  typedef std::vector<struct kevent> EventVector;
+
+  // Can only be called on |io_message_loop_|'s thread.
+  virtual void CancelOnMessageLoopThread() OVERRIDE;
+
+  // Returns true if the kevent values are error free.
+  bool AreKeventValuesValid(struct kevent* kevents, int count);
+
+  // Respond to a change of attributes of the path component represented by
+  // |event|. Sets |target_file_affected| to true if |target_| is affected.
+  // Sets |update_watches| to true if |events_| need to be updated.
+  void HandleAttributesChange(const EventVector::iterator& event,
+                              bool* target_file_affected,
+                              bool* update_watches);
+
+  // Respond to a move or deletion of the path component represented by
+  // |event|. Sets |target_file_affected| to true if |target_| is affected.
+  // Sets |update_watches| to true if |events_| need to be updated.
+  void HandleDeleteOrMoveChange(const EventVector::iterator& event,
+                                bool* target_file_affected,
+                                bool* update_watches);
+
+  // Respond to a creation of an item in the path component represented by
+  // |event|. Sets |target_file_affected| to true if |target_| is affected.
+  // Sets |update_watches| to true if |events_| need to be updated.
+  void HandleCreateItemChange(const EventVector::iterator& event,
+                              bool* target_file_affected,
+                              bool* update_watches);
+
+  // Update |events_| with the current status of the system.
+  // Sets |target_file_affected| to true if |target_| is affected.
+  // Returns false if an error occurs.
+  bool UpdateWatches(bool* target_file_affected);
+
+  // Fills |events| with one kevent per component in |path|.
+  // Returns the number of valid events created where a valid event is
+  // defined as one that has a ident (file descriptor) field != -1.
+  static int EventsForPath(FilePath path, EventVector *events);
+
+  // Release a kevent generated by EventsForPath.
+  static void ReleaseEvent(struct kevent& event);
+
+  // Returns a file descriptor that will not block the system from deleting
+  // the file it references.
+  static uintptr_t FileDescriptorForPath(const FilePath& path);
+
+  static const uintptr_t kNoFileDescriptor = static_cast<uintptr_t>(-1);
+
+  // Closes |*fd| and sets |*fd| to -1.
+  static void CloseFileDescriptor(uintptr_t* fd);
+
+  // Returns true if kevent has open file descriptor.
+  static bool IsKeventFileDescriptorOpen(const struct kevent& event) {
+    return event.ident != kNoFileDescriptor;
+  }
+
+  static EventData* EventDataForKevent(const struct kevent& event) {
+    return reinterpret_cast<EventData*>(event.udata);
+  }
+
+  EventVector events_;
+  scoped_refptr<base::MessageLoopProxy> io_message_loop_;
+  MessageLoopForIO::FileDescriptorWatcher kqueue_watcher_;
+  FilePathWatcher::Callback callback_;
+  FilePath target_;
+  int kqueue_;
+
+  DISALLOW_COPY_AND_ASSIGN(FilePathWatcherImpl);
+};
+
+void FilePathWatcherImpl::ReleaseEvent(struct kevent& event) {
   CloseFileDescriptor(&event.ident);
   EventData* entry = EventDataForKevent(event);
   delete entry;
   event.udata = NULL;
 }
 
-int FilePathWatcherKQueue::EventsForPath(FilePath path, EventVector* events) {
+int FilePathWatcherImpl::EventsForPath(FilePath path, EventVector* events) {
   DCHECK(MessageLoopForIO::current());
   // Make sure that we are working with a clean slate.
   DCHECK(events->empty());
@@ -75,14 +198,14 @@
   return last_existing_entry;
 }
 
-uintptr_t FilePathWatcherKQueue::FileDescriptorForPath(const FilePath& path) {
+uintptr_t FilePathWatcherImpl::FileDescriptorForPath(const FilePath& path) {
   int fd = HANDLE_EINTR(open(path.value().c_str(), O_EVTONLY));
   if (fd == -1)
     return kNoFileDescriptor;
   return fd;
 }
 
-void FilePathWatcherKQueue::CloseFileDescriptor(uintptr_t* fd) {
+void FilePathWatcherImpl::CloseFileDescriptor(uintptr_t* fd) {
   if (*fd == kNoFileDescriptor) {
     return;
   }
@@ -93,7 +216,7 @@
   *fd = kNoFileDescriptor;
 }
 
-bool FilePathWatcherKQueue::AreKeventValuesValid(struct kevent* kevents,
+bool FilePathWatcherImpl::AreKeventValuesValid(struct kevent* kevents,
                                                int count) {
   if (count < 0) {
     DPLOG(ERROR) << "kevent";
@@ -127,7 +250,7 @@
   return valid;
 }
 
-void FilePathWatcherKQueue::HandleAttributesChange(
+void FilePathWatcherImpl::HandleAttributesChange(
     const EventVector::iterator& event,
     bool* target_file_affected,
     bool* update_watches) {
@@ -151,7 +274,7 @@
   }
 }
 
-void FilePathWatcherKQueue::HandleDeleteOrMoveChange(
+void FilePathWatcherImpl::HandleDeleteOrMoveChange(
     const EventVector::iterator& event,
     bool* target_file_affected,
     bool* update_watches) {
@@ -167,7 +290,7 @@
   }
 }
 
-void FilePathWatcherKQueue::HandleCreateItemChange(
+void FilePathWatcherImpl::HandleCreateItemChange(
     const EventVector::iterator& event,
     bool* target_file_affected,
     bool* update_watches) {
@@ -187,7 +310,7 @@
   }
 }
 
-bool FilePathWatcherKQueue::UpdateWatches(bool* target_file_affected) {
+bool FilePathWatcherImpl::UpdateWatches(bool* target_file_affected) {
   // Iterate over events adding kevents for items that exist to the kqueue.
   // Then check to see if new components in the path have been created.
   // Repeat until no new components in the path are detected.
@@ -228,7 +351,7 @@
   return true;
 }
 
-void FilePathWatcherKQueue::OnFileCanReadWithoutBlocking(int fd) {
+void FilePathWatcherImpl::OnFileCanReadWithoutBlocking(int fd) {
   DCHECK(MessageLoopForIO::current());
   DCHECK_EQ(fd, kqueue_);
   DCHECK(events_.size());
@@ -301,24 +424,24 @@
   }
 }
 
-void FilePathWatcherKQueue::OnFileCanWriteWithoutBlocking(int fd) {
+void FilePathWatcherImpl::OnFileCanWriteWithoutBlocking(int fd) {
   NOTREACHED();
 }
 
-void FilePathWatcherKQueue::WillDestroyCurrentMessageLoop() {
+void FilePathWatcherImpl::WillDestroyCurrentMessageLoop() {
   CancelOnMessageLoopThread();
 }
 
-bool FilePathWatcherKQueue::Watch(const FilePath& path,
-                                  bool recursive,
-                                  const FilePathWatcher::Callback& callback) {
+bool FilePathWatcherImpl::Watch(const FilePath& path,
+                                bool recursive,
+                                const FilePathWatcher::Callback& callback) {
   DCHECK(MessageLoopForIO::current());
   DCHECK(target_.value().empty());  // Can only watch one path.
   DCHECK(!callback.is_null());
   DCHECK_EQ(kqueue_, -1);
 
   if (recursive) {
-    // Recursive watch is not supported using kqueue.
+    // Recursive watch is not supported on this platform.
     NOTIMPLEMENTED();
     return false;
   }
@@ -355,7 +478,7 @@
       kqueue_, true, MessageLoopForIO::WATCH_READ, &kqueue_watcher_, this);
 }
 
-void FilePathWatcherKQueue::Cancel() {
+void FilePathWatcherImpl::Cancel() {
   base::MessageLoopProxy* proxy = io_message_loop_.get();
   if (!proxy) {
     set_cancelled();
@@ -363,13 +486,13 @@
   }
   if (!proxy->BelongsToCurrentThread()) {
     proxy->PostTask(FROM_HERE,
-                    base::Bind(&FilePathWatcherKQueue::Cancel, this));
+                    base::Bind(&FilePathWatcherImpl::Cancel, this));
     return;
   }
   CancelOnMessageLoopThread();
 }
 
-void FilePathWatcherKQueue::CancelOnMessageLoopThread() {
+void FilePathWatcherImpl::CancelOnMessageLoopThread() {
   DCHECK(MessageLoopForIO::current());
   if (!is_cancelled()) {
     set_cancelled();
@@ -386,4 +509,10 @@
   }
 }
 
+}  // namespace
+
+FilePathWatcher::FilePathWatcher() {
+  impl_ = new FilePathWatcherImpl();
+}
+
 }  // namespace base