Use FSEvents in wxFileSystemWatcher on OS X

The FSEvents API allows for creating watches in entire trees of
directories in an efficient manner.

Closes #16969.

include/wx/osx/cocoa/chkconf.h

@@ -50,6 +50,16 @@
 #define wxOSX_USE_QUICKTIME 0
 #define wxOSX_USE_AUDIOTOOLBOX 1
 
+/*
+   Use the more efficient FSEvents API instead of kqueue
+   events for file system watcher, but only on OS X >= 10.7 since
+   that version introduced a flag that allows watching files as
+   well as sub directories.
+ */
+#if MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_7
+    #define wxHAVE_FSEVENTS_FILE_NOTIFICATIONS 1
+#endif
+
 /*
  * turning off capabilities that don't work under cocoa yet
  */

include/wx/osx/fswatcher_fsevents.h

@@ -0,0 +1,88 @@
+/////////////////////////////////////////////////////////////////////////////
+// Name:        wx/osx/fswatcher_fsevents.h
+// Purpose:     File System watcher that uses the FSEvents API
+//              of OS X to efficiently watch trees
+// Author:      Roberto Perpuly
+// Created:     2015-04-24
+// Copyright:   (c) 2015 Roberto Perpuly <robertop2004@gmail.com>
+// Licence:     wxWindows licence
+/////////////////////////////////////////////////////////////////////////////
+
+#ifndef _WX_FSWATCHER_FSEVENTS_H_
+#define _WX_FSWATCHER_FSEVENTS_H_
+
+#include "wx/defs.h"
+
+#if wxUSE_FSWATCHER
+
+#include <CoreServices/CoreServices.h>
+#include "wx/unix/fswatcher_kqueue.h"
+
+WX_DECLARE_STRING_HASH_MAP(FSEventStreamRef, FSEventStreamRefMap);
+
+/*
+ The FSEvents watcher uses the newer FSEvents service
+ that is available in OS X, the service allows for
+ efficient watching of entire directory hierarchies.
+ Note that adding a single file watch (or directory
+ watch) still use kqueue events.
+
+ We take care to only use this on OS X >= 10.7, as that
+ version introduced the ability to get file-level notifications.
+
+ See the following docs that outline the FSEvents API
+
+ https://developer.apple.com/library/mac/documentation/Darwin/Conceptual/FSEvents_ProgGuide/UsingtheFSEventsFramework/UsingtheFSEventsFramework.html
+
+ https://developer.apple.com/library/mac/documentation/Darwin/Reference/FSEvents_Ref/index.html
+*/
+class WXDLLIMPEXP_BASE wxFsEventsFileSystemWatcher :
+        public wxKqueueFileSystemWatcher
+{
+public:
+    wxFsEventsFileSystemWatcher();
+
+    wxFsEventsFileSystemWatcher(const wxFileName& path,
+                              int events = wxFSW_EVENT_ALL);
+
+    ~wxFsEventsFileSystemWatcher();
+
+    // reimplement adding a tree so that it does not use
+    // kqueue at all
+    bool AddTree(const wxFileName& path, int events = wxFSW_EVENT_ALL,
+                const wxString& filespec = wxEmptyString) wxOVERRIDE;
+
+    // reimplement removing a tree so that we
+    // cleanup the opened fs streams
+    bool RemoveTree(const wxFileName& path) wxOVERRIDE;
+
+    // reimplement remove all so that we cleanup
+    // watches from kqeueue and from FSEvents
+    bool RemoveAll() wxOVERRIDE;
+
+    // post an file change event to the owner
+    void PostChange(const wxFileName& oldFileName,
+      const wxFileName& newFileName, int event);
+
+    // post a warning event to the owner
+    void PostWarning(wxFSWWarningType warning, const wxString& msg);
+
+    // post an error event to the owner
+    void PostError(const wxString& msg);
+
+    // reimplement count to include the FS stream watches
+    int GetWatchedPathsCount() const;
+
+    // reimplement to include paths from FS stream watches
+    int GetWatchedPaths(wxArrayString* paths) const;
+
+private:
+
+    // map of path => FSEventStreamRef
+    FSEventStreamRefMap m_streams;
+
+};
+
+#endif /* wxUSE_FSWATCHER */
+
+#endif  /* _WX_FSWATCHER_FSEVENTS_H_ */