Make event-handlers edge-triggered and move socket-state to Dart.

runtime/bin/file_patch.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 patch class _File {
   /* patch */ static _exists(String path) native "File_Exists";
   /* patch */ static _create(String path) native "File_Create";
   /* patch */ static _createLink(String path, String target)
       native "File_CreateLink";
   /* patch */ static _linkTarget(String path) native "File_LinkTarget";
@@ skipping 132 matching lines @@
   // Called when a new path is being watched.
   Stream _pathWatched() {}
   // Called when a path is no longer being watched.
   void _donePathWatched() {}
 
   static _WatcherPath _pathFromPathId(int pathId) {
     return _idMap[pathId];
   }
 
   static Stream _listenOnSocket(int socketId, int id, int pathId) {
-    var socket = new _RawSocket(new _NativeSocket.watch(socketId));
+    var native = new _NativeSocket.watch(socketId);
+    var socket = new _RawSocket(native);
     return socket.expand((event) {
       var stops = [];
       var events = [];
       var pair = {};
       if (event == RawSocketEvent.READ) {
         String getPath(event) {
           var path = _pathFromPathId(event[4]).path;
           if (event[2] != null && event[2].isNotEmpty) {
             path += Platform.pathSeparator;
             path += event[2];
@@ skipping 11 matching lines @@
           if ((event.type & _pathFromPathId(id).events) == 0) return;
           events.add([id, event]);
         }
         void rewriteMove(event, isDir) {
           if (event[3]) {
             add(event[4], new FileSystemCreateEvent._(getPath(event), isDir));
           } else {
             add(event[4], new FileSystemDeleteEvent._(getPath(event), isDir));
           }
         }
-        while (socket.available() > 0) {
+        int eventCount;
+        do {
+          eventCount = 0;
           for (var event in _readEvents(id, pathId)) {
             if (event == null) continue;
+            eventCount++;
             int pathId = event[4];
             bool isDir = getIsDir(event);
             var path = getPath(event);
             if ((event[0] & FileSystemEvent.CREATE) != 0) {
               add(event[4], new FileSystemCreateEvent._(path, isDir));
             }
             if ((event[0] & FileSystemEvent.MODIFY) != 0) {
               add(event[4], new FileSystemModifyEvent._(path, isDir, true));
             }
             if ((event[0] & FileSystemEvent._MODIFY_ATTRIBUTES) != 0) {
@@ skipping 17 matching lines @@
             }
             if ((event[0] & FileSystemEvent.DELETE) != 0) {
               add(event[4], new FileSystemDeleteEvent._(path, isDir));
             }
             if ((event[0] & FileSystemEvent._DELETE_SELF) != 0) {
               add(event[4], new FileSystemDeleteEvent._(path, isDir));
               // Signal done event.
               stops.add([event[4], null]);
             }
           }
-        }
+        } while (eventCount > 0);
+        // Be sure to clear this manually, as the sockets are not read through
+        // the _NativeSocket interface.
+        native.available = 0;
         for (var map in pair.values) {
           for (var event in map.values) {
             rewriteMove(event, getIsDir(event));
           }
         }
       } else if (event == RawSocketEvent.CLOSED) {
       } else if (event == RawSocketEvent.READ_CLOSED) {
       } else {
         assert(false);
       }
@@ skipping 115 matching lines @@
   void _pathWatchedEnd() {
     _subscription.cancel();
     _controller.close();
   }
 }
 
 
 Uint8List _makeUint8ListView(Uint8List source, int offsetInBytes, int length) {
   return new Uint8List.view(source.buffer, offsetInBytes, length);
 }