Use a pool of native ports for directory operations

runtime/bin/directory_impl.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.
 
 
 // Used for holding error code and error message for failed OS system calls.
 class _OSStatus {
   int _errorCode;
   String _errorMessage;
 }
 
 
 class _Directory implements Directory {
   static final kCreateRequest = 0;
   static final kDeleteRequest = 1;
   static final kExistsRequest = 2;
   static final kCreateTempRequest = 3;
   static final kListRequest = 4;
 
   _Directory(String this._path);
 
   static String _createTemp(String template,
                             _OSStatus status) native "Directory_CreateTemp";
   static int _exists(String path) native "Directory_Exists";
   static bool _create(String path) native "Directory_Create";
   static bool _delete(String path, bool recursive) native "Directory_Delete";
   static SendPort _newServicePort() native "Directory_NewServicePort";
 
   void exists(void callback(bool exists)) {
-    if (_directoryService == null) {
-      _directoryService = _newServicePort();
-    }
+    _ensureDirectoryService();
     List request = new List(2);
     request[0] = kExistsRequest;
     request[1] = _path;
     _directoryService.call(request).receive((result, replyTo) {
       if (result < 0) {
         if (_onError != null) {
           _onError("Diretory exists test failed: $_path");
         }
       } else {
         callback(result == 1);
       }
     });
   }
 
   bool existsSync() {
     int exists = _exists(_path);
     if (exists < 0) {
       throw new DirectoryException("Diretory exists test failed: $_path");
     }
     return (exists == 1);
   }
 
   void create(void callback()) {
-    if (_directoryService == null) {
-      _directoryService = _newServicePort();
-    }
+    _ensureDirectoryService();
     List request = new List(2);
     request[0] = kCreateRequest;
     request[1] = _path;
     _directoryService.call(request).receive((result, replyTo) {
       if (result) {
         callback();
       } else if (_onError != null) {
         _onError("Directory creation failed: $_path");
       }
     });
   }
 
   void createSync() {
     if (!_create(_path)) {
       throw new DirectoryException("Directory creation failed: $_path");
     }
   }
 
   void createTemp(void callback()) {
-    if (_directoryService == null) {
-      _directoryService = _newServicePort();
-    }
+    _ensureDirectoryService();
     List request = new List(2);
     request[0] = kCreateTempRequest;
     request[1] = _path;
     _directoryService.call(request).receive((result, replyTo) {
       if (result is !List) {
         _path = result;
         callback();
       } else if (_onError != null) {
         _onError("Could not create temporary directory [$_path]: " +
                  "${result[1]}");
       }
     });
   }
 
   void createTempSync() {
     var status = new _OSStatus();
     var result = _createTemp(path, status);
     if (result != null) {
       _path = result;
     } else {
       throw new DirectoryException(
           "Could not create temporary directory [$_path]: " +
           "${status._errorMessage}",
           status._errorCode);
     }
   }
 
   void _deleteHelper(bool recursive, String errorMsg, void callback()) {
-    if (_directoryService == null) {
-      _directoryService = _newServicePort();
-    }
+    _ensureDirectoryService();
     List request = new List(3);
     request[0] = kDeleteRequest;
     request[1] = _path;
     request[2] = recursive;
     _directoryService.call(request).receive((result, replyTo) {
       if (result) {
         callback();
       } else if (_onError != null) {
         _onError("${errorMsg}: $_path");
       }
@@ skipping 70 matching lines @@
   }
 
   void set onDone(void onDone(bool completed)) {
     _onDone = onDone;
   }
 
   void set onError(void onError(String error)) {
     _onError = onError;
   }
 
-  void _closePort(ReceivePort port) {
-    if (port !== null) {
-      port.close();
-    }
-  }
-
   String get path() { return _path; }
 
+  void _ensureDirectoryService() {
+    if (_directoryService == null) {
+      _directoryService = _newServicePort();
+    }
+  }
+
   var _onDir;
   var _onFile;
   var _onDone;
   var _onError;
 
   String _path;
   SendPort _directoryService;
 }