Reuse HttpClient in the built-in resource loader.

runtime/bin/builtin.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.
 
 library builtin;
 import 'dart:io';
 import 'dart:async';
 import 'dart:convert';
 // import 'root_library'; happens here from C Code
 
@@ skipping 139 matching lines @@
 
 const _DART_EXT = 'dart-ext:';
 
 String _resolveUri(String base, String userString) {
   _logResolution('# Resolving: $userString from $base');
   var baseUri = Uri.parse(base);
   if (userString.startsWith(_DART_EXT)) {
     var uri = userString.substring(_DART_EXT.length);
     return '$_DART_EXT${baseUri.resolve(uri)}';
   } else {
-    return '${baseUri.resolve(userString)}';
+    return baseUri.resolve(userString).toString();
   }
 }
 
 
 // Returns either a file path or a URI starting with http:, as a String.
 String _filePathFromUri(String userUri) {
   var uri = Uri.parse(userUri);
   _logResolution('# Getting file path from: $uri');
 
   var path;
@@ skipping 27 matching lines @@
   }
 
   var packageRoot = _packageRoot == null ?
                     _entryPointScript.resolve('packages/') :
                     _packageRoot;
   return _filePathFromUri(packageRoot.resolve(uri.path).toString());
 }
 
 
 int _numOutstandingLoadRequests = 0;
-
+var _httpClient;
 
 void _httpGet(Uri uri, String libraryUri, loadCallback(List<int> data)) {
-  var httpClient = new HttpClient();
-  try {
-    httpClient.getUrl(uri)
-      .then((HttpClientRequest request) {
-        request.persistentConnection = false;
-        return request.close();
-      })
-      .then((HttpClientResponse response) {
-        // Only create a ByteBuilder if multiple chunks are received.
-        var builder = new BytesBuilder(copy: false);
-        response.listen(
-            builder.add,
-            onDone: () {
-              if (response.statusCode != 200) {
-                var msg = 'Failure getting $uri: '
-                          '${response.statusCode} ${response.reasonPhrase}';
-                _asyncLoadError(uri.toString(), libraryUri, msg);
-              }
-
-              List<int> data = builder.takeBytes();
-              httpClient.close();
-              loadCallback(data);
-            },
-            onError: (error) {
-              _asyncLoadError(uri.toString(), libraryUri, error);
-            });
-      })
-      .catchError((error) {
-        _asyncLoadError(uri.toString(), libraryUri, error);
-      });
-  } catch (error) {
-    _asyncLoadError(uri.toString(), libraryUri, error);
+  if (_httpClient == null) {
+    _httpClient = new HttpClient()..maxConnectionsPerHost = 6;
   }
+  _httpClient.getUrl(uri)
+    .then((HttpClientRequest request) => request.close())
+    .then((HttpClientResponse response) {
+      // Only create a ByteBuilder if multiple chunks are received.

[Ivan Posva, 2014/09/03 15:37:38]

I am reading this comment as a TODO, correct?

[Anders Johnsen, 2014/09/04 08:26:28]

Removing, the bytebuffer does this for us.

+      var builder = new BytesBuilder(copy: false);
+      response.listen(
+          builder.add,
+          onDone: () {
+            if (response.statusCode != 200) {
+              var msg = 'Failure getting $uri: '
+                        '${response.statusCode} ${response.reasonPhrase}';
+              _asyncLoadError(uri.toString(), libraryUri, msg);
+            }
+            loadCallback(builder.takeBytes());
+          },
+          onError: (error) {
+            _asyncLoadError(uri.toString(), libraryUri, error);
+          });
+    })
+    .catchError((error) {
+      _asyncLoadError(uri.toString(), libraryUri, error);
+    });
   // TODO(floitsch): remove this line. It's just here to push an event on the
   // event loop so that we invoke the scheduled microtasks. Also remove the
   // import of dart:async when this line is not needed anymore.
   Timer.run(() {});
 }
 
 
 void _signalDoneLoading() native "Builtin_DoneLoading";
 
 void _loadScriptCallback(int tag, String uri, String libraryUri, List<int> data)
     native "Builtin_LoadScript";
 
 void _loadScript(int tag, String uri, String libraryUri, List<int> data) {
   // TODO: Currently a compilation error while loading the script is
   // fatal for the isolate. _loadScriptCallback() does not return and
   // the _numOutstandingLoadRequests counter remains out of sync.
   _loadScriptCallback(tag, uri, libraryUri, data);
   assert(_numOutstandingLoadRequests > 0);
   _numOutstandingLoadRequests--;
   _logResolution("native Builtin_LoadScript($uri) completed, "
                  "${_numOutstandingLoadRequests} requests remaining");
   if (_numOutstandingLoadRequests == 0) {
     _signalDoneLoading();
+    if (_httpClient != null) {

[Ivan Posva, 2014/09/03 15:37:38]

Can you move this code in a helper function which closes the client and signals
the VM? Because otherwise we forget to call it in other places where we are
"done loading". Like below in the error case.

[Anders Johnsen, 2014/09/04 08:26:28]

Good catch.

+      _httpClient.close();
+      _httpClient = null;
+    }
   }
 }
 
 
 void _asyncLoadErrorCallback(uri, libraryUri, error)
     native "Builtin_AsyncLoadError";
 
 void _asyncLoadError(uri, libraryUri, error) {
   assert(_numOutstandingLoadRequests > 0);
   _logResolution("_asyncLoadError($uri), error: $error");
@@ skipping 71 matching lines @@
   } else if (Platform.isWindows) {
     filename = '$name.dll';
   } else {
     _logResolution(
         'Native extensions not supported on ${Platform.operatingSystem}');
     throw 'Native extensions not supported on ${Platform.operatingSystem}';
   }
 
   return [path, filename, name];
 }