Reuse HttpClient in the built-in resource loader.

runtime/bin/builtin.dart

Index: runtime/bin/builtin.dart
diff --git a/runtime/bin/builtin.dart b/runtime/bin/builtin.dart
index 33882c1ad8f4d11775ad85a5aeca5bea6b8e2124..40199302ea70510babcab9970ec0ab752ae59beb 100644
--- a/runtime/bin/builtin.dart
+++ b/runtime/bin/builtin.dart
@@ -157,7 +157,7 @@ String _resolveUri(String base, String userString) {
     var uri = userString.substring(_DART_EXT.length);
     return '$_DART_EXT${baseUri.resolve(uri)}';
   } else {
-    return '${baseUri.resolve(userString)}';
+    return baseUri.resolve(userString).toString();
   }
 }
 
@@ -205,42 +205,34 @@ String _filePathFromPackageUri(Uri uri) {
 
 
 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} ${response.reasonPhrase}';
+              _asyncLoadError(uri.toString(), libraryUri, msg);
+            }
+            loadCallback(builder.takeBytes());
+          },
+          onError: (error) {
+            _asyncLoadError(uri.toString(), libraryUri, error);
+          });
+    })
+    .catchError((error) {
+      _asyncLoadError(uri.toString(), libraryUri, error);
+    });
   // TODO(floitsch): remove this line. It's just here to push an event on the
   // event loop so that we invoke the scheduled microtasks. Also remove the
   // import of dart:async when this line is not needed anymore.
@@ -264,6 +256,10 @@ void _loadScript(int tag, String uri, String libraryUri, List<int> data) {
                  "${_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;
+    }
   }
 }