Show nicer errors on some server failures.

utils/pub/io.dart

Index: utils/pub/io.dart
diff --git a/utils/pub/io.dart b/utils/pub/io.dart
index e3fc8e0202c4b84edcfc59abe54584009037bf9d..a4d554c39b71097b1c23d06c5c2a4ce894d2be68 100644
--- a/utils/pub/io.dart
+++ b/utils/pub/io.dart
@@ -128,7 +128,7 @@ Future<File> writeTextFile(file, String contents) {
  * Asynchronously deletes [file], which can be a [String] or a [File]. Returns a
  * [Future] that completes when the deletion is done.
  */
-Future<Directory> deleteFile(file) {
+Future<File> deleteFile(file) {
   return new File(_getPath(file)).delete();
 }
 
@@ -309,6 +309,56 @@ InputStream httpGet(uri) {
 }
 
 /**
+ * Opens an input stream for a HTTP GET request to [uri], which may be a
+ * [String] or [Uri]. Completes with the result of the request as a String.
+ */
+Future<String> httpGetString(uri) {

[nweiz, 2012/09/04 19:29:25]

Why is this method different than httpGet? Is it just because ListInputStream
doesn't support error propagation? If so, you should add a TODO here to merge
these two when issue 3657 is fixed.

[Bob Nystrom, 2012/09/04 22:14:46]

Yup.
Done.

+  uri = _getUri(uri);
+
+  var completer = new Completer<String>();
+  var client = new HttpClient();
+  var connection = client.getUrl(uri);
+
+  connection.onError = (e) {
+    // Show a friendly error if the URL couldn't be resolved.
+    if ((e is SocketIOException) && (e.osError.errorCode == 8)) {

[nweiz, 2012/09/04 19:29:25]

I don't like these unnecessary parens. I don't think it's unclear how tightly
"&&" binds.

[Bob Nystrom, 2012/09/04 22:14:46]

Done.

+      e = 'Could not resolve URL "${uri.origin}".';
+    }
+
+    completer.completeException(e);
+  };

[nweiz, 2012/09/04 19:29:25]

Shouldn't you call client.shutdown here, too?

[Bob Nystrom, 2012/09/04 22:14:46]

Done.

+
+  connection.onResponse = (response) {
+    if (response.statusCode >= 400) {
+      client.shutdown();
+      completer.completeException(
+          new HttpException(response.statusCode, response.reasonPhrase));
+      return;
+    }
+
+    var resultStream = new ListInputStream();
+    var buffer = <int>[];
+
+    response.inputStream.onClosed = () {
+      // Make sure we aren't closing in response to an error in which case
+      // we will have already completed with that exception.

[nweiz, 2012/09/04 19:29:25]

onClosed and onError should be mutually exclusive.

[Bob Nystrom, 2012/09/04 22:14:46]

They didn't seem to be. Without this check, I get a FutureAlreadyCompleted
error.

[nweiz, 2012/09/04 22:38:18]

I believe that's a bug according to
https://docs.google.com/a/google.com/document/d/1ybQCrO6fbiTdj2h37G4Sgd-rMPzp....
I think https://chromiumcodereview.appspot.com/10836177/ will fix it, though.

[Bob Nystrom, 2012/09/04 23:01:20]

The pub tests seem to pass without the check, so I removed it. I recall seeing
an error here, but maybe that was just with my own local testing.

+      if (!completer.future.isComplete) {
+        client.shutdown();
+        completer.complete(new String.fromCharCodes(buffer));
+      }
+    };
+
+    response.inputStream.onData = () {
+      buffer.addAll(response.inputStream.read());
+    };
+
+    response.inputStream.onError = (e) => completer.completeException(e);
+  };
+
+  return completer.future;
+}
+
+/**
  * Takes all input from [source] and writes it to [sink].
  *
  * [onClosed] is called when [source] is closed.
@@ -451,6 +501,16 @@ Future<bool> extractTarGz(InputStream stream, destination) {
 }
 
 /**
+ * Exception thrown when an HTTP operation fails.
+ */
+class HttpException implements Exception {
+  final int statusCode;
+  final String reason;
+
+  const HttpException(this.statusCode, this.reason);
+}
+
+/**
  * Contains the results of invoking a [Process] and waiting for it to complete.
  */
 class PubProcessResult {