From da48e2a391b95aef15a577ae8dbf46a5d9088544 Mon Sep 17 00:00:00 2001
From: Ian Hickson <ian@hixie.ch>
Date: Thu, 24 Mar 2016 22:31:03 -0700
Subject: [PATCH] Clean up prints in services/*

We really shouldn't have two separate network library wrappers... I filed https://github.com/flutter/flutter/issues/2889 on that. But for now, this makes one of them have a generally better error handling story, and makes the other one only dump to the console in debug mode. It also makes both use debugPrint instead of print, and makes one use the 'mojom' prefix for mojom imports.
---
 .../flutter/lib/src/http/mojo_client.dart     | 10 ++++-
 packages/flutter/lib/src/services/fetch.dart  | 39 +++++++++++++------
 .../flutter/lib/src/services/image_cache.dart | 15 ++++---
 3 files changed, 42 insertions(+), 22 deletions(-)

diff --git a/packages/flutter/lib/src/http/mojo_client.dart b/packages/flutter/lib/src/http/mojo_client.dart
index 3665f4220a1..af1d8f066aa 100644
--- a/packages/flutter/lib/src/http/mojo_client.dart
+++ b/packages/flutter/lib/src/http/mojo_client.dart
@@ -149,8 +149,14 @@ class MojoClient {
       ByteData data = await mojo.DataPipeDrainer.drainHandle(response.body);
       Uint8List bodyBytes = new Uint8List.view(data.buffer);
       return new Response(bodyBytes: bodyBytes, statusCode: response.statusCode);
-    } catch (e) {
-      print("NetworkService unavailable $e");
+    } catch (exception) {
+      assert(() {
+        debugPrint('-- EXCEPTION CAUGHT BY NETWORKING HTTP LIBRARY -------------------------');
+        debugPrint('An exception was raised while sending bytes to the Mojo network library:');
+        debugPrint('$exception');
+        debugPrint('------------------------------------------------------------------------');
+        return true;
+      });
       return new Response(statusCode: 500);
     } finally {
       loader.close();
diff --git a/packages/flutter/lib/src/services/fetch.dart b/packages/flutter/lib/src/services/fetch.dart
index fbe8b594794..bf2f7fc1f8a 100644
--- a/packages/flutter/lib/src/services/fetch.dart
+++ b/packages/flutter/lib/src/services/fetch.dart
@@ -4,32 +4,47 @@
 
 import 'dart:async';
 
-import 'package:mojo/mojo/url_request.mojom.dart';
-import 'package:mojo/mojo/url_response.mojom.dart';
-import 'package:mojo_services/mojo/url_loader.mojom.dart';
+import 'package:mojo/mojo/url_request.mojom.dart' as mojom;
+import 'package:mojo/mojo/url_response.mojom.dart' as mojom;
+import 'package:mojo_services/mojo/url_loader.mojom.dart' as mojom;
 
 import '../http/mojo_client.dart';
+import 'print.dart';
 
 export 'package:mojo/mojo/url_response.mojom.dart' show UrlResponse;
 
-Future<UrlResponse> fetch(UrlRequest request) async {
-  UrlLoaderProxy loader = new UrlLoaderProxy.unbound();
+Future<mojom.UrlResponse> fetch(mojom.UrlRequest request, { bool require200: false }) async {
+  mojom.UrlLoaderProxy loader = new mojom.UrlLoaderProxy.unbound();
   try {
     MojoClient.networkService.ptr.createUrlLoader(loader);
-    UrlResponse response = (await loader.ptr.start(request)).response;
+    mojom.UrlResponse response = (await loader.ptr.start(request)).response;
+    if (require200 && (response.error != null || response.statusCode != 200)) {
+      StringBuffer message = new StringBuffer();
+      message.writeln('Could not ${request.method ?? "fetch"} ${request.url ?? "resource"}');
+      if (response.error != null)
+        message.writeln('Network error: ${response.error.code} ${response.error.description ?? "<unknown network error>"}');
+      if (response.statusCode != 200)
+        message.writeln('Protocol error: ${response.statusCode} ${response.statusLine ?? "<no server message>"}');
+      if (response.url != request.url)
+        message.writeln('Final URL after redirects was: ${response.url}');
+      throw message;
+    }
     return response;
-  } catch (e) {
-    print("NetworkService unavailable $e");
-    return new UrlResponse()..statusCode = 500;
+  } catch (exception) {
+    debugPrint('-- EXCEPTION CAUGHT BY NETWORKING HTTP LIBRARY -------------------------');
+    debugPrint('An exception was raised while sending bytes to the Mojo network library:');
+    debugPrint('$exception');
+    debugPrint('------------------------------------------------------------------------');
+    return null;
   } finally {
     loader.close();
   }
 }
 
-Future<UrlResponse> fetchUrl(String relativeUrl) {
+Future<mojom.UrlResponse> fetchUrl(String relativeUrl, { bool require200: false }) {
   String url = Uri.base.resolve(relativeUrl).toString();
-  UrlRequest request = new UrlRequest()
+  mojom.UrlRequest request = new mojom.UrlRequest()
     ..url = url
     ..autoFollowRedirects = true;
-  return fetch(request);
+  return fetch(request, require200: require200);
 }
diff --git a/packages/flutter/lib/src/services/image_cache.dart b/packages/flutter/lib/src/services/image_cache.dart
index 4141210ae9f..560e182c447 100644
--- a/packages/flutter/lib/src/services/image_cache.dart
+++ b/packages/flutter/lib/src/services/image_cache.dart
@@ -52,15 +52,14 @@ class _UrlFetcher implements ImageProvider {
 
   @override
   Future<ImageInfo> loadImage() async {
-    UrlResponse response = await fetchUrl(_url);
-    if (response.statusCode >= 400) {
-      print("Failed (${response.statusCode}) to load image $_url");
-      return null;
+    UrlResponse response = await fetchUrl(_url, require200: true);
+    if (response != null) {
+      return new ImageInfo(
+        image: await decodeImageFromDataPipe(response.body),
+        scale: _scale
+      );
     }
-    return new ImageInfo(
-      image: await decodeImageFromDataPipe(response.body),
-      scale: _scale
-    );
+    return null;
   }
 
   @override