From 30738982b40b4a7b2045377636531f7627450358 Mon Sep 17 00:00:00 2001
From: Dan Field <dnfield@google.com>
Date: Fri, 3 Apr 2020 16:05:43 -0700
Subject: [PATCH] Remove network images from cache on any exception during
 loading (#53875)

* Remove network images from cache on any exception during loading
---
 .../lib/src/painting/_network_image_io.dart   | 11 ++++++-
 .../test/painting/image_provider_test.dart    | 33 +++++++++++++++++++
 2 files changed, 43 insertions(+), 1 deletion(-)

diff --git a/packages/flutter/lib/src/painting/_network_image_io.dart b/packages/flutter/lib/src/painting/_network_image_io.dart
index 12c1aa698e..5eaf04518d 100644
--- a/packages/flutter/lib/src/painting/_network_image_io.dart
+++ b/packages/flutter/lib/src/painting/_network_image_io.dart
@@ -82,7 +82,9 @@ class NetworkImage extends image_provider.ImageProvider<image_provider.NetworkIm
       assert(key == this);
 
       final Uri resolved = Uri.base.resolve(key.url);
+
       final HttpClientRequest request = await _httpClient.getUrl(resolved);
+
       headers?.forEach((String name, String value) {
         request.headers.add(name, value);
       });
@@ -91,7 +93,6 @@ class NetworkImage extends image_provider.ImageProvider<image_provider.NetworkIm
         // The network may be only temporarily unavailable, or the file will be
         // added on the server later. Avoid having future calls to resolve
         // fail to check the network again.
-        PaintingBinding.instance.imageCache.evict(key);
         throw image_provider.NetworkImageLoadException(statusCode: response.statusCode, uri: resolved);
       }
 
@@ -108,6 +109,14 @@ class NetworkImage extends image_provider.ImageProvider<image_provider.NetworkIm
         throw Exception('NetworkImage is an empty file: $resolved');
 
       return decode(bytes);
+    } catch (e) {
+      // Depending on where the exception was thrown, the image cache may not
+      // have had a chance to track the key in the cache at all.
+      // Schedule a microtask to give the cache a chance to add the key.
+      scheduleMicrotask(() {
+        PaintingBinding.instance.imageCache.evict(key);
+      });
+      rethrow;
     } finally {
       chunkEvents.close();
     }
diff --git a/packages/flutter/test/painting/image_provider_test.dart b/packages/flutter/test/painting/image_provider_test.dart
index 47371be5e8..37b301cc16 100644
--- a/packages/flutter/test/painting/image_provider_test.dart
+++ b/packages/flutter/test/painting/image_provider_test.dart
@@ -396,6 +396,39 @@ void main() {
           expect(events[i].expectedTotalBytes, kTransparentImage.length);
         }
       }, skip: isBrowser);
+
+      test('NetworkImage is evicted from cache on SocketException', () async {
+        final MockHttpClient mockHttpClient = MockHttpClient();
+        when(mockHttpClient.getUrl(any)).thenAnswer((_) => throw const SocketException('test exception'));
+        debugNetworkImageHttpClientProvider = () => mockHttpClient;
+
+
+        final ImageProvider imageProvider = NetworkImage(nonconst('testing.url'));
+        expect(imageCache.pendingImageCount, 0);
+        expect(imageCache.statusForKey(imageProvider).untracked, true);
+
+        final ImageStream result = imageProvider.resolve(ImageConfiguration.empty);
+
+        expect(imageCache.pendingImageCount, 1);
+        expect(imageCache.statusForKey(imageProvider).pending, true);
+        final Completer<dynamic> caughtError = Completer<dynamic>();
+        result.addListener(ImageStreamListener(
+          (ImageInfo info, bool syncCall) {},
+          onError: (dynamic error, StackTrace stackTrace) {
+            caughtError.complete(error);
+          },
+        ));
+
+        final dynamic err = await caughtError.future;
+
+        expect(err, isA<SocketException>());
+
+        expect(imageCache.pendingImageCount, 0);
+        expect(imageCache.statusForKey(imageProvider).untracked, true);
+        expect(imageCache.containsKey(result), isFalse);
+
+        debugNetworkImageHttpClientProvider = null;
+      }, skip: isBrowser); // Browser does not resolve images this way.
     });
   });