Use new HTTP retry logic when fetching SDK's index.json

Author: isoos

app/lib/search/backend.dart

@@ -87,7 +87,6 @@ void registerSearchIndex(SearchIndex index) =>
 class SearchBackend {
   final DatastoreDB _db;
   final VersionedJsonStorage _snapshotStorage;
-  final _http = httpRetryClient();
 
   SearchBackend(this._db, Bucket snapshotBucket)
       : _snapshotStorage = VersionedJsonStorage(snapshotBucket, 'snapshot/');
@@ -454,11 +453,7 @@ class SearchBackend {
       }
     }
 
-    final rs = await _http.get(uri);
-    if (rs.statusCode != 200) {
-      throw Exception('Unexpected status code for $uri: ${rs.statusCode}');
-    }
-    final content = rs.body;
+    final content = await httpGetWithRetry(uri, responseFn: (rs) => rs.body);
     await file.parent.create(recursive: true);
     await file.writeAsString(content);
     return content;
@@ -519,7 +514,6 @@ class SearchBackend {
 
   Future<void> close() async {
     _snapshotStorage.close();
-    _http.close();
   }
 }
 

pkg/_pub_shared/lib/utils/http.dart

@@ -2,10 +2,12 @@
 // 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.
 
+import 'dart:async';
 import 'dart:io';
 
 import 'package:http/http.dart' as http;
 import 'package:http/retry.dart';
+import 'package:retry/retry.dart';
 
 final _transientStatusCodes = {
   // See: https://cloud.google.com/storage/docs/xml-api/reference-status
@@ -35,3 +37,45 @@ http.Client httpRetryClient({
     whenError: (e, st) => lenient || e is SocketException,
   );
 }
+
+/// Creates a HTTP client and executes a GET request to the specified [uri],
+/// making sure that the HTTP resources are freed after the [responseFn]
+/// callback finishes.
+/// The HTTP GET and the [responseFn] callback is retried on the transient
+/// network errors.
+Future<K> httpGetWithRetry<K>(
+  Uri uri, {
+  required FutureOr<K> Function(http.Response response) responseFn,
+  int maxAttempts = 3,
+}) async {
+  return await retry(
+    () async {
+      final client = http.Client();
+      try {
+        final rs = await client.get(uri);
+        if (rs.statusCode == 200) {
+          return responseFn(rs);
+        }
+        throw http.ClientException(
+            'Unexpected status code for $uri: ${rs.statusCode}.');
+      } finally {
+        client.close();
+      }
+    },
+    maxAttempts: maxAttempts,
+    retryIf: _retryIf,
+  );
+}
+
+bool _retryIf(Exception e) {
+  if (e is TimeoutException) {
+    return true; // Timeouts we can retry
+  }
+  if (e is IOException) {
+    return true; // I/O issues are worth retrying
+  }
+  if (e is http.ClientException) {
+    return true; // HTTP issues are worth retrying
+  }
+  return false;
+}

pkg/_pub_shared/pubspec.yaml

@@ -13,6 +13,7 @@ dependencies:
   logging: ^1.2.0
   meta: ^1.3.0
   pub_semver: ^2.0.0
+  retry: ^3.1.2
   sanitize_html: ^2.1.0
   api_builder: