Fix multiple commands in redis cache. (#142)

* Fix multiple commands in redis cache.

* Using future boundary to add stream.

Author: isoos

neat_cache/CHANGELOG.md

@@ -1,3 +1,6 @@
+## v2.0.1
+ * Fixed issue when adding multiple commands without waiting for them to complete first.
+
 ## v2.0.0
  * Migrated to null-safety, dropping dependency on `package:dartis`.
 

neat_cache/lib/src/providers/resp.dart

@@ -65,6 +65,7 @@ class RespClient {
 
   final _ByteStreamScanner _input;
   final StreamSink<List<int>> _output;
+  Future _pendingStream = Future.value(null);
 
   final _pending = Queue<Completer<Object?>>();
 
@@ -177,7 +178,8 @@ class RespClient {
     final c = Completer<Object?>();
     _pending.addLast(c);
     try {
-      await _output.addStream(Stream.value(out.toBytes()));
+      _pendingStream = _pendingStream
+          .then((value) => _output.addStream(Stream.value(out.toBytes())));
     } on Exception catch (e, st) {
       await _abort(e, st);
     }

neat_cache/pubspec.yaml

@@ -1,5 +1,5 @@
 name: neat_cache
-version: 2.0.0
+version: 2.0.1
 description: |
   A neat cache abstraction for wrapping in-memory or redis caches.
 homepage: https://github.com/google/dart-neats/tree/master/neat_cache

neat_cache/test/cacheprovider_test.dart

@@ -36,12 +36,42 @@ void testCacheProvider({
         expect(r, isNull);
       });
 
+      test('get multiple keys at the same time', () async {
+        await cache.purge('test-key');
+        final list = await Future.wait([
+          cache.get('test-empty-key-1'),
+          cache.get('test-empty-key-2'),
+          cache.get('test-empty-key-3'),
+          cache.get('test-empty-key-4'),
+          cache.get('test-empty-key-1'),
+          cache.get('test-empty-key-2'),
+          cache.get('test-empty-key-3'),
+          cache.get('test-empty-key-4'),
+        ]);
+        expect(list, isNotEmpty);
+        expect(list.where((e) => e != null), isEmpty);
+      });
+
       test('get/set key', () async {
         await cache.set('test-key-2', 'hello-world-42');
         final r = await cache.get('test-key-2');
         expect(r, equals('hello-world-42'));
       });
 
+      test('get/set multiple keys', () async {
+        await Future.wait([
+          cache.set('test-multi-key-1', 'hello-world-1'),
+          cache.set('test-multi-key-2', 'hello-world-2'),
+          cache.set('test-multi-key-3', 'hello-world-3'),
+        ]);
+        final values = await Future.wait([
+          cache.get('test-multi-key-1'),
+          cache.get('test-multi-key-2'),
+          cache.get('test-multi-key-3'),
+        ]);
+        expect(values, ['hello-world-1', 'hello-world-2', 'hello-world-3']);
+      });
+
       test('set key (overwrite)', () async {
         await cache.set('test-key-3', 'hello-once');
         final r = await cache.get('test-key-3');