Switch to callbacks from streams for ping handling (#137)

* Switch to callbacks from streams for ping handling

* Debugging

* Revert "Debugging"

This reverts commit 910c1e1.

* Revert "Switch to callbacks from streams for ping handling"

This reverts commit c4f4730.

* Fix by using `hasListener`

* Rev version

* Rerun checks

Author: mosuem

CHANGELOG.md

@@ -1,3 +1,7 @@
+## 2.3.0
+
+- Only send updates on frames and pings being received when there are listeners, as to not fill up memory.
+
 ## 2.2.0
 
 - Transform headers to lowercase.

lib/src/connection.dart

@@ -101,7 +101,7 @@ abstract class Connection {
 
   final StreamController<int> _pingReceived = StreamController<int>();
 
-  final StreamController<void> _receivedFrame = StreamController<void>();
+  final StreamController<void> _frameReceived = StreamController<void>();
 
   /// Future which completes when the first SETTINGS frame is received from
   /// the peer.
@@ -183,7 +183,7 @@ abstract class Connection {
     // Setup handlers.
     _settingsHandler = SettingsHandler(_hpackContext.encoder, _frameWriter,
         acknowledgedSettings, peerSettings);
-    _pingHandler = PingHandler(_frameWriter, _pingReceived.sink);
+    _pingHandler = PingHandler(_frameWriter, _pingReceived);
 
     var settings = _decodeSettings(settingsObject);
 
@@ -344,7 +344,9 @@ abstract class Connection {
       frame.decodedHeaders =
           _hpackContext.decoder.decode(frame.headerBlockFragment);
     }
-    _receivedFrame.add(null);
+    if (_frameReceived.hasListener) {
+      _frameReceived.add(null);
+    }
 
     // Handle the frame as either a connection or a stream frame.
     if (frame.header.streamId == 0) {
@@ -483,7 +485,7 @@ class ClientConnection extends Connection implements ClientTransportConnection {
   Stream<int> get onPingReceived => _pingReceived.stream;
 
   @override
-  Stream<void> get onFrameReceived => _receivedFrame.stream;
+  Stream<void> get onFrameReceived => _frameReceived.stream;
 }
 
 class ServerConnection extends Connection implements ServerTransportConnection {
@@ -505,5 +507,5 @@ class ServerConnection extends Connection implements ServerTransportConnection {
   Stream<int> get onPingReceived => _pingReceived.stream;
 
   @override
-  Stream<void> get onFrameReceived => _receivedFrame.stream;
+  Stream<void> get onFrameReceived => _frameReceived.stream;
 }

lib/src/ping/ping_handler.dart

@@ -17,16 +17,20 @@ class PingHandler extends Object with TerminatableMixin {
   final FrameWriter _frameWriter;
   final Map<int, Completer> _remainingPings = {};
   final Sink<int>? pingReceived;
+  final bool Function() isListeningToPings;
   int _nextId = 1;
 
-  PingHandler(this._frameWriter, [this.pingReceived]);
+  PingHandler(this._frameWriter, StreamController<int> pingStream)
+      : pingReceived = pingStream.sink,
+        isListeningToPings = (() => pingStream.hasListener);
 
   @override
   void onTerminated(Object? error) {
-    var values = _remainingPings.values.toList();
+    final remainingPings = _remainingPings.values.toList();
     _remainingPings.clear();
-    for (var value in values) {
-      value.completeError(error ?? 'Unspecified error');
+    for (final ping in remainingPings) {
+      ping.completeError(
+          error ?? 'Remaining ping completed with unspecified error');
     }
   }
 
@@ -37,7 +41,9 @@ class PingHandler extends Object with TerminatableMixin {
       }
 
       if (!frame.hasAckFlag) {
-        pingReceived?.add(frame.opaqueData);
+        if (isListeningToPings()) {
+          pingReceived?.add(frame.opaqueData);
+        }
         _frameWriter.writePingFrame(frame.opaqueData, ack: true);
       } else {
         var c = _remainingPings.remove(frame.opaqueData);

pubspec.yaml

@@ -1,5 +1,5 @@
 name: http2
-version: 2.2.0
+version: 2.3.0
 description: A HTTP/2 implementation in Dart.
 repository: https://github.com/dart-lang/http2
 

test/src/ping/ping_handler_test.dart

@@ -15,7 +15,7 @@ void main() {
   group('ping-handler', () {
     test('successful-ping', () async {
       var writer = FrameWriterMock();
-      var pingHandler = PingHandler(writer);
+      var pingHandler = instantiateHandler(writer);
 
       var p1 = pingHandler.ping();
       var p2 = pingHandler.ping();
@@ -37,7 +37,7 @@ void main() {
 
     test('successful-ack-to-remote-ping', () async {
       var writer = FrameWriterMock();
-      var pingHandler = PingHandler(writer);
+      var pingHandler = instantiateHandler(writer);
 
       var header = FrameHeader(8, FrameType.PING, 0, 0);
       pingHandler.processPingFrame(PingFrame(header, 1));
@@ -53,7 +53,7 @@ void main() {
 
     test('ping-unknown-opaque-data', () async {
       var writer = FrameWriterMock();
-      var pingHandler = PingHandler(writer);
+      var pingHandler = instantiateHandler(writer);
 
       var future = pingHandler.ping();
       verify(writer.writePingFrame(1)).called(1);
@@ -73,7 +73,7 @@ void main() {
 
     test('terminate-ping-handler', () async {
       var writer = FrameWriterMock();
-      var pingHandler = PingHandler(writer);
+      var pingHandler = instantiateHandler(writer);
 
       pingHandler.terminate('hello world');
       expect(
@@ -86,7 +86,7 @@ void main() {
 
     test('ping-non-zero-stream-id', () async {
       var writer = FrameWriterMock();
-      var pingHandler = PingHandler(writer);
+      var pingHandler = instantiateHandler(writer);
 
       var header = FrameHeader(8, FrameType.PING, PingFrame.FLAG_ACK, 1);
       expect(() => pingHandler.processPingFrame(PingFrame(header, 1)),
@@ -95,17 +95,32 @@ void main() {
     });
 
     test('receiving-ping-calls-stream', () async {
-      var writer = FrameWriterMock();
-      var streamController = StreamController<int>();
-      var pingHandler = PingHandler(writer, streamController.sink);
+      final pings = <int>[];
 
-      var header = FrameHeader(8, FrameType.PING, 0, 0);
-      pingHandler.processPingFrame(PingFrame(header, 1));
-      var header2 = FrameHeader(8, FrameType.PING, 0, 0);
-      pingHandler.processPingFrame(PingFrame(header2, 2));
-      await expectLater(streamController.stream, emitsInOrder([1, 2]));
+      final writer = FrameWriterMock();
+      final pingStream = StreamController<int>()
+        ..stream.listen((event) => pings.add(event));
+
+      PingHandler(writer, pingStream)
+        ..processPingFrame(PingFrame(
+          FrameHeader(8, FrameType.PING, 0, 0),
+          1,
+        ))
+        ..processPingFrame(PingFrame(
+          FrameHeader(8, FrameType.PING, 0, 0),
+          2,
+        ));
+
+      await pingStream.close();
+
+      expect(pings, [1, 2]);
     });
   });
 }
 
+PingHandler instantiateHandler(FrameWriterMock writer) {
+  StreamController<int> controller = StreamController();
+  return PingHandler(writer, controller);
+}
+
 class FrameWriterMock extends Mock implements FrameWriter {}