okhttp: Move connection window update before stream termination logic (grpc#12990)

By RFC 9113, section 6.9, receivers must take frames into account for
flow control even if they're errored.

This change moves the stream error response logic after connection
window updates

Author: eado

okhttp/src/main/java/io/grpc/okhttp/OkHttpServerTransport.java

@@ -864,6 +864,19 @@ public void data(boolean inFinished, int streamId, BufferedSource in, int length
       // concerned with the window being exceeded at this point.
       in.require(length);
 
+      // connection window update
+      // The connection window must be updated even if the stream is in an errored state.
+      // See RFC 9113, section 6.9
+      connectionUnacknowledgedBytesRead += paddedLength;
+      if (connectionUnacknowledgedBytesRead
+          >= config.flowControlWindow * Utils.DEFAULT_WINDOW_UPDATE_RATIO) {
+        synchronized (lock) {
+          frameWriter.windowUpdate(0, connectionUnacknowledgedBytesRead);
+          frameWriter.flush();
+        }
+        connectionUnacknowledgedBytesRead = 0;
+      }
+
       synchronized (lock) {
         StreamState stream = streams.get(streamId);
         if (stream == null) {
@@ -887,17 +900,6 @@ public void data(boolean inFinished, int streamId, BufferedSource in, int length
         buf.write(in.getBuffer(), length);
         stream.inboundDataReceived(buf, length, paddedLength - length, inFinished);
       }
-
-      // connection window update
-      connectionUnacknowledgedBytesRead += paddedLength;
-      if (connectionUnacknowledgedBytesRead
-          >= config.flowControlWindow * Utils.DEFAULT_WINDOW_UPDATE_RATIO) {
-        synchronized (lock) {
-          frameWriter.windowUpdate(0, connectionUnacknowledgedBytesRead);
-          frameWriter.flush();
-        }
-        connectionUnacknowledgedBytesRead = 0;
-      }
     }
 
     @Override

okhttp/src/test/java/io/grpc/okhttp/OkHttpServerTransportTest.java

@@ -1067,6 +1067,9 @@ public void windowUpdate() throws Exception {
     writeDataDirectly(clientWriterSink, FLAG_PADDED | FLAG_END_STREAM, 1, message, 100);
     clientFrameWriter.flush();
     assertThat(clientFrameReader.nextFrame(clientFramesRead)).isTrue();
+    // Receive window update for the padded data size before stream reset
+    verify(clientFramesRead).windowUpdate(0, expectedConsumed + 100);
+    assertThat(clientFrameReader.nextFrame(clientFramesRead)).isTrue();
     verify(clientFramesRead).rstStream(eq(1), eq(ErrorCode.FLOW_CONTROL_ERROR));
     clientFrameWriter.rstStream(3, ErrorCode.CANCEL);
     pingPong();