From f6c1c0ea9cbb58c1a7b210998774fb69e917fde0 Mon Sep 17 00:00:00 2001
From: Norman Maurer <norman_maurer@apple.com>
Date: Sat, 16 Jan 2021 09:55:26 +0100
Subject: [PATCH] Use GracefulShutdown when stream space is exhausted (#10946)

Motivation:

We should use GracefulShutdown when we try to create a stream and fail it because the stream space is exhausted as we may still want to process the active streams.

Modifications:

- Use graceful shutdown
- Add unit test

Result:

More graceful handling of stream creation failure due stream space exhaustation
---
 .../handler/codec/http2/DefaultHttp2Connection.java  |  5 ++++-
 .../codec/http2/DefaultHttp2ConnectionTest.java      | 12 ++++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/codec-http2/src/main/java/io/netty/handler/codec/http2/DefaultHttp2Connection.java b/codec-http2/src/main/java/io/netty/handler/codec/http2/DefaultHttp2Connection.java
index 957f2c8b8e..7c2a62bb5c 100644
--- a/codec-http2/src/main/java/io/netty/handler/codec/http2/DefaultHttp2Connection.java
+++ b/codec-http2/src/main/java/io/netty/handler/codec/http2/DefaultHttp2Connection.java
@@ -886,7 +886,10 @@ public class DefaultHttp2Connection implements Http2Connection {
                         streamId, nextStreamIdToCreate);
             }
             if (nextStreamIdToCreate <= 0) {
-                throw connectionError(REFUSED_STREAM, "Stream IDs are exhausted for this endpoint.");
+                // We exhausted the stream id space that we  can use. Let's signal this back but also signal that
+                // we still may want to process active streams.
+                throw new Http2Exception(REFUSED_STREAM, "Stream IDs are exhausted for this endpoint.",
+                        Http2Exception.ShutdownHint.GRACEFUL_SHUTDOWN);
             }
             boolean isReserved = state == RESERVED_LOCAL || state == RESERVED_REMOTE;
             if (!isReserved && !canOpenStream() || isReserved && numStreams >= maxStreams) {
diff --git a/codec-http2/src/test/java/io/netty/handler/codec/http2/DefaultHttp2ConnectionTest.java b/codec-http2/src/test/java/io/netty/handler/codec/http2/DefaultHttp2ConnectionTest.java
index 9cc072e199..777bea5957 100644
--- a/codec-http2/src/test/java/io/netty/handler/codec/http2/DefaultHttp2ConnectionTest.java
+++ b/codec-http2/src/test/java/io/netty/handler/codec/http2/DefaultHttp2ConnectionTest.java
@@ -351,6 +351,18 @@ public class DefaultHttp2ConnectionTest {
         incrementAndGetStreamShouldRespectOverflow(client.local(), MAX_VALUE);
     }
 
+    @Test
+    public void clientLocalCreateStreamExhaustedSpace() throws Http2Exception {
+        client.local().createStream(MAX_VALUE, true);
+        try {
+            client.local().createStream(MAX_VALUE, true);
+            fail();
+        } catch (Http2Exception expected) {
+            assertEquals(Http2Error.REFUSED_STREAM, expected.error());
+            assertEquals(Http2Exception.ShutdownHint.GRACEFUL_SHUTDOWN, expected.shutdownHint());
+        }
+    }
+
     @Test(expected = Http2Exception.class)
     public void newStreamBehindExpectedShouldThrow() throws Http2Exception {
         server.local().createStream(0, true);