From 93d8636fb007ee07558313b6bbfd560b982f4504 Mon Sep 17 00:00:00 2001
From: Tatsuhiro Tsujikawa <tatsuhiro.t@gmail.com>
Date: Thu, 3 Dec 2015 22:48:41 +0900
Subject: [PATCH] Keep incoming streams only at server side

We should only keep incoming closed streams because we only keep at
most max concurrent streams, which only applied to incoming streams.
---
 lib/nghttp2_session.c        | 10 +++++++---
 lib/nghttp2_session.h        | 10 ++++++----
 tests/nghttp2_session_test.c | 19 ++++++++++++++++++-
 3 files changed, 31 insertions(+), 8 deletions(-)

diff --git a/lib/nghttp2_session.c b/lib/nghttp2_session.c
index 7483c9b3..938f27c9 100644
--- a/lib/nghttp2_session.c
+++ b/lib/nghttp2_session.c
@@ -1023,6 +1023,7 @@ int nghttp2_session_close_stream(nghttp2_session *session, int32_t stream_id,
   int rv;
   nghttp2_stream *stream;
   nghttp2_mem *mem;
+  int is_my_stream_id;
 
   mem = &session->mem;
   stream = nghttp2_session_get_stream(session, stream_id);
@@ -1070,14 +1071,16 @@ int nghttp2_session_close_stream(nghttp2_session *session, int32_t stream_id,
     }
   }
 
+  is_my_stream_id = nghttp2_session_is_my_stream_id(session, stream_id);
+
   /* pushed streams which is not opened yet is not counted toward max
      concurrent limits */
   if ((stream->flags & NGHTTP2_STREAM_FLAG_PUSH)) {
-    if (!nghttp2_session_is_my_stream_id(session, stream_id)) {
+    if (!is_my_stream_id) {
       --session->num_incoming_reserved_streams;
     }
   } else {
-    if (nghttp2_session_is_my_stream_id(session, stream_id)) {
+    if (is_my_stream_id) {
       --session->num_outgoing_streams;
     } else {
       --session->num_incoming_streams;
@@ -1087,7 +1090,8 @@ int nghttp2_session_close_stream(nghttp2_session *session, int32_t stream_id,
   /* Closes both directions just in case they are not closed yet */
   stream->flags |= NGHTTP2_STREAM_FLAG_CLOSED;
 
-  if (session->server && nghttp2_stream_in_dep_tree(stream)) {
+  if (session->server && !is_my_stream_id &&
+      nghttp2_stream_in_dep_tree(stream)) {
     /* On server side, retain stream at most MAX_CONCURRENT_STREAMS
        combined with the current active incoming streams to make
        dependency tree work better. */
diff --git a/lib/nghttp2_session.h b/lib/nghttp2_session.h
index 34c06e53..dd69b5e3 100644
--- a/lib/nghttp2_session.h
+++ b/lib/nghttp2_session.h
@@ -190,11 +190,13 @@ struct nghttp2_session {
      updated when one frame was written. */
   uint64_t last_cycle;
   void *user_data;
-  /* Points to the latest closed stream.  NULL if there is no closed
-     stream.  Only used when session is initialized as server. */
+  /* Points to the latest incoming closed stream.  NULL if there is no
+     closed stream.  Only used when session is initialized as
+     server. */
   nghttp2_stream *closed_stream_head;
-  /* Points to the oldest closed stream.  NULL if there is no closed
-     stream.  Only used when session is initialized as server. */
+  /* Points to the oldest incoming closed stream.  NULL if there is no
+     closed stream.  Only used when session is initialized as
+     server. */
   nghttp2_stream *closed_stream_tail;
   /* Points to the latest idle stream.  NULL if there is no idle
      stream.  Only used when session is initialized as server .*/
diff --git a/tests/nghttp2_session_test.c b/tests/nghttp2_session_test.c
index 36f36d05..1c896535 100644
--- a/tests/nghttp2_session_test.c
+++ b/tests/nghttp2_session_test.c
@@ -7378,7 +7378,8 @@ void test_nghttp2_session_stream_get_state(void) {
 
   stream = nghttp2_session_find_stream(session, 2);
 
-  CU_ASSERT(NGHTTP2_STREAM_STATE_CLOSED == nghttp2_stream_get_state(stream));
+  /* At server, pushed stream object is not retained after closed */
+  CU_ASSERT(NULL == stream);
 
   /* Push stream 4 associated to stream 5 */
   rv = nghttp2_submit_push_promise(session, NGHTTP2_FLAG_NONE, 5, reqnv,
@@ -7599,6 +7600,22 @@ void test_nghttp2_session_keep_closed_stream(void) {
   CU_ASSERT(NULL == session->closed_stream_tail);
   CU_ASSERT(NULL == session->closed_stream_head);
 
+  nghttp2_session_close_stream(session, 3, NGHTTP2_NO_ERROR);
+
+  CU_ASSERT(1 == session->num_closed_streams);
+  CU_ASSERT(3 == session->closed_stream_head->stream_id);
+
+  /* server initiated stream is not counted to max concurrent limit */
+  open_stream(session, 2);
+
+  CU_ASSERT(1 == session->num_closed_streams);
+  CU_ASSERT(3 == session->closed_stream_head->stream_id);
+
+  nghttp2_session_close_stream(session, 2, NGHTTP2_NO_ERROR);
+
+  CU_ASSERT(1 == session->num_closed_streams);
+  CU_ASSERT(3 == session->closed_stream_head->stream_id);
+
   nghttp2_session_del(session);
 }