nghttpx: Don't reuse backend connection if it is not clean

src/shrpx_downstream.cc

@@ -1207,4 +1207,10 @@ void Downstream::add_request_headers_sum(size_t amount) {
   request_headers_sum_ += amount;
 }
 
+bool Downstream::can_detach_downstream_connection() const {
+  return dconn_ && response_state_ == Downstream::MSG_COMPLETE &&
+         request_state_ == Downstream::MSG_COMPLETE && !upgraded_ &&
+         !response_connection_close_;
+}
+
 } // namespace shrpx

src/shrpx_downstream.h

@@ -332,6 +332,9 @@ public:
   void attach_blocked_link(BlockedLink *l);
   BlockedLink *detach_blocked_link();
 
+  // Returns true if downstream_connection can be detached and reused.
+  bool can_detach_downstream_connection() const;
+
   enum {
     EVENT_ERROR = 0x1,
     EVENT_TIMEOUT = 0x2,

src/shrpx_http2_upstream.cc

@@ -74,22 +74,13 @@ int on_stream_close_callback(nghttp2_session *session, int32_t stream_id,
     return 0;
   }
 
-  downstream->set_request_state(Downstream::STREAM_CLOSED);
-
-  if (downstream->get_response_state() == Downstream::MSG_COMPLETE) {
-    // At this point, downstream response was read
-    if (!downstream->get_upgraded() &&
-        !downstream->get_response_connection_close()) {
-      // Keep-alive
-      downstream->detach_downstream_connection();
-    }
-
-    upstream->remove_downstream(downstream);
-    // downstream was deleted
-
-    return 0;
+  if (downstream->can_detach_downstream_connection()) {
+    // Keep-alive
+    downstream->detach_downstream_connection();
   }
 
+  downstream->set_request_state(Downstream::STREAM_CLOSED);
+
   // At this point, downstream read may be paused.
 
   // If shrpx_downstream::push_request_headers() failed, the
@@ -915,10 +906,8 @@ int Http2Upstream::downstream_read(DownstreamConnection *dconn) {
       }
       return downstream_error(dconn, Downstream::EVENT_ERROR);
     }
-    // Detach downstream connection early so that it could be reused
-    // without hitting server's request timeout.
-    if (downstream->get_response_state() == Downstream::MSG_COMPLETE &&
-        !downstream->get_response_connection_close()) {
+
+    if (downstream->can_detach_downstream_connection()) {
       // Keep-alive
       downstream->detach_downstream_connection();
     }

src/shrpx_https_upstream.cc

@@ -540,7 +540,8 @@ int HttpsUpstream::on_write() {
   // We need to postpone detachment until all data are sent so that
   // we can notify nghttp2 library all data consumed.
   if (downstream->get_response_state() == Downstream::MSG_COMPLETE) {
-    if (downstream->get_response_connection_close()) {
+    if (downstream->get_response_connection_close() ||
+        downstream->get_request_state() != Downstream::MSG_COMPLETE) {
       // Connection close
       downstream->pop_downstream_connection();
       // dconn was deleted
@@ -607,10 +608,7 @@ int HttpsUpstream::downstream_read(DownstreamConnection *dconn) {
     goto end;
   }
 
-  // Detach downstream connection early so that it could be reused
-  // without hitting server's request timeout.
-  if (downstream->get_response_state() == Downstream::MSG_COMPLETE &&
-      !downstream->get_response_connection_close()) {
+  if (downstream->can_detach_downstream_connection()) {
     // Keep-alive
     downstream->detach_downstream_connection();
   }

src/shrpx_spdy_upstream.cc

@@ -109,20 +109,13 @@ void on_stream_close_callback(spdylay_session *session, int32_t stream_id,
     return;
   }
 
-  downstream->set_request_state(Downstream::STREAM_CLOSED);
-  if (downstream->get_response_state() == Downstream::MSG_COMPLETE) {
-    // At this point, downstream response was read
-    if (!downstream->get_upgraded() &&
-        !downstream->get_response_connection_close()) {
-      // Keep-alive
-      downstream->detach_downstream_connection();
-    }
-    upstream->remove_downstream(downstream);
-    // downstrea was deleted
-
-    return;
+  if (downstream->can_detach_downstream_connection()) {
+    // Keep-alive
+    downstream->detach_downstream_connection();
   }
 
+  downstream->set_request_state(Downstream::STREAM_CLOSED);
+
   // At this point, downstream read may be paused.
 
   // If shrpx_downstream::push_request_headers() failed, the
@@ -589,10 +582,7 @@ int SpdyUpstream::downstream_read(DownstreamConnection *dconn) {
       }
       return downstream_error(dconn, Downstream::EVENT_ERROR);
     }
-    // Detach downstream connection early so that it could be reused
-    // without hitting server's request timeout.
-    if (downstream->get_response_state() == Downstream::MSG_COMPLETE &&
-        !downstream->get_response_connection_close()) {
+    if (downstream->can_detach_downstream_connection()) {
       // Keep-alive
       downstream->detach_downstream_connection();
     }