commit 75dad742e547f766ff17e38deda44d8dcb2caf9b
author Valentin Bartenev <vbart@nginx.com> Thu Dec 26 17:03:16 2013 +0400
committer Valentin Bartenev <vbart@nginx.com> Thu Dec 26 17:03:16 2013 +0400
tree ad18d80d87adb37e30357c48544d355cda1d1fec
parent 9b4a99cf5d5c12557136dc205c87ffa0bdc60012

SPDY: fixed possible request hang.

Processing events from upstream connection can result in sending queued frames
from other streams.  In this case such streams were not added to handling queue
and properly handled.

A global per connection flag was replaced by a per stream flag that indicates
currently sending stream while all other streams can be added to handling
queue.

src/http/ngx_http_spdy.c

diff --git a/src/http/ngx_http_spdy.c b/src/http/ngx_http_spdy.c
index 2346ad7..9a3550a 100644
--- a/src/http/ngx_http_spdy.c
+++ b/src/http/ngx_http_spdy.c
@@ -411,7 +411,7 @@
 
     ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0, "spdy write handler");
 
-    sc->blocked = 2;
+    sc->blocked = 1;
 
     rc = ngx_http_spdy_send_output_queue(sc);
 
@@ -430,8 +430,6 @@
 
     sc->last_stream = NULL;
 
-    sc->blocked = 1;
-
     for ( /* void */ ; stream; stream = sn) {
         sn = stream->next;
         stream->handled = 0;
@@ -2658,6 +2656,15 @@
         }
     }
 
+    if (stream->handled) {
+        for (s = sc->last_stream; s; s = s->next) {
+            if (s->next == stream) {
+                s->next = stream->next;
+                break;
+            }
+        }
+    }
+
     sscf = ngx_http_get_module_srv_conf(sc->http_connection->conf_ctx,
                                         ngx_http_spdy_module);
 
@@ -2847,9 +2854,11 @@
         stream = sc->streams_index[i];
 
         while (stream) {
-            r = stream->request;
+            stream->handled = 0;
 
+            r = stream->request;
             fc = r->connection;
+
             fc->error = 1;
 
             if (stream->waiting) {

src/http/ngx_http_spdy.h

diff --git a/src/http/ngx_http_spdy.h b/src/http/ngx_http_spdy.h
index c47243f..c011a3d 100644
--- a/src/http/ngx_http_spdy.h
+++ b/src/http/ngx_http_spdy.h
@@ -106,7 +106,7 @@
 
     ngx_uint_t                       last_sid;
 
-    unsigned                         blocked:2;
+    unsigned                         blocked:1;
     unsigned                         waiting:1; /* FIXME better name */
 };
 
@@ -125,6 +125,7 @@
 
     unsigned                         priority:2;
     unsigned                         handled:1;
+    unsigned                         blocked:1;
     unsigned                         in_closed:1;
     unsigned                         out_closed:1;
     unsigned                         skip_data:2;

src/http/ngx_http_spdy_filter_module.c

diff --git a/src/http/ngx_http_spdy_filter_module.c b/src/http/ngx_http_spdy_filter_module.c
index 4497e8b..c6926b2 100644
--- a/src/http/ngx_http_spdy_filter_module.c
+++ b/src/http/ngx_http_spdy_filter_module.c
@@ -795,11 +795,15 @@
 static ngx_inline ngx_int_t
 ngx_http_spdy_filter_send(ngx_connection_t *fc, ngx_http_spdy_stream_t *stream)
 {
+    stream->blocked = 1;
+
     if (ngx_http_spdy_send_output_queue(stream->connection) == NGX_ERROR) {
         fc->error = 1;
         return NGX_ERROR;
     }
 
+    stream->blocked = 0;
+
     if (stream->waiting) {
         fc->buffered |= NGX_SPDY_WRITE_BUFFERED;
         fc->write->delayed = 1;
@@ -946,16 +950,14 @@
 
     fc->write->delayed = 0;
 
-    if (stream->handled) {
+    if (stream->handled || stream->blocked) {
         return;
     }
 
-    if (sc->blocked == 2) {
-        stream->handled = 1;
+    stream->handled = 1;
 
-        stream->next = sc->last_stream;
-        sc->last_stream = stream;
-    }
+    stream->next = sc->last_stream;
+    sc->last_stream = stream;
 }