SPDY: use ngx_queue_t to queue streams for post processing.

It simplifies the code and allows easy reuse the same queue pointer to store
streams in various queues with different requirements.  Future implementation
of SPDY/3.1 will take advantage of this quality.

src/http/ngx_http_spdy.c

diff --git a/src/http/ngx_http_spdy.c b/src/http/ngx_http_spdy.c
index accfcb1..27c8aa1 100644
--- a/src/http/ngx_http_spdy.c
+++ b/src/http/ngx_http_spdy.c
@@ -302,6 +302,8 @@
         return;
     }
 
+    ngx_queue_init(&sc->posted);
+
     c->data = sc;
 
     rev->handler = ngx_http_spdy_read_handler;
@@ -405,8 +407,9 @@
 ngx_http_spdy_write_handler(ngx_event_t *wev)
 {
     ngx_int_t                    rc;
+    ngx_queue_t                 *q;
     ngx_connection_t            *c;
-    ngx_http_spdy_stream_t      *stream, *s, *sn;
+    ngx_http_spdy_stream_t      *stream;
     ngx_http_spdy_connection_t  *sc;
 
     c = wev->data;
@@ -430,18 +433,13 @@
         return;
     }
 
-    stream = NULL;
+    while (!ngx_queue_empty(&sc->posted)) {
+        q = ngx_queue_head(&sc->posted);
 
-    for (s = sc->last_stream; s; s = sn) {
-         sn = s->next;
-         s->next = stream;
-         stream = s;
-    }
+        ngx_queue_remove(q);
 
-    sc->last_stream = NULL;
+        stream = ngx_queue_data(q, ngx_http_spdy_stream_t, queue);
 
-    for ( /* void */ ; stream; stream = sn) {
-        sn = stream->next;
         stream->handled = 0;
 
         ngx_log_debug1(NGX_LOG_DEBUG_HTTP, c->log, 0,
@@ -2593,6 +2591,11 @@
                    "spdy close stream %ui, queued %ui, processing %ui",
                    stream->id, stream->queued, sc->processing);
 
+    if (stream->handled) {
+        stream->handled = 0;
+        ngx_queue_remove(&stream->queue);
+    }
+
     fc = stream->request->connection;
 
     if (stream->queued) {
@@ -2614,15 +2617,6 @@
         sc->stream = NULL;
     }
 
-    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);