SPDY: use frame->next pointer to chain free frames.

There is no need in separate "free" pointer and like it is for ngx_chain_t
the "next" pointer can be used.  But after this change successfully handled
frame should not be accessed, so the frame handling cycle was improved to
store pointer to the next frame before processing.

Also worth noting that initializing "free" pointer to NULL in the original
code was surplus.

3 files changed, 7 insertions, 11 deletions

diff --git a/src/http/ngx_http_spdy.c b/src/http/ngx_http_spdy.c
index a040a388f..b5aa9931c 100644
--- a/src/http/ngx_http_spdy.c
+++ b/src/http/ngx_http_spdy.c
@@ -527,7 +527,9 @@ ngx_http_spdy_send_output_queue(ngx_http_spdy_connection_t *sc)
         }
     }
 
-    for ( /* void */ ; out; out = out->next) {
+    for ( /* void */ ; out; out = fn) {
+        fn = out->next;
+
         if (out->handler(sc, out) != NGX_OK) {
             out->blocked = 1;
             out->priority = NGX_SPDY_HIGHEST_PRIORITY;
@@ -1644,7 +1646,7 @@ ngx_http_spdy_get_ctl_frame(ngx_http_spdy_connection_t *sc, size_t size,
     frame = sc->free_ctl_frames;
 
     if (frame) {
-        sc->free_ctl_frames = frame->free;
+        sc->free_ctl_frames = frame->next;
 
         cl = frame->first;
         cl->buf->pos = cl->buf->start;
@@ -1674,8 +1676,6 @@ ngx_http_spdy_get_ctl_frame(ngx_http_spdy_connection_t *sc, size_t size,
         frame->stream = NULL;
     }
 
-    frame->free = NULL;
-
 #if (NGX_DEBUG)
     if (size > NGX_SPDY_CTL_FRAME_BUFFER_SIZE - NGX_SPDY_FRAME_HEADER_SIZE) {
         ngx_log_error(NGX_LOG_ALERT, sc->pool->log, 0,
@@ -1705,7 +1705,7 @@ ngx_http_spdy_ctl_frame_handler(ngx_http_spdy_connection_t *sc,
         return NGX_AGAIN;
     }
 
-    frame->free = sc->free_ctl_frames;
+    frame->next = sc->free_ctl_frames;
     sc->free_ctl_frames = frame;
 
     return NGX_OK;
diff --git a/src/http/ngx_http_spdy.h b/src/http/ngx_http_spdy.h
index 49b07caef..3dab0fecb 100644
--- a/src/http/ngx_http_spdy.h
+++ b/src/http/ngx_http_spdy.h
@@ -141,8 +141,6 @@ struct ngx_http_spdy_out_frame_s {
     ngx_int_t                      (*handler)(ngx_http_spdy_connection_t *sc,
                                         ngx_http_spdy_out_frame_t *frame);
 
-    ngx_http_spdy_out_frame_t       *free;
-
     ngx_http_spdy_stream_t          *stream;
     size_t                           size;
 
diff --git a/src/http/ngx_http_spdy_filter_module.c b/src/http/ngx_http_spdy_filter_module.c
index 7a7559ee8..bc39ec2aa 100644
--- a/src/http/ngx_http_spdy_filter_module.c
+++ b/src/http/ngx_http_spdy_filter_module.c
@@ -587,7 +587,6 @@ ngx_http_spdy_header_filter(ngx_http_request_t *r)
     frame->first = cl;
     frame->last = cl;
     frame->handler = ngx_http_spdy_syn_frame_handler;
-    frame->free = NULL;
     frame->stream = stream;
     frame->size = len;
     frame->priority = stream->priority;
@@ -821,7 +820,7 @@ ngx_http_spdy_filter_get_data_frame(ngx_http_spdy_stream_t *stream,
     frame = stream->free_frames;
 
     if (frame) {
-        stream->free_frames = frame->free;
+        stream->free_frames = frame->next;
 
     } else {
         frame = ngx_palloc(stream->request->pool,
@@ -881,7 +880,6 @@ ngx_http_spdy_filter_get_data_frame(ngx_http_spdy_stream_t *stream,
     frame->first = first;
     frame->last = last;
     frame->handler = ngx_http_spdy_data_frame_handler;
-    frame->free = NULL;
     frame->stream = stream;
     frame->size = NGX_SPDY_FRAME_HEADER_SIZE + len;
     frame->priority = stream->priority;
@@ -1051,7 +1049,7 @@ ngx_http_spdy_handle_frame(ngx_http_spdy_stream_t *stream,
         stream->out_closed = 1;
     }
 
-    frame->free = stream->free_frames;
+    frame->next = stream->free_frames;
     stream->free_frames = frame;
 
     stream->queued--;