# HG changeset patch
# User Valentin Bartenev <vbart@nginx.com>
# Date 1396899333 -14400
# Node ID b948f9c73111c014edae3ae1d9cb1a1241b1ee1c
# Parent  436f3605195a8308a495949caee25d4083bacc7f
SPDY: avoid creating flush frames.

Previously, an empty frame object was created for an output chain that contains
only sync or flush empty buffers.  But since 39d7eef2e332 every DATA frame has
the flush flag set on its last buffer, so there's no need any more in additional
flush buffers in the output queue and they can be skipped.

Note that such flush frames caused an incorrect $body_bytes_sent value.

diff --git a/src/http/ngx_http_spdy_filter_module.c b/src/http/ngx_http_spdy_filter_module.c
--- a/src/http/ngx_http_spdy_filter_module.c
+++ b/src/http/ngx_http_spdy_filter_module.c
@@ -625,6 +625,20 @@ ngx_http_spdy_send_chain(ngx_connection_
     r = fc->data;
     stream = r->spdy_stream;
 
+#if (NGX_SUPPRESS_WARN)
+    size = 0;
+#endif
+
+    while (in) {
+        size = ngx_buf_size(in->buf);
+
+        if (size || in->buf->last_buf) {
+            break;
+        }
+
+        in = in->next;
+    }
+
     if (in == NULL) {
 
         if (stream->queued) {
@@ -638,8 +652,6 @@ ngx_http_spdy_send_chain(ngx_connection_
 
     sc = stream->connection;
 
-    size = ngx_buf_size(in->buf);
-
     if (size && ngx_http_spdy_flow_control(sc, stream) == NGX_DECLINED) {
         fc->write->delayed = 1;
         return in;
@@ -850,48 +862,45 @@ ngx_http_spdy_filter_get_data_frame(ngx_
                    "spdy:%ui create DATA frame %p: len:%uz flags:%ui",
                    stream->id, frame, len, flags);
 
-    if (len || flags) {
+    cl = ngx_chain_get_free_buf(stream->request->pool,
+                                &stream->free_data_headers);
+    if (cl == NULL) {
+        return NULL;
+    }
+
+    buf = cl->buf;
 
-        cl = ngx_chain_get_free_buf(stream->request->pool,
-                                    &stream->free_data_headers);
-        if (cl == NULL) {
+    if (buf->start) {
+        p = buf->start;
+        buf->pos = p;
+
+        p += NGX_SPDY_SID_SIZE;
+
+        (void) ngx_spdy_frame_write_flags_and_len(p, flags, len);
+
+    } else {
+        p = ngx_palloc(stream->request->pool, NGX_SPDY_FRAME_HEADER_SIZE);
+        if (p == NULL) {
             return NULL;
         }
 
-        buf = cl->buf;
-
-        if (buf->start) {
-            p = buf->start;
-            buf->pos = p;
-
-            p += NGX_SPDY_SID_SIZE;
+        buf->pos = p;
+        buf->start = p;
 
-            (void) ngx_spdy_frame_write_flags_and_len(p, flags, len);
+        p = ngx_spdy_frame_write_sid(p, stream->id);
+        p = ngx_spdy_frame_write_flags_and_len(p, flags, len);
 
-        } else {
-            p = ngx_palloc(stream->request->pool, NGX_SPDY_FRAME_HEADER_SIZE);
-            if (p == NULL) {
-                return NULL;
-            }
+        buf->last = p;
+        buf->end = p;
 
-            buf->pos = p;
-            buf->start = p;
-
-            p = ngx_spdy_frame_write_sid(p, stream->id);
-            p = ngx_spdy_frame_write_flags_and_len(p, flags, len);
-
-            buf->last = p;
-            buf->end = p;
+        buf->tag = (ngx_buf_tag_t) &ngx_http_spdy_filter_get_data_frame;
+        buf->memory = 1;
+    }
 
-            buf->tag = (ngx_buf_tag_t) &ngx_http_spdy_filter_get_data_frame;
-            buf->memory = 1;
-        }
+    cl->next = first;
+    first = cl;
 
-        cl->next = first;
-        first = cl;
-
-        last->buf->flush = 1;
-    }
+    last->buf->flush = 1;
 
     frame->first = first;
     frame->last = last;