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.

1 files changed, 42 insertions, 33 deletions

diff --git a/src/http/ngx_http_spdy_filter_module.c b/src/http/ngx_http_spdy_filter_module.c
index 92c760243..559fb4aab 100644
--- 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_t *fc, ngx_chain_t *in, off_t limit)
     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_t *fc, ngx_chain_t *in, off_t limit)
 
     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_http_spdy_stream_t *stream,
                    "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;
-        }
+    cl = ngx_chain_get_free_buf(stream->request->pool,
+                                &stream->free_data_headers);
+    if (cl == NULL) {
+        return NULL;
+    }
 
-        buf = cl->buf;
+    buf = cl->buf;
 
-        if (buf->start) {
-            p = buf->start;
-            buf->pos = p;
+    if (buf->start) {
+        p = buf->start;
+        buf->pos = p;
 
-            p += NGX_SPDY_SID_SIZE;
+        p += NGX_SPDY_SID_SIZE;
 
-            (void) ngx_spdy_frame_write_flags_and_len(p, flags, len);
+        (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;
-            }
+    } else {
+        p = ngx_palloc(stream->request->pool, NGX_SPDY_FRAME_HEADER_SIZE);
+        if (p == NULL) {
+            return NULL;
+        }
 
-            buf->pos = p;
-            buf->start = 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);
+        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->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;