[nginx] Upstream: no last buffer on errors.

[Maxim Dounin]

details:   http://hg.nginx.org/nginx/rev/d3eab5e2df5f
branches:  
changeset: 5304:d3eab5e2df5f
user:      Maxim Dounin <mdounin at mdounin.ru>
date:      Thu Jul 25 15:00:41 2013 +0400
description:
Upstream: no last buffer on errors.

Previously, after sending a header we always sent a last buffer and
finalized a request with code 0, even in case of errors.  In some cases
this resulted in a loss of ability to detect the response wasn't complete
(e.g. if Content-Length was removed from a response by gzip filter).

This change tries to propogate to a client information that a response
isn't complete in such cases.  In particular, with this change we no longer
pretend a returned response is complete if we wasn't able to create
a temporary file.

If an error code suggests the error wasn't fatal, we flush buffered data
and disable keepalive, then finalize request normally.  This allows to to
propogate information about a problem to a client, while still sending all
the data we've got from an upstream.

diffstat:

 src/http/ngx_http_upstream.c |  12 ++++++++++--
 1 files changed, 10 insertions(+), 2 deletions(-)

diffs (36 lines):

diff --git a/src/http/ngx_http_upstream.c b/src/http/ngx_http_upstream.c
--- a/src/http/ngx_http_upstream.c
+++ b/src/http/ngx_http_upstream.c
@@ -3297,6 +3297,7 @@ static void
 ngx_http_upstream_finalize_request(ngx_http_request_t *r,
     ngx_http_upstream_t *u, ngx_int_t rc)
 {
+    ngx_uint_t   flush;
     ngx_time_t  *tp;
 
     ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
@@ -3417,8 +3418,11 @@ ngx_http_upstream_finalize_request(ngx_h
         return;
     }
 
-    if (rc == NGX_ERROR || rc >= NGX_HTTP_SPECIAL_RESPONSE) {
-        rc = 0;
+    flush = 0;
+
+    if (rc >= NGX_HTTP_SPECIAL_RESPONSE) {
+        rc = NGX_ERROR;
+        flush = 1;
     }
 
     if (r->header_only) {
@@ -3428,6 +3432,10 @@ ngx_http_upstream_finalize_request(ngx_h
 
     if (rc == 0) {
         rc = ngx_http_send_special(r, NGX_HTTP_LAST);
+
+    } else if (flush) {
+        r->keepalive = 0;
+        rc = ngx_http_send_special(r, NGX_HTTP_FLUSH);
     }
 
     ngx_http_finalize_request(r, rc);