[PATCH 10 of 31] Better handle late upstream creation

[Maxim Dounin]

# HG changeset patch
# User Maxim Dounin <mdounin at mdounin.ru>
# Date 1297776673 -10800
# Node ID 2b82abbe232805e1a0122af2cce71bcd586a0038
# Parent  b9e6b52e3baebb078a15f7e72566de8413a550af
Better handle late upstream creation.

Configuration with duplicate upstream blocks defined after first use, i.e.
like

    server {
        ...
        location / {
            proxy_pass http://backend;
        }
    }

    upstream backend { ... }
    upstream backend { ... }

now correctly results in "duplicate upstream" error.

Additionally, upstream blocks defined after first use now handle various
server directive parameters ("weight", "max_fails", etc.).  Previously
configuration like

    server {
        ...
        location / {
            proxy_pass http://backend;
        }
    }

    upstream backend {
        server 127.0.0.1 max_fails=5;
    }

incorrectly resulted in "invalid parameter "max_fails=5"" error.

Note that an attempt to redefine unix socket would produce unexpected
results.  Config like

    server {
        ...
        location / {
            proxy_pass http://unix:/path/to/socket;
        }
    }

    upstream "/path/to/socket" {
        server 127.0.0.1;
    }

would use upstream with two servers: one with unix socket "/path/to/socket",
and one 127.0.0.1.

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
@@ -4245,6 +4245,10 @@ ngx_http_upstream_add(ngx_conf_t *cf, ng
             continue;
         }
 
+        if (flags & NGX_HTTP_UPSTREAM_CREATE) {
+            uscfp[i]->flags = flags;
+        }
+
         return uscfp[i];
     }