#! /bin/sh /usr/share/dpatch/dpatch-run
## ngx_http_upstream_count_limit-0.1.dpatch by Kirill A. Korinskiy <catap@catap.ru>
##
## All lines beginning with `## DP:' are a description of the patch.
## DP: Implement upstream_count_limit

@DPATCH@

diff --git a/src/http/ngx_http_upstream.c b/src/http/ngx_http_upstream.c
index 6ed7c8f..c1cd8ed 100644
--- a/src/http/ngx_http_upstream.c
+++ b/src/http/ngx_http_upstream.c
@@ -9,6 +9,11 @@
 #include <ngx_http.h>
 
 
+typedef struct {
+    ngx_uint_t           count_limit;
+} ngx_http_upstream_local_conf_t;
+
+
 static void ngx_http_upstream_resolve_handler(ngx_resolver_ctx_t *ctx);
 static void ngx_http_upstream_rd_check_broken_connection(ngx_http_request_t *r);
 static void ngx_http_upstream_wr_check_broken_connection(ngx_http_request_t *r);
@@ -106,6 +111,10 @@ static char *ngx_http_upstream_server(ngx_conf_t *cf, ngx_command_t *cmd,
 static void *ngx_http_upstream_create_main_conf(ngx_conf_t *cf);
 static char *ngx_http_upstream_init_main_conf(ngx_conf_t *cf, void *conf);
 
+static void *ngx_http_upstream_create_local_conf(ngx_conf_t *cf);
+static char *ngx_http_upstream_merge_local_conf(ngx_conf_t *cf,
+    void *parent, void *child);
+
 #if (NGX_HTTP_SSL)
 static void ngx_http_upstream_ssl_init_connection(ngx_http_request_t *,
     ngx_http_upstream_t *u, ngx_connection_t *c);
@@ -249,6 +258,14 @@ static ngx_command_t  ngx_http_upstream_commands[] = {
       0,
       NULL },
 
+    { ngx_string("upstream_count_limit"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_HTTP_LIF_CONF
+                        |NGX_CONF_FLAG,
+      ngx_conf_set_num_slot,
+      NGX_HTTP_LOC_CONF_OFFSET,
+      offsetof(ngx_http_upstream_local_conf_t, count_limit),
+      NULL },
+
       ngx_null_command
 };
 
@@ -263,8 +280,8 @@ static ngx_http_module_t  ngx_http_upstream_module_ctx = {
     NULL,                                  /* create server configuration */
     NULL,                                  /* merge server configuration */
 
-    NULL,                                  /* create location configuration */
-    NULL                                   /* merge location configuration */
+    ngx_http_upstream_create_local_conf,   /* create location configuration */
+    ngx_http_upstream_merge_local_conf     /* merge location configuration */
 };
 
 
@@ -327,6 +344,9 @@ ngx_http_upstream_init(ngx_http_request_t *r)
     ngx_http_core_loc_conf_t       *clcf;
     ngx_http_upstream_srv_conf_t   *uscf, **uscfp;
     ngx_http_upstream_main_conf_t  *umcf;
+    ngx_http_upstream_local_conf_t  *conf;
+
+    conf = ngx_http_get_module_loc_conf(r, ngx_http_upstream_module);
 
     c = r->connection;
 
@@ -344,6 +364,11 @@ ngx_http_upstream_init(ngx_http_request_t *r)
         r->write_event_handler = ngx_http_upstream_wr_check_broken_connection;
     }
 
+    if (conf->count_limit) {
+	u->count_limit = conf->count_limit;
+	u->count_limit_origin = conf->count_limit;
+    }
+
     if (ngx_event_flags & NGX_USE_CLEAR_EVENT) {
 
         if (!c->write->active) {
@@ -760,6 +785,10 @@ ngx_http_upstream_connect(ngx_http_request_t *r, ngx_http_upstream_t *u)
 
     u->state->peer = u->peer.name;
 
+    if (u->count_limit_origin) {
+	u->count_limit--;
+    }
+
     if (rc == NGX_BUSY) {
         ngx_log_error(NGX_LOG_ERR, r->connection->log, 0, "no live upstreams");
         ngx_http_upstream_next(r, u, NGX_HTTP_UPSTREAM_FT_NOLIVE);
@@ -2375,6 +2404,14 @@ ngx_http_upstream_next(ngx_http_request_t *r, ngx_http_upstream_t *u,
 {
     ngx_uint_t  status, state;
 
+    if (u->count_limit_origin && u->count_limit == 0) {
+	ngx_log_error(NGX_LOG_INFO, r->connection->log, 0,
+		      "http next upstream limited by upstream_count_limit %d ",
+		      u->count_limit_origin);
+        ngx_http_upstream_finalize_request(r, u, NGX_HTTP_BAD_GATEWAY);
+        return;
+    }
+
     ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                    "http next upstream, %xi", ft_type);
 
@@ -3782,3 +3819,31 @@ ngx_http_upstream_init_main_conf(ngx_conf_t *cf, void *conf)
 
     return NGX_CONF_OK;
 }
+
+
+static void *
+ngx_http_upstream_create_local_conf(ngx_conf_t *cf)
+{
+    ngx_http_upstream_local_conf_t  *conf;
+
+    conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_upstream_local_conf_t));
+    if (conf == NULL) {
+        return NGX_CONF_ERROR;
+    }
+
+    conf->count_limit = NGX_CONF_UNSET_UINT;
+
+    return conf;
+}
+
+static char *
+ngx_http_upstream_merge_local_conf(ngx_conf_t *cf, void *parent, void *child)
+{
+    ngx_http_upstream_local_conf_t  *prev = parent;
+    ngx_http_upstream_local_conf_t  *conf = child;
+
+    ngx_conf_merge_uint_value(conf->count_limit,
+                              prev->count_limit, 0);
+
+    return NGX_CONF_OK;
+}
diff --git a/src/http/ngx_http_upstream.h b/src/http/ngx_http_upstream.h
index 3c14127..c2faead 100644
--- a/src/http/ngx_http_upstream.h
+++ b/src/http/ngx_http_upstream.h
@@ -273,6 +273,9 @@ struct ngx_http_upstream_s {
 
     ngx_http_cleanup_pt            *cleanup;
 
+    ngx_flag_t                      count_limit;
+    ngx_uint_t                      count_limit_origin;
+
     unsigned                        store:1;
     unsigned                        cacheable:1;
     unsigned                        accel:1;