nginx-1.4.7.patch

diff --git c/src/http/modules/ngx_http_upstream_ip_hash_module.c w/src/http/modules/ngx_http_upstream_ip_hash_module.c
index 29c74fd..704c0ab 100644
--- c/src/http/modules/ngx_http_upstream_ip_hash_module.c
+++ w/src/http/modules/ngx_http_upstream_ip_hash_module.c
@@ -208,6 +208,14 @@ ngx_http_upstream_get_ip_hash_peer(ngx_peer_connection_t *pc, void *data)
 
             if (!peer->down) {
 
+#if (NGX_HTTP_UPSTREAM_CHECK)
+                ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0,
+                               "get ip_hash peer, check_index: %ui",
+                               peer->check_index);
+
+                if (!ngx_http_upstream_check_peer_down(peer->check_index)) {
+#endif
+
                 if (peer->max_fails == 0 || peer->fails < peer->max_fails) {
                     break;
                 }
@@ -216,6 +224,9 @@ ngx_http_upstream_get_ip_hash_peer(ngx_peer_connection_t *pc, void *data)
                     peer->checked = now;
                     break;
                 }
+#if (NGX_HTTP_UPSTREAM_CHECK)
+                }
+#endif
             }
 
             iphp->rrp.tried[n] |= m;
diff --git c/src/http/modules/ngx_http_upstream_least_conn_module.c w/src/http/modules/ngx_http_upstream_least_conn_module.c
index dbef95d..f49e609 100644
--- c/src/http/modules/ngx_http_upstream_least_conn_module.c
+++ w/src/http/modules/ngx_http_upstream_least_conn_module.c
@@ -203,6 +203,16 @@ ngx_http_upstream_get_least_conn_peer(ngx_peer_connection_t *pc, void *data)
             continue;
         }
 
+#if (NGX_HTTP_UPSTREAM_CHECK)
+        ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0,
+                       "get least_conn peer, check_index: %ui",
+                       peer->check_index);
+
+        if (ngx_http_upstream_check_peer_down(peer->check_index)) {
+            continue;
+        }
+#endif
+
         if (peer->max_fails
             && peer->fails >= peer->max_fails
             && now - peer->checked <= peer->fail_timeout)
@@ -256,6 +266,16 @@ ngx_http_upstream_get_least_conn_peer(ngx_peer_connection_t *pc, void *data)
                 continue;
             }
 
+#if (NGX_HTTP_UPSTREAM_CHECK)
+            ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0,
+                           "get least_conn peer, check_index: %ui",
+                           peer->check_index);
+
+            if (ngx_http_upstream_check_peer_down(peer->check_index)) {
+                continue;
+            }
+#endif
+
             if (lcp->conns[i] * best->weight != lcp->conns[p] * peer->weight) {
                 continue;
             }
diff --git c/src/http/ngx_http_upstream.h w/src/http/ngx_http_upstream.h
index 29ebf9b..b491bb5 100644
--- c/src/http/ngx_http_upstream.h
+++ w/src/http/ngx_http_upstream.h
@@ -370,6 +370,17 @@ ngx_int_t ngx_http_upstream_hide_headers_hash(ngx_conf_t *cf,
 #define ngx_http_conf_upstream_srv_conf(uscf, module)                         \
     uscf->srv_conf[module.ctx_index]
 
+#if (NGX_HTTP_UPSTREAM_CHECK)
+
+ngx_uint_t ngx_http_upstream_check_add_peer(ngx_conf_t *cf,
+        ngx_http_upstream_srv_conf_t *us, ngx_addr_t *peer);
+
+ngx_uint_t ngx_http_upstream_check_peer_down(ngx_uint_t index);
+
+void ngx_http_upstream_check_get_peer(ngx_uint_t index);
+void ngx_http_upstream_check_free_peer(ngx_uint_t index);
+
+#endif
 
 extern ngx_module_t        ngx_http_upstream_module;
 extern ngx_conf_bitmask_t  ngx_http_upstream_cache_method_mask[];
diff --git c/src/http/ngx_http_upstream_round_robin.c w/src/http/ngx_http_upstream_round_robin.c
index e0c6c58..8eccfcb 100644
--- c/src/http/ngx_http_upstream_round_robin.c
+++ w/src/http/ngx_http_upstream_round_robin.c
@@ -85,6 +85,17 @@ ngx_http_upstream_init_round_robin(ngx_conf_t *cf,
                 peers->peer[n].weight = server[i].weight;
                 peers->peer[n].effective_weight = server[i].weight;
                 peers->peer[n].current_weight = 0;
+
+#if (NGX_HTTP_UPSTREAM_CHECK)
+                if (!server[i].down) {
+                    peers->peer[n].check_index =
+                        ngx_http_upstream_check_add_peer(cf, us,
+                                                         &server[i].addrs[j]);
+                } else {
+                    peers->peer[n].check_index = (ngx_uint_t) NGX_ERROR;
+                }
+#endif
+
                 n++;
             }
         }
@@ -139,6 +150,17 @@ ngx_http_upstream_init_round_robin(ngx_conf_t *cf,
                 backup->peer[n].max_fails = server[i].max_fails;
                 backup->peer[n].fail_timeout = server[i].fail_timeout;
                 backup->peer[n].down = server[i].down;
+
+#if (NGX_HTTP_UPSTREAM_CHECK)
+                if (!server[i].down) {
+                    backup->peer[n].check_index =
+                        ngx_http_upstream_check_add_peer(cf, us,
+                                                         &server[i].addrs[j]);
+                } else {
+                    backup->peer[n].check_index = (ngx_uint_t) NGX_ERROR;
+                }
+#endif
+
                 n++;
             }
         }
@@ -196,6 +218,10 @@ ngx_http_upstream_init_round_robin(ngx_conf_t *cf,
         peers->peer[i].current_weight = 0;
         peers->peer[i].max_fails = 1;
         peers->peer[i].fail_timeout = 10;
+
+#if (NGX_HTTP_UPSTREAM_CHECK)
+        peers->peer[i].check_index = (ngx_uint_t) NGX_ERROR;
+#endif
     }
 
     us->peer.data = peers;
@@ -302,6 +328,10 @@ ngx_http_upstream_create_round_robin_peer(ngx_http_request_t *r,
         peers->peer[0].max_fails = 1;
         peers->peer[0].fail_timeout = 10;
 
+#if (NGX_HTTP_UPSTREAM_CHECK)
+        peers->peer[0].check_index = (ngx_uint_t) NGX_ERROR;
+#endif
+
     } else {
 
         for (i = 0; i < ur->naddrs; i++) {
@@ -334,6 +364,10 @@ ngx_http_upstream_create_round_robin_peer(ngx_http_request_t *r,
             peers->peer[i].current_weight = 0;
             peers->peer[i].max_fails = 1;
             peers->peer[i].fail_timeout = 10;
+
+#if (NGX_HTTP_UPSTREAM_CHECK)
+            peers->peer[i].check_index = (ngx_uint_t) NGX_ERROR;
+#endif
         }
     }
 
@@ -391,6 +425,12 @@ ngx_http_upstream_get_round_robin_peer(ngx_peer_connection_t *pc, void *data)
             goto failed;
         }
 
+#if (NGX_HTTP_UPSTREAM_CHECK)
+        if (ngx_http_upstream_check_peer_down(peer->check_index)) {
+            goto failed;
+        }
+#endif
+
     } else {
 
         /* there are several peers */
@@ -490,6 +530,12 @@ ngx_http_upstream_get_peer(ngx_http_upstream_rr_peer_data_t *rrp)
             continue;
         }
 
+#if (NGX_HTTP_UPSTREAM_CHECK)
+        if (ngx_http_upstream_check_peer_down(peer->check_index)) {
+            continue;
+        }
+#endif
+
         if (peer->max_fails
             && peer->fails >= peer->max_fails
             && now - peer->checked <= peer->fail_timeout)
diff --git c/src/http/ngx_http_upstream_round_robin.h w/src/http/ngx_http_upstream_round_robin.h
index ea90ab9..a6fb33f 100644
--- c/src/http/ngx_http_upstream_round_robin.h
+++ w/src/http/ngx_http_upstream_round_robin.h
@@ -30,6 +30,10 @@ typedef struct {
     ngx_uint_t                      max_fails;
     time_t                          fail_timeout;
 
+#if (NGX_HTTP_UPSTREAM_CHECK)
+    ngx_uint_t                      check_index;
+#endif
+
     ngx_uint_t                      down;          /* unsigned  down:1; */
 
 #if (NGX_HTTP_SSL)