@@ -0,0 +1,209 @@
+diff --git a/src/http/modules/ngx_http_upstream_ip_hash_module.c b/src/http/modules/ngx_http_upstream_ip_hash_module.c
+index 89ccc2b..a552044 100644
+--- a/src/http/modules/ngx_http_upstream_ip_hash_module.c
++++ b/src/http/modules/ngx_http_upstream_ip_hash_module.c
+@@ -9,6 +9,10 @@
+ #include <ngx_core.h>
+ #include <ngx_http.h>
+
++#if (NGX_UPSTREAM_CHECK_MODULE)
++#include "ngx_http_upstream_check_handler.h"
++#endif
++
+
+ typedef struct {
+ /* the round robin data must be first */
+@@ -208,6 +212,12 @@ ngx_http_upstream_get_ip_hash_peer(ngx_peer_connection_t *pc, void *data)
+
+ if (!peer->down) {
+
++#if (NGX_UPSTREAM_CHECK_MODULE)
++ ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0,
++ "get ip_hash peer, check_index: %ui",
++ peer->check_index);
++ if (!ngx_http_check_peer_down(peer->check_index)) {
++#endif
+ if (peer->max_fails == 0 || peer->fails < peer->max_fails) {
+ break;
+ }
+@@ -216,6 +226,9 @@ ngx_http_upstream_get_ip_hash_peer(ngx_peer_connection_t *pc, void *data)
+ peer->checked = now;
+ break;
+ }
++#if (NGX_UPSTREAM_CHECK_MODULE)
++ }
++#endif
+ }
+
+ iphp->rrp.tried[n] |= m;
+diff --git a/src/http/modules/ngx_http_upstream_least_conn_module.c b/src/http/modules/ngx_http_upstream_least_conn_module.c
+index 21156ae..c57393d 100644
+--- a/src/http/modules/ngx_http_upstream_least_conn_module.c
++++ b/src/http/modules/ngx_http_upstream_least_conn_module.c
+@@ -9,6 +9,10 @@
+ #include <ngx_core.h>
+ #include <ngx_http.h>
+
++#if (NGX_UPSTREAM_CHECK_MODULE)
++#include "ngx_http_upstream_check_handler.h"
++#endif
++
+
+ typedef struct {
+ ngx_uint_t *conns;
+@@ -203,6 +207,16 @@ ngx_http_upstream_get_least_conn_peer(ngx_peer_connection_t *pc, void *data)
+ continue;
+ }
+
++#if (NGX_UPSTREAM_CHECK_MODULE)
++ ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0,
++ "get least_conn peer, check_index: %ui",
++ peer->check_index);
++
++ if (ngx_http_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 +270,16 @@ ngx_http_upstream_get_least_conn_peer(ngx_peer_connection_t *pc, void *data)
+ continue;
+ }
+
++#if (NGX_UPSTREAM_CHECK_MODULE)
++ ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0,
++ "get least_conn peer, check_index: %ui",
++ peer->check_index);
++
++ if (ngx_http_check_peer_down(peer->check_index)) {
++ continue;
++ }
++#endif
++
+ if (lcp->conns[i] * best->weight != lcp->conns[p] * peer->weight) {
+ continue;
+ }
+diff --git a/src/http/ngx_http_upstream_round_robin.c b/src/http/ngx_http_upstream_round_robin.c
+index 4b78cff..f077b46 100644
+--- a/src/http/ngx_http_upstream_round_robin.c
++++ b/src/http/ngx_http_upstream_round_robin.c
+@@ -9,6 +9,9 @@
+ #include <ngx_core.h>
+ #include <ngx_http.h>
+
++#if (NGX_UPSTREAM_CHECK_MODULE)
++#include "ngx_http_upstream_check_handler.h"
++#endif
+
+ static ngx_int_t ngx_http_upstream_cmp_servers(const void *one,
+ const void *two);
+@@ -87,7 +90,17 @@ 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;
+- n++;
++
++#if (NGX_UPSTREAM_CHECK_MODULE)
++ if (!server[i].down) {
++ peers->peer[n].check_index =
++ ngx_http_check_add_peer(cf, us, &server[i].addrs[j]);
++ }
++ else {
++ peers->peer[n].check_index = (ngx_uint_t) NGX_ERROR;
++ }
++#endif
++ n++;
+ }
+ }
+
+@@ -145,6 +158,17 @@ 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_UPSTREAM_CHECK_MODULE)
++ if (!server[i].down) {
++ backup->peer[n].check_index =
++ ngx_http_check_add_peer(cf, us, &server[i].addrs[j]);
++ }
++ else {
++ backup->peer[n].check_index = (ngx_uint_t) NGX_ERROR;
++ }
++#endif
++
+ n++;
+ }
+ }
+@@ -206,6 +230,9 @@ 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_UPSTREAM_CHECK_MODULE)
++ peers->peer[i].check_index = (ngx_uint_t) NGX_ERROR;
++#endif
+ }
+
+ us->peer.data = peers;
+@@ -323,6 +350,9 @@ ngx_http_upstream_create_round_robin_peer(ngx_http_request_t *r,
+ peers->peer[0].current_weight = 0;
+ peers->peer[0].max_fails = 1;
+ peers->peer[0].fail_timeout = 10;
++#if (NGX_UPSTREAM_CHECK_MODULE)
++ peers->peer[0].check_index = (ngx_uint_t) NGX_ERROR;
++#endif
+
+ } else {
+
+@@ -356,6 +386,9 @@ 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_UPSTREAM_CHECK_MODULE)
++ peers->peer[i].check_index = (ngx_uint_t) NGX_ERROR;
++#endif
+ }
+ }
+
+@@ -434,6 +467,12 @@ ngx_http_upstream_get_round_robin_peer(ngx_peer_connection_t *pc, void *data)
+ goto failed;
+ }
+
++#if (NGX_UPSTREAM_CHECK_MODULE)
++ if (ngx_http_check_peer_down(peer->check_index)) {
++ goto failed;
++ }
++#endif
++
+ } else {
+
+ /* there are several peers */
+@@ -531,6 +570,12 @@ ngx_http_upstream_get_peer(ngx_http_upstream_rr_peer_data_t *rrp)
+ continue;
+ }
+
++#if (NGX_UPSTREAM_CHECK_MODULE)
++ if (ngx_http_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 a/src/http/ngx_http_upstream_round_robin.h b/src/http/ngx_http_upstream_round_robin.h
+index 3f8cbf8..1613168 100644
+--- a/src/http/ngx_http_upstream_round_robin.h
++++ b/src/http/ngx_http_upstream_round_robin.h
+@@ -30,6 +30,10 @@ typedef struct {
|