new file mode 100644
--- /dev/null
+++ b/src/http/ngx_http_busy_lock.c
@@ -0,0 +1,80 @@
+
+#include <ngx_config.h>
+#include <ngx_core.h>
+#include <ngx_http.h>
+
+
+char *ngx_http_set_busy_lock_slot(ngx_conf_t *cf, ngx_command_t *cmd,
+                                  void *conf)
+{
+    char  *p = conf;
+
+    int                    i;
+    ngx_str_t             *value;
+    ngx_http_busy_lock_t  *bl, **blp;
+
+    blp = (ngx_http_busy_lock_t **) (p + cmd->offset);
+    if (*blp) {
+        return "is duplicate";
+    }
+
+    /* ngx_calloc_shared() */
+    if (!(bl = ngx_pcalloc(cf->pool, sizeof(ngx_http_busy_lock_t)))) {
+        return NGX_CONF_ERROR;
+    }
+    *blp = bl;
+
+    value = (ngx_str_t *) cf->args->elts;
+
+    for (i = 1; i < 3; i++) {
+
+        if (value[i].len > 2 && ngx_strncasecmp(value[i].data, "c:", 2) == 0) {
+            if (bl->max_conn) {
+                ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
+                               "duplicate \"%s\"", value[i].data);
+                return NGX_CONF_ERROR;
+            }
+
+            bl->max_conn = ngx_atoi(value[i].data + 2, value[i].len - 2);
+            if (bl->max_conn == NGX_ERROR) {
+                ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
+                               "invalid value \"%s\"", value[i].data);
+                return NGX_CONF_ERROR;
+            }
+
+            continue;
+        }
+
+        if (value[i].len > 2 && ngx_strncasecmp(value[i].data, "w:", 2) == 0) {
+            if (bl->max_waiting) {
+                ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
+                               "duplicate \"%s\"", value[i].data);
+                return NGX_CONF_ERROR;
+            }
+
+            bl->max_waiting = ngx_atoi(value[i].data + 2, value[i].len - 2);
+            if (bl->max_waiting == NGX_ERROR) {
+                ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
+                               "invalid value \"%s\"", value[i].data);
+                return NGX_CONF_ERROR;
+            }
+
+            continue;
+        }
+
+        if (bl->timeout) {
+            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
+                               "duplicate timeout \"%s\"", value[i].data);
+            return NGX_CONF_ERROR;
+        }
+
+        bl->timeout = ngx_parse_time(&value[1], 0);
+        if (bl->timeout == NGX_ERROR) {
+            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
+                               "invalid timeout \"%s\"", value[i].data);
+            return NGX_CONF_ERROR;
+        }
+    }
+
+    return NGX_CONF_OK;
+}