added 7 predefined counters from the Nginx stub status module

README.md

@@ -13,7 +13,7 @@ Table of contents
 - [Reloading Nginx configuration](#reloading-nginx-configuration)
 - [Persistent counters](#persistent-counters)
 - [Histograms](#histograms)
-- [Nginx master uptime counters](#nginx-master-uptime-counters)
+- [Predefined counters](#predefined-counters)
 - [An example](#an-example)
 - [Remarks on using location ifs and complex conditions](#remarks-on-using-location-ifs-and-complex-conditions)
 - [See also](#see-also)
@@ -248,14 +248,20 @@ if the request time was more than *0.05* then its value will be *3*.
 
 Histograms layout can be observed via predefined variable `$cnt_histograms`.
 
-Nginx master uptime counters
-----------------------------
+Predefined counters
+-------------------
 
-There are two predefined counter variables `$cnt_uptime` and
-`$cnt_uptime_reload` which contain the number of seconds elapsed since the start
-of Nginx. Reloading Nginx with *SIGHUP* won't restart the former counter. The
-counters are not associated with any counter set identifier, nor are they
-collected in variable `$cnt_collection`.
+There is a number of predefined counter variables: 7 counters from the Nginx
+stub status module (available only when Nginx was compiled with option
+*--with-http_stub_status_module*): `$cnt_stub_status_accepted`,
+`$cnt_stub_status_handled`, `$cnt_stub_status_requests`,
+`$cnt_stub_status_active`, `$cnt_stub_status_reading`,
+`$cnt_stub_status_writing`, `$cnt_stub_status_waiting`, and 2 counters related
+to Nginx master process uptime: `$cnt_uptime` and `$cnt_uptime_reload`, they
+contain the number of seconds elapsed since the start of Nginx. Reloading Nginx
+with *SIGHUP* won't restart the former counter. All predefined counters are not
+associated with any counter set identifier, nor are they collected in variable
+`$cnt_collection`.
 
 An example
 ----------

nginx.conf

@@ -147,7 +147,12 @@ http {
         }
 
         location /uptime {
-            echo "Uptime: $cnt_uptime ($cnt_uptime_reload)";
+            echo "Uptime (after reload): $cnt_uptime ($cnt_uptime_reload)";
+        }
+
+        location /requests {
+            echo -n "Requests (active): ";
+            echo "$cnt_stub_status_requests ($cnt_stub_status_active)";
         }
     }
 

src/ngx_http_custom_counters_module.c

@@ -90,6 +90,10 @@ static ngx_int_t ngx_http_cnt_collection(ngx_http_request_t *r,
 static void ngx_http_cnt_set_collection_buf_len(ngx_http_cnt_main_conf_t *mcf);
 static ngx_int_t ngx_http_cnt_uptime(ngx_http_request_t *r,
     ngx_http_variable_value_t *v, uintptr_t data);
+#if NGX_STAT_STUB
+static ngx_int_t ngx_http_cnt_stub_status(ngx_http_request_t *r,
+    ngx_http_variable_value_t *v, uintptr_t data);
+#endif
 static char *ngx_http_cnt_counter(ngx_conf_t *cf, ngx_command_t *cmd,
     void *conf);
 static char *ngx_http_cnt_early_counter(ngx_conf_t *cf, ngx_command_t *cmd,
@@ -168,6 +172,22 @@ static ngx_http_variable_t  ngx_http_cnt_vars[] =
     { ngx_string("cnt_histograms"), NULL, ngx_http_cnt_histograms, 0, 0, 0 },
     { ngx_string("cnt_uptime"), NULL, ngx_http_cnt_uptime, 0, 0, 0 },
     { ngx_string("cnt_uptime_reload"), NULL, ngx_http_cnt_uptime, 1, 0, 0 },
+#if NGX_STAT_STUB
+    { ngx_string("cnt_stub_status_accepted"), NULL, ngx_http_cnt_stub_status,
+                 0, 0, 0 },
+    { ngx_string("cnt_stub_status_handled"), NULL, ngx_http_cnt_stub_status,
+                 1, 0, 0 },
+    { ngx_string("cnt_stub_status_requests"), NULL, ngx_http_cnt_stub_status,
+                 2, 0, 0 },
+    { ngx_string("cnt_stub_status_active"), NULL, ngx_http_cnt_stub_status,
+                 3, 0, 0 },
+    { ngx_string("cnt_stub_status_reading"), NULL, ngx_http_cnt_stub_status,
+                 4, 0, 0 },
+    { ngx_string("cnt_stub_status_writing"), NULL, ngx_http_cnt_stub_status,
+                 5, 0, 0 },
+    { ngx_string("cnt_stub_status_waiting"), NULL, ngx_http_cnt_stub_status,
+                 6, 0, 0 },
+#endif
 
     { ngx_null_string, NULL, NULL, 0, 0, 0 }
 };
@@ -761,6 +781,69 @@ ngx_http_cnt_uptime(ngx_http_request_t *r, ngx_http_variable_value_t *v,
 }
 
 
+#if NGX_STAT_STUB
+
+/* this handler was mostly taken from Nginx stub status module */
+
+static ngx_int_t
+ngx_http_cnt_stub_status(ngx_http_request_t *r, ngx_http_variable_value_t *v,
+                         uintptr_t data)
+{
+    u_char            *p;
+    ngx_atomic_int_t   value;
+
+    p = ngx_pnalloc(r->pool, NGX_ATOMIC_T_LEN);
+    if (p == NULL) {
+        return NGX_ERROR;
+    }
+
+    switch (data) {
+    case 0:
+        value = *ngx_stat_accepted;
+        break;
+
+    case 1:
+        value = *ngx_stat_handled;
+        break;
+
+    case 2:
+        value = *ngx_stat_requests;
+        break;
+
+    case 3:
+        value = *ngx_stat_active;
+        break;
+
+    case 4:
+        value = *ngx_stat_reading;
+        break;
+
+    case 5:
+        value = *ngx_stat_writing;
+        break;
+
+    case 6:
+        value = *ngx_stat_waiting;
+        break;
+
+    /* suppress warning */
+    default:
+        value = 0;
+        break;
+    }
+
+    v->len = ngx_sprintf(p, "%uA", value) - p;
+    v->valid = 1;
+    v->no_cacheable = 0;
+    v->not_found = 0;
+    v->data = p;
+
+    return NGX_OK;
+}
+
+#endif
+
+
 ngx_int_t
 ngx_http_cnt_counter_set_init(ngx_conf_t *cf, ngx_http_cnt_main_conf_t *mcf,
                               ngx_http_cnt_srv_conf_t *scf)