Implement vhost_traffic_status_upstream_no_cache filter

This enables monitoring upstream backend events that are configured not to
use cache.

Add the following line to nginx config to create a group:

        vhost_traffic_status_filter_upstream_no_cache "NO_CACHE";

README.md

@@ -64,6 +64,7 @@ Table of Contents
   * [vhost_traffic_status_filter_by_set_key](#vhost_traffic_status_filter_by_set_key)
   * [vhost_traffic_status_filter_check_duplicate](#vhost_traffic_status_filter_check_duplicate)
   * [vhost_traffic_status_filter_max_node](#vhost_traffic_status_filter_max_node)
+  * [vhost_traffic_status_filter_upstream_no_cache](#vhost_traffic_status_filter_upstream_no_cache)
   * [vhost_traffic_status_limit](#vhost_traffic_status_limit)
   * [vhost_traffic_status_limit_traffic](#vhost_traffic_status_limit_traffic)
   * [vhost_traffic_status_limit_traffic_by_set_key](#vhost_traffic_status_limit_traffic_by_set_key)
@@ -1479,6 +1480,32 @@ http {
 In the above example, the `/^uris.*/` and `/^client::ports.*/` group string patterns are limited to a total of 16 nodes.
 The other filters like `country::.*` are not limited.
 
+### vhost_traffic_status_filter_upstream_no_cache
+
+| -   | - |
+| --- | --- |
+| **Syntax**  | **vhost_traffic_status_filter_upstream_no_cache** *name* |
+| **Default** | - |
+| **Context** | http, server, location |
+
+`Description:` Create a group name that counts requests that have an upstream
+but should not be cached. The group is visible under serverZones.
+Note: This is event is not "cache miss" or "bypass cache". Example:
+`$ edit nginx.conf`
+
+```Nginx
+http {
+    ...
+    vhost_traffic_status_zone;
+    ...
+    server {
+        server_name example.org;
+        ...
+        vhost_traffic_status_filter_upstream_no_cache NO_CACHE;
+    }
+}
+```
+
 ### vhost_traffic_status_limit
 
 | -   | - |

src/ngx_http_vhost_traffic_status_module.c

@@ -210,6 +210,13 @@ static ngx_command_t ngx_http_vhost_traffic_status_commands[] = {
       offsetof(ngx_http_vhost_traffic_status_loc_conf_t, bypass_stats),
       NULL },
 
+    { ngx_string("vhost_traffic_status_filter_upstream_no_cache"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
+      ngx_conf_set_str_slot,
+      NGX_HTTP_LOC_CONF_OFFSET,
+      offsetof(ngx_http_vhost_traffic_status_loc_conf_t, no_cache_server_zone),
+      NULL },
+
     ngx_null_command
 };
 
@@ -265,12 +272,21 @@ ngx_http_vhost_traffic_status_handler(ngx_http_request_t *r)
         return NGX_DECLINED;
     }
 
-    rc = ngx_http_vhost_traffic_status_shm_add_server(r);
+    rc = ngx_http_vhost_traffic_status_shm_add_server(r, NULL);
     if (rc != NGX_OK) {
         ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                       "handler::shm_add_server() failed");
     }
 
+    if (ngx_strlen(vtscf->no_cache_server_zone.data) > 0) {
+	rc = ngx_http_vhost_traffic_status_shm_add_server(
+	    r, &vtscf->no_cache_server_zone);
+	if (rc != NGX_OK) {
+	    ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+			  "handler::shm_add_server(NO_CACHE) failed");
+	}
+    }
+
     rc = ngx_http_vhost_traffic_status_shm_add_upstream(r);
     if (rc != NGX_OK) {
         ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
@@ -889,6 +905,8 @@ ngx_http_vhost_traffic_status_create_loc_conf(ngx_conf_t *cf)
      *     conf->histogram_buckets = { NULL, ... };
      *     conf->bypass_limit = 0;
      *     conf->bypass_stats = 0;
+     *
+     *     conf->no_cache_server_zone = { 0, NULL };
      */
 
     conf->shm_zone = NGX_CONF_UNSET_PTR;
@@ -1019,6 +1037,9 @@ ngx_http_vhost_traffic_status_merge_loc_conf(ngx_conf_t *cf, void *parent, void
     ngx_conf_merge_value(conf->bypass_limit, prev->bypass_limit, 0);
     ngx_conf_merge_value(conf->bypass_stats, prev->bypass_stats, 0);
 
+    ngx_conf_merge_str_value(conf->no_cache_server_zone,
+			     prev->no_cache_server_zone, "");
+
     name = ctx->shm_name;
 
     shm_zone = ngx_shared_memory_add(cf, &name, 0,

src/ngx_http_vhost_traffic_status_module.h

@@ -297,6 +297,9 @@ typedef struct {
     ngx_flag_t                              bypass_limit;
     ngx_flag_t                              bypass_stats;
 
+    /* Controls name of "no cache" server zone */
+    ngx_str_t                              no_cache_server_zone;
+
     ngx_rbtree_node_t                     **node_caches;
 } ngx_http_vhost_traffic_status_loc_conf_t;
 

src/ngx_http_vhost_traffic_status_shm.c

@@ -354,7 +354,8 @@ ngx_http_vhost_traffic_status_shm_add_filter_node(ngx_http_request_t *r,
 
 
 ngx_int_t
-ngx_http_vhost_traffic_status_shm_add_server(ngx_http_request_t *r)
+ngx_http_vhost_traffic_status_shm_add_server(ngx_http_request_t *r,
+	const ngx_str_t *no_cache_server_zone)
 {
     unsigned                                   type;
     ngx_int_t                                  rc;
@@ -366,17 +367,25 @@ ngx_http_vhost_traffic_status_shm_add_server(ngx_http_request_t *r)
 
     cscf = ngx_http_get_module_srv_conf(r, ngx_http_core_module);
 
-    if (vtscf->filter && vtscf->filter_host && r->headers_in.server.len) {
-        /* set the key by host header */
-        dst = r->headers_in.server;
-
+    if (no_cache_server_zone != NULL &&
+	ngx_strlen(no_cache_server_zone->data) > 0) {
+	if (r->upstream == NULL || r->upstream->cache_status != 0) {
+	    return NGX_OK;
+	}
+	dst.len = no_cache_server_zone->len;
+	dst.data = no_cache_server_zone->data;
     } else {
-        /* set the key by server_name variable */
-        dst = cscf->server_name;
-        if (dst.len == 0) {
-            dst.len = 1;
-            dst.data = (u_char *) "_";
-        }
+	if (vtscf->filter && vtscf->filter_host && r->headers_in.server.len) {
+	    /* set the key by host header */
+	    dst = r->headers_in.server;
+	} else {
+	    /* set the key by server_name variable */
+	    dst = cscf->server_name;
+	    if (dst.len == 0) {
+		dst.len = 1;
+		dst.data = (u_char *) "_";
+	    }
+	}
     }
 
     type = NGX_HTTP_VHOST_TRAFFIC_STATUS_UPSTREAM_NO;

src/ngx_http_vhost_traffic_status_shm.h

@@ -19,7 +19,8 @@ typedef struct {
 } ngx_http_vhost_traffic_status_shm_info_t;
 
 
-ngx_int_t ngx_http_vhost_traffic_status_shm_add_server(ngx_http_request_t *r);
+ngx_int_t ngx_http_vhost_traffic_status_shm_add_server(
+    ngx_http_request_t *r, const ngx_str_t *no_cache_server_zone);
 ngx_int_t ngx_http_vhost_traffic_status_shm_add_filter(ngx_http_request_t *r);
 ngx_int_t ngx_http_vhost_traffic_status_shm_add_upstream(ngx_http_request_t *r);