# HG changeset patch
# User Ruslan Ermilov <ru@nginx.com>
# Date 1481208709 -10800
# Node ID ec10ce307dc03b29d681365e5d5477ceb8738fab
# Parent  014905eb7b3da3ab8c5d03c5ed296c84e3d75329
Map: the "volatile" parameter.

By default, "map" creates cacheable variables [1].  With this
parameter it creates a non-cacheable variable.

An original idea was to deduce the cacheability of the "map"
variable by checking the cacheability of variables specified
in source and resulting values, but it turned to be too hard.
For example, a cacheable variable can be overridden with the
"set" directive or with the SSI "set" command.  Also, keeping
"map" variables cacheable by default is good for performance
reasons.  This required adding a new parameter.

[1] Before db699978a33f (1.11.0), the cacheability of the
"map" variable could vary depending on the cacheability of
variables specified in resulting values (ticket #1090).
This is believed to be a bug rather than a feature.

diff --git a/src/http/modules/ngx_http_map_module.c b/src/http/modules/ngx_http_map_module.c
--- a/src/http/modules/ngx_http_map_module.c
+++ b/src/http/modules/ngx_http_map_module.c
@@ -26,7 +26,8 @@ typedef struct {
 
     ngx_http_variable_value_t  *default_value;
     ngx_conf_t                 *cf;
-    ngx_uint_t                  hostnames;      /* unsigned  hostnames:1 */
+    unsigned                    hostnames:1;
+    unsigned                    no_cacheable:1;
 } ngx_http_map_conf_ctx_t;
 
 
@@ -265,6 +266,7 @@ ngx_http_map_block(ngx_conf_t *cf, ngx_c
     ctx.default_value = NULL;
     ctx.cf = &save;
     ctx.hostnames = 0;
+    ctx.no_cacheable = 0;
 
     save = *cf;
     cf->pool = pool;
@@ -281,6 +283,10 @@ ngx_http_map_block(ngx_conf_t *cf, ngx_c
         return rv;
     }
 
+    if (ctx.no_cacheable) {
+        var->flags |= NGX_HTTP_VAR_NOCACHEABLE;
+    }
+
     map->default_value = ctx.default_value ? ctx.default_value:
                                              &ngx_http_variable_null_value;
 
@@ -395,6 +401,13 @@ ngx_http_map(ngx_conf_t *cf, ngx_command
         return NGX_CONF_OK;
     }
 
+    if (cf->args->nelts == 1
+        && ngx_strcmp(value[0].data, "volatile") == 0)
+    {
+        ctx->no_cacheable = 1;
+        return NGX_CONF_OK;
+    }
+
     if (cf->args->nelts != 2) {
         ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                            "invalid number of the map parameters");
diff --git a/src/stream/ngx_stream_map_module.c b/src/stream/ngx_stream_map_module.c
--- a/src/stream/ngx_stream_map_module.c
+++ b/src/stream/ngx_stream_map_module.c
@@ -26,7 +26,8 @@ typedef struct {
 
     ngx_stream_variable_value_t  *default_value;
     ngx_conf_t                   *cf;
-    ngx_uint_t                    hostnames;      /* unsigned  hostnames:1 */
+    unsigned                      hostnames:1;
+    unsigned                      no_cacheable:1;
 } ngx_stream_map_conf_ctx_t;
 
 
@@ -264,6 +265,7 @@ ngx_stream_map_block(ngx_conf_t *cf, ngx
     ctx.default_value = NULL;
     ctx.cf = &save;
     ctx.hostnames = 0;
+    ctx.no_cacheable = 0;
 
     save = *cf;
     cf->pool = pool;
@@ -280,6 +282,10 @@ ngx_stream_map_block(ngx_conf_t *cf, ngx
         return rv;
     }
 
+    if (ctx.no_cacheable) {
+        var->flags |= NGX_STREAM_VAR_NOCACHEABLE;
+    }
+
     map->default_value = ctx.default_value ? ctx.default_value:
                                              &ngx_stream_variable_null_value;
 
@@ -394,6 +400,13 @@ ngx_stream_map(ngx_conf_t *cf, ngx_comma
         return NGX_CONF_OK;
     }
 
+    if (cf->args->nelts == 1
+        && ngx_strcmp(value[0].data, "volatile") == 0)
+    {
+        ctx->no_cacheable = 1;
+        return NGX_CONF_OK;
+    }
+
     if (cf->args->nelts != 2) {
         ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                            "invalid number of the map parameters");