Cache: proxy_cache_lock_age and friends.

Once this age is reached, the cache lock is discarded and another
request can acquire the lock.  Requests which failed to acquire
the lock are not allowed to cache the response.

src/http/modules/ngx_http_fastcgi_module.c

@@ -419,6 +419,13 @@ static ngx_command_t  ngx_http_fastcgi_commands[] = {
       offsetof(ngx_http_fastcgi_loc_conf_t, upstream.cache_lock_timeout),
       NULL },
 
+    { ngx_string("fastcgi_cache_lock_age"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
+      ngx_conf_set_msec_slot,
+      NGX_HTTP_LOC_CONF_OFFSET,
+      offsetof(ngx_http_fastcgi_loc_conf_t, upstream.cache_lock_age),
+      NULL },
+
     { ngx_string("fastcgi_cache_revalidate"),
       NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_FLAG,
       ngx_conf_set_flag_slot,
@@ -2374,6 +2381,7 @@ ngx_http_fastcgi_create_loc_conf(ngx_conf_t *cf)
     conf->upstream.cache_valid = NGX_CONF_UNSET_PTR;
     conf->upstream.cache_lock = NGX_CONF_UNSET;
     conf->upstream.cache_lock_timeout = NGX_CONF_UNSET_MSEC;
+    conf->upstream.cache_lock_age = NGX_CONF_UNSET_MSEC;
     conf->upstream.cache_revalidate = NGX_CONF_UNSET;
 #endif
 
@@ -2638,6 +2646,9 @@ ngx_http_fastcgi_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child)
     ngx_conf_merge_msec_value(conf->upstream.cache_lock_timeout,
                               prev->upstream.cache_lock_timeout, 5000);
 
+    ngx_conf_merge_msec_value(conf->upstream.cache_lock_age,
+                              prev->upstream.cache_lock_age, 5000);
+
     ngx_conf_merge_value(conf->upstream.cache_revalidate,
                               prev->upstream.cache_revalidate, 0);
 

src/http/modules/ngx_http_proxy_module.c

@@ -489,6 +489,13 @@ static ngx_command_t  ngx_http_proxy_commands[] = {
       offsetof(ngx_http_proxy_loc_conf_t, upstream.cache_lock_timeout),
       NULL },
 
+    { ngx_string("proxy_cache_lock_age"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
+      ngx_conf_set_msec_slot,
+      NGX_HTTP_LOC_CONF_OFFSET,
+      offsetof(ngx_http_proxy_loc_conf_t, upstream.cache_lock_age),
+      NULL },
+
     { ngx_string("proxy_cache_revalidate"),
       NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_FLAG,
       ngx_conf_set_flag_slot,
@@ -2544,6 +2551,7 @@ ngx_http_proxy_create_loc_conf(ngx_conf_t *cf)
     conf->upstream.cache_valid = NGX_CONF_UNSET_PTR;
     conf->upstream.cache_lock = NGX_CONF_UNSET;
     conf->upstream.cache_lock_timeout = NGX_CONF_UNSET_MSEC;
+    conf->upstream.cache_lock_age = NGX_CONF_UNSET_MSEC;
     conf->upstream.cache_revalidate = NGX_CONF_UNSET;
 #endif
 
@@ -2818,6 +2826,9 @@ ngx_http_proxy_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child)
     ngx_conf_merge_msec_value(conf->upstream.cache_lock_timeout,
                               prev->upstream.cache_lock_timeout, 5000);
 
+    ngx_conf_merge_msec_value(conf->upstream.cache_lock_age,
+                              prev->upstream.cache_lock_age, 5000);
+
     ngx_conf_merge_value(conf->upstream.cache_revalidate,
                               prev->upstream.cache_revalidate, 0);
 

src/http/modules/ngx_http_scgi_module.c

@@ -276,6 +276,13 @@ static ngx_command_t ngx_http_scgi_commands[] = {
       offsetof(ngx_http_scgi_loc_conf_t, upstream.cache_lock_timeout),
       NULL },
 
+    { ngx_string("scgi_cache_lock_age"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
+      ngx_conf_set_msec_slot,
+      NGX_HTTP_LOC_CONF_OFFSET,
+      offsetof(ngx_http_scgi_loc_conf_t, upstream.cache_lock_age),
+      NULL },
+
     { ngx_string("scgi_cache_revalidate"),
       NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_FLAG,
       ngx_conf_set_flag_slot,
@@ -1133,6 +1140,7 @@ ngx_http_scgi_create_loc_conf(ngx_conf_t *cf)
     conf->upstream.cache_valid = NGX_CONF_UNSET_PTR;
     conf->upstream.cache_lock = NGX_CONF_UNSET;
     conf->upstream.cache_lock_timeout = NGX_CONF_UNSET_MSEC;
+    conf->upstream.cache_lock_age = NGX_CONF_UNSET_MSEC;
     conf->upstream.cache_revalidate = NGX_CONF_UNSET;
 #endif
 
@@ -1392,6 +1400,9 @@ ngx_http_scgi_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child)
     ngx_conf_merge_msec_value(conf->upstream.cache_lock_timeout,
                               prev->upstream.cache_lock_timeout, 5000);
 
+    ngx_conf_merge_msec_value(conf->upstream.cache_lock_age,
+                              prev->upstream.cache_lock_age, 5000);
+
     ngx_conf_merge_value(conf->upstream.cache_revalidate,
                               prev->upstream.cache_revalidate, 0);
 

src/http/modules/ngx_http_uwsgi_module.c

@@ -336,6 +336,13 @@ static ngx_command_t ngx_http_uwsgi_commands[] = {
       offsetof(ngx_http_uwsgi_loc_conf_t, upstream.cache_lock_timeout),
       NULL },
 
+    { ngx_string("uwsgi_cache_lock_age"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
+      ngx_conf_set_msec_slot,
+      NGX_HTTP_LOC_CONF_OFFSET,
+      offsetof(ngx_http_uwsgi_loc_conf_t, upstream.cache_lock_age),
+      NULL },
+
     { ngx_string("uwsgi_cache_revalidate"),
       NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_FLAG,
       ngx_conf_set_flag_slot,
@@ -1339,6 +1346,7 @@ ngx_http_uwsgi_create_loc_conf(ngx_conf_t *cf)
     conf->upstream.cache_valid = NGX_CONF_UNSET_PTR;
     conf->upstream.cache_lock = NGX_CONF_UNSET;
     conf->upstream.cache_lock_timeout = NGX_CONF_UNSET_MSEC;
+    conf->upstream.cache_lock_age = NGX_CONF_UNSET_MSEC;
     conf->upstream.cache_revalidate = NGX_CONF_UNSET;
 #endif
 
@@ -1606,6 +1614,9 @@ ngx_http_uwsgi_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child)
     ngx_conf_merge_msec_value(conf->upstream.cache_lock_timeout,
                               prev->upstream.cache_lock_timeout, 5000);
 
+    ngx_conf_merge_msec_value(conf->upstream.cache_lock_age,
+                              prev->upstream.cache_lock_age, 5000);
+
     ngx_conf_merge_value(conf->upstream.cache_revalidate,
                               prev->upstream.cache_revalidate, 0);
 

src/http/ngx_http_cache.h

@@ -57,6 +57,7 @@ typedef struct {
     time_t                           valid_sec;
     size_t                           body_start;
     off_t                            fs_size;
+    ngx_msec_t                       lock_time;
 } ngx_http_file_cache_node_t;
 
 
@@ -91,6 +92,8 @@ struct ngx_http_cache_s {
     ngx_http_file_cache_node_t      *node;
 
     ngx_msec_t                       lock_timeout;
+    ngx_msec_t                       lock_age;
+    ngx_msec_t                       lock_time;
     ngx_msec_t                       wait_time;
 
     ngx_event_t                      wait_event;

src/http/ngx_http_file_cache.c

@@ -396,13 +396,19 @@ ngx_http_file_cache_lock(ngx_http_request_t *r, ngx_http_cache_t *c)
         return NGX_DECLINED;
     }
 
+    now = ngx_current_msec;
+
     cache = c->file_cache;
 
     ngx_shmtx_lock(&cache->shpool->mutex);
 
-    if (!c->node->updating) {
+    timer = c->node->lock_time - now;
+
+    if (!c->node->updating || (ngx_msec_int_t) timer <= 0) {
         c->node->updating = 1;
+        c->node->lock_time = now + c->lock_age;
         c->updating = 1;
+        c->lock_time = c->node->lock_time;
     }
 
     ngx_shmtx_unlock(&cache->shpool->mutex);
@@ -415,9 +421,11 @@ ngx_http_file_cache_lock(ngx_http_request_t *r, ngx_http_cache_t *c)
         return NGX_DECLINED;
     }
 
-    c->waiting = 1;
+    if (c->lock_timeout == 0) {
+        return NGX_HTTP_CACHE_SCARCE;
+    }
 
-    now = ngx_current_msec;
+    c->waiting = 1;
 
     if (c->wait_time == 0) {
         c->wait_time = now + c->lock_timeout;
@@ -441,7 +449,7 @@ static void
 ngx_http_file_cache_lock_wait_handler(ngx_event_t *ev)
 {
     ngx_uint_t                 wait;
-    ngx_msec_t                 timer;
+    ngx_msec_t                 now, timer;
     ngx_http_cache_t          *c;
     ngx_http_request_t        *r;
     ngx_http_file_cache_t     *cache;
@@ -449,15 +457,17 @@ ngx_http_file_cache_lock_wait_handler(ngx_event_t *ev)
     r = ev->data;
     c = r->cache;
 
+    now = ngx_current_msec;
+
     ngx_log_debug2(NGX_LOG_DEBUG_HTTP, ev->log, 0,
                    "http file cache wait handler wt:%M cur:%M",
-                   c->wait_time, ngx_current_msec);
+                   c->wait_time, now);
 
-    timer = c->wait_time - ngx_current_msec;
+    timer = c->wait_time - now;
 
     if ((ngx_msec_int_t) timer <= 0) {
         ngx_log_error(NGX_LOG_INFO, ev->log, 0, "cache lock timeout");
-        c->lock = 0;
+        c->lock_timeout = 0;
         goto wakeup;
     }
 
@@ -466,7 +476,9 @@ ngx_http_file_cache_lock_wait_handler(ngx_event_t *ev)
 
     ngx_shmtx_lock(&cache->shpool->mutex);
 
-    if (c->node->updating) {
+    timer = c->node->lock_time - now;
+
+    if (c->node->updating && (ngx_msec_int_t) timer > 0) {
         wait = 1;
     }
 
@@ -588,6 +600,7 @@ ngx_http_file_cache_read(ngx_http_request_t *r, ngx_http_cache_t *c)
         } else {
             c->node->updating = 1;
             c->updating = 1;
+            c->lock_time = c->node->lock_time;
             rc = NGX_HTTP_CACHE_STALE;
         }
 
@@ -1453,7 +1466,7 @@ ngx_http_file_cache_free(ngx_http_cache_t *c, ngx_temp_file_t *tf)
     fcn = c->node;
     fcn->count--;
 
-    if (c->updating) {
+    if (c->updating && fcn->lock_time == c->lock_time) {
         fcn->updating = 0;
     }
 

src/http/ngx_http_upstream.c

@@ -784,6 +784,7 @@ ngx_http_upstream_cache(ngx_http_request_t *r, ngx_http_upstream_t *u)
 
         c->lock = u->conf->cache_lock;
         c->lock_timeout = u->conf->cache_lock_timeout;
+        c->lock_age = u->conf->cache_lock_age;
 
         u->cache_status = NGX_HTTP_CACHE_MISS;
     }

src/http/ngx_http_upstream.h

@@ -183,6 +183,7 @@ typedef struct {
 
     ngx_flag_t                       cache_lock;
     ngx_msec_t                       cache_lock_timeout;
+    ngx_msec_t                       cache_lock_age;
 
     ngx_flag_t                       cache_revalidate;