[PATCH 3 of 5] Cache: only complain on long locked entries

[Maxim Dounin]

# HG changeset patch
# User Maxim Dounin <mdounin at mdounin.ru>
# Date 1323615350 -10800
# Node ID 71a5724d332ff7cc5935e0f6c87e8a0036f3e682
# Parent  a013347f89334734a7a0f65031895be52d87a5a0
Cache: only complain on long locked entries.

There have been multiple reports of cases where a real locked entry was
removed, resulting in a segmentation fault later in a worker which locked
the entry.  It looks like default inactive timeout isn't enough in real
life.

For now just ignore such locked entries, and move them to the top of the
inactive queue to allow processing of other entries.

diff --git a/src/http/ngx_http_file_cache.c b/src/http/ngx_http_file_cache.c
--- a/src/http/ngx_http_file_cache.c
+++ b/src/http/ngx_http_file_cache.c
@@ -1113,12 +1113,12 @@ ngx_http_file_cache_expire(ngx_http_file
         /*
          * abnormally exited workers may leave locked cache entries,
          * and although it may be safe to remove them completely,
-         * we prefer to remove them from inactive queue and rbtree
-         * only, and to allow other leaks
+         * we prefer to just move them to the top of the inactive queue
          */
 
         ngx_queue_remove(q);
-        ngx_rbtree_delete(&cache->sh->rbtree, &fcn->node);
+        fcn->expire = ngx_time() + cache->inactive;
+        ngx_queue_insert_head(&cache->sh->queue, &fcn->queue);
 
         ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, 0,
                       "ignore long locked inactive cache entry %*s, count:%d",