apr_reslist: always expire oldest entries first.

When a resource is to be acquired, we should check for expiring entries
starting from the oldest to the youngest one, otherwise it's only when
the latter expires that all of the resources are killed in a batch.


git-svn-id: https://svn.apache.org/repos/asf/apr/apr/trunk@1834030 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 20 insertions, 13 deletions

diff --git a/util-misc/apr_reslist.c b/util-misc/apr_reslist.c
index 3a146d746..7b6ff3507 100644
--- a/util-misc/apr_reslist.c
+++ b/util-misc/apr_reslist.c
@@ -227,14 +227,14 @@ APR_DECLARE(apr_status_t) apr_reslist_maintain(apr_reslist_t *reslist)
     /* Check if we need to expire old resources */
     now = apr_time_now();
     while (reslist->nidle > reslist->smax && reslist->nidle > 0) {
-        /* Peak at the last resource in the list */
+        /* Peek at the oldest resource in the list */
         res = APR_RING_LAST(&reslist->avail_list);
-        /* See if the oldest entry should be expired */
         if (now - res->freed < reslist->ttl) {
             /* If this entry is too young, none of the others
              * will be ready to be expired either, so we are done. */
             break;
         }
+        /* this res is expired - kill it */
         APR_RING_REMOVE(res, link);
         reslist->nidle--;
         reslist->ntotal--;
@@ -334,22 +334,26 @@ APR_DECLARE(apr_status_t) apr_reslist_acquire(apr_reslist_t *reslist,
 {
     apr_status_t rv;
     apr_res_t *res;
-    apr_time_t now = 0;
 
 #if APR_HAS_THREADS
     apr_thread_mutex_lock(reslist->listlock);
     apr_pool_owner_set(reslist->pool, 0);
 #endif
-    /* If there are idle resources on the available list, use
+    /* If there are expired resources in the available list, kill
      * them right away. */
-    if (reslist->ttl) {
-        now = apr_time_now();
-    }
-    while (reslist->nidle > 0) {
-        /* Pop off the first resource */
-        res = pop_resource(reslist);
-        if (reslist->ttl && (now - res->freed >= reslist->ttl)) {
+    if (reslist->ttl && reslist->nidle > 0) {
+        apr_time_t now = apr_time_now();
+        do {
+            /* Peek at the oldest resource in the list */
+            res = APR_RING_LAST(&reslist->avail_list);
+            if (now - res->freed < reslist->ttl) {
+                /* If this entry is too young, none of the others
+                 * will be ready to be expired either, so we are done. */
+                break;
+            }
             /* this res is expired - kill it */
+            APR_RING_REMOVE(res, link);
+            reslist->nidle--;
             reslist->ntotal--;
             rv = destroy_resource(reslist, res);
             free_container(reslist, res);
@@ -359,8 +363,11 @@ APR_DECLARE(apr_status_t) apr_reslist_acquire(apr_reslist_t *reslist,
 #endif
                 return rv;  /* FIXME: this might cause unnecessary fails */
             }
-            continue;
-        }
+        } while (reslist->nidle > 0);
+    }
+    /* If there is still an idle resource, use it right away */
+    if (reslist->nidle > 0) {
+        res = pop_resource(reslist);
         *resource = res->opaque;
         free_container(reslist, res);
 #if APR_HAS_THREADS