sync code with last improvements from OpenBSD

usr.sbin/unbound/daemon/daemon.c

@@ -488,6 +488,27 @@ static int daemon_get_shufport(struct daemon* daemon, int* shufport)
 	return avail;
 }
 
+/**
+ * Clear and delete per-worker alloc caches, and free memory maintained in
+ * superalloc.
+ * The rrset and message caches must be empty at the time of call.
+ * @param daemon: the daemon that maintains the alloc caches to be cleared.
+ */
+static void
+daemon_clear_allocs(struct daemon* daemon)
+{
+	int i;
+
+	for(i=0; i<daemon->num; i++) {
+		alloc_clear(daemon->worker_allocs[i]);
+		free(daemon->worker_allocs[i]);
+	}
+	free(daemon->worker_allocs);
+	daemon->worker_allocs = NULL;
+
+	alloc_clear_special(&daemon->superalloc);
+}
+
 /**
  * Allocate empty worker structures. With backptr and thread-number,
  * from 0..numthread initialised. Used as user arguments to new threads.
@@ -540,6 +561,21 @@ daemon_create_workers(struct daemon* daemon)
 			/* the above is not ports/numthr, due to rounding */
 			fatal_exit("could not create worker");
 	}
+	/* create per-worker alloc caches if not reusing existing ones. */
+	if(!daemon->worker_allocs) {
+		daemon->worker_allocs = (struct alloc_cache**)calloc(
+			(size_t)daemon->num, sizeof(struct alloc_cache*));
+		if(!daemon->worker_allocs)
+			fatal_exit("could not allocate worker allocs");
+		for(i=0; i<daemon->num; i++) {
+			struct alloc_cache* alloc = calloc(1,
+				sizeof(struct alloc_cache));
+			if (!alloc)
+				fatal_exit("could not allocate worker alloc");
+			alloc_init(alloc, &daemon->superalloc, i);
+			daemon->worker_allocs[i] = alloc;
+		}
+	}
 	free(shufport);
 }
 
@@ -771,6 +807,7 @@ daemon_fork(struct daemon* daemon)
 	/* Shutdown SHM */
 	shm_main_shutdown(daemon);
 
+	daemon->reuse_cache = daemon->workers[0]->reuse_cache;
 	daemon->need_to_exit = daemon->workers[0]->need_to_exit;
 }
 
@@ -785,9 +822,16 @@ daemon_cleanup(struct daemon* daemon)
 	log_thread_set(NULL);
 	/* clean up caches because
 	 * a) RRset IDs will be recycled after a reload, causing collisions
-	 * b) validation config can change, thus rrset, msg, keycache clear */
+	 * b) validation config can change, thus rrset, msg, keycache clear
+	 *
+	 * If we are trying to keep the cache as long as possible, we should
+	 * defer the cleanup until we know whether the new configuration allows
+	 * the reuse.  (If we're exiting, cleanup should be done here). */
+	if(!daemon->reuse_cache || daemon->need_to_exit) {
 	slabhash_clear(&daemon->env->rrset_cache->table);
 	slabhash_clear(daemon->env->msg_cache);
+	}
+	daemon->old_num = daemon->num; /* save the current num */
 	local_zones_delete(daemon->local_zones);
 	daemon->local_zones = NULL;
 	respip_set_delete(daemon->respip_set);
@@ -802,8 +846,13 @@ daemon_cleanup(struct daemon* daemon)
 		worker_delete(daemon->workers[i]);
 	free(daemon->workers);
 	daemon->workers = NULL;
+	/* Unless we're trying to keep the cache, worker alloc_caches should be
+	 * cleared and freed here. We do this after deleting workers to
+	 * guarantee that the alloc caches are valid throughout the lifetime
+	 * of workers. */
+	if(!daemon->reuse_cache || daemon->need_to_exit)
+		daemon_clear_allocs(daemon);
 	daemon->num = 0;
-	alloc_clear_special(&daemon->superalloc);
 #ifdef USE_DNSTAP
 	dt_delete(daemon->dtenv);
 	daemon->dtenv = NULL;
@@ -900,8 +949,42 @@ daemon_delete(struct daemon* daemon)
 
 void daemon_apply_cfg(struct daemon* daemon, struct config_file* cfg)
 {
+	int new_num = cfg->num_threads?cfg->num_threads:1;
+
         daemon->cfg = cfg;
 	config_apply(cfg);
+
+	/* If this is a reload and we deferred the decision on whether to
+	 * reuse the alloc, RRset, and message caches, then check to see if
+	 * it's safe to keep the caches:
+	 * - changing the number of threads is obviously incompatible with
+	 *   keeping the per-thread alloc caches. It also means we have to
+	 *   clear RRset and message caches. (note that 'new_num' may be
+	 *   adjusted in daemon_create_workers, but for our purpose we can
+	 *   simply compare it with 'old_num'; if they are equal here,
+	 *   'new_num' won't be adjusted to a different value than 'old_num').
+	 * - changing RRset cache size effectively clears any remaining cache
+	 *   entries. We could keep their keys in alloc caches, but it would
+	 *   be more consistent with the sense of the change to clear allocs
+	 *   and free memory. To do so we also have to clear message cache.
+	 * - only changing message cache size does not necessarily affect
+	 *   RRset or alloc cache. But almost all new subsequent queries will
+	 *   require recursive resolution anyway, so it doesn't help much to
+	 *   just keep RRset and alloc caches. For simplicity we clear/free
+	 *   the other two, too. */
+	if(daemon->worker_allocs &&
+		(new_num != daemon->old_num ||
+		 !slabhash_is_size(daemon->env->msg_cache, cfg->msg_cache_size,
+			cfg->msg_cache_slabs) ||
+		 !slabhash_is_size(&daemon->env->rrset_cache->table,
+			cfg->rrset_cache_size, cfg->rrset_cache_slabs)))
+	{
+		log_warn("cannot reuse caches due to critical config change");
+		slabhash_clear(&daemon->env->rrset_cache->table);
+		slabhash_clear(daemon->env->msg_cache);
+		daemon_clear_allocs(daemon);
+	}
+
 	if(!slabhash_is_size(daemon->env->msg_cache, cfg->msg_cache_size,
 	   	cfg->msg_cache_slabs)) {
 		slabhash_delete(daemon->env->msg_cache);