[Minor] Add a hack to fix termination race condition

diff --git a/src/libserver/fuzzy_backend/fuzzy_backend_redis.c b/src/libserver/fuzzy_backend/fuzzy_backend_redis.c
index 18e049926f8c8dff14e8a09a1623685068fd0890..efed2fea2e2a7e628c25e373b7521133721a0f86 100644 (file)
--- a/src/libserver/fuzzy_backend/fuzzy_backend_redis.c
+++ b/src/libserver/fuzzy_backend/fuzzy_backend_redis.c
@@ -58,6 +58,7 @@ struct rspamd_fuzzy_backend_redis {
        struct rspamd_redis_pool *pool;
        gdouble timeout;
        gint conf_ref;
+       bool terminated;
        ref_entry_t ref;
 };
 
@@ -170,10 +171,8 @@ rspamd_fuzzy_redis_session_dtor (struct rspamd_fuzzy_redis_session *session,
 static void
 rspamd_fuzzy_backend_redis_dtor (struct rspamd_fuzzy_backend_redis *backend)
 {
-       lua_State *L = backend->L;
-
-       if (backend->conf_ref != -1) {
-               luaL_unref (L, LUA_REGISTRYINDEX, backend->conf_ref);
+       if (!backend->terminated && backend->conf_ref != -1) {
+               luaL_unref (backend->L, LUA_REGISTRYINDEX, backend->conf_ref);
        }
 
        if (backend->id) {
@@ -1641,5 +1640,17 @@ rspamd_fuzzy_backend_close_redis (struct rspamd_fuzzy_backend *bk,
 
        g_assert (backend != NULL);
 
+       /*
+        * XXX: we leak lua registry element there to avoid crashing
+        * due to chicken-egg problem between lua state termination and
+        * redis pool termination.
+        * Here, we assume that redis pool is destroyed AFTER lua_state,
+        * so all connections pending will release references but due to
+        * `terminated` hack they will not try to access Lua stuff
+        * This is enabled merely if we have connections pending (e.g. refcount > 1)
+        */
+       if (backend->ref.refcount > 1) {
+               backend->terminated = true;
+       }
        REF_RELEASE (backend);
 }