From 9c349dd55147690c553bfd63abe4a69206a82014 Mon Sep 17 00:00:00 2001
From: Roman Tsisyk <roman@tsisyk.com>
Date: Fri, 4 Dec 2015 09:00:25 +0300
Subject: [PATCH] Rewrite lbox_select() using port_buf
Don't allow Lua exceptions inside box_select() callbacks.
A Lua exception may break internal state of box (leak transactions,
pass try-catch handlers in fibers and so on).
Please note that this binding still can leak on OOM.
https://github.com/tarantool/tarantool/issues/1182
---
src/box/lua/misc.cc | 63 +++++++++++++++++++--------------------------
1 file changed, 27 insertions(+), 36 deletions(-)
diff --git a/src/box/lua/misc.cc b/src/box/lua/misc.cc
index 7adffe883f..c89829fd2a 100644
--- a/src/box/lua/misc.cc
+++ b/src/box/lua/misc.cc
@@ -59,37 +59,16 @@ lbox_encode_tuple_on_gc(lua_State *L, int idx, size_t *p_len)
/** {{{ Lua/C implementation of index:select(): used only by Sophia **/
-struct port_lua
+static inline void
+lbox_port_buf_to_table(lua_State *L, struct port_buf *port_buf)
{
- struct port_vtab *vtab;
- struct lua_State *L;
- size_t size; /* for port_lua_add_tuple */
-};
-
-static inline struct port_lua *
-port_lua(struct port *port) { return (struct port_lua *) port; }
-
-static void
-port_lua_table_add_tuple(struct port *port, struct tuple *tuple)
-{
- lua_State *L = port_lua(port)->L;
- lbox_pushtuple(L, tuple);
- lua_rawseti(L, -2, ++port_lua(port)->size);
-}
-
-/** Add all tuples to a Lua table. */
-void
-port_lua_table_create(struct port_lua *port, struct lua_State *L)
-{
- static struct port_vtab port_lua_vtab = {
- port_lua_table_add_tuple,
- null_port_eof,
- };
- port->vtab = &port_lua_vtab;
- port->L = L;
- port->size = 0;
- /* The destination table to append tuples to. */
- lua_newtable(L);
+ lua_createtable(L, port_buf->size, 0);
+ struct port_buf_entry *entry = port_buf->first;
+ for (size_t i = 0 ; i < port_buf->size; i++) {
+ lbox_pushtuple(L, entry->tuple);
+ lua_rawseti(L, -2, i + 1);
+ entry = entry->next;
+ }
}
static int
@@ -110,14 +89,26 @@ lbox_select(lua_State *L)
size_t key_len;
const char *key = lbox_encode_tuple_on_gc(L, 6, &key_len);
- /* TODO: This code definetly leaks without EXTERNAL_UNWIND */
- int top = lua_gettop(L);
- struct port_lua port;
- port_lua_table_create(&port, L);
+ struct port_buf port;
+ port_buf_create(&port);
if (box_select((struct port *) &port, space_id, index_id, iterator,
- offset, limit, key, key + key_len) != 0)
+ offset, limit, key, key + key_len) != 0) {
+ port_buf_destroy(&port);
return lbox_error(L);
- return lua_gettop(L) - top;
+ }
+
+ /*
+ * Lua may raise an exception during allocating table or pushing
+ * tuples. In this case `port' definitely will leak. It is possible to
+ * wrap lbox_port_buf_to_table() to pcall(), but it was too expensive
+ * for this binding according to our benchmarks (~5% decrease).
+ * However, we tried to simulate this situation and LuaJIT finalizers
+ * table always crashed the first (can't be fixed with pcall).
+ * https://github.com/tarantool/tarantool/issues/1182
+ */
+ lbox_port_buf_to_table(L, &port);
+ port_buf_destroy(&port);
+ return 1; /* lua table with tuples */
}
/* }}} */
--
GitLab