[Tarantool-patches] [PATCH v3 4/4] fiber: keep reference to userdata if fiber created once
olegrok at tarantool.org
olegrok at tarantool.org
Fri Sep 3 23:49:18 MSK 2021
From: Oleg Babin <babinoleg at mail.ru>
This patch reworks approach to fiber management in Lua. Before
this patch each action that should return fiber led to new
userdata creation that was quite slow and made GC suffer. This
patch introduces new field in struct fiber to store a reference to
userdata that was created once for a fiber. It allows speedup
operations as fiber.self() and fiber.id().
Simple benchmark shows that access to fiber storage is faster in
two times, fiber.find() - 2-3 times and fiber.new/create functions
don't have any changes.
---
src/lib/core/fiber.c | 2 +
src/lib/core/fiber.h | 5 ++
src/lua/fiber.c | 110 +++++++++++++------------------------------
3 files changed, 39 insertions(+), 78 deletions(-)
diff --git a/src/lib/core/fiber.c b/src/lib/core/fiber.c
index 21afde209..1e5b2fb80 100644
--- a/src/lib/core/fiber.c
+++ b/src/lib/core/fiber.c
@@ -897,6 +897,7 @@ fiber_recycle(struct fiber *fiber)
fiber->wait_pad = NULL;
memset(&fiber->storage, 0, sizeof(fiber->storage));
fiber->storage.lua.storage_ref = luaL_no_ref;
+ fiber->storage.lua.fid_ref = luaL_no_ref;
unregister_fid(fiber);
fiber->fid = 0;
region_free(&fiber->gc);
@@ -1239,6 +1240,7 @@ fiber_new_ex(const char *name, const struct fiber_attr *fiber_attr,
}
memset(fiber, 0, sizeof(struct fiber));
fiber->storage.lua.storage_ref = luaL_no_ref;
+ fiber->storage.lua.fid_ref = luaL_no_ref;
if (fiber_stack_create(fiber, &cord()->slabc,
fiber_attr->stack_size)) {
diff --git a/src/lib/core/fiber.h b/src/lib/core/fiber.h
index 593847df7..2d4443544 100644
--- a/src/lib/core/fiber.h
+++ b/src/lib/core/fiber.h
@@ -623,6 +623,11 @@ struct fiber {
* Should not be used in other fibers.
*/
struct lua_State *stack;
+ /**
+ * Optional reference to userdata
+ * represented current fiber id in Lua.
+ */
+ int fid_ref;
/**
* Optional fiber.storage Lua reference.
*/
diff --git a/src/lua/fiber.c b/src/lua/fiber.c
index 6457a1428..70addd8f6 100644
--- a/src/lua/fiber.c
+++ b/src/lua/fiber.c
@@ -87,27 +87,26 @@ luaL_testcancel(struct lua_State *L)
static const char *fiberlib_name = "fiber";
/**
- * @pre: stack top contains a table
- * @post: sets table field specified by name of the table on top
- * of the stack to a weak kv table and pops that weak table.
+ * Trigger invoked when the fiber has stopped execution of its
+ * current request. Only purpose - delete storage.lua.fid_ref and
+ * storage.lua.storage_ref keeping a reference of Lua
+ * fiber and fiber.storage objects. Unlike Lua stack,
+ * Lua fiber storage may be created not only for fibers born from
+ * Lua land. For example, an IProto request may execute a Lua
+ * function, which can create the storage. Trigger guarantees,
+ * that even for non-Lua fibers the Lua storage is destroyed.
*/
-static void
-lbox_create_weak_table(struct lua_State *L, const char *name)
+static int
+lbox_fiber_on_stop(struct trigger *trigger, void *event)
{
- lua_newtable(L);
- /* and a metatable */
- lua_newtable(L);
- /* weak keys and values */
- lua_pushstring(L, "kv");
- /* pops 'kv' */
- lua_setfield(L, -2, "__mode");
- /* pops the metatable */
- lua_setmetatable(L, -2);
- /* assigns and pops table */
- lua_setfield(L, -2, name);
- /* gets memoize back. */
- lua_getfield(L, -1, name);
- assert(! lua_isnil(L, -1));
+ struct fiber *f = event;
+ luaL_unref(tarantool_L, LUA_REGISTRYINDEX, f->storage.lua.storage_ref);
+ f->storage.lua.storage_ref = LUA_NOREF;
+ luaL_unref(tarantool_L, LUA_REGISTRYINDEX, f->storage.lua.fid_ref);
+ f->storage.lua.fid_ref = LUA_NOREF;
+ trigger_clear(trigger);
+ free(trigger);
+ return 0;
}
/**
@@ -116,42 +115,26 @@ lbox_create_weak_table(struct lua_State *L, const char *name)
static void
lbox_pushfiber(struct lua_State *L, struct fiber *f)
{
- /*
- * Use 'memoize' pattern and keep a single userdata for
- * the given fiber. This is important to not run __gc
- * twice for a copy of an attached fiber -- __gc should
- * not remove attached fiber's coro prematurely.
- */
- luaL_getmetatable(L, fiberlib_name);
- lua_getfield(L, -1, "memoize");
- if (lua_isnil(L, -1)) {
- /* first access - instantiate memoize */
- /* pop the nil */
- lua_pop(L, 1);
- /* create memoize table */
- lbox_create_weak_table(L, "memoize");
- }
- /* Find out whether the fiber is already in the memoize table. */
- uint64_t fid = f->fid;
- luaL_pushuint64(L, fid);
- lua_gettable(L, -2);
- if (lua_isnil(L, -1)) {
- /* no userdata for fiber created so far */
- /* pop the nil */
- lua_pop(L, 1);
- /* push the key back */
- luaL_pushuint64(L, fid);
+ int fid_ref = f->storage.lua.fid_ref;
+ if (fid_ref == LUA_NOREF) {
+ struct trigger *t = malloc(sizeof(*t));
+ if (t == NULL) {
+ diag_set(OutOfMemory, sizeof(*t), "malloc", "t");
+ luaT_error(L);
+ }
+ trigger_create(t, lbox_fiber_on_stop, NULL, (trigger_f0)free);
+ trigger_add(&f->on_stop, t);
+
+ uint64_t fid = f->fid;
/* create a new userdata */
uint64_t *ptr = lua_newuserdata(L, sizeof(*ptr));
*ptr = fid;
luaL_getmetatable(L, fiberlib_name);
lua_setmetatable(L, -2);
- /* memoize it */
- lua_settable(L, -3);
- luaL_pushuint64(L, fid);
- /* get it back */
- lua_gettable(L, -2);
+ fid_ref = luaL_ref(L, LUA_REGISTRYINDEX);
+ f->storage.lua.fid_ref = fid_ref;
}
+ lua_rawgeti(L, LUA_REGISTRYINDEX, fid_ref);
}
static struct fiber *
@@ -669,41 +652,12 @@ lbox_fiber_name(struct lua_State *L)
}
}
-/**
- * Trigger invoked when the fiber has stopped execution of its
- * current request. Only purpose - delete storage.lua.storage_ref keeping
- * a reference of Lua fiber.storage object. Unlike Lua stack,
- * Lua fiber storage may be created not only for fibers born from
- * Lua land. For example, an IProto request may execute a Lua
- * function, which can create the storage. Trigger guarantees,
- * that even for non-Lua fibers the Lua storage is destroyed.
- */
-static int
-lbox_fiber_on_stop(struct trigger *trigger, void *event)
-{
- struct fiber *f = (struct fiber *) event;
- int storage_ref = f->storage.lua.storage_ref;
- luaL_unref(tarantool_L, LUA_REGISTRYINDEX, storage_ref);
- f->storage.lua.storage_ref = LUA_NOREF;
- trigger_clear(trigger);
- free(trigger);
- return 0;
-}
-
static int
lbox_fiber_storage(struct lua_State *L)
{
struct fiber *f = lbox_checkfiber(L, 1);
int storage_ref = f->storage.lua.storage_ref;
if (storage_ref == LUA_NOREF) {
- struct trigger *t = (struct trigger *)
- malloc(sizeof(*t));
- if (t == NULL) {
- diag_set(OutOfMemory, sizeof(*t), "malloc", "t");
- return luaT_error(L);
- }
- trigger_create(t, lbox_fiber_on_stop, NULL, (trigger_f0) free);
- trigger_add(&f->on_stop, t);
lua_newtable(L); /* create local storage on demand */
storage_ref = luaL_ref(L, LUA_REGISTRYINDEX);
f->storage.lua.storage_ref = storage_ref;
--
2.32.0
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