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From f31efa83bd76ac375c00b31c30eb731cf4fd2226 Mon Sep 17 00:00:00 2001
From: Matthew Wild <mwild1@gmail.com>
Date: Sat, 15 Jun 2013 22:51:03 +0100
Subject: [PATCH] Ensure that callback object is always anchored to prevent the
possibility of it being garbage-collected before/while the C callback runs
---
include/event_callback.h | 2 +
src/event_callback.c | 110 ++++++++++++++++++++++++-----------------------
2 files changed, 59 insertions(+), 53 deletions(-)
diff --git a/include/event_callback.h b/include/event_callback.h
index 9d68b26..6d7a2f1 100644
--- a/include/event_callback.h
+++ b/include/event_callback.h
@@ -28,7 +28,9 @@
typedef struct {
struct event ev;
le_base* base;
+ int selfRef;
int callbackRef;
+ int running;
struct timeval timeout;
} le_callback;
diff --git a/src/event_callback.c b/src/event_callback.c
index afe8773..9e705be 100644
--- a/src/event_callback.c
+++ b/src/event_callback.c
@@ -27,11 +27,10 @@
#define EVENT_CALLBACK_ARG_MT "EVENT_CALLBACK_ARG_MT"
-void freeCallbackArgs(le_callback* arg, lua_State* L) {
- if(arg->base) {
- arg->base = NULL;
- event_del(&arg->ev);
- luaL_unref(L, LUA_REGISTRYINDEX, arg->callbackRef);
+void freeCallback(le_callback* cb, lua_State* L) {
+ if(cb->callbackRef != LUA_NOREF) {
+ luaL_unref(L, LUA_REGISTRYINDEX, cb->callbackRef);
+ cb->callbackRef = LUA_NOREF;
}
}
/* le_callback is allocated at the beginning of the coroutine in which it
@@ -40,60 +39,62 @@ is used, no need to manually de-allocate */
/* Index for coroutine is fd as integer for *nix, as lightuserdata for Win */
void luaevent_callback(int fd, short event, void* p) {
le_callback* cb = p;
+ struct event *ev = &cb->ev;
lua_State* L;
- int ret;
+ int ret = -1;
struct timeval new_tv = { 0, 0 };
- le_base* base;
- assert(cb);
- if(!cb->base)
- return; /* Event has already been collected + destroyed */
- assert(cb->base->loop_L);
- L = cb->base->loop_L;
- lua_rawgeti(L, LUA_REGISTRYINDEX, cb->callbackRef);
- lua_pushinteger(L, event);
- /* cb->base may be NULL after the pcall, if the event is destroyed */
- base = cb->base;
- if(lua_pcall(L, 1, 2, 0))
- {
- base->errorMessage = luaL_ref(L, LUA_REGISTRYINDEX);
- event_base_loopbreak(base->base);
- lua_pop(L, 1);
- return;
- }
- if(!cb->base) {
- lua_pop(L, 2);
- return; /* event was destroyed during callback */
- }
- /* If nothing is returned, re-use the old event value */
- ret = luaL_optinteger(L, -2, event);
- /* Clone the old timeout value in case a new one wasn't set */
- memcpy(&new_tv, &cb->timeout, sizeof(new_tv));
- if(lua_isnumber(L, -1)) {
- double newTimeout = lua_tonumber(L, -1);
- if(newTimeout > 0) {
- load_timeval(newTimeout, &new_tv);
+ if(cb->callbackRef != LUA_NOREF) {
+ L = cb->base->loop_L;
+ lua_rawgeti(L, LUA_REGISTRYINDEX, cb->callbackRef);
+ lua_pushinteger(L, event);
+ cb->running = 1;
+ if(lua_pcall(L, 1, 2, 0))
+ {
+ cb->running = 0;
+ cb->base->errorMessage = luaL_ref(L, LUA_REGISTRYINDEX);
+ event_base_loopbreak(cb->base->base);
+ lua_pop(L, 1); /* Pop the 'false' from pcall */
+ return;
}
+ cb->running = 0;
+ /* If nothing is returned, re-use the old event value */
+ ret = luaL_optinteger(L, -2, event);
}
- lua_pop(L, 2);
- if(ret == -1) {
- freeCallbackArgs(cb, L);
- } else {
- struct event *ev = &cb->ev;
- int newEvent = ret;
- if( newEvent != event || (cb->timeout.tv_sec != new_tv.tv_sec || cb->timeout.tv_usec != new_tv.tv_usec) ) {
- struct timeval *ptv = &cb->timeout;
- cb->timeout = new_tv;
- event_del(ev);
- event_set(ev, fd, EV_PERSIST | newEvent, luaevent_callback, cb);
- /* Assume cannot set a new timeout.. */
- event_add(ev, ptv);
+ if(ret == -1 || cb->callbackRef == LUA_NOREF) {
+ event_del(ev);
+ freeCallback(cb, L);
+ assert(cb->selfRef != LUA_NOREF);
+ luaL_unref(L, LUA_REGISTRYINDEX, cb->selfRef);
+ cb->selfRef = LUA_NOREF;
+ } else if( ret != event || (cb->timeout.tv_sec != new_tv.tv_sec || cb->timeout.tv_usec != new_tv.tv_usec) ) {
+ /* Clone the old timeout value in case a new one wasn't set */
+ memcpy(&new_tv, &cb->timeout, sizeof(new_tv));
+ if(lua_isnumber(L, -1)) {
+ double newTimeout = lua_tonumber(L, -1);
+ if(newTimeout > 0) {
+ load_timeval(newTimeout, &new_tv);
+ }
}
+ struct timeval *ptv = &cb->timeout;
+ cb->timeout = new_tv;
+ event_del(ev);
+ event_set(ev, fd, EV_PERSIST | ret, luaevent_callback, cb);
+ /* Assume cannot set a new timeout.. */
+ event_add(ev, ptv);
}
+ lua_pop(L, 2); /* Pop two results from call */
}
static int luaevent_cb_gc(lua_State* L) {
- le_callback* arg = luaL_checkudata(L, 1, EVENT_CALLBACK_ARG_MT);
- freeCallbackArgs(arg, L);
+ freeCallback(luaL_checkudata(L, 1, EVENT_CALLBACK_ARG_MT), L);
+ return 0;
+}
+
+static int luaevent_cb_close(lua_State* L) {
+ le_callback *cb = luaL_checkudata(L, 1, EVENT_CALLBACK_ARG_MT);
+ if(!cb->running)
+ event_del(&cb->ev);
+ freeCallback(cb, L); // Release reference to Lua callback
return 0;
}
@@ -104,6 +105,9 @@ le_callback* event_callback_push(lua_State* L, int baseIdx, int callbackIdx) {
le_base *base = event_base_get(L, baseIdx);
luaL_checktype(L, callbackIdx, LUA_TFUNCTION);
cb = lua_newuserdata(L, sizeof(*cb));
+ lua_pushvalue(L, -1);
+ cb->selfRef = luaL_ref(L, LUA_REGISTRYINDEX);
+ cb->running = 0;
luaL_getmetatable(L, EVENT_CALLBACK_ARG_MT);
lua_setmetatable(L, -2);
@@ -119,7 +123,7 @@ void event_callback_register(lua_State* L) {
lua_pushcfunction(L, luaevent_cb_gc);
lua_setfield(L, -2, "__gc");
lua_newtable(L);
- lua_pushcfunction(L, luaevent_cb_gc);
+ lua_pushcfunction(L, luaevent_cb_close);
lua_setfield(L, -2, "close");
lua_setfield(L, -2, "__index");
lua_pop(L, 1);
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