MEDIUM: lua: interrupt the Lua execution for running other process
This patch permits to interrupt the Lua execution each n# of
instructions. It is useful for controling the execution time
of an Lua code, and permits at the HAProxy schedule to process
some others tasks waiting execution.
diff --git a/src/hlua.c b/src/hlua.c
index ef55922..0e0ad12 100644
--- a/src/hlua.c
+++ b/src/hlua.c
@@ -87,6 +87,33 @@
static unsigned int hlua_timeout_session = 4000; /* session timeout. */
static unsigned int hlua_timeout_task = TICK_ETERNITY; /* task timeout. */
+/* Interrupts the Lua processing each "hlua_nb_instruction" instructions.
+ * it is used for preventing infinite loops.
+ *
+ * I test the scheer with an infinite loop containing one incrementation
+ * and one test. I run this loop between 10 seconds, I raise a ceil of
+ * 710M loops from one interrupt each 9000 instructions, so I fix the value
+ * to one interrupt each 10 000 instructions.
+ *
+ * configured | Number of
+ * instructions | loops executed
+ * between two | in milions
+ * forced yields |
+ * ---------------+---------------
+ * 10 | 160
+ * 500 | 670
+ * 1000 | 680
+ * 5000 | 700
+ * 7000 | 700
+ * 8000 | 700
+ * 9000 | 710 <- ceil
+ * 10000 | 710
+ * 100000 | 710
+ * 1000000 | 710
+ *
+ */
+static unsigned int hlua_nb_instruction = 10000;
+
/* These functions converts types between HAProxy internal args or
* sample and LUA types. Another function permits to check if the
* LUA stack contains arguments according with an required ARG_T
@@ -620,6 +647,11 @@
return 1;
}
+void hlua_hook(lua_State *L, lua_Debug *ar)
+{
+ hlua_yieldk(L, 0, 0, NULL, TICK_ETERNITY, HLUA_CTRLYIELD);
+}
+
/* This function start or resumes the Lua stack execution. If the flag
* "yield_allowed" if no set and the LUA stack execution returns a yield
* The function return an error.
@@ -642,6 +674,13 @@
HLUA_SET_RUN(lua);
+resume_execution:
+
+ /* This hook interrupts the Lua processing each 'hlua_nb_instruction'
+ * instructions. it is used for preventing infinite loops.
+ */
+ lua_sethook(lua->T, hlua_hook, LUA_MASKCOUNT, hlua_nb_instruction);
+
/* Call the function. */
ret = lua_resume(lua->T, gL.T, lua->nargs);
switch (ret) {
@@ -651,6 +690,31 @@
break;
case LUA_YIELD:
+ /* If the yield id received join to the flag HLUA_CTRLYIELD,
+ * we check the Lua timeout execution.
+ */
+ if (HLUA_IS_CTRLYIELDING(lua)) {
+ /* If the timeout is expired, we break the Lua execution. */
+ if (tick_is_expired(lua->expire, now_ms)) {
+ lua_settop(lua->T, 0); /* Empty the stack. */
+ if (!lua_checkstack(lua->T, 1)) {
+ ret = HLUA_E_ERR;
+ break;
+ }
+ lua_pushfstring(lua->T, "execution timeout");
+ ret = HLUA_E_ERRMSG;
+ break;
+ }
+ /* if the general yield is not allowed or if no task were
+ * associated this the current Lua execution coroutine, we
+ * resume the execution.
+ */
+ if (!yield_allowed || !lua->task)
+ goto resume_execution;
+ /* Re-schedule the task. */
+ task_wakeup(lua->task, TASK_WOKEN_MSG);
+
+ }
if (!yield_allowed) {
lua_settop(lua->T, 0); /* Empty the stack. */
if (!lua_checkstack(lua->T, 1)) {
@@ -3358,6 +3422,20 @@
file, line, err, &hlua_timeout_task);
}
+static int hlua_forced_yield(char **args, int section_type, struct proxy *curpx,
+ struct proxy *defpx, const char *file, int line,
+ char **err)
+{
+ char *error;
+
+ hlua_nb_instruction = strtoll(args[1], &error, 10);
+ if (*error != '\0') {
+ memprintf(err, "%s: invalid number", args[0]);
+ return -1;
+ }
+ return 0;
+}
+
/* This function is called by the main configuration key "lua-load". It loads and
* execute an lua file during the parsing of the HAProxy configuration file. It is
* the main lua entry point.
@@ -3416,6 +3494,7 @@
{ CFG_GLOBAL, "lua-load", hlua_load },
{ CFG_GLOBAL, "tune.lua.session-timeout", hlua_session_timeout },
{ CFG_GLOBAL, "tune.lua.task-timeout", hlua_task_timeout },
+ { CFG_GLOBAL, "tune.lua.forced-yield", hlua_forced_yield },
{ 0, NULL, NULL },
}};