Allow timers with an interval of 0 (it means ASAP)

Author: HaroldCindy

VM/src/llltimers.cpp

@@ -122,8 +122,8 @@ static int lltimers_on(lua_State *L)
         luaL_typeerror(L, 3, "function or callable table");
     lua_settop(L, 3);
 
-    if (seconds <= 0.0)
-        luaL_errorL(L, "timer interval must be positive");
+    if (seconds < 0.0)
+        luaL_errorL(L, "timer interval must be positive or 0");
 
     // Get current time
     double current_time = sl_state->clockProvider ? sl_state->clockProvider(L) : 0.0;
@@ -176,8 +176,8 @@ static int lltimers_once(lua_State *L)
         luaL_typeerror(L, 3, "function or callable table");
     lua_settop(L, 3);
 
-    if (seconds <= 0.0)
-        luaL_errorL(L, "timer interval must be positive");
+    if (seconds < 0.0)
+        luaL_errorL(L, "timer interval must be positive or 0");
 
     // Get current time
     double current_time = sl_state->clockProvider ? sl_state->clockProvider(L) : 0.0;

tests/conformance/lltimers.lua

@@ -135,11 +135,15 @@ local success, err = pcall(function()
 end)
 assert(success == false)
 
--- Test zero interval
-success, err = pcall(function()
-    LLTimers:on(0, function() end)
-end)
-assert(success == false)
+-- Test zero interval (0 means "ASAP" and is valid)
+timer1_count = 0
+local function zero_interval_handler()
+    timer1_count += 1
+end
+LLTimers:on(0, zero_interval_handler)
+LLTimers:_tick()
+assert(timer1_count == 1)
+LLTimers:off(zero_interval_handler)
 
 -- Test invalid handler type
 success, err = pcall(function()