Process requests using a zero-delay timer

README.md

@@ -85,6 +85,14 @@ The value is passed to libcurl as-is and is not checked for validity by CHTTP,
 so make sure to review the documentation for
 [libcurl's CURLOPT_INTERFACE option](https://curl.se/libcurl/c/CURLOPT_INTERFACE.html).
 
+### Zero-delay timers
+
+CHTTP has switched to using a zero-delay timer instead of a hook to allow for running
+requests while in singleplayer or while the server is hibernating.
+
+In case there are any issues (bug reports greatly appreciated), you can return to
+using the old hooking method by setting the environment variable `CHTTP_FORCE_HOOK`.
+
 ## Addon development
 
 This is only required for developers who want to use CHTTP in their addons.

src/chttp.cpp

@@ -136,7 +136,13 @@ GMOD_MODULE_OPEN() {
 	// Pop the global table from the stack again
 	LUA->Pop();
 
-	registerHook(LUA, "Think", "__chttpThinkHook", threadingDoThink);
+	if (getenv("CHTTP_FORCE_HOOK")) {
+		Logger::msg("Processing requests using a hook...");
+		registerHook(LUA, "Think", "__chttpThinkHook", threadingDoThink);
+	} else {
+		Logger::msg("Processing requests using a zero-delay timer...");
+		registerZeroDelayTimer(LUA, "__chttpThinkTimer", threadingDoThink);
+	}
 
 	// Start the background thread
 	RequestWorker::the();

src/lua.cpp

@@ -48,6 +48,19 @@ void luaTableToMap(GarrysMod::Lua::ILuaBase *LUA, int index, std::map<std::strin
 	}
 }
 
+void registerZeroDelayTimer(GarrysMod::Lua::ILuaBase *LUA, char const* identifier, GarrysMod::Lua::CFunc function) {
+	LUA->PushSpecial(GarrysMod::Lua::SPECIAL_GLOB);
+	LUA->GetField(-1, "timer");
+	LUA->GetField(-1, "Create");
+	LUA->PushString(identifier);
+	LUA->PushNumber(0);
+	LUA->PushNumber(0);
+	LUA->PushCFunction(function);
+	LUA->Call(4, 0);
+	LUA->Pop();
+	LUA->Pop();
+}
+
 void registerHook(GarrysMod::Lua::ILuaBase *LUA, char const* event, char const* identifier, GarrysMod::Lua::CFunc function) {
 	// We are working on the global table today
 	LUA->PushSpecial(GarrysMod::Lua::SPECIAL_GLOB);

src/lua.h

@@ -9,4 +9,6 @@ void mapToLuaTable(GarrysMod::Lua::ILuaBase *LUA, const std::map<std::string, st
 
 void luaTableToMap(GarrysMod::Lua::ILuaBase *LUA, int index, std::map<std::string, std::string> &map);
 
+void registerZeroDelayTimer(GarrysMod::Lua::ILuaBase *LUA, char const* identifier, GarrysMod::Lua::CFunc function);
+
 void registerHook(GarrysMod::Lua::ILuaBase *LUA, char const* event, char const* identifier, GarrysMod::Lua::CFunc function);