Sleep for unused tick time & optional realtime

- Optional luasocket dependency for realtime measurements (instead of CPU time)
- lua_async.run() will wait for the time to be ready

events.lua

@@ -9,7 +9,7 @@ function Event(type, data)
 		type = type,
 		data = data,
 		defaultPrevented = false,
-		timeStamp = os.clock(),
+		timeStamp = lua_async.clock(),
 	}, {__index = EventPrototype})
 end
 

init.lua

@@ -1,5 +1,13 @@
 lua_async = {}
 
+if rawget(_G, "require") then
+	lua_async.socket = require("socket")
+end
+
+function lua_async.clock()
+	return lua_async.socket and lua_async.socket.gettime() or os.clock()
+end
+
 function lua_async.step(dtime)
 	-- timers phase
 	lua_async.timeouts.step(dtime)

limiting.lua

@@ -13,7 +13,7 @@ function lua_async.set_limit(ms)
 
 	lua_async.limiting.pool[co] = {
 		limit = limit,
-		next_yield = os.clock() + limit,
+		next_yield = lua_async.clock() + limit,
 	}
 end
 
@@ -26,9 +26,9 @@ function lua_async.check_limit()
 	local co = assert(coroutine.running(), "check_limit called outside of an async function")
 	local limit = lua_async.limiting.pool[co]
 
-	if limit and os.clock() >= limit.next_yield then
+	if limit and lua_async.clock() >= limit.next_yield then
 		lua_async.yield()
-		limit.next_yield = os.clock() + limit.limit
+		limit.next_yield = lua_async.clock() + limit.limit
 		return true
 	end
 

util.lua

@@ -27,13 +27,30 @@ function lua_async.resume(co)
 end
 
 function lua_async.run()
-	local last_time = os.clock()
+	assert(lua_async.socket)
+	local last_time = lua_async.clock()
 
 	while true do
-		local current_time = os.clock()
+		local current_time = lua_async.clock()
 		local dtime = current_time - last_time
 		last_time = current_time
 
 		lua_async.step(dtime)
+
+		local next = math.huge
+
+		for _, timeout in pairs(lua_async.timeouts.pool)
+			next = math.min(next, timeout.time_left)
+		end
+
+		for _, interval in pairs(lua_async.intervals.pool)
+			next = math.min(next, interval.time_left)
+		end
+
+		if next == math.huge then
+			return
+		end
+
+		lua_async.socket.sleep(next)
 	end
 end