--
-- 用户操作锁
--

local skynet = require "skynet"
local coroutine = coroutine
local xpcall = xpcall
local traceback = debug.traceback
local table = table

local queue = {
	queue = {}
}

function queue.critical_section(uid)
	local pq = queue.queue[uid]
	if pq == nil then
		pq = {ref = 0, thread_queue = {}}
		queue.queue[uid] = pq
	end

	local function xpcall_ret(ok, ...)
		pq.ref = pq.ref - 1
		if pq.ref == 0 then
			pq.current_thread = table.remove(pq.thread_queue, 1)
			if pq.current_thread then
				skynet.wakeup(pq.current_thread)
			end
		end
		assert(ok, (...))
		return ...
	end

	return function(f, ...)
		local thread = coroutine.running()
		if pq.current_thread and pq.current_thread ~= thread then
			table.insert(pq.thread_queue, thread)
			skynet.wait()
			assert(pq.ref == 0) -- current_thread == thread
		end
		pq.current_thread = thread

		pq.ref = pq.ref + 1
		return xpcall_ret(xpcall(f, traceback, ...))
	end
end

return queue