Skynet 动态控制无状态服务的数量

calculate.lua

-- calculate.lua
local skynet = require "skynet"

local CMD = {}
function CMD.calculate(a, b)
    return a^b
end

function CMD.exit()
    skynet.error("slave exit.")
    skynet.ret()
    skynet.exit()
    -- exit() 之后的代码是不会执行的
end

skynet.start(function()
    skynet.dispatch("lua", function(_,_,cmd, ...)
        local f = CMD[cmd]
        if f then
            skynet.ret(skynet.pack(f(...)))
        else
            error(string.format("Unknown cmd:%s", tostring(cmd)))
        end
    end)
end)

calculate_mng.lua

-- calculate_mng.lua
local skynet = require "skynet"
require "skynet.manager"    -- import skynet.register

-- 存放无状态服务
local SLAVE_SERVICE_NAME = "calculate"
local MASTER_SERVICE_NAME = "calculate_mng"
local slave = {}
local balance = 1

local CMD = {}
-- 找一个 slave 帮忙做点复杂的计算
function CMD.calculate(a, b)
    local s = slave[balance]
    balance = balance + 1
    if balance > #slave then
        balance = 1
    end
    return skynet.call(s, "lua", "calculate", a, b)
end

-- 返回每个 slave 的信息
function CMD.info()
    local msg = string.format("total slave count:%d", #slave)
    return msg
end

-- 重置 slave 的数量(收缩)
-- skynet.call("calculate_mng", "lua", "set_slave_count", 3)
function CMD.set_slave_count(cnt)
    local now_cnt = #slave
    if now_cnt == cnt then
        skynet.error(string.format("slave count is:%d", now_cnt))
        return
    end

    balance = 1
    if now_cnt > cnt then
        local kill_cnt = now_cnt - cnt
        for _=1,kill_cnt do
            local s = slave[#slave]
            skynet.call(s, "lua", "exit")
            table.remove(slave)
        end
        skynet.error(string.format("slave old_cnt:%d, new_cnt:%d", now_cnt, #slave))
        return
    end

    if now_cnt < cnt then
        local add_cnt = cnt - now_cnt
        for _=1,add_cnt do
            table.insert(slave, skynet.newservice(SLAVE_SERVICE_NAME))
        end
        skynet.error(string.format("slave old_cnt:%d, new_cnt:%d", now_cnt, #slave))
        return
    end
end

skynet.start(function()
    skynet.register(MASTER_SERVICE_NAME)
    local instance = 8 -- 默认值可以读取配置

    skynet.dispatch("lua", function(_,_,cmd, ...)
        local f = CMD[cmd]
        if f then
            skynet.ret(skynet.pack(f(...)))
        else
            error(string.format("Unknown cmd:%s", tostring(cmd)))
        end
    end)

    for _=1,instance do
        table.insert(slave, skynet.newservice(SLAVE_SERVICE_NAME))
    end
end)

test.lua

-- test.lua
skynet.start(function()
    skynet.uniqueservice("calculate_mng")
    skynet.exit()
end)