【运维发布】熔断机制：依赖故障的自动隔离与恢复

local CIRCUIT = { state = "closed", failCnt = 0, lastFail = 0 }
local FAIL_THRESHOLD = 5
local TIMEOUT_MS = 30000
local function call(failFn, successFn)
    if CIRCUIT.state == "open" then
        if os.time() - CIRCUIT.lastFail > TIMEOUT_MS / 1000 then
            CIRCUIT.state = "half-open"
        else
            successFn()
            return
        end
    end
    local ok = pcall(failFn)
    if ok then
        CIRCUIT.state = "closed"
        CIRCUIT.failCnt = 0
    else
        CIRCUIT.failCnt = CIRCUIT.failCnt + 1
        CIRCUIT.lastFail = os.time()
        if CIRCUIT.failCnt >= FAIL_THRESHOLD then
            CIRCUIT.state = "open"
        end
    end
end

local fallbackResponse = { code = 503, msg = "服务暂时不可用，请稍后重试" }
local function degradedCall()
    return fallbackResponse
end
local function probe()
    CIRCUIT.state = "half-open"
    local ok = pcall(callDependency)
    if ok then
        CIRCUIT.state = "closed"
        sendcentermsg("依赖服务已恢复，熔断关闭")
    else
        CIRCUIT.state = "open"
        CIRCUIT.lastFail = os.time()
    end
end