Activities

Activity 是执行非确定性操作的函数。任何 function.lua 或 process.lua 条目都可以通过添加元数据注册为 Temporal activity。

注册 Activity

添加 meta.temporal.activity 将函数注册为 activity：

- name: charge_payment
  kind: function.lua
  source: file://payment.lua
  method: charge
  modules:
    - http_client
    - json
  meta:
    temporal:
      activity:
        worker: app:worker

元数据字段

实现

Activity 是普通的 Lua 函数：

-- payment.lua
local http = require("http_client")
local json = require("json")

local function charge(input)
    local response, err = http.post("https://api.stripe.com/v1/charges", {
        headers = {
            ["Authorization"] = "Bearer " .. input.api_key,
            ["Content-Type"] = "application/json"
        },
        body = json.encode({
            amount = input.amount,
            currency = input.currency,
            source = input.token
        })
    })

    if err then
        return nil, err
    end

    return json.decode(response:body())
end

return { charge = charge }

调用 Activity

在 workflow 中，使用 funcs 模块：

local funcs = require("funcs")

local result, err = funcs.call("app:charge_payment", {
    amount = 5000,
    currency = "usd",
    token = "tok_visa",
    api_key = ctx.stripe_key
})

if err then
    return nil, err
end

Activity 选项

使用执行器构建器配置超时、重试行为和其他执行参数：

local funcs = require("funcs")

local executor = funcs.new():with_options({
    ["activity.start_to_close_timeout"] = "30s",
    ["activity.schedule_to_close_timeout"] = "5m",
    ["activity.heartbeat_timeout"] = "10s",
    ["activity.retry_policy"] = {
        maximum_attempts = 3,
        initial_interval = 1000,
        backoff_coefficient = 2.0,
        maximum_interval = 60000,
    }
})

local result, err = executor:call("app:charge_payment", input)

执行器不可变且可复用。构建一次即可用于多次调用：

local reliable = funcs.new():with_options({
    ["activity.start_to_close_timeout"] = "60s",
    ["activity.retry_policy"] = {
        maximum_attempts = 5,
        initial_interval = 2000,
        backoff_coefficient = 2.0,
        maximum_interval = 120000,
    }
})

local a, err = reliable:call("app:step_one", input)
local b, err = reliable:call("app:step_two", a)

选项参考

Duration 值可使用字符串（"5s"、"10m"、"1h"）或以毫秒为单位的数字。

重试策略

为失败的 activity 配置自动重试行为：

["activity.retry_policy"] = {
    initial_interval = 1000,         -- ms before first retry
    backoff_coefficient = 2.0,       -- multiplier for each retry
    maximum_interval = 300000,       -- max interval between retries (ms)
    maximum_attempts = 10,           -- max retry attempts (0 = unlimited)
    non_retryable_error_types = {    -- errors that skip retries
        "INVALID",
        "PERMISSION_DENIED"
    }
}

超时关系

|--- schedule_to_close_timeout --------------------------------|
|--- schedule_to_start_timeout ---|--- start_to_close_timeout -|
     (waiting in queue)                (executing)

• start_to_close_timeout：activity 本身可运行的最长时间。这是最常用的超时设置。
• schedule_to_close_timeout：从 activity 调度到完成的总时间，包括队列等待时间和重试。
• schedule_to_start_timeout：activity 在任务队列中等待 worker 接取的最长时间。
• heartbeat_timeout：对于长时间运行的 activity，两次 heartbeat 报告之间的最长间隔。

本地 Activity

本地 activity 在 workflow worker 进程中执行，无需单独的任务队列轮询：

- name: validate_input
  kind: function.lua
  source: file://validate.lua
  method: validate
  modules:
    - json
  meta:
    temporal:
      activity:
        worker: app:worker
        local: true

特点：

• 在 workflow worker 进程中执行
• 延迟更低（无任务队列往返）
• 无单独任务队列开销
• 仅限短时执行
• 无 heartbeat 机制

适合快速、短时的操作，如输入验证、数据转换或缓存查找。

Activity 命名

Activity 以其完整条目 ID 作为名称注册：

namespace: app
entries:
  - name: charge_payment
    kind: function.lua
    # ...

Activity 名称：app:charge_payment

上下文传播

启动 workflow 时设置的上下文值在 activity 内部可用：

-- Spawner sets context
local spawner = process.with_context({
    user_id = "user-1",
    tenant = "tenant-1",
})
local pid = spawner:spawn("app:order_workflow", "app:worker", order)

-- Activity reads context
local ctx = require("ctx")

local function process_order(input)
    local user_id = ctx.get("user_id")   -- "user-1"
    local tenant = ctx.get("tenant")     -- "tenant-1"
    -- use context for authorization, logging, etc.
end

通过 funcs.new():with_context() 调用的 activity 也会传播上下文：

-- Inside workflow
local executor = funcs.new():with_context({trace_id = "abc-123"})
local result, err = executor:call("app:charge_payment", input)

错误处理

通过标准 Lua 模式返回错误：

local errors = require("errors")

local function charge(input)
    if not input.amount or input.amount <= 0 then
        return nil, errors.new("INVALID", "amount must be positive")
    end

    local response, err = http.post(url, options)
    if err then
        return nil, errors.wrap(err, "payment API failed")
    end

    if response:status() >= 400 then
        return nil, errors.new("FAILED", "payment declined")
    end

    return json.decode(response:body())
end

错误对象

传播到 workflow 的 activity 错误携带结构化元数据：

local result, err = funcs.call("app:charge_payment", input)
if err then
    err:kind()       -- error classification string
    err:retryable()  -- boolean, whether retry makes sense
    err:message()    -- human-readable error message
end

故障模式

local executor = funcs.new():with_options({
    ["activity.retry_policy"] = {maximum_attempts = 1}
})

local result, err = executor:call("app:missing_activity", input)
if err then
    print(err:kind())      -- "NOT_FOUND"
    print(err:retryable())  -- false
end

Process Activity

process.lua 条目也可以注册为 activity，用于长时间运行的操作：

- name: long_task
  kind: process.lua
  source: file://long_task.lua
  method: main
  modules:
    - http_client
  meta:
    temporal:
      activity:
        worker: app:worker

另请参阅

• Overview - 配置
• Workflows - Workflow 实现
• Functions - 函数模块
• Error Handling - 错误类型与模式