100 lines
2.7 KiB
Go
100 lines
2.7 KiB
Go
package main
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import (
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"context"
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"errors"
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"fmt"
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"net"
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"net/http"
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"sync/atomic"
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"time"
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)
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// component 不接管进程信号；宿主负责为每一类生命周期提供独立取消和等待。
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type component struct {
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name string
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run func(context.Context) error
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}
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type completion struct {
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name string
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err error
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}
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// serve 在HTTP监听已成功后启动后台组件；返回前完成HTTP→发送/执行→结果消费的关闭顺序。
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func serve(parent context.Context, listener net.Listener, server *http.Server, ready *atomic.Bool, workers []component, consumer component, grace time.Duration) error {
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workCtx, stopWork := context.WithCancel(context.Background())
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defer stopWork()
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eventCtx, stopEvents := context.WithCancel(context.Background())
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defer stopEvents()
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workDone := make(chan completion, len(workers))
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eventDone := make(chan completion, 1)
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for _, c := range workers {
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go func() { workDone <- completion{c.name, c.run(workCtx)} }()
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}
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go func() { eventDone <- completion{consumer.name, consumer.run(eventCtx)} }()
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httpDone := make(chan error, 1)
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ready.Store(true)
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go func() { httpDone <- server.Serve(listener) }()
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remaining := len(workers)
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eventsPending := true
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var result error
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add := func(c completion) {
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if c.err != nil {
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result = errors.Join(result, fmt.Errorf("%s: %w", c.name, c.err))
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}
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}
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select {
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case <-parent.Done():
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case err := <-httpDone:
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if !errors.Is(err, http.ErrServerClosed) {
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result = errors.Join(result, err)
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}
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case c := <-workDone:
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remaining--
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if c.err == nil {
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c.err = errors.New("unexpected component exit")
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}
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add(c)
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case c := <-eventDone:
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eventsPending = false
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if c.err == nil {
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c.err = errors.New("unexpected component exit")
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}
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add(c)
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}
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ready.Store(false)
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// 用新的关闭上下文；进程信号的context此时可能已取消，不能用它调用Shutdown。
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shut, cancel := context.WithTimeout(context.Background(), grace)
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if err := server.Shutdown(shut); err != nil {
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result = errors.Join(result, fmt.Errorf("http shutdown: %w", err))
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_ = server.Close()
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}
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cancel()
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stopWork()
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deadline := time.NewTimer(grace)
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defer deadline.Stop()
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for remaining > 0 {
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select {
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case c := <-workDone:
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remaining--
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add(c)
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case <-deadline.C:
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result = errors.Join(result, errors.New("background shutdown deadline exceeded"))
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remaining = 0
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}
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}
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// 结果消费器最后停止。仍未投递的结果会在重启后由持久订阅恢复，不以本地空闲判断全局完成。
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stopEvents()
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if eventsPending {
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timer := time.NewTimer(grace)
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defer timer.Stop()
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select {
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case c := <-eventDone:
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add(c)
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case <-timer.C:
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result = errors.Join(result, errors.New("consumer shutdown deadline exceeded"))
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}
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}
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return result
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}
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