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tangled.org/core
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cmd/grace/main.go
Signed-off-by: Seongmin Lee <git@boltless.me>
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cmd/grace/main.go
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cmd/grace/main.go
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package main
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import (
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"context"
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"fmt"
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"log"
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"net"
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"net/http"
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"os"
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"os/signal"
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"sync"
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"syscall"
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"time"
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)
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type Config struct {
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Host string
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Port string
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}
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func NewConfig() Config {
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return Config{
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Host: "127.0.0.1",
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Port: "8080",
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}
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}
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func run(ctx context.Context) error {
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ctx, stop := signal.NotifyContext(ctx, syscall.SIGINT, syscall.SIGTERM)
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defer stop()
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// setup process
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cfg := NewConfig()
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httpServer := &http.Server{
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Addr: net.JoinHostPort(cfg.Host, cfg.Port),
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Handler: NewRoute(),
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BaseContext: func(l net.Listener) context.Context {
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return ctx
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},
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}
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go func() {
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log.Printf("listening on %s\n", httpServer.Addr)
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if err := httpServer.ListenAndServe(); err != nil && err != http.ErrServerClosed {
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fmt.Fprintf(os.Stderr, "error listening and serving: %s\n", err)
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}
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}()
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log.Println("server intialized successfully")
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// listen to signal
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<-ctx.Done()
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stop() // allow second CTRL-C to forcefully terminate the process
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// graceful shutdown
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func() {
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// new context from background for graceful shutdown
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ctx, cancel := context.WithTimeout(context.Background(), 25*time.Second)
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defer cancel()
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var wg sync.WaitGroup
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wg.Go(func() {
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log.Println("graceful http server shutdown")
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if err := httpServer.Shutdown(ctx); err != nil {
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fmt.Fprintf(os.Stderr, "error shutting down http server: %s\n", err)
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}
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})
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wg.Go(func() {
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log.Println("graceful backgroud job shutdown")
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select {
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case <-ctx.Done():
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ctx.Err()
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case <-time.After(8 * time.Second):
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}
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})
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wg.Wait()
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log.Println("server exited gracefully")
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}()
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return nil
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}
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func NewRoute() http.Handler {
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mux := http.NewServeMux()
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mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
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for range 15 {
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log.Println("serving...")
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time.Sleep(2 * time.Second);
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}
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w.WriteHeader(http.StatusOK)
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})
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return mux
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}
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func main() {
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ctx := context.Background()
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if err := run(ctx); err != nil {
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fmt.Fprintf(os.Stderr, "%s\n", err)
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os.Exit(1)
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}
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}