Graceful shutdown

To implement a graceful shutdown for a GOCACHEPROG subprocess, listen for the close command in the incoming JSON stream and exit immediately after responding. The go command sends a Request with Command set to CmdClose ("close"), and the subprocess must reply with a Response containing the matching ID before terminating.

package main

import (
	"encoding/json"
	"os"
	"cmd/go/internal/cacheprog"
)

func main() {
	for {
		var req cacheprog.Request
		if err := json.NewDecoder(os.Stdin).Decode(&req); err != nil {
			return
		}

		if req.Command == cacheprog.CmdClose {
			resp := cacheprog.Response{ID: req.ID}
			json.NewEncoder(os.Stdout).Encode(resp)
			os.Exit(0)
		}
		// Handle other commands (put, get) here
	}
}

Graceful shutdown tells your external cache helper program how to shut down cleanly when the Go command is finished. Instead of crashing or hanging, your program waits for a specific "close" signal, sends a quick confirmation back, and then exits. Think of it like a waiter waiting for a customer to finish their meal before clearing the table and leaving.