Merge pull request #578 from devlights/add-send-signal-example

Author: devlights

examples/signal/send/Taskfile.yml

@@ -0,0 +1,21 @@
+version: "3"
+
+tasks:
+  default:
+    cmds:
+      - task: run-receiver
+      - ps
+      - task: run-sender
+      - ps
+  run-receiver:
+    dir: receiver
+    cmds:
+      - go clean
+      - go build -o receiver main.go
+      - ./receiver &
+  run-sender:
+    dir: sender
+    cmds:
+      - go clean
+      - go build -o sender main.go
+      - ./sender

examples/signal/send/receiver/.gitignore

@@ -0,0 +1 @@
+receiver

examples/signal/send/receiver/main.go

@@ -0,0 +1,44 @@
+//go:build !windows
+
+// シグナルを受信する側です
+//
+// # 処理手順
+//
+// 		- signal.NotifyContext を利用して SIGTERM をフック
+// 		- シグナルが送信されるのを待機
+//
+// REFERENCES:
+// 		- https://stackoverflow.com/questions/9030680/list-of-currently-running-process-in-go
+package main
+
+import (
+	"context"
+	"log"
+	"os"
+	"os/signal"
+	"syscall"
+	"time"
+)
+
+var (
+	appLog = log.New(os.Stderr, "[receiver] >>> ", 0)
+)
+
+func main() {
+	var (
+		mainCtx          = context.Background()
+		procCtx, procCxl = context.WithTimeout(mainCtx, 10*time.Second)
+	)
+	defer procCxl()
+
+	signalCtx, signalCxl := signal.NotifyContext(procCtx, syscall.SIGTERM)
+	defer signalCxl()
+
+	appLog.Println("wait for SIGTERM")
+	select {
+	case <-procCtx.Done():
+		appLog.Println("timeout")
+	case <-signalCtx.Done():
+		appLog.Println("receive SIGTERM from sender")
+	}
+}

examples/signal/send/sender/.gitignore

@@ -0,0 +1 @@
+sender

examples/signal/send/sender/main.go

@@ -0,0 +1,86 @@
+//go:build !windows
+
+// シグナルを送信する側です
+//
+// # 処理手順
+//
+// 		- receiver プロセスを探して pid を取得
+// 		- 対象 pid に対して SIGTERM を送る
+//
+// REFERENCES:
+// 		- https://stackoverflow.com/questions/9030680/list-of-currently-running-process-in-go
+package main
+
+import (
+	"errors"
+	"log"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"syscall"
+)
+
+const (
+	procName = "receiver"
+)
+
+var (
+	appLog = log.New(os.Stderr, "[sender  ] >>> ", 0)
+)
+
+func main() {
+	pid, err := find(procName)
+	if err != nil {
+		panic(err)
+	}
+
+	if pid == -1 {
+		panic("receiver pid not found")
+	}
+
+	proc, err := os.FindProcess(pid)
+	if err != nil {
+		panic(err)
+	}
+
+	appLog.Printf("send SIGTERM to receiver(%d)", pid)
+	err = proc.Signal(syscall.SIGTERM)
+	if err != nil {
+		panic(err)
+	}
+}
+
+func find(name string) (int, error) {
+	var (
+		matches []string
+		err     error
+		pid     = -1
+	)
+
+	matches, err = filepath.Glob("/proc/*/exe")
+	if err != nil {
+		return pid, err
+	}
+
+	for _, f := range matches {
+		real, err := os.Readlink(f)
+		if err != nil && !errors.Is(err, os.ErrPermission) {
+			return pid, err
+		}
+
+		if len(real) > 0 && strings.Contains(real, "receiver") {
+			dir := filepath.Base(filepath.Dir(f))
+
+			pid, err = strconv.Atoi(dir)
+			if err != nil {
+				return pid, err
+			}
+
+			appLog.Printf("receiver pid is %v\n", pid)
+			break
+		}
+	}
+
+	return pid, nil
+}

examples/signal/sigquit_like_javavm/Taskfile.yml

@@ -0,0 +1,6 @@
+version: "3"
+
+tasks:
+  default:
+    cmds:
+      - go run main.go