pkg/server/signal.go

// Copyright 2022 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package server

import (
	"context"
	"os"
	"os/signal"
	"syscall"
)

var onlyOneSignalHandler = make(chan struct{})
var shutdownHandler chan os.Signal

// Only one of SetupSignalContext should be called, and only can
// be called once.
func SetupSignalContext() context.Context {
	close(onlyOneSignalHandler)

	shutdownHandler = make(chan os.Signal, 2)

	ctx, cancel := context.WithCancel(context.Background())
	signal.Notify(shutdownHandler, syscall.SIGINT, syscall.SIGTERM)
	go func() {
		<-shutdownHandler
		cancel()
		<-shutdownHandler
		os.Exit(1) // second signal. Exit directly.
	}()

	return ctx
}