asteris-llc/converge

// Copyright © 2016 Asteris, 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 cmd

import (
    "os"
    "os/signal"

    log "github.com/Sirupsen/logrus"
    "golang.org/x/net/context"
)

// GracefulExit traps interrupt signals for a graceful exit
func GracefulExit(cancel context.CancelFunc) {
    go GracefulExitBlocking(cancel)
}

// GracefulExitBlocking handles graceful exits, and blocks until exit
func GracefulExitBlocking(cancel context.CancelFunc) {
    c := make(chan os.Signal, 1)
    signal.Notify(c, os.Interrupt)

    interruptCount := 0

    for range c {
        interruptCount++

        switch interruptCount {
        case 1:
            log.Info("gracefully shutting down (interrupt again to halt)")
            cancel()
        case 2:
            log.Warn("hard stop! System may be left in an incomplete state")
            os.Exit(2)
        }
    }
}