mirror of https://github.com/knative/pkg.git
85 lines
2.1 KiB
Go
85 lines
2.1 KiB
Go
/*
|
|
Copyright 2018 The Knative Authors
|
|
|
|
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 signals
|
|
|
|
import (
|
|
"context"
|
|
"os"
|
|
"os/signal"
|
|
"time"
|
|
)
|
|
|
|
var onlyOneSignalHandler = make(chan struct{})
|
|
|
|
// SetupSignalHandler registered for SIGTERM and SIGINT. A stop channel is returned
|
|
// which is closed on one of these signals. If a second signal is caught, the program
|
|
// is terminated with exit code 1.
|
|
func SetupSignalHandler() (stopCh <-chan struct{}) {
|
|
close(onlyOneSignalHandler) // panics when called twice
|
|
|
|
stop := make(chan struct{})
|
|
c := make(chan os.Signal, 2)
|
|
signal.Notify(c, shutdownSignals...)
|
|
go func() {
|
|
<-c
|
|
close(stop)
|
|
<-c
|
|
os.Exit(1) // second signal. Exit directly.
|
|
}()
|
|
|
|
return stop
|
|
}
|
|
|
|
// NewContext creates a new context with SetupSignalHandler()
|
|
// as our Done() channel.
|
|
func NewContext() context.Context {
|
|
return &signalContext{stopCh: SetupSignalHandler()}
|
|
}
|
|
|
|
type signalContext struct {
|
|
stopCh <-chan struct{}
|
|
}
|
|
|
|
// Deadline implements context.Context
|
|
func (scc *signalContext) Deadline() (deadline time.Time, ok bool) {
|
|
return
|
|
}
|
|
|
|
// Done implements context.Context
|
|
func (scc *signalContext) Done() <-chan struct{} {
|
|
return scc.stopCh
|
|
}
|
|
|
|
// Err implements context.Context. If the underlying stop channel is closed, Err
|
|
// always returns context.Canceled, and nil otherwise.
|
|
func (scc *signalContext) Err() error {
|
|
select {
|
|
case _, ok := <-scc.Done():
|
|
if !ok {
|
|
// TODO: revisit this behavior when Deadline() implementation is changed
|
|
return context.Canceled
|
|
}
|
|
default:
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// Value implements context.Context
|
|
func (scc *signalContext) Value(key interface{}) interface{} {
|
|
return nil
|
|
}
|