buildkit/util/appcontext/appcontext.go

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package appcontext
import (
"context"
"os"
"os/signal"
"sync"
"github.com/Sirupsen/logrus"
"golang.org/x/sys/unix"
)
var appContextCache context.Context
var appContextOnce sync.Once
// Context returns a static context that reacts to termination signals of the
// running process. Useful in CLI tools.
func Context() context.Context {
appContextOnce.Do(func() {
signals := make(chan os.Signal, 2048)
signal.Notify(signals, unix.SIGTERM, unix.SIGINT)
const exitLimit = 3
retries := 0
ctx, cancel := context.WithCancel(context.Background())
appContextCache = ctx
go func() {
for {
<-signals
cancel()
retries++
if retries >= exitLimit {
logrus.Errorf("got %d SIGTERM/SIGINTs, forcing shutdown", retries)
os.Exit(1)
}
}
}()
})
return appContextCache
}