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package signal
import (
"fmt"
"os"
gosignal "os/signal"
"path/filepath"
"runtime"
"strings"
"sync/atomic"
"syscall"
"time"
"github.com/Sirupsen/logrus"
"github.com/pkg/errors"
)
// Trap sets up a simplified signal "trap", appropriate for common
// behavior expected from a vanilla unix command-line tool in general
// (and the Docker engine in particular).
//
// * If SIGINT or SIGTERM are received, `cleanup` is called, then the process is terminated.
// * If SIGINT or SIGTERM are received 3 times before cleanup is complete, then cleanup is
// skipped and the process is terminated immediately (allows force quit of stuck daemon)
// * A SIGQUIT always causes an exit without cleanup, with a goroutine dump preceding exit.
// * Ignore SIGPIPE events. These are generated by systemd when journald is restarted while
// the docker daemon is not restarted and also running under systemd.
// Fixes https://github.com/docker/docker/issues/19728
//
func Trap(cleanup func()) {
c := make(chan os.Signal, 1)
// we will handle INT, TERM, QUIT, SIGPIPE here
signals := []os.Signal{os.Interrupt, syscall.SIGTERM, syscall.SIGQUIT, syscall.SIGPIPE}
gosignal.Notify(c, signals...)
go func() {
interruptCount := uint32(0)
for sig := range c {
if sig == syscall.SIGPIPE {
continue
}
go func(sig os.Signal) {
logrus.Infof("Processing signal '%v'", sig)
switch sig {
case os.Interrupt, syscall.SIGTERM:
if atomic.LoadUint32(&interruptCount) < 3 {
// Initiate the cleanup only once
if atomic.AddUint32(&interruptCount, 1) == 1 {
// Call the provided cleanup handler
cleanup()
os.Exit(0)
} else {
return
}
} else {
// 3 SIGTERM/INT signals received; force exit without cleanup
logrus.Info("Forcing docker daemon shutdown without cleanup; 3 interrupts received")
}
case syscall.SIGQUIT:
DumpStacks("")
logrus.Info("Forcing docker daemon shutdown without cleanup on SIGQUIT")
}
//for the SIGINT/TERM, and SIGQUIT non-clean shutdown case, exit with 128 + signal #
os.Exit(128 + int(sig.(syscall.Signal)))
}(sig)
}
}()
}
const stacksLogNameTemplate = "goroutine-stacks-%s.log"
// DumpStacks appends the runtime stack into file in dir and returns full path
// to that file.
func DumpStacks(dir string) (string, error) {
var (
buf []byte
stackSize int
)
bufferLen := 16384
for stackSize == len(buf) {
buf = make([]byte, bufferLen)
stackSize = runtime.Stack(buf, true)
bufferLen *= 2
}
buf = buf[:stackSize]
var f *os.File
if dir != "" {
path := filepath.Join(dir, fmt.Sprintf(stacksLogNameTemplate, strings.Replace(time.Now().Format(time.RFC3339), ":", "", -1)))
var err error
f, err = os.OpenFile(path, os.O_CREATE|os.O_WRONLY, 0666)
if err != nil {
return "", errors.Wrap(err, "failed to open file to write the goroutine stacks")
}
defer f.Close()
defer f.Sync()
} else {
f = os.Stderr
}
if _, err := f.Write(buf); err != nil {
return "", errors.Wrap(err, "failed to write goroutine stacks")
}
return f.Name(), nil
}
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