github.com/jingleWang/moby@v1.13.1/pkg/signal/trap.go (about)

     1  package signal
     2  
     3  import (
     4  	"fmt"
     5  	"os"
     6  	gosignal "os/signal"
     7  	"path/filepath"
     8  	"runtime"
     9  	"strings"
    10  	"sync/atomic"
    11  	"syscall"
    12  	"time"
    13  
    14  	"github.com/Sirupsen/logrus"
    15  	"github.com/pkg/errors"
    16  )
    17  
    18  // Trap sets up a simplified signal "trap", appropriate for common
    19  // behavior expected from a vanilla unix command-line tool in general
    20  // (and the Docker engine in particular).
    21  //
    22  // * If SIGINT or SIGTERM are received, `cleanup` is called, then the process is terminated.
    23  // * If SIGINT or SIGTERM are received 3 times before cleanup is complete, then cleanup is
    24  //   skipped and the process is terminated immediately (allows force quit of stuck daemon)
    25  // * A SIGQUIT always causes an exit without cleanup, with a goroutine dump preceding exit.
    26  // * Ignore SIGPIPE events. These are generated by systemd when journald is restarted while
    27  //   the docker daemon is not restarted and also running under systemd.
    28  //   Fixes https://github.com/docker/docker/issues/19728
    29  //
    30  func Trap(cleanup func()) {
    31  	c := make(chan os.Signal, 1)
    32  	// we will handle INT, TERM, QUIT, SIGPIPE here
    33  	signals := []os.Signal{os.Interrupt, syscall.SIGTERM, syscall.SIGQUIT, syscall.SIGPIPE}
    34  	gosignal.Notify(c, signals...)
    35  	go func() {
    36  		interruptCount := uint32(0)
    37  		for sig := range c {
    38  			if sig == syscall.SIGPIPE {
    39  				continue
    40  			}
    41  
    42  			go func(sig os.Signal) {
    43  				logrus.Infof("Processing signal '%v'", sig)
    44  				switch sig {
    45  				case os.Interrupt, syscall.SIGTERM:
    46  					if atomic.LoadUint32(&interruptCount) < 3 {
    47  						// Initiate the cleanup only once
    48  						if atomic.AddUint32(&interruptCount, 1) == 1 {
    49  							// Call the provided cleanup handler
    50  							cleanup()
    51  							os.Exit(0)
    52  						} else {
    53  							return
    54  						}
    55  					} else {
    56  						// 3 SIGTERM/INT signals received; force exit without cleanup
    57  						logrus.Info("Forcing docker daemon shutdown without cleanup; 3 interrupts received")
    58  					}
    59  				case syscall.SIGQUIT:
    60  					DumpStacks("")
    61  					logrus.Info("Forcing docker daemon shutdown without cleanup on SIGQUIT")
    62  				}
    63  				//for the SIGINT/TERM, and SIGQUIT non-clean shutdown case, exit with 128 + signal #
    64  				os.Exit(128 + int(sig.(syscall.Signal)))
    65  			}(sig)
    66  		}
    67  	}()
    68  }
    69  
    70  const stacksLogNameTemplate = "goroutine-stacks-%s.log"
    71  
    72  // DumpStacks appends the runtime stack into file in dir and returns full path
    73  // to that file.
    74  func DumpStacks(dir string) (string, error) {
    75  	var (
    76  		buf       []byte
    77  		stackSize int
    78  	)
    79  	bufferLen := 16384
    80  	for stackSize == len(buf) {
    81  		buf = make([]byte, bufferLen)
    82  		stackSize = runtime.Stack(buf, true)
    83  		bufferLen *= 2
    84  	}
    85  	buf = buf[:stackSize]
    86  	var f *os.File
    87  	if dir != "" {
    88  		path := filepath.Join(dir, fmt.Sprintf(stacksLogNameTemplate, strings.Replace(time.Now().Format(time.RFC3339), ":", "", -1)))
    89  		var err error
    90  		f, err = os.OpenFile(path, os.O_CREATE|os.O_WRONLY, 0666)
    91  		if err != nil {
    92  			return "", errors.Wrap(err, "failed to open file to write the goroutine stacks")
    93  		}
    94  		defer f.Close()
    95  		defer f.Sync()
    96  	} else {
    97  		f = os.Stderr
    98  	}
    99  	if _, err := f.Write(buf); err != nil {
   100  		return "", errors.Wrap(err, "failed to write goroutine stacks")
   101  	}
   102  	return f.Name(), nil
   103  }