Initial commit

vendor/github.com/hyperhq/hypercli/pkg/signal/trap.go

@@ -0,0 +1,74 @@
+package signal
+
+import (
+	"os"
+	gosignal "os/signal"
+	"runtime"
+	"sync/atomic"
+	"syscall"
+
+	"github.com/Sirupsen/logrus"
+)
+
+// 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.
+//
+func Trap(cleanup func()) {
+	c := make(chan os.Signal, 1)
+	// we will handle INT, TERM, QUIT here
+	signals := []os.Signal{os.Interrupt, syscall.SIGTERM, syscall.SIGQUIT}
+	gosignal.Notify(c, signals...)
+	go func() {
+		interruptCount := uint32(0)
+		for sig := range c {
+			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.Infof("Forcing docker daemon shutdown without cleanup; 3 interrupts received")
+					}
+				case syscall.SIGQUIT:
+					DumpStacks()
+					logrus.Infof("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)
+		}
+	}()
+}
+
+// DumpStacks dumps the runtime stack.
+func DumpStacks() {
+	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]
+	// Note that if the daemon is started with a less-verbose log-level than "info" (the default), the goroutine
+	// traces won't show up in the log.
+	logrus.Infof("=== BEGIN goroutine stack dump ===\n%s\n=== END goroutine stack dump ===", buf)
+}