vendor files

vendor/k8s.io/kubernetes/pkg/util/interrupt/interrupt.go

@@ -0,0 +1,104 @@
+/*
+Copyright 2016 The Kubernetes 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 interrupt
+
+import (
+	"os"
+	"os/signal"
+	"sync"
+	"syscall"
+)
+
+// terminationSignals are signals that cause the program to exit in the
+// supported platforms (linux, darwin, windows).
+var terminationSignals = []os.Signal{syscall.SIGHUP, syscall.SIGINT, syscall.SIGTERM, syscall.SIGQUIT}
+
+// Handler guarantees execution of notifications after a critical section (the function passed
+// to a Run method), even in the presence of process termination. It guarantees exactly once
+// invocation of the provided notify functions.
+type Handler struct {
+	notify []func()
+	final  func(os.Signal)
+	once   sync.Once
+}
+
+// Chain creates a new handler that invokes all notify functions when the critical section exits
+// and then invokes the optional handler's notifications. This allows critical sections to be
+// nested without losing exactly once invocations. Notify functions can invoke any cleanup needed
+// but should not exit (which is the responsibility of the parent handler).
+func Chain(handler *Handler, notify ...func()) *Handler {
+	if handler == nil {
+		return New(nil, notify...)
+	}
+	return New(handler.Signal, append(notify, handler.Close)...)
+}
+
+// New creates a new handler that guarantees all notify functions are run after the critical
+// section exits (or is interrupted by the OS), then invokes the final handler. If no final
+// handler is specified, the default final is `os.Exit(1)`. A handler can only be used for
+// one critical section.
+func New(final func(os.Signal), notify ...func()) *Handler {
+	return &Handler{
+		final:  final,
+		notify: notify,
+	}
+}
+
+// Close executes all the notification handlers if they have not yet been executed.
+func (h *Handler) Close() {
+	h.once.Do(func() {
+		for _, fn := range h.notify {
+			fn()
+		}
+	})
+}
+
+// Signal is called when an os.Signal is received, and guarantees that all notifications
+// are executed, then the final handler is executed. This function should only be called once
+// per Handler instance.
+func (h *Handler) Signal(s os.Signal) {
+	h.once.Do(func() {
+		for _, fn := range h.notify {
+			fn()
+		}
+		if h.final == nil {
+			os.Exit(1)
+		}
+		h.final(s)
+	})
+}
+
+// Run ensures that any notifications are invoked after the provided fn exits (even if the
+// process is interrupted by an OS termination signal). Notifications are only invoked once
+// per Handler instance, so calling Run more than once will not behave as the user expects.
+func (h *Handler) Run(fn func() error) error {
+	ch := make(chan os.Signal, 1)
+	signal.Notify(ch, terminationSignals...)
+	defer func() {
+		signal.Stop(ch)
+		close(ch)
+	}()
+	go func() {
+		sig, ok := <-ch
+		if !ok {
+			return
+		}
+		h.Signal(sig)
+	}()
+	defer h.Close()
+	return fn()
+}