add vendoring with go dep

vendor/github.com/vmware/govmomi/session/keep_alive.go

@@ -0,0 +1,127 @@
+/*
+Copyright (c) 2015 VMware, Inc. All Rights Reserved.
+
+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 session
+
+import (
+	"context"
+	"sync"
+	"time"
+
+	"github.com/vmware/govmomi/vim25/methods"
+	"github.com/vmware/govmomi/vim25/soap"
+)
+
+type keepAlive struct {
+	sync.Mutex
+
+	roundTripper    soap.RoundTripper
+	idleTime        time.Duration
+	notifyRequest   chan struct{}
+	notifyStop      chan struct{}
+	notifyWaitGroup sync.WaitGroup
+
+	// keepAlive executes a request in the background with the purpose of
+	// keeping the session active. The response for this request is discarded.
+	keepAlive func(soap.RoundTripper) error
+}
+
+func defaultKeepAlive(roundTripper soap.RoundTripper) error {
+	_, _ = methods.GetCurrentTime(context.Background(), roundTripper)
+	return nil
+}
+
+// KeepAlive wraps the specified soap.RoundTripper and executes a meaningless
+// API request in the background after the RoundTripper has been idle for the
+// specified amount of idle time. The keep alive process only starts once a
+// user logs in and runs until the user logs out again.
+func KeepAlive(roundTripper soap.RoundTripper, idleTime time.Duration) soap.RoundTripper {
+	return KeepAliveHandler(roundTripper, idleTime, defaultKeepAlive)
+}
+
+// KeepAliveHandler works as KeepAlive() does, but the handler param can decide how to handle errors.
+// For example, if connectivity to ESX/VC is down long enough for a session to expire, a handler can choose to
+// Login() on a types.NotAuthenticated error.  If handler returns non-nil, the keep alive go routine will be stopped.
+func KeepAliveHandler(roundTripper soap.RoundTripper, idleTime time.Duration, handler func(soap.RoundTripper) error) soap.RoundTripper {
+	k := &keepAlive{
+		roundTripper:  roundTripper,
+		idleTime:      idleTime,
+		notifyRequest: make(chan struct{}),
+	}
+
+	k.keepAlive = handler
+
+	return k
+}
+
+func (k *keepAlive) start() {
+	k.Lock()
+	defer k.Unlock()
+
+	if k.notifyStop != nil {
+		return
+	}
+
+	// This channel must be closed to terminate idle timer.
+	k.notifyStop = make(chan struct{})
+	k.notifyWaitGroup.Add(1)
+
+	go func() {
+		defer k.notifyWaitGroup.Done()
+
+		for t := time.NewTimer(k.idleTime); ; {
+			select {
+			case <-k.notifyStop:
+				return
+			case <-k.notifyRequest:
+				t.Reset(k.idleTime)
+			case <-t.C:
+				if err := k.keepAlive(k.roundTripper); err != nil {
+					k.stop()
+				}
+				t = time.NewTimer(k.idleTime)
+			}
+		}
+	}()
+}
+
+func (k *keepAlive) stop() {
+	k.Lock()
+	defer k.Unlock()
+
+	if k.notifyStop != nil {
+		close(k.notifyStop)
+		k.notifyWaitGroup.Wait()
+		k.notifyStop = nil
+	}
+}
+
+func (k *keepAlive) RoundTrip(ctx context.Context, req, res soap.HasFault) error {
+	err := k.roundTripper.RoundTrip(ctx, req, res)
+	if err != nil {
+		return err
+	}
+
+	// Start ticker on login, stop ticker on logout.
+	switch req.(type) {
+	case *methods.LoginBody, *methods.LoginExtensionByCertificateBody:
+		k.start()
+	case *methods.LogoutBody:
+		k.stop()
+	}
+
+	return nil
+}