Simplify executorKubelet decorator and move to kubelet.go

- simplify
- rename kubeletExecutor -> executorKubelet
- move executorKubelet code into kubelet.go
- remove duplicated executorKubelet.ListenAndServe
- fix executorKubelet.Run comment

contrib/mesos/pkg/executor/service/kubelet.go

@@ -0,0 +1,83 @@
+/*
+Copyright 2015 The Kubernetes Authors 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 service
+
+import (
+	log "github.com/golang/glog"
+	"k8s.io/kubernetes/pkg/kubelet"
+	kubetypes "k8s.io/kubernetes/pkg/kubelet/types"
+	"k8s.io/kubernetes/pkg/util"
+)
+
+// executorKubelet decorates the kubelet with a Run function that notifies the
+// executor by closing kubeletDone before entering blocking state.
+type executorKubelet struct {
+	*kubelet.Kubelet
+	kubeletDone  chan<- struct{} // closed once kubelet.Run() returns
+	executorDone <-chan struct{} // closed when executor terminates
+}
+
+// Run runs the main kubelet loop, closing the kubeletFinished chan when the
+// loop exits. Like the upstream Run, it will never return.
+func (kl *executorKubelet) Run(mergedUpdates <-chan kubetypes.PodUpdate) {
+	defer func() {
+		// When this Run function is called, we close it here.
+		// Otherwise, KubeletExecutorServer.runKubelet will.
+		close(kl.kubeletDone)
+		util.HandleCrash()
+		log.Infoln("kubelet run terminated") //TODO(jdef) turn down verbosity
+		// important: never return! this is in our contract
+		select {}
+	}()
+
+	// push merged updates into another, closable update channel which is closed
+	// when the executor shuts down.
+	closableUpdates := make(chan kubetypes.PodUpdate)
+	go func() {
+		// closing closableUpdates will cause our patched kubelet's syncLoop() to exit
+		defer close(closableUpdates)
+	pipeLoop:
+		for {
+			select {
+			case <-kl.executorDone:
+				break pipeLoop
+			default:
+				select {
+				case u := <-mergedUpdates:
+					select {
+					case closableUpdates <- u: // noop
+					case <-kl.executorDone:
+						break pipeLoop
+					}
+				case <-kl.executorDone:
+					break pipeLoop
+				}
+			}
+		}
+	}()
+
+	// we expect that Run() will complete after closableUpdates is closed and the
+	// kubelet's syncLoop() has finished processing its backlog, which hopefully
+	// will not take very long. Peeking into the future (current k8s master) it
+	// seems that the backlog has grown from 1 to 50 -- this may negatively impact
+	// us going forward, time will tell.
+	util.Until(func() { kl.Kubelet.Run(closableUpdates) }, 0, kl.executorDone)
+
+	//TODO(jdef) revisit this if/when executor failover lands
+	// Force kubelet to delete all pods.
+	kl.HandlePodDeletions(kl.GetPods())
+}

contrib/mesos/pkg/executor/service/service.go

@@ -309,10 +309,9 @@ func (ks *KubeletExecutorServer) createAndInitKubelet(
 	ks.klet = klet
 	ks.kletLock.Unlock()
 
-	k := &kubeletExecutor{
+	// decorate kubelet such that it shuts down when the executor is
+	k := &executorKubelet{
 		Kubelet:      ks.klet,
-		address:      ks.Address,
-		dockerClient: kc.DockerClient,
 		kubeletDone:  kubeletDone,
 		executorDone: executorDone,
 	}
@@ -385,4 +384,3 @@ func (kl *kubeletExecutor) Run(mergedUpdates <-chan kubetypes.PodUpdate) {
 	// Force kubelet to delete all pods.
 	kl.HandlePodDeletions(kl.GetPods())
 }
-