Work around for PDs stop mounting after a few hours issue

pkg/util/operationmanager/operationmanager.go

@@ -0,0 +1,92 @@
+/*
+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 operationmanager
+
+import (
+	"fmt"
+	"sync"
+)
+
+// Operation Manager is a thread-safe interface for keeping track of multiple pending async operations.
+type OperationManager interface {
+	// Called when the operation with the given ID has started.
+	// Creates a new channel with specified buffer size tracked with the specified ID.
+	// Returns a read-only version of the newly created channel.
+	// Returns an error if an entry with the specified ID already exists (previous entry must be removed by calling Close).
+	Start(id string, bufferSize uint) (<-chan interface{}, error)
+
+	// Called when the operation with the given ID has terminated.
+	// Closes and removes the channel associated with ID.
+	// Returns an error if no associated channel exists.
+	Close(id string) error
+
+	// Attempts to send msg to the channel associated with ID.
+	// Returns an error if no associated channel exists.
+	Send(id string, msg interface{}) error
+}
+
+// Returns a new instance of a channel manager.
+func NewOperationManager() OperationManager {
+	return &operationManager{
+		chanMap: make(map[string]chan interface{}),
+	}
+}
+
+type operationManager struct {
+	sync.RWMutex
+	chanMap map[string]chan interface{}
+}
+
+// Called when the operation with the given ID has started.
+// Creates a new channel with specified buffer size tracked with the specified ID.
+// Returns a read-only version of the newly created channel.
+// Returns an error if an entry with the specified ID already exists (previous entry must be removed by calling Close).
+func (cm *operationManager) Start(id string, bufferSize uint) (<-chan interface{}, error) {
+	cm.Lock()
+	defer cm.Unlock()
+	if _, exists := cm.chanMap[id]; exists {
+		return nil, fmt.Errorf("id %q already exists", id)
+	}
+	cm.chanMap[id] = make(chan interface{}, bufferSize)
+	return cm.chanMap[id], nil
+}
+
+// Called when the operation with the given ID has terminated.
+// Closes and removes the channel associated with ID.
+// Returns an error if no associated channel exists.
+func (cm *operationManager) Close(id string) error {
+	cm.Lock()
+	defer cm.Unlock()
+	if _, exists := cm.chanMap[id]; !exists {
+		return fmt.Errorf("id %q not found", id)
+	}
+	close(cm.chanMap[id])
+	delete(cm.chanMap, id)
+	return nil
+}
+
+// Attempts to send msg to the channel associated with ID.
+// Returns an error if no associated channel exists.
+func (cm *operationManager) Send(id string, msg interface{}) error {
+	cm.RLock()
+	defer cm.RUnlock()
+	if _, exists := cm.chanMap[id]; !exists {
+		return fmt.Errorf("id %q not found", id)
+	}
+	cm.chanMap[id] <- msg
+	return nil
+}