130 lines
3.2 KiB
Go
130 lines
3.2 KiB
Go
// Copyright 2014 Google Inc. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package container
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import (
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"fmt"
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"log"
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"strings"
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"sync"
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)
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type ContainerHandlerFactory interface {
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NewContainerHandler(name string) (ContainerHandler, error)
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// for testability
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String() string
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}
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type factoryTreeNode struct {
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defaultFactory ContainerHandlerFactory
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children map[string]*factoryTreeNode
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}
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func (self *factoryTreeNode) find(elems ...string) ContainerHandlerFactory {
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node := self
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for _, elem := range elems {
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if len(node.children) == 0 {
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break
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}
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if child, ok := node.children[elem]; ok {
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node = child
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} else {
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return node.defaultFactory
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}
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}
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return node.defaultFactory
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}
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func (self *factoryTreeNode) add(factory ContainerHandlerFactory, elems ...string) {
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node := self
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for _, elem := range elems {
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if node.children == nil {
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node.children = make(map[string]*factoryTreeNode, 16)
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}
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child, ok := self.children[elem]
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if !ok {
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child = &factoryTreeNode{
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defaultFactory: node.defaultFactory,
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children: make(map[string]*factoryTreeNode, 16),
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}
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node.children[elem] = child
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}
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node = child
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}
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node.defaultFactory = factory
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}
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type factoryManager struct {
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root *factoryTreeNode
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lock sync.RWMutex
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}
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func dropEmptyString(elems ...string) []string {
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ret := make([]string, 0, len(elems))
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for _, e := range elems {
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if len(e) > 0 {
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ret = append(ret, e)
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}
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}
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return ret
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}
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// Must register factory for root container!
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func (self *factoryManager) Register(path string, factory ContainerHandlerFactory) {
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self.lock.Lock()
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defer self.lock.Unlock()
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if self.root == nil {
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self.root = &factoryTreeNode{
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defaultFactory: nil,
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children: make(map[string]*factoryTreeNode, 10),
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}
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}
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elems := dropEmptyString(strings.Split(path, "/")...)
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self.root.add(factory, elems...)
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}
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func (self *factoryManager) NewContainerHandler(path string) (ContainerHandler, error) {
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self.lock.RLock()
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defer self.lock.RUnlock()
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if self.root == nil {
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err := fmt.Errorf("nil factory for container %v: no factory registered", path)
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return nil, err
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}
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elems := dropEmptyString(strings.Split(path, "/")...)
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factory := self.root.find(elems...)
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if factory == nil {
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err := fmt.Errorf("nil factory for container %v", path)
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return nil, err
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}
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log.Printf("container handler factory for %v is %v\n", path, factory)
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return factory.NewContainerHandler(path)
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}
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var globalFactoryManager factoryManager
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func RegisterContainerHandlerFactory(path string, factory ContainerHandlerFactory) {
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globalFactoryManager.Register(path, factory)
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}
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func NewContainerHandler(path string) (ContainerHandler, error) {
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return globalFactoryManager.NewContainerHandler(path)
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}
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