73 lines
2.2 KiB
Go
73 lines
2.2 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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"sync"
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)
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type ContainerHandlerFactory interface {
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// Create a new ContainerHandler using this factory. CanHandle() must have returned true.
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NewContainerHandler(name string) (ContainerHandler, error)
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// Returns whether this factory can handle the specified container.
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CanHandle(name string) bool
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// Name of the factory.
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String() string
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}
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// TODO(vmarmol): Consider not making this global.
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// Global list of factories.
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var (
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factories []ContainerHandlerFactory
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factoriesLock sync.RWMutex
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)
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// Register a ContainerHandlerFactory. These should be registered from least general to most general
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// as they will be asked in order whether they can handle a particular container.
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func RegisterContainerHandlerFactory(factory ContainerHandlerFactory) {
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factoriesLock.Lock()
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defer factoriesLock.Unlock()
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factories = append(factories, factory)
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}
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// Create a new ContainerHandler for the specified container.
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func NewContainerHandler(name string) (ContainerHandler, error) {
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factoriesLock.RLock()
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defer factoriesLock.RUnlock()
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// Create the ContainerHandler with the first factory that supports it.
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for _, factory := range factories {
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if factory.CanHandle(name) {
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log.Printf("Using factory %q for container %q", factory.String(), name)
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return factory.NewContainerHandler(name)
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}
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}
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return nil, fmt.Errorf("no known factory can handle creation of container")
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}
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// Clear the known factories.
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func ClearContainerHandlerFactories() {
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factoriesLock.Lock()
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defer factoriesLock.Unlock()
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factories = make([]ContainerHandlerFactory, 0, 4)
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}
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