110 lines
3.2 KiB
Go
110 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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"sync"
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"github.com/golang/glog"
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)
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type ContainerHandlerFactory interface {
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// Create a new ContainerHandler using this factory. CanHandleAndAccept() must have returned true.
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NewContainerHandler(name string) (c ContainerHandler, err error)
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// Returns whether this factory can handle and accept the specified container.
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CanHandleAndAccept(name string) (handle bool, accept bool, err error)
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// Name of the factory.
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String() string
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// Returns debugging information. Map of lines per category.
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DebugInfo() map[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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// Returns whether there are any container handler factories registered.
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func HasFactories() bool {
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factoriesLock.Lock()
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defer factoriesLock.Unlock()
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return len(factories) != 0
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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, bool, 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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canHandle, canAccept, err := factory.CanHandleAndAccept(name)
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if err != nil {
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glog.V(4).Infof("Error trying to work out if we can handle %s: %v", name, err)
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}
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if canHandle {
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if !canAccept {
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glog.V(3).Infof("Factory %q can handle container %q, but ignoring.", factory, name)
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return nil, false, nil
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}
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glog.V(3).Infof("Using factory %q for container %q", factory, name)
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handle, err := factory.NewContainerHandler(name)
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return handle, canAccept, err
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} else {
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glog.V(4).Infof("Factory %q was unable to handle container %q", factory, name)
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}
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}
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return nil, false, 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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func DebugInfo() map[string][]string {
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factoriesLock.RLock()
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defer factoriesLock.RUnlock()
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// Get debug information for all factories.
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out := make(map[string][]string)
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for _, factory := range factories {
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for k, v := range factory.DebugInfo() {
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out[k] = v
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}
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}
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return out
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}
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