mirror of https://github.com/perkeep/perkeep.git
98 lines
3.0 KiB
Go
98 lines
3.0 KiB
Go
/*
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Copyright 2011 Google Inc.
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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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http://www.apache.org/licenses/LICENSE-2.0
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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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*/
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package blobserver
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import (
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"errors"
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"fmt"
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"net/http"
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"sync"
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"camlistore.org/pkg/jsonconfig"
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)
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var ErrHandlerTypeNotFound = errors.New("requested handler type not loaded")
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type Loader interface {
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// MyPrefix returns the prefix of the handler currently being constructed.
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MyPrefix() string
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GetStorage(prefix string) (Storage, error)
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GetHandlerType(prefix string) string // returns "" if unknown
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// Returns either a Storage or an http.Handler
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GetHandler(prefix string) (interface{}, error)
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// FindHandlerByType finds a handler by its handlerType and
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// returns its prefix and handler if it's loaded. If it's not
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// loaded, the error will be ErrHandlerTypeNotFound.
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//
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// This is used by handler constructors to find siblings (such as the "ui" type handler)
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// which might have more knowledge about the configuration for discovery, etc.
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FindHandlerByType(handlerType string) (prefix string, handler interface{}, err error)
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// If we're loading configuration in response to a web request
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// (as we do with App Engine), then this returns a request and
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// true.
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GetRequestContext() (ctx *http.Request, ok bool)
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}
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type StorageConstructor func(Loader, jsonconfig.Obj) (Storage, error)
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type HandlerConstructor func(Loader, jsonconfig.Obj) (http.Handler, error)
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var mapLock sync.Mutex
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var storageConstructors = make(map[string]StorageConstructor)
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var handlerConstructors = make(map[string]HandlerConstructor)
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func RegisterStorageConstructor(typ string, ctor StorageConstructor) {
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mapLock.Lock()
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defer mapLock.Unlock()
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if _, ok := storageConstructors[typ]; ok {
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panic("blobserver: StorageConstructor already registered for type: " + typ)
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}
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storageConstructors[typ] = ctor
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}
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func CreateStorage(typ string, loader Loader, config jsonconfig.Obj) (Storage, error) {
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mapLock.Lock()
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ctor, ok := storageConstructors[typ]
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mapLock.Unlock()
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if !ok {
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return nil, fmt.Errorf("Storage type %q not known or loaded", typ)
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}
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return ctor(loader, config)
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}
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func RegisterHandlerConstructor(typ string, ctor HandlerConstructor) {
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mapLock.Lock()
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defer mapLock.Unlock()
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if _, ok := handlerConstructors[typ]; ok {
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panic("blobserver: HandlerConstrutor already registered for type: " + typ)
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}
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handlerConstructors[typ] = ctor
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}
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func CreateHandler(typ string, loader Loader, config jsonconfig.Obj) (http.Handler, error) {
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mapLock.Lock()
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ctor, ok := handlerConstructors[typ]
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mapLock.Unlock()
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if !ok {
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return nil, fmt.Errorf("blobserver: Handler type %q not known or loaded", typ)
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}
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return ctor(loader, config)
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}
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