90 lines
2.5 KiB
Go
90 lines
2.5 KiB
Go
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// Copyright 2019 Google Inc. All rights reserved.
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// Use of this source code is governed by the Apache 2.0
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// license that can be found in the LICENSE file.
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package datastore
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import (
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"sync"
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"golang.org/x/net/context"
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"google.golang.org/appengine/datastore/internal/cloudkey"
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"google.golang.org/appengine/internal"
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)
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var keyConversion struct {
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mu sync.RWMutex
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appID string // read using getKeyConversionAppID
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}
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// EnableKeyConversion enables encoded key compatibility with the Cloud
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// Datastore client library (cloud.google.com/go/datastore). Encoded keys
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// generated by the Cloud Datastore client library will be decoded into App
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// Engine datastore keys.
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//
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// The context provided must be an App Engine context if running in App Engine
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// first generation runtime. This can be called in the /_ah/start handler. It is
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// safe to call multiple times, and is cheap to call, so can also be inserted as
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// middleware.
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//
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// Enabling key compatibility does not affect the encoding format used by
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// Key.Encode, it only expands the type of keys that are able to be decoded with
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// DecodeKey.
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func EnableKeyConversion(ctx context.Context) {
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// Only attempt to set appID if it's unset.
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// If already set, ignore.
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if getKeyConversionAppID() != "" {
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return
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}
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keyConversion.mu.Lock()
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// Check again to avoid race where another goroutine set appID between the call
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// to getKeyConversionAppID above and taking the write lock.
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if keyConversion.appID == "" {
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keyConversion.appID = internal.FullyQualifiedAppID(ctx)
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}
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keyConversion.mu.Unlock()
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}
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func getKeyConversionAppID() string {
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keyConversion.mu.RLock()
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appID := keyConversion.appID
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keyConversion.mu.RUnlock()
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return appID
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}
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// decodeCloudKey attempts to decode the given encoded key generated by the
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// Cloud Datastore client library (cloud.google.com/go/datastore), returning nil
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// if the key couldn't be decoded.
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func decodeCloudKey(encoded string) *Key {
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appID := getKeyConversionAppID()
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if appID == "" {
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return nil
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}
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k, err := cloudkey.DecodeKey(encoded)
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if err != nil {
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return nil
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}
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return convertCloudKey(k, appID)
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}
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// convertCloudKey converts a Cloud Datastore key and converts it to an App
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// Engine Datastore key. Cloud Datastore keys don't include the project/app ID,
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// so we must add it back in.
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func convertCloudKey(key *cloudkey.Key, appID string) *Key {
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if key == nil {
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return nil
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}
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k := &Key{
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intID: key.ID,
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kind: key.Kind,
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namespace: key.Namespace,
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parent: convertCloudKey(key.Parent, appID),
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stringID: key.Name,
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appID: appID,
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}
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return k
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}
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