Refactor current GAE abstraction library to be free of the SDK*

go/src/infra/gae/libs/wrapper/datastore.go

-// Copyright 2015 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-package wrapper
-
-import (
-        "fmt"
-
-        "golang.org/x/net/context"
-
-        "appengine/datastore"
-
-        "github.com/mjibson/goon"
-)
-
-/// Kinds + Keys
-
-// DSKinder simply allows you to resolve the datastore 'kind' of an object.
-// See goon.Goon.Kind().
-type DSKinder interface {
-        Kind(src interface{}) string
-}
-
-// DSKindSetter allows you to manipulate the current Kind resolution function.
-// See goon.Goon.KindNameResolver.
-type DSKindSetter interface {
-        KindNameResolver() goon.KindNameResolver
-        SetKindNameResolver(goon.KindNameResolver)
-}
-
-// DSNewKeyer allows you to generate a new *datastore.Key in a couple ways.
-// See goon.Goon.Key* for the NewKeyObj* methods, as well as datastore.NewKey.
-type DSNewKeyer interface {
-        NewKey(kind, stringID string, intID int64, parent *datastore.Key) *datastore.Key
-        NewKeyObj(src interface{}) *datastore.Key
-        NewKeyObjError(src interface{}) (*datastore.Key, error)
-}
-
-/// Read + Write
-
-// DSSingleReadWriter allows you to read and write a single datastore object.
-// See goon.Goon for more detail on the same-named functions.
-type DSSingleReadWriter interface {
-        Put(src interface{}) (*datastore.Key, error)
-        Get(dst interface{}) error
-        Delete(key *datastore.Key) error
-}
-
-// DSMultiReadWriter allows you to read and write a multiple datastore objects
-// in a non-atomic batch. See goon.Goon for more detail on the same-named.
-// functions. Also implies DSSingleReadWriter.
-type DSMultiReadWriter interface {
-        DSSingleReadWriter
-        DeleteMulti(keys []*datastore.Key) error
-        GetMulti(dst interface{}) error
-        PutMulti(src interface{}) ([]*datastore.Key, error)
-}
-
-/// Queries
-
-// DSCursor wraps datastore.Cursor.
-type DSCursor interface {
-        fmt.Stringer
-}
-
-// DSIterator wraps datastore.Iterator.
-type DSIterator interface {
-        Cursor() (DSCursor, error)
-        Next(dst interface{}) (*datastore.Key, error)
-}
-
-// DSQuery wraps datastore.Query.
-type DSQuery interface {
-        Ancestor(ancestor *datastore.Key) DSQuery
-        Distinct() DSQuery
-        End(c DSCursor) DSQuery
-        EventualConsistency() DSQuery
-        Filter(filterStr string, value interface{}) DSQuery
-        KeysOnly() DSQuery
-        Limit(limit int) DSQuery
-        Offset(offset int) DSQuery
-        Order(fieldName string) DSQuery
-        Project(fieldNames ...string) DSQuery
-        Start(c DSCursor) DSQuery
-}
-
-// DSQueryer implements all query-related functionality of goon.Goon/datastore.
-type DSQueryer interface {
-        NewQuery(kind string) DSQuery
-        Run(q DSQuery) DSIterator
-        GetAll(q DSQuery, dst interface{}) ([]*datastore.Key, error)
-        Count(q DSQuery) (int, error)
-}
-
-/// Transactions
-
-// DSTransactioner implements the function for entering a transaction with
-// datastore. The function receives a context without the ability to enter a
-// transaction again (since recursive transactions are not implemented in
-// datastore).
-type DSTransactioner interface {
-        RunInTransaction(f func(c context.Context) error, opts *datastore.TransactionOptions) error
-}
-
-// Datastore implements the full datastore functionality.
-type Datastore interface {
-        DSKinder
-        DSNewKeyer
-        DSMultiReadWriter
-        DSQueryer
-        DSKindSetter
-        DSTransactioner
-}
-
-// DSFactory is the function signature for factory methods compatible with
-// SetDSFactory.
-type DSFactory func(context.Context) Datastore
-
-// GetDS gets the Datastore implementation from context.
-func GetDS(c context.Context) Datastore {
-        if f, ok := c.Value(datastoreKey).(DSFactory); ok && f != nil {
-                return f(c)
-        }
-        return nil
-}
-
-// SetDSFactory sets the function to produce Datastore instances, as returned by
-// the GetDS method.
-func SetDSFactory(c context.Context, dsf DSFactory) context.Context {
-        return context.WithValue(c, datastoreKey, dsf)
-}
-
-// SetDS sets the current Datastore object in the context. Useful for testing
-// with a quick mock. This is just a shorthand SetDSFactory invocation to set
-// a factory which always returns the same object.
-func SetDS(c context.Context, ds Datastore) context.Context {
-        return SetDSFactory(c, func(context.Context) Datastore { return ds })
-}