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

go/src/infra/gae/libs/gae/raw_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 gae
+
+import (
+        "fmt"
+
+        "golang.org/x/net/context"
+)
+
+/// Kinds + Keys
+
+// DSKey is the equivalent of *datastore.Key from the original SDK, except that
+// it can have multiple implementations. See helper.DSKey* methods for missing
+// methods like DSKeyIncomplete (and some new ones like DSKeyValid).
+type DSKey interface {
+        Kind() string
+        StringID() string
+        IntID() int64
+        Parent() DSKey
+        AppID() string
+        Namespace() string
+
+        String() string
+}
+
+// DSKeyTok is a single token from a multi-part DSKey.
+type DSKeyTok struct {
+        Kind     string
+        IntID    int64
+        StringID string
+}
+
+// DSCursor wraps datastore.Cursor.
+type DSCursor interface {
+        fmt.Stringer
+}
+
+// DSIterator wraps datastore.Iterator.
+type DSIterator interface {
+        Cursor() (DSCursor, error)
+        Next(dst interface{}) (DSKey, error)
+}
+
+// DSQuery wraps datastore.Query.
+type DSQuery interface {
+        Ancestor(ancestor DSKey) 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
+}
+
+// CommonDatastore is the interface for the methods which are common between
+// Datastore and RawDatastore.
+type CommonDatastore interface {
+        NewKey(kind, stringID string, intID int64, parent DSKey) DSKey
+        DecodeKey(encoded string) (DSKey, error)
+
+        NewQuery(kind string) DSQuery
+        Run(q DSQuery) DSIterator
+        GetAll(q DSQuery, dst interface{}) ([]DSKey, error)
+        Count(q DSQuery) (int, error)
+
+        RunInTransaction(f func(c context.Context) error, opts *DSTransactionOptions) error
+}
+
+// RawDatastore implements the datastore functionality as described by
+// the raw appengine documentation. No key inference occurs, nor does any
+// caching. See Datastore for a nicer interface.
+type RawDatastore interface {
+        CommonDatastore
+
+        Put(key DSKey, src interface{}) (DSKey, error)
+        Get(key DSKey, dst interface{}) error
+        Delete(key DSKey) error
+
+        // These allow you to read and write a multiple datastore objects in
+        // a non-atomic batch.
+        DeleteMulti(keys []DSKey) error
+        GetMulti(keys []DSKey, dst interface{}) error
+        PutMulti(keys []DSKey, src interface{}) ([]DSKey, error)
+}
+
+// RDSFactory is the function signature for factory methods compatible with
+// SetRDSFactory.
+type RDSFactory func(context.Context) RawDatastore
+
+// GetRDS gets the RawDatastore implementation from context.
+func GetRDS(c context.Context) RawDatastore {
+        if f, ok := c.Value(rawDatastoreKey).(RDSFactory); ok && f != nil {
+                return f(c)
+        }
+        return nil
+}
+
+// SetRDSFactory sets the function to produce Datastore instances, as returned by
+// the GetRDS method.
+func SetRDSFactory(c context.Context, rdsf RDSFactory) context.Context {
+        return context.WithValue(c, rawDatastoreKey, rdsf)
+}
+
+// SetRDS 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 SetRDS(c context.Context, rds RawDatastore) context.Context {
+        return SetRDSFactory(c, func(context.Context) RawDatastore { return rds })
+}