mirror of
https://github.com/restic/restic.git
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407 lines
12 KiB
Go
407 lines
12 KiB
Go
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// Copyright 2011 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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"errors"
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"fmt"
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"reflect"
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"github.com/golang/protobuf/proto"
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"golang.org/x/net/context"
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"google.golang.org/appengine"
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"google.golang.org/appengine/internal"
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pb "google.golang.org/appengine/internal/datastore"
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)
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var (
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// ErrInvalidEntityType is returned when functions like Get or Next are
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// passed a dst or src argument of invalid type.
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ErrInvalidEntityType = errors.New("datastore: invalid entity type")
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// ErrInvalidKey is returned when an invalid key is presented.
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ErrInvalidKey = errors.New("datastore: invalid key")
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// ErrNoSuchEntity is returned when no entity was found for a given key.
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ErrNoSuchEntity = errors.New("datastore: no such entity")
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)
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// ErrFieldMismatch is returned when a field is to be loaded into a different
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// type than the one it was stored from, or when a field is missing or
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// unexported in the destination struct.
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// StructType is the type of the struct pointed to by the destination argument
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// passed to Get or to Iterator.Next.
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type ErrFieldMismatch struct {
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StructType reflect.Type
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FieldName string
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Reason string
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}
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func (e *ErrFieldMismatch) Error() string {
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return fmt.Sprintf("datastore: cannot load field %q into a %q: %s",
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e.FieldName, e.StructType, e.Reason)
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}
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// protoToKey converts a Reference proto to a *Key.
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func protoToKey(r *pb.Reference) (k *Key, err error) {
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appID := r.GetApp()
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namespace := r.GetNameSpace()
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for _, e := range r.Path.Element {
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k = &Key{
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kind: e.GetType(),
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stringID: e.GetName(),
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intID: e.GetId(),
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parent: k,
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appID: appID,
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namespace: namespace,
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}
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if !k.valid() {
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return nil, ErrInvalidKey
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}
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}
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return
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}
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// keyToProto converts a *Key to a Reference proto.
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func keyToProto(defaultAppID string, k *Key) *pb.Reference {
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appID := k.appID
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if appID == "" {
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appID = defaultAppID
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}
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n := 0
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for i := k; i != nil; i = i.parent {
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n++
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}
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e := make([]*pb.Path_Element, n)
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for i := k; i != nil; i = i.parent {
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n--
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e[n] = &pb.Path_Element{
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Type: &i.kind,
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}
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// At most one of {Name,Id} should be set.
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// Neither will be set for incomplete keys.
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if i.stringID != "" {
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e[n].Name = &i.stringID
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} else if i.intID != 0 {
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e[n].Id = &i.intID
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}
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}
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var namespace *string
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if k.namespace != "" {
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namespace = proto.String(k.namespace)
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}
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return &pb.Reference{
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App: proto.String(appID),
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NameSpace: namespace,
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Path: &pb.Path{
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Element: e,
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},
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}
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}
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// multiKeyToProto is a batch version of keyToProto.
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func multiKeyToProto(appID string, key []*Key) []*pb.Reference {
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ret := make([]*pb.Reference, len(key))
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for i, k := range key {
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ret[i] = keyToProto(appID, k)
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}
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return ret
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}
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// multiValid is a batch version of Key.valid. It returns an error, not a
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// []bool.
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func multiValid(key []*Key) error {
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invalid := false
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for _, k := range key {
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if !k.valid() {
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invalid = true
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break
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}
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}
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if !invalid {
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return nil
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}
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err := make(appengine.MultiError, len(key))
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for i, k := range key {
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if !k.valid() {
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err[i] = ErrInvalidKey
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}
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}
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return err
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}
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// It's unfortunate that the two semantically equivalent concepts pb.Reference
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// and pb.PropertyValue_ReferenceValue aren't the same type. For example, the
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// two have different protobuf field numbers.
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// referenceValueToKey is the same as protoToKey except the input is a
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// PropertyValue_ReferenceValue instead of a Reference.
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func referenceValueToKey(r *pb.PropertyValue_ReferenceValue) (k *Key, err error) {
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appID := r.GetApp()
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namespace := r.GetNameSpace()
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for _, e := range r.Pathelement {
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k = &Key{
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kind: e.GetType(),
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stringID: e.GetName(),
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intID: e.GetId(),
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parent: k,
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appID: appID,
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namespace: namespace,
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}
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if !k.valid() {
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return nil, ErrInvalidKey
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}
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}
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return
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}
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// keyToReferenceValue is the same as keyToProto except the output is a
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// PropertyValue_ReferenceValue instead of a Reference.
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func keyToReferenceValue(defaultAppID string, k *Key) *pb.PropertyValue_ReferenceValue {
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ref := keyToProto(defaultAppID, k)
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pe := make([]*pb.PropertyValue_ReferenceValue_PathElement, len(ref.Path.Element))
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for i, e := range ref.Path.Element {
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pe[i] = &pb.PropertyValue_ReferenceValue_PathElement{
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Type: e.Type,
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Id: e.Id,
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Name: e.Name,
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}
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}
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return &pb.PropertyValue_ReferenceValue{
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App: ref.App,
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NameSpace: ref.NameSpace,
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Pathelement: pe,
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}
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}
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type multiArgType int
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const (
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multiArgTypeInvalid multiArgType = iota
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multiArgTypePropertyLoadSaver
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multiArgTypeStruct
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multiArgTypeStructPtr
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multiArgTypeInterface
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)
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// checkMultiArg checks that v has type []S, []*S, []I, or []P, for some struct
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// type S, for some interface type I, or some non-interface non-pointer type P
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// such that P or *P implements PropertyLoadSaver.
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//
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// It returns what category the slice's elements are, and the reflect.Type
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// that represents S, I or P.
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//
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// As a special case, PropertyList is an invalid type for v.
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func checkMultiArg(v reflect.Value) (m multiArgType, elemType reflect.Type) {
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if v.Kind() != reflect.Slice {
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return multiArgTypeInvalid, nil
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}
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if v.Type() == typeOfPropertyList {
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return multiArgTypeInvalid, nil
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}
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elemType = v.Type().Elem()
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if reflect.PtrTo(elemType).Implements(typeOfPropertyLoadSaver) {
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return multiArgTypePropertyLoadSaver, elemType
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}
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switch elemType.Kind() {
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case reflect.Struct:
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return multiArgTypeStruct, elemType
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case reflect.Interface:
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return multiArgTypeInterface, elemType
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case reflect.Ptr:
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elemType = elemType.Elem()
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if elemType.Kind() == reflect.Struct {
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return multiArgTypeStructPtr, elemType
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}
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}
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return multiArgTypeInvalid, nil
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}
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// Get loads the entity stored for k into dst, which must be a struct pointer
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// or implement PropertyLoadSaver. If there is no such entity for the key, Get
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// returns ErrNoSuchEntity.
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//
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// The values of dst's unmatched struct fields are not modified, and matching
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// slice-typed fields are not reset before appending to them. In particular, it
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// is recommended to pass a pointer to a zero valued struct on each Get call.
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//
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// ErrFieldMismatch is returned when a field is to be loaded into a different
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// type than the one it was stored from, or when a field is missing or
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// unexported in the destination struct. ErrFieldMismatch is only returned if
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// dst is a struct pointer.
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func Get(c context.Context, key *Key, dst interface{}) error {
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if dst == nil { // GetMulti catches nil interface; we need to catch nil ptr here
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return ErrInvalidEntityType
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}
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err := GetMulti(c, []*Key{key}, []interface{}{dst})
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if me, ok := err.(appengine.MultiError); ok {
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return me[0]
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}
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return err
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}
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// GetMulti is a batch version of Get.
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//
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// dst must be a []S, []*S, []I or []P, for some struct type S, some interface
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// type I, or some non-interface non-pointer type P such that P or *P
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// implements PropertyLoadSaver. If an []I, each element must be a valid dst
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// for Get: it must be a struct pointer or implement PropertyLoadSaver.
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//
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// As a special case, PropertyList is an invalid type for dst, even though a
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// PropertyList is a slice of structs. It is treated as invalid to avoid being
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// mistakenly passed when []PropertyList was intended.
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func GetMulti(c context.Context, key []*Key, dst interface{}) error {
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v := reflect.ValueOf(dst)
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multiArgType, _ := checkMultiArg(v)
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if multiArgType == multiArgTypeInvalid {
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return errors.New("datastore: dst has invalid type")
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}
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if len(key) != v.Len() {
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return errors.New("datastore: key and dst slices have different length")
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}
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if len(key) == 0 {
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return nil
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}
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if err := multiValid(key); err != nil {
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return err
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}
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req := &pb.GetRequest{
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Key: multiKeyToProto(internal.FullyQualifiedAppID(c), key),
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}
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res := &pb.GetResponse{}
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if err := internal.Call(c, "datastore_v3", "Get", req, res); err != nil {
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return err
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}
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if len(key) != len(res.Entity) {
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return errors.New("datastore: internal error: server returned the wrong number of entities")
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}
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multiErr, any := make(appengine.MultiError, len(key)), false
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for i, e := range res.Entity {
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if e.Entity == nil {
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multiErr[i] = ErrNoSuchEntity
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} else {
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elem := v.Index(i)
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if multiArgType == multiArgTypePropertyLoadSaver || multiArgType == multiArgTypeStruct {
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elem = elem.Addr()
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}
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if multiArgType == multiArgTypeStructPtr && elem.IsNil() {
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elem.Set(reflect.New(elem.Type().Elem()))
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}
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multiErr[i] = loadEntity(elem.Interface(), e.Entity)
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}
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if multiErr[i] != nil {
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any = true
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}
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}
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if any {
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return multiErr
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}
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return nil
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}
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// Put saves the entity src into the datastore with key k. src must be a struct
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// pointer or implement PropertyLoadSaver; if a struct pointer then any
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// unexported fields of that struct will be skipped. If k is an incomplete key,
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// the returned key will be a unique key generated by the datastore.
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func Put(c context.Context, key *Key, src interface{}) (*Key, error) {
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k, err := PutMulti(c, []*Key{key}, []interface{}{src})
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if err != nil {
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if me, ok := err.(appengine.MultiError); ok {
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return nil, me[0]
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}
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return nil, err
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}
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return k[0], nil
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}
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// PutMulti is a batch version of Put.
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//
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// src must satisfy the same conditions as the dst argument to GetMulti.
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func PutMulti(c context.Context, key []*Key, src interface{}) ([]*Key, error) {
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v := reflect.ValueOf(src)
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multiArgType, _ := checkMultiArg(v)
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if multiArgType == multiArgTypeInvalid {
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return nil, errors.New("datastore: src has invalid type")
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}
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if len(key) != v.Len() {
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return nil, errors.New("datastore: key and src slices have different length")
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}
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if len(key) == 0 {
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return nil, nil
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}
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appID := internal.FullyQualifiedAppID(c)
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if err := multiValid(key); err != nil {
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return nil, err
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}
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req := &pb.PutRequest{}
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for i := range key {
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elem := v.Index(i)
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if multiArgType == multiArgTypePropertyLoadSaver || multiArgType == multiArgTypeStruct {
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elem = elem.Addr()
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}
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sProto, err := saveEntity(appID, key[i], elem.Interface())
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if err != nil {
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return nil, err
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}
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req.Entity = append(req.Entity, sProto)
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}
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res := &pb.PutResponse{}
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if err := internal.Call(c, "datastore_v3", "Put", req, res); err != nil {
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return nil, err
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}
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if len(key) != len(res.Key) {
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return nil, errors.New("datastore: internal error: server returned the wrong number of keys")
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}
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ret := make([]*Key, len(key))
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for i := range ret {
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var err error
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ret[i], err = protoToKey(res.Key[i])
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if err != nil || ret[i].Incomplete() {
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return nil, errors.New("datastore: internal error: server returned an invalid key")
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}
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}
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return ret, nil
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}
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// Delete deletes the entity for the given key.
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func Delete(c context.Context, key *Key) error {
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err := DeleteMulti(c, []*Key{key})
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if me, ok := err.(appengine.MultiError); ok {
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return me[0]
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}
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return err
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}
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// DeleteMulti is a batch version of Delete.
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func DeleteMulti(c context.Context, key []*Key) error {
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if len(key) == 0 {
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return nil
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}
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if err := multiValid(key); err != nil {
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return err
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}
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req := &pb.DeleteRequest{
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Key: multiKeyToProto(internal.FullyQualifiedAppID(c), key),
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}
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res := &pb.DeleteResponse{}
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return internal.Call(c, "datastore_v3", "Delete", req, res)
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}
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func namespaceMod(m proto.Message, namespace string) {
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// pb.Query is the only type that has a name_space field.
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// All other namespace support in datastore is in the keys.
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switch m := m.(type) {
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case *pb.Query:
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if m.NameSpace == nil {
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m.NameSpace = &namespace
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}
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}
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}
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func init() {
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internal.NamespaceMods["datastore_v3"] = namespaceMod
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internal.RegisterErrorCodeMap("datastore_v3", pb.Error_ErrorCode_name)
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internal.RegisterTimeoutErrorCode("datastore_v3", int32(pb.Error_TIMEOUT))
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}
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