This repository has been archived by the owner on Apr 27, 2021. It is now read-only.
-
Notifications
You must be signed in to change notification settings - Fork 12
/
key.go
309 lines (274 loc) · 7.31 KB
/
key.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
// Copyright 2011 Google Inc. All rights reserved.
// Use of this source code is governed by the Apache 2.0
// license that can be found in the LICENSE file.
package datastore
import (
"bytes"
"encoding/base64"
"encoding/gob"
"errors"
"fmt"
"strconv"
"strings"
"code.google.com/p/goprotobuf/proto"
"google.golang.org/appengine"
"google.golang.org/appengine/internal"
pb "google.golang.org/appengine/internal/datastore"
)
// Key represents the datastore key for a stored entity, and is immutable.
type Key struct {
kind string
stringID string
intID int64
parent *Key
appID string
namespace string
}
// Kind returns the key's kind (also known as entity type).
func (k *Key) Kind() string {
return k.kind
}
// StringID returns the key's string ID (also known as an entity name or key
// name), which may be "".
func (k *Key) StringID() string {
return k.stringID
}
// IntID returns the key's integer ID, which may be 0.
func (k *Key) IntID() int64 {
return k.intID
}
// Parent returns the key's parent key, which may be nil.
func (k *Key) Parent() *Key {
return k.parent
}
// AppID returns the key's application ID.
func (k *Key) AppID() string {
return k.appID
}
// Namespace returns the key's namespace.
func (k *Key) Namespace() string {
return k.namespace
}
// Incomplete returns whether the key does not refer to a stored entity.
// In particular, whether the key has a zero StringID and a zero IntID.
func (k *Key) Incomplete() bool {
return k.stringID == "" && k.intID == 0
}
// valid returns whether the key is valid.
func (k *Key) valid() bool {
if k == nil {
return false
}
for ; k != nil; k = k.parent {
if k.kind == "" || k.appID == "" {
return false
}
if k.stringID != "" && k.intID != 0 {
return false
}
if k.parent != nil {
if k.parent.Incomplete() {
return false
}
if k.parent.appID != k.appID || k.parent.namespace != k.namespace {
return false
}
}
}
return true
}
// Equal returns whether two keys are equal.
func (k *Key) Equal(o *Key) bool {
for k != nil && o != nil {
if k.kind != o.kind || k.stringID != o.stringID || k.intID != o.intID || k.appID != o.appID || k.namespace != o.namespace {
return false
}
k, o = k.parent, o.parent
}
return k == o
}
// root returns the furthest ancestor of a key, which may be itself.
func (k *Key) root() *Key {
for k.parent != nil {
k = k.parent
}
return k
}
// marshal marshals the key's string representation to the buffer.
func (k *Key) marshal(b *bytes.Buffer) {
if k.parent != nil {
k.parent.marshal(b)
}
b.WriteByte('/')
b.WriteString(k.kind)
b.WriteByte(',')
if k.stringID != "" {
b.WriteString(k.stringID)
} else {
b.WriteString(strconv.FormatInt(k.intID, 10))
}
}
// String returns a string representation of the key.
func (k *Key) String() string {
if k == nil {
return ""
}
b := bytes.NewBuffer(make([]byte, 0, 512))
k.marshal(b)
return b.String()
}
type gobKey struct {
Kind string
StringID string
IntID int64
Parent *gobKey
AppID string
Namespace string
}
func keyToGobKey(k *Key) *gobKey {
if k == nil {
return nil
}
return &gobKey{
Kind: k.kind,
StringID: k.stringID,
IntID: k.intID,
Parent: keyToGobKey(k.parent),
AppID: k.appID,
Namespace: k.namespace,
}
}
func gobKeyToKey(gk *gobKey) *Key {
if gk == nil {
return nil
}
return &Key{
kind: gk.Kind,
stringID: gk.StringID,
intID: gk.IntID,
parent: gobKeyToKey(gk.Parent),
appID: gk.AppID,
namespace: gk.Namespace,
}
}
func (k *Key) GobEncode() ([]byte, error) {
buf := new(bytes.Buffer)
if err := gob.NewEncoder(buf).Encode(keyToGobKey(k)); err != nil {
return nil, err
}
return buf.Bytes(), nil
}
func (k *Key) GobDecode(buf []byte) error {
gk := new(gobKey)
if err := gob.NewDecoder(bytes.NewBuffer(buf)).Decode(gk); err != nil {
return err
}
*k = *gobKeyToKey(gk)
return nil
}
func (k *Key) MarshalJSON() ([]byte, error) {
return []byte(`"` + k.Encode() + `"`), nil
}
func (k *Key) UnmarshalJSON(buf []byte) error {
if len(buf) < 2 || buf[0] != '"' || buf[len(buf)-1] != '"' {
return errors.New("datastore: bad JSON key")
}
k2, err := DecodeKey(string(buf[1 : len(buf)-1]))
if err != nil {
return err
}
*k = *k2
return nil
}
// Encode returns an opaque representation of the key
// suitable for use in HTML and URLs.
// This is compatible with the Python and Java runtimes.
func (k *Key) Encode() string {
ref := keyToProto("", k)
b, err := proto.Marshal(ref)
if err != nil {
panic(err)
}
// Trailing padding is stripped.
return strings.TrimRight(base64.URLEncoding.EncodeToString(b), "=")
}
// DecodeKey decodes a key from the opaque representation returned by Encode.
func DecodeKey(encoded string) (*Key, error) {
// Re-add padding.
if m := len(encoded) % 4; m != 0 {
encoded += strings.Repeat("=", 4-m)
}
b, err := base64.URLEncoding.DecodeString(encoded)
if err != nil {
return nil, err
}
ref := new(pb.Reference)
if err := proto.Unmarshal(b, ref); err != nil {
return nil, err
}
return protoToKey(ref)
}
// NewIncompleteKey creates a new incomplete key.
// kind cannot be empty.
func NewIncompleteKey(c appengine.Context, kind string, parent *Key) *Key {
return NewKey(c, kind, "", 0, parent)
}
// NewKey creates a new key.
// kind cannot be empty.
// Either one or both of stringID and intID must be zero. If both are zero,
// the key returned is incomplete.
// parent must either be a complete key or nil.
func NewKey(c appengine.Context, kind, stringID string, intID int64, parent *Key) *Key {
// If there's a parent key, use its namespace.
// Otherwise, do a fake RPC to try to get a namespace if c is a namespacedContext (or wraps one).
var namespace string
if parent != nil {
namespace = parent.namespace
} else {
namespace = internal.VirtAPI(c, "GetNamespace")
}
return &Key{
kind: kind,
stringID: stringID,
intID: intID,
parent: parent,
appID: c.FullyQualifiedAppID(),
namespace: namespace,
}
}
// AllocateIDs returns a range of n integer IDs with the given kind and parent
// combination. kind cannot be empty; parent may be nil. The IDs in the range
// returned will not be used by the datastore's automatic ID sequence generator
// and may be used with NewKey without conflict.
//
// The range is inclusive at the low end and exclusive at the high end. In
// other words, valid intIDs x satisfy low <= x && x < high.
//
// If no error is returned, low + n == high.
func AllocateIDs(c appengine.Context, kind string, parent *Key, n int) (low, high int64, err error) {
if kind == "" {
return 0, 0, errors.New("datastore: AllocateIDs given an empty kind")
}
if n < 0 {
return 0, 0, fmt.Errorf("datastore: AllocateIDs given a negative count: %d", n)
}
if n == 0 {
return 0, 0, nil
}
req := &pb.AllocateIdsRequest{
ModelKey: keyToProto("", NewIncompleteKey(c, kind, parent)),
Size: proto.Int64(int64(n)),
}
res := &pb.AllocateIdsResponse{}
if err := c.Call("datastore_v3", "AllocateIds", req, res, nil); err != nil {
return 0, 0, err
}
// The protobuf is inclusive at both ends. Idiomatic Go (e.g. slices, for loops)
// is inclusive at the low end and exclusive at the high end, so we add 1.
low = res.GetStart()
high = res.GetEnd() + 1
if low+int64(n) != high {
return 0, 0, fmt.Errorf("datastore: internal error: could not allocate %d IDs", n)
}
return low, high, nil
}