forked from open-policy-agent/opa
-
Notifications
You must be signed in to change notification settings - Fork 0
/
txn.go
444 lines (382 loc) · 10.3 KB
/
txn.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
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
// Copyright 2017 The OPA Authors. All rights reserved.
// Use of this source code is governed by an Apache2
// license that can be found in the LICENSE file.
package inmem
import (
"container/list"
"encoding/json"
"strconv"
"github.com/open-policy-agent/opa/storage"
)
// transaction implements the low-level read/write operations on the in-memory
// store and contains the state required for pending transactions.
//
// For write transactions, the struct contains a logical set of updates
// performed by write operations in the transaction. Each write operation
// compacts the set such that two updates never overlap:
//
// - If new update path is a prefix of existing update path, existing update is
// removed, new update is added.
//
// - If existing update path is a prefix of new update path, existing update is
// modified.
//
// - Otherwise, new update is added.
//
// Read transactions do not require any special handling and simply passthrough
// to the underlying store. Read transactions do not support upgrade.
type transaction struct {
xid uint64
write bool
stale bool
db *store
updates *list.List
policies map[string]policyUpdate
context *storage.Context
}
type policyUpdate struct {
value []byte
remove bool
}
func newTransaction(xid uint64, write bool, context *storage.Context, db *store) *transaction {
return &transaction{
xid: xid,
write: write,
db: db,
policies: map[string]policyUpdate{},
updates: list.New(),
context: context,
}
}
func (txn *transaction) ID() uint64 {
return txn.xid
}
func (txn *transaction) Write(op storage.PatchOp, path storage.Path, value interface{}) error {
if !txn.write {
return &storage.Error{
Code: storage.InvalidTransactionErr,
Message: "data write during read transaction",
}
}
if len(path) == 0 {
return txn.updateRoot(op, value)
}
for curr := txn.updates.Front(); curr != nil; {
update := curr.Value.(*update)
// Check if new update masks existing update exactly. In this case, the
// existing update can be removed and no other updates have to be
// visited (because no two updates overlap.)
if update.path.Equal(path) {
if update.remove {
if op != storage.AddOp {
return notFoundError(path)
}
}
txn.updates.Remove(curr)
break
}
// Check if new update masks existing update. In this case, the
// existing update has to be removed but other updates may overlap, so
// we must continue.
if update.path.HasPrefix(path) {
remove := curr
curr = curr.Next()
txn.updates.Remove(remove)
continue
}
// Check if new update modifies existing update. In this case, the
// existing update is mutated.
if path.HasPrefix(update.path) {
if update.remove {
return notFoundError(path)
}
suffix := path[len(update.path):]
newUpdate, err := newUpdate(update.value, op, suffix, 0, value)
if err != nil {
return err
}
update.value = newUpdate.Apply(update.value)
return nil
}
curr = curr.Next()
}
update, err := newUpdate(txn.db.data, op, path, 0, value)
if err != nil {
return err
}
txn.updates.PushFront(update)
return nil
}
func (txn *transaction) updateRoot(op storage.PatchOp, value interface{}) error {
if op == storage.RemoveOp {
return invalidPatchError(rootCannotBeRemovedMsg)
}
if _, ok := value.(map[string]interface{}); !ok {
return invalidPatchError(rootMustBeObjectMsg)
}
txn.updates.Init()
txn.updates.PushFront(&update{
path: storage.Path{},
remove: false,
value: value,
})
return nil
}
func (txn *transaction) Commit() (result storage.TriggerEvent) {
result.Context = txn.context
for curr := txn.updates.Front(); curr != nil; curr = curr.Next() {
action := curr.Value.(*update)
updated := action.Apply(txn.db.data)
txn.db.data = updated.(map[string]interface{})
result.Data = append(result.Data, storage.DataEvent{
Path: action.path,
Data: action.value,
Removed: action.remove,
})
}
for id, update := range txn.policies {
if update.remove {
delete(txn.db.policies, id)
} else {
txn.db.policies[id] = update.value
}
result.Policy = append(result.Policy, storage.PolicyEvent{
ID: id,
Data: update.value,
Removed: update.remove,
})
}
return result
}
func (txn *transaction) Read(path storage.Path) (interface{}, error) {
if !txn.write {
return ptr(txn.db.data, path)
}
merge := []*update{}
for curr := txn.updates.Front(); curr != nil; curr = curr.Next() {
update := curr.Value.(*update)
if path.HasPrefix(update.path) {
if update.remove {
return nil, notFoundError(path)
}
return ptr(update.value, path[len(update.path):])
}
if update.path.HasPrefix(path) {
merge = append(merge, update)
}
}
data, err := ptr(txn.db.data, path)
if err != nil {
return nil, err
}
if len(merge) == 0 {
return data, nil
}
cpy := deepCopy(data)
for _, update := range merge {
cpy = update.Relative(path).Apply(cpy)
}
return cpy, nil
}
func (txn *transaction) ListPolicies() []string {
var ids []string
for id := range txn.db.policies {
if _, ok := txn.policies[id]; !ok {
ids = append(ids, id)
}
}
for id, update := range txn.policies {
if !update.remove {
ids = append(ids, id)
}
}
return ids
}
func (txn *transaction) GetPolicy(id string) ([]byte, error) {
if update, ok := txn.policies[id]; ok {
if !update.remove {
return update.value, nil
}
return nil, notFoundErrorf("policy id %q", id)
}
if exist, ok := txn.db.policies[id]; ok {
return exist, nil
}
return nil, notFoundErrorf("policy id %q", id)
}
func (txn *transaction) UpsertPolicy(id string, bs []byte) error {
if !txn.write {
return &storage.Error{
Code: storage.InvalidTransactionErr,
Message: "policy write during read transaction",
}
}
txn.policies[id] = policyUpdate{bs, false}
return nil
}
func (txn *transaction) DeletePolicy(id string) error {
if !txn.write {
return &storage.Error{
Code: storage.InvalidTransactionErr,
Message: "policy write during read transaction",
}
}
txn.policies[id] = policyUpdate{nil, true}
return nil
}
// update contains state associated with an update to be applied to the
// in-memory data store.
type update struct {
path storage.Path // data path modified by update
remove bool // indicates whether update removes the value at path
value interface{} // value to add/replace at path (ignored if remove is true)
}
func newUpdate(data interface{}, op storage.PatchOp, path storage.Path, idx int, value interface{}) (*update, error) {
switch data := data.(type) {
case map[string]interface{}:
return newUpdateObject(data, op, path, idx, value)
case []interface{}:
return newUpdateArray(data, op, path, idx, value)
case nil, bool, json.Number, string:
return nil, notFoundError(path)
}
return nil, &storage.Error{
Code: storage.InternalErr,
Message: "invalid data value encountered",
}
}
func newUpdateArray(data []interface{}, op storage.PatchOp, path storage.Path, idx int, value interface{}) (*update, error) {
if idx == len(path)-1 {
if path[idx] == "-" {
if op != storage.AddOp {
return nil, invalidPatchError("%v: invalid patch path", path)
}
cpy := make([]interface{}, len(data)+1)
copy(cpy, data)
cpy[len(data)] = value
return &update{path[:len(path)-1], false, cpy}, nil
}
pos, err := validateArrayIndex(data, path[idx], path)
if err != nil {
return nil, err
}
if op == storage.AddOp {
cpy := make([]interface{}, len(data)+1)
copy(cpy[:pos], data[:pos])
copy(cpy[pos+1:], data[pos:])
cpy[pos] = value
return &update{path[:len(path)-1], false, cpy}, nil
} else if op == storage.RemoveOp {
cpy := make([]interface{}, len(data)-1)
copy(cpy[:pos], data[:pos])
copy(cpy[pos:], data[pos+1:])
return &update{path[:len(path)-1], false, cpy}, nil
} else {
cpy := make([]interface{}, len(data))
copy(cpy, data)
cpy[pos] = value
return &update{path[:len(path)-1], false, cpy}, nil
}
}
pos, err := validateArrayIndex(data, path[idx], path)
if err != nil {
return nil, err
}
return newUpdate(data[pos], op, path, idx+1, value)
}
func newUpdateObject(data map[string]interface{}, op storage.PatchOp, path storage.Path, idx int, value interface{}) (*update, error) {
if idx == len(path)-1 {
switch op {
case storage.ReplaceOp, storage.RemoveOp:
if _, ok := data[path[idx]]; !ok {
return nil, notFoundError(path)
}
}
return &update{path, op == storage.RemoveOp, value}, nil
}
if data, ok := data[path[idx]]; ok {
return newUpdate(data, op, path, idx+1, value)
}
return nil, notFoundError(path)
}
func (u *update) Apply(data interface{}) interface{} {
if len(u.path) == 0 {
return u.value
}
parent, err := ptr(data, u.path[:len(u.path)-1])
if err != nil {
panic(err)
}
key := u.path[len(u.path)-1]
if u.remove {
obj := parent.(map[string]interface{})
delete(obj, key)
return data
}
switch parent := parent.(type) {
case map[string]interface{}:
parent[key] = u.value
case []interface{}:
idx, err := strconv.Atoi(key)
if err != nil {
panic(err)
}
parent[idx] = u.value
}
return data
}
func (u *update) Relative(path storage.Path) *update {
cpy := *u
cpy.path = cpy.path[len(path):]
return &cpy
}
func deepCopy(val interface{}) interface{} {
switch val := val.(type) {
case []interface{}:
cpy := make([]interface{}, len(val))
for i := range cpy {
cpy[i] = deepCopy(val[i])
}
return cpy
case map[string]interface{}:
cpy := make(map[string]interface{}, len(val))
for k := range val {
cpy[k] = deepCopy(val[k])
}
return cpy
default:
return val
}
}
func ptr(data interface{}, path storage.Path) (interface{}, error) {
node := data
for i := range path {
key := path[i]
switch curr := node.(type) {
case map[string]interface{}:
var ok bool
if node, ok = curr[key]; !ok {
return nil, notFoundError(path)
}
case []interface{}:
pos, err := validateArrayIndex(curr, key, path)
if err != nil {
return nil, err
}
node = curr[pos]
default:
return nil, notFoundError(path)
}
}
return node, nil
}
func validateArrayIndex(arr []interface{}, s string, path storage.Path) (int, error) {
idx, err := strconv.Atoi(s)
if err != nil {
return 0, notFoundErrorHint(path, arrayIndexTypeMsg)
}
if idx < 0 || idx >= len(arr) {
return 0, notFoundErrorHint(path, outOfRangeMsg)
}
return idx, nil
}