forked from snapcore/snapd
-
Notifications
You must be signed in to change notification settings - Fork 0
/
context.go
312 lines (268 loc) · 8.08 KB
/
context.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
// -*- Mode: Go; indent-tabs-mode: t -*-
/*
* Copyright (C) 2016 Canonical Ltd
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 3 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
package hookstate
import (
"bytes"
"encoding/json"
"fmt"
"sync"
"sync/atomic"
"time"
"github.com/snapcore/snapd/jsonutil"
"github.com/snapcore/snapd/logger"
"github.com/snapcore/snapd/overlord/state"
"github.com/snapcore/snapd/randutil"
"github.com/snapcore/snapd/snap"
)
// Context represents the context under which the snap is calling back into snapd.
// It is associated with a task when the callback is happening from within a hook,
// or otherwise considered an ephemeral context in that its associated data will
// be discarded once that individual call is finished.
type Context struct {
task *state.Task
state *state.State
setup *HookSetup
id string
handler Handler
cache map[interface{}]interface{}
onDone []func() error
mutex sync.Mutex
mutexChecker int32
}
// NewContext returns a new context associated with the provided task or
// an ephemeral context if task is nil.
//
// A random ID is generated if contextID is empty.
func NewContext(task *state.Task, state *state.State, setup *HookSetup, handler Handler, contextID string) (*Context, error) {
if contextID == "" {
var err error
contextID, err = randutil.CryptoToken(32)
if err != nil {
return nil, err
}
}
return &Context{
task: task,
state: state,
setup: setup,
id: contextID,
handler: handler,
cache: make(map[interface{}]interface{}),
}, nil
}
func newEphemeralHookContextWithData(st *state.State, setup *HookSetup, contextData map[string]interface{}) (*Context, error) {
context, err := NewContext(nil, st, setup, nil, "")
if err != nil {
return nil, err
}
if contextData != nil {
serialized, err := json.Marshal(contextData)
if err != nil {
return nil, err
}
var data map[string]*json.RawMessage
if err := json.Unmarshal(serialized, &data); err != nil {
return nil, err
}
context.cache["ephemeral-context"] = data
}
return context, nil
}
// InstanceName returns the name of the snap instance containing the hook.
func (c *Context) InstanceName() string {
return c.setup.Snap
}
// SnapRevision returns the revision of the snap containing the hook.
func (c *Context) SnapRevision() snap.Revision {
return c.setup.Revision
}
// Task returns the task associated with the hook or (nil, false) if the context is ephemeral
// and task is not available.
func (c *Context) Task() (*state.Task, bool) {
return c.task, c.task != nil
}
// HookName returns the name of the hook in this context.
func (c *Context) HookName() string {
return c.setup.Hook
}
// Timeout returns the maximum time this hook can run
func (c *Context) Timeout() time.Duration {
return c.setup.Timeout
}
// ID returns the ID of the context.
func (c *Context) ID() string {
return c.id
}
// Handler returns the handler for this context
func (c *Context) Handler() Handler {
return c.handler
}
// Lock acquires the lock for this context (required for Set/Get, Cache/Cached, Logf/Errorf),
// and OnDone/Done).
func (c *Context) Lock() {
c.mutex.Lock()
c.state.Lock()
atomic.AddInt32(&c.mutexChecker, 1)
}
// Unlock releases the lock for this context.
func (c *Context) Unlock() {
atomic.AddInt32(&c.mutexChecker, -1)
c.state.Unlock()
c.mutex.Unlock()
}
func (c *Context) reading() {
if atomic.LoadInt32(&c.mutexChecker) != 1 {
panic("internal error: accessing context without lock")
}
}
func (c *Context) writing() {
if atomic.LoadInt32(&c.mutexChecker) != 1 {
panic("internal error: accessing context without lock")
}
}
// Set associates value with key. The provided value must properly marshal and
// unmarshal with encoding/json. Note that the context needs to be locked and
// unlocked by the caller.
func (c *Context) Set(key string, value interface{}) {
c.writing()
var data map[string]*json.RawMessage
if c.IsEphemeral() {
data, _ = c.cache["ephemeral-context"].(map[string]*json.RawMessage)
} else {
if err := c.task.Get("hook-context", &data); err != nil && err != state.ErrNoState {
panic(fmt.Sprintf("internal error: cannot unmarshal context: %v", err))
}
}
if data == nil {
data = make(map[string]*json.RawMessage)
}
marshalledValue, err := json.Marshal(value)
if err != nil {
panic(fmt.Sprintf("internal error: cannot marshal context value for %q: %s", key, err))
}
raw := json.RawMessage(marshalledValue)
data[key] = &raw
if c.IsEphemeral() {
c.cache["ephemeral-context"] = data
} else {
c.task.Set("hook-context", data)
}
}
// Get unmarshals the stored value associated with the provided key into the
// value parameter. Note that the context needs to be locked/unlocked by the
// caller.
func (c *Context) Get(key string, value interface{}) error {
c.reading()
var data map[string]*json.RawMessage
if c.IsEphemeral() {
data, _ = c.cache["ephemeral-context"].(map[string]*json.RawMessage)
if data == nil {
return state.ErrNoState
}
} else {
if err := c.task.Get("hook-context", &data); err != nil {
return err
}
}
raw, ok := data[key]
if !ok {
return state.ErrNoState
}
err := jsonutil.DecodeWithNumber(bytes.NewReader(*raw), &value)
if err != nil {
return fmt.Errorf("cannot unmarshal context value for %q: %s", key, err)
}
return nil
}
// State returns the state contained within the context
func (c *Context) State() *state.State {
return c.state
}
// Cached returns the cached value associated with the provided key. It returns
// nil if there is no entry for key. Note that the context needs to be locked
// and unlocked by the caller.
func (c *Context) Cached(key interface{}) interface{} {
c.reading()
return c.cache[key]
}
// Cache associates value with key. The cached value is not persisted. Note that
// the context needs to be locked/unlocked by the caller.
func (c *Context) Cache(key, value interface{}) {
c.writing()
c.cache[key] = value
}
// OnDone requests the provided function to be run once the context knows it's
// complete. This can be called multiple times; each function will be called in
// the order in which they were added. Note that the context needs to be locked
// and unlocked by the caller.
func (c *Context) OnDone(f func() error) {
c.writing()
c.onDone = append(c.onDone, f)
}
// Done is called to notify the context that its hook has exited successfully.
// It will call all of the functions added in OnDone (even if one of them
// returns an error) and will return the first error encountered. Note that the
// context needs to be locked/unlocked by the caller.
func (c *Context) Done() error {
c.reading()
var firstErr error
for _, f := range c.onDone {
if err := f(); err != nil && firstErr == nil {
firstErr = err
}
}
return firstErr
}
func (c *Context) IsEphemeral() bool {
return c.task == nil
}
// ChangeID returns change ID for non-ephemeral context
// or empty string otherwise.
func (c *Context) ChangeID() string {
if task, ok := c.Task(); ok {
if chg := task.Change(); chg != nil {
return chg.ID()
}
}
return ""
}
// Logf logs to the context, either to the logger for ephemeral contexts
// or the task log.
//
// Context must be locked.
func (c *Context) Logf(fmt string, args ...interface{}) {
c.writing()
if c.IsEphemeral() {
logger.Noticef(fmt, args...)
} else {
c.task.Logf(fmt, args...)
}
}
// Errorf logs errors to the context, either to the logger for
// ephemeral contexts or the task log.
//
// Context must be locked.
func (c *Context) Errorf(fmt string, args ...interface{}) {
c.writing()
if c.IsEphemeral() {
// XXX: loger has no Errorf() :/
logger.Noticef(fmt, args...)
} else {
c.task.Errorf(fmt, args...)
}
}