/usr/share/gocode/src/github.com/docker/libkv/store/zookeeper/zookeeper.go is in golang-github-docker-libkv-dev 0.1.0-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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 | package zookeeper
import (
"strings"
"time"
"github.com/docker/libkv"
"github.com/docker/libkv/store"
zk "github.com/samuel/go-zookeeper/zk"
)
const (
// SOH control character
SOH = "\x01"
defaultTimeout = 10 * time.Second
)
// Zookeeper is the receiver type for
// the Store interface
type Zookeeper struct {
timeout time.Duration
client *zk.Conn
}
type zookeeperLock struct {
client *zk.Conn
lock *zk.Lock
key string
value []byte
}
// Register registers zookeeper to libkv
func Register() {
libkv.AddStore(store.ZK, New)
}
// New creates a new Zookeeper client given a
// list of endpoints and an optional tls config
func New(endpoints []string, options *store.Config) (store.Store, error) {
s := &Zookeeper{}
s.timeout = defaultTimeout
// Set options
if options != nil {
if options.ConnectionTimeout != 0 {
s.setTimeout(options.ConnectionTimeout)
}
}
// Connect to Zookeeper
conn, _, err := zk.Connect(endpoints, s.timeout)
if err != nil {
return nil, err
}
s.client = conn
return s, nil
}
// setTimeout sets the timeout for connecting to Zookeeper
func (s *Zookeeper) setTimeout(time time.Duration) {
s.timeout = time
}
// Get the value at "key", returns the last modified index
// to use in conjunction to Atomic calls
func (s *Zookeeper) Get(key string) (pair *store.KVPair, err error) {
resp, meta, err := s.client.Get(s.normalize(key))
if err != nil {
if err == zk.ErrNoNode {
return nil, store.ErrKeyNotFound
}
return nil, err
}
// FIXME handle very rare cases where Get returns the
// SOH control character instead of the actual value
if string(resp) == SOH {
return s.Get(store.Normalize(key))
}
pair = &store.KVPair{
Key: key,
Value: resp,
LastIndex: uint64(meta.Version),
}
return pair, nil
}
// createFullPath creates the entire path for a directory
// that does not exist
func (s *Zookeeper) createFullPath(path []string, ephemeral bool) error {
for i := 1; i <= len(path); i++ {
newpath := "/" + strings.Join(path[:i], "/")
if i == len(path) && ephemeral {
_, err := s.client.Create(newpath, []byte{}, zk.FlagEphemeral, zk.WorldACL(zk.PermAll))
return err
}
_, err := s.client.Create(newpath, []byte{}, 0, zk.WorldACL(zk.PermAll))
if err != nil {
// Skip if node already exists
if err != zk.ErrNodeExists {
return err
}
}
}
return nil
}
// Put a value at "key"
func (s *Zookeeper) Put(key string, value []byte, opts *store.WriteOptions) error {
fkey := s.normalize(key)
exists, err := s.Exists(key)
if err != nil {
return err
}
if !exists {
if opts != nil && opts.TTL > 0 {
s.createFullPath(store.SplitKey(strings.TrimSuffix(key, "/")), true)
} else {
s.createFullPath(store.SplitKey(strings.TrimSuffix(key, "/")), false)
}
}
_, err = s.client.Set(fkey, value, -1)
return err
}
// Delete a value at "key"
func (s *Zookeeper) Delete(key string) error {
err := s.client.Delete(s.normalize(key), -1)
if err == zk.ErrNoNode {
return store.ErrKeyNotFound
}
return err
}
// Exists checks if the key exists inside the store
func (s *Zookeeper) Exists(key string) (bool, error) {
exists, _, err := s.client.Exists(s.normalize(key))
if err != nil {
return false, err
}
return exists, nil
}
// Watch for changes on a "key"
// It returns a channel that will receive changes or pass
// on errors. Upon creation, the current value will first
// be sent to the channel. Providing a non-nil stopCh can
// be used to stop watching.
func (s *Zookeeper) Watch(key string, stopCh <-chan struct{}) (<-chan *store.KVPair, error) {
// Get the key first
pair, err := s.Get(key)
if err != nil {
return nil, err
}
// Catch zk notifications and fire changes into the channel.
watchCh := make(chan *store.KVPair)
go func() {
defer close(watchCh)
// Get returns the current value to the channel prior
// to listening to any event that may occur on that key
watchCh <- pair
for {
_, _, eventCh, err := s.client.GetW(s.normalize(key))
if err != nil {
return
}
select {
case e := <-eventCh:
if e.Type == zk.EventNodeDataChanged {
if entry, err := s.Get(key); err == nil {
watchCh <- entry
}
}
case <-stopCh:
// There is no way to stop GetW so just quit
return
}
}
}()
return watchCh, nil
}
// WatchTree watches for changes on a "directory"
// It returns a channel that will receive changes or pass
// on errors. Upon creating a watch, the current childs values
// will be sent to the channel .Providing a non-nil stopCh can
// be used to stop watching.
func (s *Zookeeper) WatchTree(directory string, stopCh <-chan struct{}) (<-chan []*store.KVPair, error) {
// List the childrens first
entries, err := s.List(directory)
if err != nil {
return nil, err
}
// Catch zk notifications and fire changes into the channel.
watchCh := make(chan []*store.KVPair)
go func() {
defer close(watchCh)
// List returns the children values to the channel
// prior to listening to any events that may occur
// on those keys
watchCh <- entries
for {
_, _, eventCh, err := s.client.ChildrenW(s.normalize(directory))
if err != nil {
return
}
select {
case e := <-eventCh:
if e.Type == zk.EventNodeChildrenChanged {
if kv, err := s.List(directory); err == nil {
watchCh <- kv
}
}
case <-stopCh:
// There is no way to stop GetW so just quit
return
}
}
}()
return watchCh, nil
}
// List child nodes of a given directory
func (s *Zookeeper) List(directory string) ([]*store.KVPair, error) {
keys, stat, err := s.client.Children(s.normalize(directory))
if err != nil {
if err == zk.ErrNoNode {
return nil, store.ErrKeyNotFound
}
return nil, err
}
kv := []*store.KVPair{}
// FIXME Costly Get request for each child key..
for _, key := range keys {
pair, err := s.Get(strings.TrimSuffix(directory, "/") + s.normalize(key))
if err != nil {
// If node is not found: List is out of date, retry
if err == zk.ErrNoNode {
return s.List(directory)
}
return nil, err
}
kv = append(kv, &store.KVPair{
Key: key,
Value: []byte(pair.Value),
LastIndex: uint64(stat.Version),
})
}
return kv, nil
}
// DeleteTree deletes a range of keys under a given directory
func (s *Zookeeper) DeleteTree(directory string) error {
pairs, err := s.List(directory)
if err != nil {
return err
}
var reqs []interface{}
for _, pair := range pairs {
reqs = append(reqs, &zk.DeleteRequest{
Path: s.normalize(directory + "/" + pair.Key),
Version: -1,
})
}
_, err = s.client.Multi(reqs...)
return err
}
// AtomicPut put a value at "key" if the key has not been
// modified in the meantime, throws an error if this is the case
func (s *Zookeeper) AtomicPut(key string, value []byte, previous *store.KVPair, _ *store.WriteOptions) (bool, *store.KVPair, error) {
var lastIndex uint64
if previous != nil {
meta, err := s.client.Set(s.normalize(key), value, int32(previous.LastIndex))
if err != nil {
// Compare Failed
if err == zk.ErrBadVersion {
return false, nil, store.ErrKeyModified
}
return false, nil, err
}
lastIndex = uint64(meta.Version)
} else {
// Interpret previous == nil as create operation.
_, err := s.client.Create(s.normalize(key), value, 0, zk.WorldACL(zk.PermAll))
if err != nil {
// Directory does not exist
if err == zk.ErrNoNode {
// Create the directory
parts := store.SplitKey(strings.TrimSuffix(key, "/"))
parts = parts[:len(parts)-1]
if err = s.createFullPath(parts, false); err != nil {
// Failed to create the directory.
return false, nil, err
}
// Create the node
if _, err := s.client.Create(s.normalize(key), value, 0, zk.WorldACL(zk.PermAll)); err != nil {
// Node exist error (when previous nil)
if err == zk.ErrNodeExists {
return false, nil, store.ErrKeyExists
}
return false, nil, err
}
} else {
// Node Exists error (when previous nil)
if err == zk.ErrNodeExists {
return false, nil, store.ErrKeyExists
}
// Unhandled error
return false, nil, err
}
}
lastIndex = 0 // Newly created nodes have version 0.
}
pair := &store.KVPair{
Key: key,
Value: value,
LastIndex: lastIndex,
}
return true, pair, nil
}
// AtomicDelete deletes a value at "key" if the key
// has not been modified in the meantime, throws an
// error if this is the case
func (s *Zookeeper) AtomicDelete(key string, previous *store.KVPair) (bool, error) {
if previous == nil {
return false, store.ErrPreviousNotSpecified
}
err := s.client.Delete(s.normalize(key), int32(previous.LastIndex))
if err != nil {
// Key not found
if err == zk.ErrNoNode {
return false, store.ErrKeyNotFound
}
// Compare failed
if err == zk.ErrBadVersion {
return false, store.ErrKeyModified
}
// General store error
return false, err
}
return true, nil
}
// NewLock returns a handle to a lock struct which can
// be used to provide mutual exclusion on a key
func (s *Zookeeper) NewLock(key string, options *store.LockOptions) (lock store.Locker, err error) {
value := []byte("")
// Apply options
if options != nil {
if options.Value != nil {
value = options.Value
}
}
lock = &zookeeperLock{
client: s.client,
key: s.normalize(key),
value: value,
lock: zk.NewLock(s.client, s.normalize(key), zk.WorldACL(zk.PermAll)),
}
return lock, err
}
// Lock attempts to acquire the lock and blocks while
// doing so. It returns a channel that is closed if our
// lock is lost or if an error occurs
func (l *zookeeperLock) Lock(stopChan chan struct{}) (<-chan struct{}, error) {
err := l.lock.Lock()
if err == nil {
// We hold the lock, we can set our value
// FIXME: The value is left behind
// (problematic for leader election)
_, err = l.client.Set(l.key, l.value, -1)
}
return make(chan struct{}), err
}
// Unlock the "key". Calling unlock while
// not holding the lock will throw an error
func (l *zookeeperLock) Unlock() error {
return l.lock.Unlock()
}
// Close closes the client connection
func (s *Zookeeper) Close() {
s.client.Close()
}
// Normalize the key for usage in Zookeeper
func (s *Zookeeper) normalize(key string) string {
key = store.Normalize(key)
return strings.TrimSuffix(key, "/")
}
|