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global.go
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global.go
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// Copyright 2012, Google Inc. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package zk emulates a "global" namespace across n zk quorums.
package zk
import (
"fmt"
"sort"
"time"
"launchpad.net/gozk/zookeeper"
)
const (
DEFAULT_MAX_RETRIES = 3
)
type GlobalZookeeperError string
func (e GlobalZookeeperError) Error() string {
return string(e)
}
type GlobalConn struct {
serverAddrs []string
zconns []*zookeeper.Conn
maxRetries int
}
func Dial(serverAddrs []string, recvTimeout time.Duration) (*GlobalConn, <-chan zookeeper.Event, error) {
zconns := make([]*zookeeper.Conn, len(serverAddrs))
zchans := make([]<-chan zookeeper.Event, len(serverAddrs))
for i, addr := range serverAddrs {
conn, eventChan, err := zookeeper.Dial(addr, recvTimeout)
if err != nil {
// teardown
for j := 0; j < i; j++ {
zconns[j].Close()
}
return nil, nil, err
}
zconns[i] = conn
zchans[i] = eventChan
}
eventChan := make(chan zookeeper.Event, 1)
go func() {
var e zookeeper.Event
for _, c := range zchans {
e = <-c
}
eventChan <- e
close(eventChan)
}()
return &GlobalConn{serverAddrs, zconns, DEFAULT_MAX_RETRIES}, eventChan, nil
}
func (gzc *GlobalConn) Close() (err error) {
for _, zc := range gzc.zconns {
if zcErr := zc.Close(); zcErr != nil {
err = zcErr
}
}
return
}
func (gzc *GlobalConn) Create(path, value string, flags int, aclv []zookeeper.ACL) (pathCreated string, err error) {
createdPaths := make([]string, len(gzc.zconns))
errs := make([]error, len(gzc.zconns))
for i, zconn := range gzc.zconns {
createdPaths[i], errs[i] = zconn.Create(path, value, flags, aclv)
if errs[i] != nil {
return "", fmt.Errorf("global create error: %v %v", createdPaths, errs[i])
}
if createdPaths[0] != createdPaths[i] {
return "", fmt.Errorf("inconsistent global create: %v", createdPaths)
}
}
return createdPaths[0], errs[0]
}
func (gzc *GlobalConn) Get(path string) (data string, stat Stat, err error) {
datas := make([]string, len(gzc.zconns))
for i, zconn := range gzc.zconns {
data, stat, err = zconn.Get(path)
if err != nil {
return "", nil, fmt.Errorf("global get error: %v", err)
}
datas[i] = data
if datas[0] != data {
return "", nil, fmt.Errorf("inconsistent global get: %v", err)
}
}
return
}
func (gzc *GlobalConn) Children(path string) (children []string, stat Stat, err error) {
childrens := make([][]string, len(gzc.zconns))
for i, zconn := range gzc.zconns {
children, stat, err = zconn.Children(path)
sort.Strings(children)
if err != nil {
return nil, nil, fmt.Errorf("global children error: %v", err)
}
childrens[i] = children
if !eqSlice(childrens[0], children) {
return nil, nil, fmt.Errorf("inconsistent global children: %v", err)
}
}
return
}
func eqSlice(a, b []string) bool {
if len(a) != len(b) {
return false
}
for i, x := range a {
if b[i] != x {
return false
}
}
return true
}
func (gzc *GlobalConn) Set(path, value string, version int) (stat Stat, err error) {
for _, zconn := range gzc.zconns {
stat, err = zconn.Set(path, value, version)
if err != nil {
return nil, fmt.Errorf("inconsistent global set: %v", err)
}
}
return stat, nil
}
func (gzc *GlobalConn) Delete(path string, version int) (err error) {
for _, zconn := range gzc.zconns {
err = zconn.Delete(path, version)
if err != nil {
return fmt.Errorf("inconsistent global delete: %v", err)
}
}
return
}