Create etcd_sequencer.go

the 1st version
This commit is contained in:
stlpmo 2019-11-04 16:36:06 +08:00
parent 08c83b1a59
commit 364f7200ad

View file

@ -0,0 +1,378 @@
package sequence
import (
"context"
"fmt"
"github.com/chrislusf/seaweedfs/weed/glog"
"go.etcd.io/etcd/client"
"io"
"os"
"strconv"
"strings"
"sync"
"time"
)
const (
EtcdKeySequence = "/master/sequence"
EtcdKeyPrefix = "/seaweedfs"
EtcdContextTimeoutSecond = 100 * time.Second
DefaultEtcdSteps uint64 = 500 // internal counter
SequencerFileName = "sequencer.dat"
FileMaxSequenceLength = 128
)
type EtcdSequencer struct {
sequenceLock sync.Mutex
// available sequence range : [steps, maxCounter)
maxCounter uint64
steps uint64
etcdClient client.Client
keysAPI client.KeysAPI
seqFile *os.File
}
func NewEtcdSequencer(etcdUrls string, metaFolder string) (*EtcdSequencer, error) {
file, err := openSequenceFile(metaFolder + "/" + SequencerFileName)
if nil != err {
return nil, fmt.Errorf("open sequence file fialed, %v", err)
}
cli, err := client.New(client.Config{
Endpoints: strings.Split(etcdUrls, ","),
Username: "",
Password: "",
})
if err != nil {
return nil, err
}
keysApi := client.NewKeysAPI(cli)
maxValue, _, err := readSequenceFile(file)
if err != nil {
return nil, fmt.Errorf("read sequence from file failed, %v", err)
}
glog.V(4).Infof("read sequence from file : %d", maxValue)
newSeq, err := setMaxSequenceToEtcd(keysApi, maxValue)
if err != nil {
return nil, err
}
// make the step and max the same, and then they are fake,
// after invoking the NextFileId(), they are different and real
maxCounter, steps := newSeq, newSeq
sequencer := &EtcdSequencer{maxCounter: maxCounter,
steps: steps,
etcdClient: cli,
keysAPI: keysApi,
seqFile: file,
}
return sequencer, nil
}
func (es *EtcdSequencer) NextFileId(count uint64) (new uint64, cnt uint64) {
es.sequenceLock.Lock()
defer es.sequenceLock.Unlock()
if (es.steps + count) >= es.maxCounter {
reqSteps := DefaultEtcdSteps
if count > DefaultEtcdSteps {
reqSteps += count
}
maxId, err := batchGetSequenceFromEtcd(es.keysAPI, reqSteps)
glog.V(4).Infof("get max sequence id from etcd, %d", maxId)
if err != nil {
glog.Error(err)
return 0, 0
}
es.steps, es.maxCounter = maxId-reqSteps, maxId
glog.V(4).Infof("current id : %d, max id : %d", es.steps, es.maxCounter)
if err := writeSequenceFile(es.seqFile, es.maxCounter, es.steps); err != nil {
glog.Errorf("flush sequence to file failed, %v", err)
}
}
ret := es.steps
es.steps += count
return ret, count
}
/**
instead of collecting the max value from volume server,
the max value should be saved in local config file and ETCD cluster
*/
func (es *EtcdSequencer) SetMax(seenValue uint64) {
es.sequenceLock.Lock()
defer es.sequenceLock.Unlock()
if seenValue > es.maxCounter {
maxId, err := setMaxSequenceToEtcd(es.keysAPI, seenValue)
if err != nil {
glog.Errorf("set Etcd Max sequence failed : %v", err)
return
}
es.steps, es.maxCounter = maxId, maxId
if err := writeSequenceFile(es.seqFile, maxId, maxId); err != nil {
glog.Errorf("flush sequence to file failed, %v", err)
}
}
}
func (es *EtcdSequencer) GetMax() uint64 {
return es.maxCounter
}
func (es *EtcdSequencer) Peek() uint64 {
return es.steps
}
func batchGetSequenceFromEtcd(kvApi client.KeysAPI, step uint64) (uint64, error) {
if step <= 0 {
return 0, fmt.Errorf("the step must be large than 1")
}
ctx, cancel := context.WithTimeout(context.Background(), EtcdContextTimeoutSecond)
var endSeqValue uint64 = 0
defer cancel()
for {
getResp, err := kvApi.Get(ctx, EtcdKeySequence, &client.GetOptions{Recursive: false, Quorum: true})
if err != nil {
return 0, err
}
if getResp.Node == nil {
continue
}
prevValue := getResp.Node.Value
prevSeqValue, err := strconv.ParseUint(prevValue, 10, 64)
if err != nil {
return 0, fmt.Errorf("get sequence from etcd failed, %v", err)
}
endSeqValue = prevSeqValue + step
endSeqStr := strconv.FormatUint(endSeqValue, 10)
_, err = kvApi.Set(ctx, EtcdKeySequence, endSeqStr, &client.SetOptions{PrevValue: prevValue})
if err == nil {
break
}
glog.Error(err)
}
return endSeqValue, nil
}
/**
update the key of EtcdKeySequence in ETCD cluster with the parameter of maxSeq,
until the value of EtcdKeySequence is equal to or larger than the maxSeq
*/
func setMaxSequenceToEtcd(kvApi client.KeysAPI, maxSeq uint64) (uint64, error) {
maxSeqStr := strconv.FormatUint(maxSeq, 10)
ctx, cancel := context.WithTimeout(context.Background(), EtcdContextTimeoutSecond)
defer cancel()
for {
getResp, err := kvApi.Get(ctx, EtcdKeySequence, &client.GetOptions{Recursive: false, Quorum: true})
if err != nil {
if ce, ok := err.(client.Error); ok && (ce.Code == client.ErrorCodeKeyNotFound) {
_, err := kvApi.Create(ctx, EtcdKeySequence, maxSeqStr)
if err == nil {
continue // create ETCD key success, retry get ETCD value
}
if ce, ok = err.(client.Error); ok && (ce.Code == client.ErrorCodeNodeExist) {
continue // ETCD key exist, retry get ETCD value
}
return 0, err
} else {
return 0, err
}
}
if getResp.Node == nil {
continue
}
prevSeqStr := getResp.Node.Value
prevSeq, err := strconv.ParseUint(prevSeqStr, 10, 64)
if err != nil {
return 0, err
}
if prevSeq >= maxSeq {
return prevSeq, nil
}
_, err = kvApi.Set(ctx, EtcdKeySequence, maxSeqStr, &client.SetOptions{PrevValue: prevSeqStr})
if err != nil {
return 0, err
}
}
return maxSeq, nil
}
func openSequenceFile(file string) (*os.File, error) {
_, err := os.Stat(file)
if os.IsNotExist(err) {
fid, err := os.OpenFile(file, os.O_RDWR|os.O_CREATE, 0644)
if err != nil {
return nil, err
}
if err := writeSequenceFile(fid, 1, 0); err != nil {
return nil, err
}
return fid, nil
} else {
return os.OpenFile(file, os.O_RDWR|os.O_CREATE, 0644)
}
}
/*
sequence : step 以冒号分割
*/
func readSequenceFile(file *os.File) (uint64, uint64, error) {
sequence := make([]byte, FileMaxSequenceLength)
size, err := file.ReadAt(sequence, 0)
if (err != nil) && (err != io.EOF) {
err := fmt.Errorf("cannot read file %s, %v", file.Name(), err)
return 0, 0, err
}
sequence = sequence[0:size]
seqs := strings.Split(string(sequence), ":")
maxId, err := strconv.ParseUint(seqs[0], 10, 64)
if err != nil {
return 0, 0, fmt.Errorf("parse sequence from file failed, %v", err)
}
if len(seqs) > 1 {
step, err := strconv.ParseUint(seqs[1], 10, 64)
if err != nil {
return 0, 0, fmt.Errorf("parse sequence from file failed, %v", err)
}
return maxId, step, nil
}
return maxId, 0, nil
}
/**
先不存放step到文件中
*/
func writeSequenceFile(file *os.File, sequence, step uint64) error {
_ = step
seqStr := fmt.Sprintf("%d:%d", sequence, sequence)
if _, err := file.Seek(0, 0); err != nil {
err = fmt.Errorf("cannot seek to the beginning of %s: %v", file.Name(), err)
return err
}
if err := file.Truncate(0); err != nil {
return fmt.Errorf("truncate sequence file faield : %v", err)
}
if _, err := file.WriteString(seqStr); err != nil {
return fmt.Errorf("write file %s failed, %v", file.Name(), err)
}
if err := file.Sync(); err != nil {
return fmt.Errorf("flush file %s failed, %v", file.Name(), err)
}
return nil
}
func deleteEtcdKey(kvApi client.KeysAPI, key string) error {
ctx, cancel := context.WithTimeout(context.Background(), EtcdContextTimeoutSecond)
defer cancel()
_, err := kvApi.Delete(ctx, key, &client.DeleteOptions{Dir: false})
if err != nil {
return err
}
return nil
}
//func (es *EtcdSequencer) Load() error {
// es.sequenceLock.Lock()
// defer es.sequenceLock.Unlock()
// reqSteps := DefaultEtcdSteps
// maxId, err := batchGetSequenceFromEtcd(es.keysAPI, reqSteps)
// glog.V(4).Infof("get max sequence id from etcd, %d", maxId)
// if err != nil {
// glog.Error(err)
// return err
// }
// es.steps, es.maxCounter = maxId-reqSteps, maxId
// glog.V(4).Infof("current id : %d, max id : %d", es.steps, es.maxCounter)
//
// if err := writeSequenceFile(es.seqFile, es.maxCounter, es.steps); err != nil {
// glog.Errorf("flush sequence to file failed, %v", err)
// return err
// }
// return nil
//}
//func getEtcdKey(kv client.KeysAPI, key string) (string, error) {
// resp, err := kv.Get(context.Background(), key, &client.GetOptions{Recursive: false, Quorum: true})
// if err != nil {
// glog.Warningf("key:%s result:%v", EtcdKeySequence, err)
// return "", err
// }
// if resp.Node == nil {
// return "", fmt.Errorf("the key is not exist, %s", key)
// }
// return resp.Node.Value, nil
//}
//func (es *EtcdSequencer) setLocalSequence(maxValue uint64) {
// es.sequenceLock.Lock()
// defer es.sequenceLock.Unlock()
// if maxValue > es.maxCounter {
// es.maxCounter, es.steps = maxValue, maxValue-DefaultEtcdSteps
//
// if err := writeSequenceFile(es.seqFile, es.maxCounter, es.steps); err != nil {
// glog.Errorf("flush sequence to file failed, %v", err)
// }
// }
//}
//func getEtcdKeysApi(etcdUrls, user, passwd string) (client.KeysAPI, error) {
// cli, err := client.New(client.Config{
// Endpoints: strings.Split(etcdUrls, ","),
// Username: user,
// Password: passwd,
// })
// if err != nil {
// return nil, err
// }
// keysApi := client.NewKeysAPI(cli)
// return keysApi, nil
//}
//func (es *EtcdSequencer) asyncStartWatcher() {
// es.startWatcher(es.keysAPI, EtcdKeySequence, func(value string, index uint64) {
// newValue, err := strconv.ParseUint(value, 10, 64)
// if err != nil {
// glog.Warning(err)
// }
// es.setLocalSequence(newValue)
// })
//}
//func (es *EtcdSequencer) startWatcher(kvApi client.KeysAPI, key string, callback func(value string, index uint64)) {
// ctx, cancel := context.WithTimeout(context.Background(), EtcdContextTimeoutSecond)
// defer cancel()
// ctx.Done()
//
// getResp, err := kvApi.Get(ctx, key, &client.GetOptions{Recursive: false, Quorum: true})
// if err != nil {
// return
// }
//
// watcher := kvApi.Watcher(key, &client.WatcherOptions{AfterIndex: getResp.Index, Recursive: false})
// go func(w client.Watcher) {
// for {
// resp, err := w.Next(context.Background())
// if err != nil {
// glog.Error(err)
// continue
// }
// callback(resp.Node.Value, resp.Index)
// }
// }(watcher)
// return
//}