Create etcd_sequencer.go

the 1st version

weed/sequence/etcd_sequencer.go

@@ -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
+//}