initial import

rq/update/incrementalupdater.go

@@ -0,0 +1,179 @@
+package update
+
+import (
+	"sync"
+	"time"
+
+	"zero/core/hash"
+	"zero/core/stringx"
+)
+
+const (
+	incrementalStep = 5
+	stepDuration    = time.Second * 3
+)
+
+type (
+	updateEvent struct {
+		keys    []string
+		newKey  string
+		servers []string
+	}
+
+	UpdateFunc func(change ServerChange)
+
+	IncrementalUpdater struct {
+		lock          sync.Mutex
+		started       bool
+		taskChan      chan updateEvent
+		updates       ServerChange
+		updateFn      UpdateFunc
+		pendingEvents []updateEvent
+	}
+)
+
+func NewIncrementalUpdater(updateFn UpdateFunc) *IncrementalUpdater {
+	return &IncrementalUpdater{
+		taskChan: make(chan updateEvent),
+		updates: ServerChange{
+			Current: Snapshot{
+				Keys:         make([]string, 0),
+				WeightedKeys: make([]weightedKey, 0),
+			},
+			Servers: make([]string, 0),
+		},
+		updateFn: updateFn,
+	}
+}
+
+func (ru *IncrementalUpdater) Update(keys []string, servers []string, newKey string) {
+	ru.lock.Lock()
+	defer ru.lock.Unlock()
+
+	if !ru.started {
+		go ru.run()
+		ru.started = true
+	}
+
+	ru.taskChan <- updateEvent{
+		keys:    keys,
+		newKey:  newKey,
+		servers: servers,
+	}
+}
+
+// Return true if incremental update is done
+func (ru *IncrementalUpdater) advance() bool {
+	previous := ru.updates.Current
+	keys := make([]string, 0)
+	weightedKeys := make([]weightedKey, 0)
+	servers := ru.updates.Servers
+	for _, key := range ru.updates.Current.Keys {
+		keys = append(keys, key)
+	}
+	for _, wkey := range ru.updates.Current.WeightedKeys {
+		weight := wkey.Weight + incrementalStep
+		if weight >= hash.TopWeight {
+			keys = append(keys, wkey.Key)
+		} else {
+			weightedKeys = append(weightedKeys, weightedKey{
+				Key:    wkey.Key,
+				Weight: weight,
+			})
+		}
+	}
+
+	for _, event := range ru.pendingEvents {
+		// ignore reload events
+		if len(event.newKey) == 0 || len(event.servers) == 0 {
+			continue
+		}
+
+		// anyway, add the servers, just to avoid missing notify any server
+		servers = stringx.Union(servers, event.servers)
+		if keyExists(keys, weightedKeys, event.newKey) {
+			continue
+		}
+
+		weightedKeys = append(weightedKeys, weightedKey{
+			Key:    event.newKey,
+			Weight: incrementalStep,
+		})
+	}
+
+	// clear pending events
+	ru.pendingEvents = ru.pendingEvents[:0]
+
+	change := ServerChange{
+		Previous: previous,
+		Current: Snapshot{
+			Keys:         keys,
+			WeightedKeys: weightedKeys,
+		},
+		Servers: servers,
+	}
+	ru.updates = change
+	ru.updateFn(change)
+
+	return len(weightedKeys) == 0
+}
+
+func (ru *IncrementalUpdater) run() {
+	defer func() {
+		ru.lock.Lock()
+		ru.started = false
+		ru.lock.Unlock()
+	}()
+
+	ticker := time.NewTicker(stepDuration)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-ticker.C:
+			if ru.advance() {
+				return
+			}
+		case event := <-ru.taskChan:
+			ru.updateKeys(event)
+		}
+	}
+}
+
+func (ru *IncrementalUpdater) updateKeys(event updateEvent) {
+	isWeightedKey := func(key string) bool {
+		for _, wkey := range ru.updates.Current.WeightedKeys {
+			if wkey.Key == key {
+				return true
+			}
+		}
+
+		return false
+	}
+
+	keys := make([]string, 0, len(event.keys))
+	for _, key := range event.keys {
+		if !isWeightedKey(key) {
+			keys = append(keys, key)
+		}
+	}
+
+	ru.updates.Current.Keys = keys
+	ru.pendingEvents = append(ru.pendingEvents, event)
+}
+
+func keyExists(keys []string, weightedKeys []weightedKey, key string) bool {
+	for _, each := range keys {
+		if key == each {
+			return true
+		}
+	}
+
+	for _, wkey := range weightedKeys {
+		if wkey.Key == key {
+			return true
+		}
+	}
+
+	return false
+}

rq/update/serverchange.go

@@ -0,0 +1,106 @@
+package update
+
+import (
+	"crypto/md5"
+	"errors"
+	"fmt"
+	"io"
+	"sort"
+
+	"zero/core/hash"
+	"zero/core/jsonx"
+	"zero/rq/constant"
+)
+
+var ErrInvalidServerChange = errors.New("not a server change message")
+
+type (
+	weightedKey struct {
+		Key    string
+		Weight int
+	}
+
+	Snapshot struct {
+		Keys         []string
+		WeightedKeys []weightedKey
+	}
+
+	ServerChange struct {
+		Previous Snapshot
+		Current  Snapshot
+		Servers  []string
+	}
+)
+
+func (s Snapshot) GetCode() string {
+	keys := append([]string(nil), s.Keys...)
+	sort.Strings(keys)
+	weightedKeys := append([]weightedKey(nil), s.WeightedKeys...)
+	sort.SliceStable(weightedKeys, func(i, j int) bool {
+		return weightedKeys[i].Key < weightedKeys[j].Key
+	})
+
+	digest := md5.New()
+	for _, key := range keys {
+		io.WriteString(digest, fmt.Sprintf("%s\n", key))
+	}
+	for _, wkey := range weightedKeys {
+		io.WriteString(digest, fmt.Sprintf("%s:%d\n", wkey.Key, wkey.Weight))
+	}
+
+	return fmt.Sprintf("%x", digest.Sum(nil))
+}
+
+func (sc ServerChange) CreateCurrentHash() *hash.ConsistentHash {
+	curHash := hash.NewConsistentHash()
+
+	for _, key := range sc.Current.Keys {
+		curHash.Add(key)
+	}
+	for _, wkey := range sc.Current.WeightedKeys {
+		curHash.AddWithWeight(wkey.Key, wkey.Weight)
+	}
+
+	return curHash
+}
+
+func (sc ServerChange) CreatePrevHash() *hash.ConsistentHash {
+	prevHash := hash.NewConsistentHash()
+
+	for _, key := range sc.Previous.Keys {
+		prevHash.Add(key)
+	}
+	for _, wkey := range sc.Previous.WeightedKeys {
+		prevHash.AddWithWeight(wkey.Key, wkey.Weight)
+	}
+
+	return prevHash
+}
+
+func (sc ServerChange) GetCode() string {
+	return sc.Current.GetCode()
+}
+
+func IsServerChange(message string) bool {
+	return len(message) > 0 && message[0] == constant.ServerSensitivePrefix
+}
+
+func (sc ServerChange) Marshal() (string, error) {
+	body, err := jsonx.Marshal(sc)
+	if err != nil {
+		return "", err
+	}
+
+	return string(append([]byte{constant.ServerSensitivePrefix}, body...)), nil
+}
+
+func UnmarshalServerChange(body string) (ServerChange, error) {
+	if len(body) == 0 {
+		return ServerChange{}, ErrInvalidServerChange
+	}
+
+	var change ServerChange
+	err := jsonx.UnmarshalFromString(body[1:], &change)
+
+	return change, err
+}