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package lock_manager
import (
"sort"
"sync"
"time"
"github.com/seaweedfs/seaweedfs/weed/glog"
"github.com/seaweedfs/seaweedfs/weed/pb"
"github.com/seaweedfs/seaweedfs/weed/util"
)
type LockRingSnapshot struct {
servers []pb.ServerAddress
ts time.Time
}
type LockRing struct {
sync.RWMutex
snapshots []*LockRingSnapshot
candidateServers map[pb.ServerAddress]struct{}
lastUpdateTime time.Time
lastCompactTime time.Time
snapshotInterval time.Duration
onTakeSnapshot func(snapshot []pb.ServerAddress)
cleanupWg sync.WaitGroup
}
func NewLockRing(snapshotInterval time.Duration) *LockRing {
return &LockRing{
snapshotInterval: snapshotInterval,
candidateServers: make(map[pb.ServerAddress]struct{}),
}
}
func (r *LockRing) SetTakeSnapshotCallback(onTakeSnapshot func(snapshot []pb.ServerAddress)) {
r.Lock()
defer r.Unlock()
r.onTakeSnapshot = onTakeSnapshot
}
// AddServer adds a server to the ring
// if the previous snapshot passed the snapshot interval, create a new snapshot
func (r *LockRing) AddServer(server pb.ServerAddress) {
glog.V(0).Infof("add server %v", server)
r.Lock()
if _, found := r.candidateServers[server]; found {
glog.V(0).Infof("add server: already exists %v", server)
r.Unlock()
return
}
r.lastUpdateTime = time.Now()
r.candidateServers[server] = struct{}{}
r.Unlock()
r.takeSnapshotWithDelayedCompaction()
}
func (r *LockRing) RemoveServer(server pb.ServerAddress) {
glog.V(0).Infof("remove server %v", server)
r.Lock()
if _, found := r.candidateServers[server]; !found {
r.Unlock()
return
}
r.lastUpdateTime = time.Now()
delete(r.candidateServers, server)
r.Unlock()
r.takeSnapshotWithDelayedCompaction()
}
func (r *LockRing) SetSnapshot(servers []pb.ServerAddress) {
sort.Slice(servers, func(i, j int) bool {
return servers[i] < servers[j]
})
r.Lock()
r.lastUpdateTime = time.Now()
// init candidateServers
for _, server := range servers {
r.candidateServers[server] = struct{}{}
}
r.Unlock()
r.addOneSnapshot(servers)
r.cleanupWg.Add(1)
go func() {
defer r.cleanupWg.Done()
<-time.After(r.snapshotInterval)
r.compactSnapshots()
}()
}
func (r *LockRing) takeSnapshotWithDelayedCompaction() {
r.doTakeSnapshot()
r.cleanupWg.Add(1)
go func() {
defer r.cleanupWg.Done()
<-time.After(r.snapshotInterval)
r.compactSnapshots()
}()
}
func (r *LockRing) doTakeSnapshot() {
servers := r.getSortedServers()
r.addOneSnapshot(servers)
}
func (r *LockRing) addOneSnapshot(servers []pb.ServerAddress) {
r.Lock()
defer r.Unlock()
ts := time.Now()
t := &LockRingSnapshot{
servers: servers,
ts: ts,
}
r.snapshots = append(r.snapshots, t)
for i := len(r.snapshots) - 2; i >= 0; i-- {
r.snapshots[i+1] = r.snapshots[i]
}
r.snapshots[0] = t
if r.onTakeSnapshot != nil {
r.onTakeSnapshot(t.servers)
}
}
func (r *LockRing) compactSnapshots() {
r.Lock()
defer r.Unlock()
if r.lastCompactTime.After(r.lastUpdateTime) {
return
}
ts := time.Now()
// remove old snapshots
recentSnapshotIndex := 1
for ; recentSnapshotIndex < len(r.snapshots); recentSnapshotIndex++ {
if ts.Sub(r.snapshots[recentSnapshotIndex].ts) > r.snapshotInterval {
break
}
}
// keep the one that has been running for a while
if recentSnapshotIndex+1 <= len(r.snapshots) {
r.snapshots = r.snapshots[:recentSnapshotIndex+1]
}
r.lastCompactTime = ts
}
func (r *LockRing) getSortedServers() []pb.ServerAddress {
sortedServers := make([]pb.ServerAddress, 0, len(r.candidateServers))
for server := range r.candidateServers {
sortedServers = append(sortedServers, server)
}
sort.Slice(sortedServers, func(i, j int) bool {
return sortedServers[i] < sortedServers[j]
})
return sortedServers
}
func (r *LockRing) GetSnapshot() (servers []pb.ServerAddress) {
r.RLock()
defer r.RUnlock()
if len(r.snapshots) == 0 {
return
}
return r.snapshots[0].servers
}
// WaitForCleanup waits for all pending cleanup operations to complete
// This is useful for testing to ensure deterministic behavior
func (r *LockRing) WaitForCleanup() {
r.cleanupWg.Wait()
}
// GetSnapshotCount safely returns the number of snapshots for testing
func (r *LockRing) GetSnapshotCount() int {
r.RLock()
defer r.RUnlock()
return len(r.snapshots)
}
func hashKeyToServer(key string, servers []pb.ServerAddress) pb.ServerAddress {
if len(servers) == 0 {
return ""
}
x := util.HashStringToLong(key)
if x < 0 {
x = -x
}
x = x % int64(len(servers))
return servers[x]
}
|
