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92 lines
2.5 KiB
Go
92 lines
2.5 KiB
Go
package lock_manager
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import (
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"fmt"
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"github.com/seaweedfs/seaweedfs/weed/pb"
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"time"
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)
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const MaxDuration = 1<<63 - 1
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var NoLockServerError = fmt.Errorf("no lock server found")
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type DistributedLockManager struct {
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lockManager *LockManager
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LockRing *LockRing
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Host pb.ServerAddress
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}
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func NewDistributedLockManager(host pb.ServerAddress) *DistributedLockManager {
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return &DistributedLockManager{
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lockManager: NewLockManager(),
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LockRing: NewLockRing(time.Second * 5),
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Host: host,
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}
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}
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func (dlm *DistributedLockManager) Lock(key string, token string) (renewToken string, movedTo pb.ServerAddress, err error) {
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return dlm.LockWithTimeout(key, MaxDuration, token)
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}
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func (dlm *DistributedLockManager) LockWithTimeout(key string, expiredAtNs int64, token string) (renewToken string, movedTo pb.ServerAddress, err error) {
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movedTo, err = dlm.FindLockOwner(key)
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if err != nil {
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return
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}
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if movedTo != dlm.Host {
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return
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}
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renewToken, err = dlm.lockManager.Lock(key, expiredAtNs, token)
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return
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}
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func (dlm *DistributedLockManager) FindLockOwner(key string) (movedTo pb.ServerAddress, err error) {
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servers := dlm.LockRing.GetSnapshot()
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if servers == nil {
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err = NoLockServerError
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return
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}
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movedTo = hashKeyToServer(key, servers)
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return
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}
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func (dlm *DistributedLockManager) Unlock(key string, token string) (movedTo pb.ServerAddress, err error) {
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servers := dlm.LockRing.GetSnapshot()
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if servers == nil {
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err = NoLockServerError
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return
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}
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server := hashKeyToServer(key, servers)
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if server != dlm.Host {
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movedTo = server
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return
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}
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_, err = dlm.lockManager.Unlock(key, token)
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return
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}
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// InsertLock is used to insert a lock to a server unconditionally
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// It is used when a server is down and the lock is moved to another server
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func (dlm *DistributedLockManager) InsertLock(key string, expiredAtNs int64, token string) {
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dlm.lockManager.InsertLock(key, expiredAtNs, token)
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}
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func (dlm *DistributedLockManager) SelectNotOwnedLocks(servers []pb.ServerAddress) (locks []*Lock) {
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return dlm.lockManager.SelectLocks(func(key string) bool {
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server := hashKeyToServer(key, servers)
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return server != dlm.Host
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})
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}
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func (dlm *DistributedLockManager) CalculateTargetServer(key string, servers []pb.ServerAddress) pb.ServerAddress {
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return hashKeyToServer(key, servers)
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}
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func (dlm *DistributedLockManager) IsLocal(key string) bool {
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servers := dlm.LockRing.GetSnapshot()
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if len(servers) <= 1 {
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return true
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}
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return hashKeyToServer(key, servers) == dlm.Host
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}
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