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package weed_server
import (
"context"
"fmt"
"github.com/seaweedfs/seaweedfs/weed/stats"
"math/rand"
"sync"
"time"
"github.com/seaweedfs/raft"
"github.com/seaweedfs/seaweedfs/weed/cluster"
"github.com/seaweedfs/seaweedfs/weed/glog"
"github.com/seaweedfs/seaweedfs/weed/pb"
"github.com/seaweedfs/seaweedfs/weed/pb/filer_pb"
"github.com/seaweedfs/seaweedfs/weed/pb/volume_server_pb"
"github.com/seaweedfs/seaweedfs/weed/pb/master_pb"
)
/*
How exclusive lock works?
-----------
Shell
------
When shell lock,
* lease an admin token (lockTime, token)
* start a goroutine to renew the admin token periodically
When shell unlock
* stop the renewal goroutine
* sends a release lock request
Master
------
Master maintains:
* randomNumber
* lastLockTime
When master receives the lease/renew request from shell
If lastLockTime still fresh {
if is a renew and token is valid {
// for renew
generate the randomNumber => token
return
}
refuse
return
} else {
// for fresh lease request
generate the randomNumber => token
return
}
When master receives the release lock request from shell
set the lastLockTime to zero
The volume server does not need to verify.
This makes the lock/unlock optional, similar to what golang code usually does.
*/
const (
LockDuration = 10 * time.Second
)
type AdminLock struct {
accessSecret int64
accessLockTime time.Time
lastClient string
lastMessage string
}
type AdminLocks struct {
locks map[string]*AdminLock
sync.RWMutex
}
func NewAdminLocks() *AdminLocks {
return &AdminLocks{
locks: make(map[string]*AdminLock),
}
}
func (locks *AdminLocks) isLocked(lockName string) (clientName string, message string, isLocked bool) {
locks.RLock()
defer locks.RUnlock()
adminLock, found := locks.locks[lockName]
if !found {
return "", "", false
}
glog.V(4).Infof("isLocked %v: %v", adminLock.lastClient, adminLock.lastMessage)
return adminLock.lastClient, adminLock.lastMessage, adminLock.accessLockTime.Add(LockDuration).After(time.Now())
}
func (locks *AdminLocks) isValidToken(lockName string, ts time.Time, token int64) bool {
locks.RLock()
defer locks.RUnlock()
adminLock, found := locks.locks[lockName]
if !found {
return false
}
return adminLock.accessLockTime.Equal(ts) && adminLock.accessSecret == token
}
func (locks *AdminLocks) generateToken(lockName string, clientName string) (ts time.Time, token int64) {
locks.Lock()
defer locks.Unlock()
lock := &AdminLock{
accessSecret: rand.Int63(),
accessLockTime: time.Now(),
lastClient: clientName,
}
locks.locks[lockName] = lock
stats.MasterAdminLock.WithLabelValues(clientName).Set(1)
return lock.accessLockTime, lock.accessSecret
}
func (locks *AdminLocks) deleteLock(lockName string) {
locks.Lock()
stats.MasterAdminLock.WithLabelValues(locks.locks[lockName].lastClient).Set(0)
defer locks.Unlock()
delete(locks.locks, lockName)
}
func (ms *MasterServer) LeaseAdminToken(ctx context.Context, req *master_pb.LeaseAdminTokenRequest) (*master_pb.LeaseAdminTokenResponse, error) {
resp := &master_pb.LeaseAdminTokenResponse{}
if !ms.Topo.IsLeader() {
return resp, raft.NotLeaderError
}
if lastClient, lastMessage, isLocked := ms.adminLocks.isLocked(req.LockName); isLocked {
glog.V(4).Infof("LeaseAdminToken %v", lastClient)
if req.PreviousToken != 0 && ms.adminLocks.isValidToken(req.LockName, time.Unix(0, req.PreviousLockTime), req.PreviousToken) {
// for renew
ts, token := ms.adminLocks.generateToken(req.LockName, req.ClientName)
resp.Token, resp.LockTsNs = token, ts.UnixNano()
return resp, nil
}
// refuse since still locked
return resp, fmt.Errorf("already locked by %v: %v", lastClient, lastMessage)
}
// for fresh lease request
ts, token := ms.adminLocks.generateToken(req.LockName, req.ClientName)
resp.Token, resp.LockTsNs = token, ts.UnixNano()
return resp, nil
}
func (ms *MasterServer) ReleaseAdminToken(ctx context.Context, req *master_pb.ReleaseAdminTokenRequest) (*master_pb.ReleaseAdminTokenResponse, error) {
resp := &master_pb.ReleaseAdminTokenResponse{}
if ms.adminLocks.isValidToken(req.LockName, time.Unix(0, req.PreviousLockTime), req.PreviousToken) {
ms.adminLocks.deleteLock(req.LockName)
}
return resp, nil
}
func (ms *MasterServer) Ping(ctx context.Context, req *master_pb.PingRequest) (resp *master_pb.PingResponse, pingErr error) {
resp = &master_pb.PingResponse{
StartTimeNs: time.Now().UnixNano(),
}
if req.TargetType == cluster.FilerType {
pingErr = pb.WithFilerClient(false, pb.ServerAddress(req.Target), ms.grpcDialOption, func(client filer_pb.SeaweedFilerClient) error {
pingResp, err := client.Ping(ctx, &filer_pb.PingRequest{})
if pingResp != nil {
resp.RemoteTimeNs = pingResp.StartTimeNs
}
return err
})
}
if req.TargetType == cluster.VolumeServerType {
pingErr = pb.WithVolumeServerClient(false, pb.ServerAddress(req.Target), ms.grpcDialOption, func(client volume_server_pb.VolumeServerClient) error {
pingResp, err := client.Ping(ctx, &volume_server_pb.PingRequest{})
if pingResp != nil {
resp.RemoteTimeNs = pingResp.StartTimeNs
}
return err
})
}
if req.TargetType == cluster.MasterType {
pingErr = pb.WithMasterClient(false, pb.ServerAddress(req.Target), ms.grpcDialOption, false, func(client master_pb.SeaweedClient) error {
pingResp, err := client.Ping(ctx, &master_pb.PingRequest{})
if pingResp != nil {
resp.RemoteTimeNs = pingResp.StartTimeNs
}
return err
})
}
if pingErr != nil {
pingErr = fmt.Errorf("ping %s %s: %v", req.TargetType, req.Target, pingErr)
}
resp.StopTimeNs = time.Now().UnixNano()
return
}
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