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lease.go
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lease.go
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// Copyright 2016 CoreOS, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package recipe
import (
"sync"
"time"
"github.com/coreos/etcd/Godeps/_workspace/src/golang.org/x/net/context"
"github.com/coreos/etcd/clientv3"
pb "github.com/coreos/etcd/etcdserver/etcdserverpb"
"github.com/coreos/etcd/lease"
)
// only keep one ephemeral lease per clientection
var clientLeases clientLeaseMgr = clientLeaseMgr{leases: make(map[*clientv3.Client]*leaseKeepAlive)}
type clientLeaseMgr struct {
leases map[*clientv3.Client]*leaseKeepAlive
mu sync.Mutex
}
type leaseKeepAlive struct {
id lease.LeaseID
donec chan struct{}
}
func SessionLease(client *clientv3.Client) (lease.LeaseID, error) {
return clientLeases.sessionLease(client, 120)
}
func SessionLeaseTTL(client *clientv3.Client, ttl int64) (lease.LeaseID, error) {
return clientLeases.sessionLease(client, ttl)
}
// StopSessionLease ends the refresh for the session lease. This is useful
// in case the state of the client clientection is indeterminate (revoke
// would fail) or if transferring lease ownership.
func StopSessionLease(client *clientv3.Client) {
clientLeases.mu.Lock()
lka, ok := clientLeases.leases[client]
if ok {
delete(clientLeases.leases, client)
}
clientLeases.mu.Unlock()
if lka != nil {
lka.donec <- struct{}{}
<-lka.donec
}
}
// RevokeSessionLease revokes the session lease.
func RevokeSessionLease(client *clientv3.Client) (err error) {
clientLeases.mu.Lock()
lka := clientLeases.leases[client]
clientLeases.mu.Unlock()
StopSessionLease(client)
if lka != nil {
req := &pb.LeaseRevokeRequest{ID: int64(lka.id)}
_, err = client.Lease.LeaseRevoke(context.TODO(), req)
}
return err
}
func (clm *clientLeaseMgr) sessionLease(client *clientv3.Client, ttl int64) (lease.LeaseID, error) {
clm.mu.Lock()
defer clm.mu.Unlock()
if lka, ok := clm.leases[client]; ok {
return lka.id, nil
}
resp, err := client.Lease.LeaseCreate(context.TODO(), &pb.LeaseCreateRequest{TTL: ttl})
if err != nil {
return lease.NoLease, err
}
id := lease.LeaseID(resp.ID)
ctx, cancel := context.WithCancel(context.Background())
keepAlive, err := client.Lease.LeaseKeepAlive(ctx)
if err != nil || keepAlive == nil {
return lease.NoLease, err
}
lka := &leaseKeepAlive{id: id, donec: make(chan struct{})}
clm.leases[client] = lka
// keep the lease alive until clientection error
go func() {
defer func() {
keepAlive.CloseSend()
clm.mu.Lock()
delete(clm.leases, client)
clm.mu.Unlock()
cancel()
close(lka.donec)
}()
ttl := resp.TTL
for {
lreq := &pb.LeaseKeepAliveRequest{ID: int64(id)}
select {
case <-lka.donec:
return
case <-time.After(time.Duration(ttl/2) * time.Second):
}
if err := keepAlive.Send(lreq); err != nil {
break
}
resp, err := keepAlive.Recv()
if err != nil {
break
}
ttl = resp.TTL
}
}()
return id, nil
}