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Merge pull request #6284 from glycerine/fix6278

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fix unintended deadlock on key prefixes
This commit is contained in:
Xiang Li 2016-08-29 19:50:50 -07:00 committed by GitHub
commit 547bf1a92d
3 changed files with 32 additions and 5 deletions
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5
clientv3/concurrency/election.go
View File

@ -40,7 +40,7 @@ type Election struct {
// NewElection returns a new election on a given key prefix.
func NewElection(s *Session, pfx string) *Election {
return &Election{session: s, keyPrefix: pfx}
return &Election{session: s, keyPrefix: pfx + "/"}
}
// Campaign puts a value as eligible for the election. It blocks until
@ -49,7 +49,7 @@ func (e *Election) Campaign(ctx context.Context, val string) error {
s := e.session
client := e.session.Client()
k := fmt.Sprintf("%s/%x", e.keyPrefix, s.Lease())
k := fmt.Sprintf("%s%x", e.keyPrefix, s.Lease())
txn := client.Txn(ctx).If(v3.Compare(v3.CreateRevision(k), "=", 0))
txn = txn.Then(v3.OpPut(k, val, v3.WithLease(s.Lease())))
txn = txn.Else(v3.OpGet(k))
@ -57,7 +57,6 @@ func (e *Election) Campaign(ctx context.Context, val string) error {
if err != nil {
return err
}
e.leaderKey, e.leaderRev, e.leaderSession = k, resp.Header.Revision, s
if !resp.Succeeded {
kv := resp.Responses[0].GetResponseRange().Kvs[0]

4
clientv3/concurrency/mutex.go
View File

@ -32,7 +32,7 @@ type Mutex struct {
}
func NewMutex(s *Session, pfx string) *Mutex {
return &Mutex{s, pfx, "", -1}
return &Mutex{s, pfx + "/", "", -1}
}
// Lock locks the mutex with a cancellable context. If the context is cancelled
@ -41,7 +41,7 @@ func (m *Mutex) Lock(ctx context.Context) error {
s := m.s
client := m.s.Client()
m.myKey = fmt.Sprintf("%s/%x", m.pfx, s.Lease())
m.myKey = fmt.Sprintf("%s%x", m.pfx, s.Lease())
cmp := v3.Compare(v3.CreateRevision(m.myKey), "=", 0)
// put self in lock waiters via myKey; oldest waiter holds lock
put := v3.OpPut(m.myKey, "", v3.WithLease(s.Lease()))

28
integration/v3_election_test.go
View File

@ -197,3 +197,31 @@ func TestElectionSessionRecampaign(t *testing.T) {
t.Fatalf("expected value=%q, got response %v", "def", resp)
}
}
// TestElectionOnPrefixOfExistingKey checks that a single
// candidate can be elected on a new key that is a prefix
// of an existing key. To wit, check for regression
// of bug #6278. https://github.com/coreos/etcd/issues/6278
//
func TestElectionOnPrefixOfExistingKey(t *testing.T) {
clus := NewClusterV3(t, &ClusterConfig{Size: 1})
defer clus.Terminate(t)
cli := clus.RandClient()
if _, err := cli.Put(context.TODO(), "testa", "value"); err != nil {
t.Fatal(err)
}
s, serr := concurrency.NewSession(cli)
if serr != nil {
t.Fatal(serr)
}
e := concurrency.NewElection(s, "test")
ctx, cancel := context.WithTimeout(context.TODO(), 5*time.Second)
err := e.Campaign(ctx, "abc")
cancel()
if err != nil {
// after 5 seconds, deadlock results in
// 'context deadline exceeded' here.
t.Fatal(err)
}
}