Merge pull request #2576 from xiang90/fix_wal

wal: releastTo should work with large release index

wal/wal.go

@@ -336,6 +336,7 @@ func (w *WAL) sync() error {
 // lock 1,2 but keep 3. ReleaseLockTo(5) will release 1,2,3 but keep 4.
 func (w *WAL) ReleaseLockTo(index uint64) error {
 	var smaller int
+	found := false
 
 	for i, l := range w.locks {
 		_, lockIndex, err := parseWalName(path.Base(l.Name()))
@@ -344,10 +345,17 @@ func (w *WAL) ReleaseLockTo(index uint64) error {
 		}
 		if lockIndex >= index {
 			smaller = i - 1
+			found = true
 			break
 		}
 	}
 
+	// if no lock index is greater than the release index, we can
+	// release lock upto the last one(excluding).
+	if !found && len(w.locks) != 0 {
+		smaller = len(w.locks) - 1
+	}
+
 	if smaller <= 0 {
 		return nil
 	}

wal/wal_test.go

@@ -20,7 +20,6 @@ import (
 	"os"
 	"path"
 	"reflect"
-	"testing"
 
 	"github.com/coreos/etcd/pkg/pbutil"
 	"github.com/coreos/etcd/raft/raftpb"
@@ -504,4 +503,21 @@ func TestReleaseLockTo(t *testing.T) {
 			t.Errorf("#%d: lockindex = %d, want %d", i, lockIndex, uint64(i+4))
 		}
 	}
+
+	// release the lock to 15
+	unlockIndex = uint64(15)
+	w.ReleaseLockTo(unlockIndex)
+
+	// expected remaining is 10
+	if len(w.locks) != 1 {
+		t.Errorf("len(w.locks) = %d, want %d", len(w.locks), 1)
+	}
+	_, lockIndex, err := parseWalName(path.Base(w.locks[0].Name()))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if lockIndex != uint64(10) {
+		t.Errorf("lockindex = %d, want %d", lockIndex, 10)
+	}
 }