Merge pull request #8286 from heyitsanthony/wal-check-locks

wal: fall back to closing wal if locked dir rename fails

wal/wal.go

@@ -157,6 +157,48 @@ func Create(dirpath string, metadata []byte) (*WAL, error) {
 	return w, nil
 }
 
+func (w *WAL) renameWal(tmpdirpath string) (*WAL, error) {
+	if err := os.RemoveAll(w.dir); err != nil {
+		return nil, err
+	}
+	// On non-Windows platforms, hold the lock while renaming. Releasing
+	// the lock and trying to reacquire it quickly can be flaky because
+	// it's possible the process will fork to spawn a process while this is
+	// happening. The fds are set up as close-on-exec by the Go runtime,
+	// but there is a window between the fork and the exec where another
+	// process holds the lock.
+	if err := os.Rename(tmpdirpath, w.dir); err != nil {
+		if _, ok := err.(*os.LinkError); ok {
+			return w.renameWalUnlock(tmpdirpath)
+		}
+		return nil, err
+	}
+	w.fp = newFilePipeline(w.dir, SegmentSizeBytes)
+	df, err := fileutil.OpenDir(w.dir)
+	w.dirFile = df
+	return w, err
+}
+
+func (w *WAL) renameWalUnlock(tmpdirpath string) (*WAL, error) {
+	// rename of directory with locked files doesn't work on windows/cifs;
+	// close the WAL to release the locks so the directory can be renamed.
+	plog.Infof("releasing file lock to rename %q to %q", tmpdirpath, w.dir)
+	w.Close()
+	if err := os.Rename(tmpdirpath, w.dir); err != nil {
+		return nil, err
+	}
+	// reopen and relock
+	newWAL, oerr := Open(w.dir, walpb.Snapshot{})
+	if oerr != nil {
+		return nil, oerr
+	}
+	if _, _, _, err := newWAL.ReadAll(); err != nil {
+		newWAL.Close()
+		return nil, err
+	}
+	return newWAL, nil
+}
+
 // Open opens the WAL at the given snap.
 // The snap SHOULD have been previously saved to the WAL, or the following
 // ReadAll will fail.

wal/wal_unix.go

@@ -1,44 +0,0 @@
-// Copyright 2016 The etcd Authors
-//
-// 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.
-
-// +build !windows
-
-package wal
-
-import (
-	"os"
-
-	"github.com/coreos/etcd/pkg/fileutil"
-)
-
-func (w *WAL) renameWal(tmpdirpath string) (*WAL, error) {
-	// On non-Windows platforms, hold the lock while renaming. Releasing
-	// the lock and trying to reacquire it quickly can be flaky because
-	// it's possible the process will fork to spawn a process while this is
-	// happening. The fds are set up as close-on-exec by the Go runtime,
-	// but there is a window between the fork and the exec where another
-	// process holds the lock.
-
-	if err := os.RemoveAll(w.dir); err != nil {
-		return nil, err
-	}
-	if err := os.Rename(tmpdirpath, w.dir); err != nil {
-		return nil, err
-	}
-
-	w.fp = newFilePipeline(w.dir, SegmentSizeBytes)
-	df, err := fileutil.OpenDir(w.dir)
-	w.dirFile = df
-	return w, err
-}

wal/wal_windows.go

@@ -1,41 +0,0 @@
-// Copyright 2016 The etcd Authors
-//
-// 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 wal
-
-import (
-	"os"
-
-	"github.com/coreos/etcd/wal/walpb"
-)
-
-func (w *WAL) renameWal(tmpdirpath string) (*WAL, error) {
-	// rename of directory with locked files doesn't work on
-	// windows; close the WAL to release the locks so the directory
-	// can be renamed
-	w.Close()
-	if err := os.Rename(tmpdirpath, w.dir); err != nil {
-		return nil, err
-	}
-	// reopen and relock
-	newWAL, oerr := Open(w.dir, walpb.Snapshot{})
-	if oerr != nil {
-		return nil, oerr
-	}
-	if _, _, _, err := newWAL.ReadAll(); err != nil {
-		newWAL.Close()
-		return nil, err
-	}
-	return newWAL, nil
-}