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

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Detecting windows at compile time isn't enough since etcd might be
on linux but the fs is backed by windows.

Fixes: #8178
Fixes: #6984
This commit is contained in:
Anthony Romano 2017-07-19 15:57:42 -07:00
parent 46ee06a85c
commit fe1ddab714
3 changed files with 42 additions and 85 deletions
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42
wal/wal.go
View File

@ -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.

44
wal/wal_unix.go
View File

@ -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
}

41
wal/wal_windows.go
View File

@ -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
}