node: switching prometheus flock location to tsdb (#19376)

* node: switching prometheus flock location to tsdb

* rookie mistake

vendor/github.com/prometheus/tsdb/fileutil/mmap.go

@@ -0,0 +1,61 @@
+// Copyright 2018 The Prometheus 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 fileutil
+
+import (
+	"os"
+
+	"github.com/pkg/errors"
+)
+
+type MmapFile struct {
+	f *os.File
+	b []byte
+}
+
+func OpenMmapFile(path string) (*MmapFile, error) {
+	f, err := os.Open(path)
+	if err != nil {
+		return nil, errors.Wrap(err, "try lock file")
+	}
+	info, err := f.Stat()
+	if err != nil {
+		return nil, errors.Wrap(err, "stat")
+	}
+
+	b, err := mmap(f, int(info.Size()))
+	if err != nil {
+		return nil, errors.Wrap(err, "mmap")
+	}
+
+	return &MmapFile{f: f, b: b}, nil
+}
+
+func (f *MmapFile) Close() error {
+	err0 := munmap(f.b)
+	err1 := f.f.Close()
+
+	if err0 != nil {
+		return err0
+	}
+	return err1
+}
+
+func (f *MmapFile) File() *os.File {
+	return f.f
+}
+
+func (f *MmapFile) Bytes() []byte {
+	return f.b
+}