55 lines
1.2 KiB
Go
55 lines
1.2 KiB
Go
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// Copyright 2016 The Prometheus Authors
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// +build darwin dragonfly freebsd linux netbsd openbsd
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package fileutil
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import (
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"os"
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"syscall"
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)
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type unixLock struct {
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f *os.File
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}
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func (l *unixLock) Release() error {
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if err := l.set(false); err != nil {
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return err
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}
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return l.f.Close()
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}
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func (l *unixLock) set(lock bool) error {
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how := syscall.LOCK_UN
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if lock {
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how = syscall.LOCK_EX
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}
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return syscall.Flock(int(l.f.Fd()), how|syscall.LOCK_NB)
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}
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func newLock(fileName string) (Releaser, error) {
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f, err := os.OpenFile(fileName, os.O_RDWR|os.O_CREATE, 0644)
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if err != nil {
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return nil, err
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}
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l := &unixLock{f}
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err = l.set(true)
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if err != nil {
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f.Close()
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return nil, err
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}
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return l, nil
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}
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