/
lock.go
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/
lock.go
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//go:build !windows
// +build !windows
// Copyright 2020 Antrea 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 iptables
import (
"fmt"
"os"
"time"
"golang.org/x/sys/unix"
"k8s.io/apimachinery/pkg/util/wait"
)
const (
XtablesLockFilePath = "/var/run/xtables.lock"
xtablesLockFilePermission = 0600
)
// Lock acquires the provided file lock. It's thread-safe.
// It will block until the lock is acquired or the timeout is reached.
func Lock(lockFilePath string, timeout time.Duration) (func() error, error) {
lockFile, err := os.OpenFile(lockFilePath, os.O_CREATE, xtablesLockFilePermission)
if err != nil {
return nil, fmt.Errorf("error opening xtables lock file: %v", err)
}
// Check whether the lock is available every 200ms.
if err := wait.PollImmediate(waitIntervalMicroSeconds*time.Microsecond, timeout, func() (bool, error) {
if err := unix.Flock(int(lockFile.Fd()), unix.LOCK_EX|unix.LOCK_NB); err != nil {
return false, nil
}
return true, nil
}); err != nil {
lockFile.Close()
return nil, fmt.Errorf("error acquiring xtables lock: %v", err)
}
return lockFile.Close, nil
}