79 lines
2.2 KiB
Go
79 lines
2.2 KiB
Go
/*
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Copyright 2019 The Kubernetes Authors All rights reserved.
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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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http://www.apache.org/licenses/LICENSE-2.0
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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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*/
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package lock
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import (
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"crypto/sha1"
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"fmt"
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"os"
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"time"
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"github.com/juju/clock"
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"github.com/juju/mutex/v2"
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"github.com/pkg/errors"
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"k8s.io/klog/v2"
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)
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// WriteFile decorates os.WriteFile with a file lock and retry
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func WriteFile(filename string, data []byte, perm os.FileMode) error {
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spec := PathMutexSpec(filename)
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klog.Infof("WriteFile acquiring %s: %+v", filename, spec)
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releaser, err := mutex.Acquire(spec)
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if err != nil {
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return errors.Wrapf(err, "failed to acquire lock for %s: %+v", filename, spec)
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}
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defer releaser.Release()
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return os.WriteFile(filename, data, perm)
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}
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// AppendToFile appends DATA bytes to the specified FILENAME in a mutually exclusive way.
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// The file is created if it does not exist, using the specified PERM (before umask)
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func AppendToFile(filename string, data []byte, perm os.FileMode) error {
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spec := PathMutexSpec(filename)
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klog.Infof("WriteFile acquiring %s: %+v", filename, spec)
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releaser, err := mutex.Acquire(spec)
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if err != nil {
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return errors.Wrapf(err, "failed to acquire lock for %s: %+v", filename, spec)
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}
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defer releaser.Release()
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fd, err := os.OpenFile(filename, os.O_APPEND|os.O_CREATE|os.O_WRONLY, perm)
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if err != nil {
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return errors.Wrapf(err, "failed to open %s: %+v", filename, spec)
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}
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_, err = fd.Write(data)
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return err
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}
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// PathMutexSpec returns a mutex spec for a path
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func PathMutexSpec(path string) mutex.Spec {
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s := mutex.Spec{
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Name: fmt.Sprintf("mk%x", sha1.Sum([]byte(path)))[0:40],
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Clock: clock.WallClock,
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// Poll the lock twice a second
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Delay: 500 * time.Millisecond,
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// panic after a minute instead of locking infinitely
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Timeout: 60 * time.Second,
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}
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return s
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}
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