94 lines
2.1 KiB
Go
94 lines
2.1 KiB
Go
// Copyright 2020-2021 Buf Technologies, Inc.
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//
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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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package filelock
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import (
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"context"
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"fmt"
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"os"
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"path/filepath"
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"time"
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"github.com/gofrs/flock"
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)
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func lock(
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ctx context.Context,
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filePath string,
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options ...LockOption,
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) (Unlocker, error) {
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return lockForFunc(
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ctx,
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filePath,
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(*flock.Flock).TryLockContext,
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options...,
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)
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}
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func rlock(
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ctx context.Context,
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filePath string,
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options ...LockOption,
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) (Unlocker, error) {
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return lockForFunc(
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ctx,
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filePath,
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(*flock.Flock).TryRLockContext,
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options...,
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)
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}
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func lockForFunc(
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ctx context.Context,
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filePath string,
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tryLockContextFunc func(*flock.Flock, context.Context, time.Duration) (bool, error),
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options ...LockOption,
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) (Unlocker, error) {
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lockOptions := newLockOptions()
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for _, option := range options {
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option(lockOptions)
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}
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// mkdir is an atomic operation
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if err := os.MkdirAll(filepath.Dir(filePath), 0755); err != nil {
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return nil, err
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}
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var cancel context.CancelFunc
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if lockOptions.timeout != 0 {
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ctx, cancel = context.WithTimeout(ctx, lockOptions.timeout)
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defer cancel()
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}
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flock := flock.New(filePath)
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locked, err := tryLockContextFunc(flock, ctx, lockOptions.retryDelay)
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if err != nil {
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return nil, fmt.Errorf("could not get file lock %q: %w", filePath, err)
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}
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if !locked {
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return nil, fmt.Errorf("could not lock %q", filePath)
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}
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return flock, nil
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}
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type lockOptions struct {
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timeout time.Duration
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retryDelay time.Duration
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}
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func newLockOptions() *lockOptions {
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return &lockOptions{
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timeout: DefaultLockTimeout,
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retryDelay: DefaultLockRetryDelay,
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}
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}
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