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81 lines
2.1 KiB
81 lines
2.1 KiB
9 years ago
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/*
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* Minio Cloud Storage, (C) 2016 Minio, 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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*/
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package main
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import (
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"io"
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"sync"
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)
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// blockingWriteCloser is a WriteCloser that blocks until released.
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type blockingWriteCloser struct {
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writer io.WriteCloser // Embedded writer.
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release *sync.WaitGroup // Waitgroup for atomicity.
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mutex *sync.Mutex // Mutex for thread safety.
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err error
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}
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// Write to the underlying writer.
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func (b *blockingWriteCloser) Write(data []byte) (int, error) {
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n, err := b.writer.Write(data)
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if err != nil {
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b.mutex.Lock()
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b.err = err
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b.mutex.Unlock()
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}
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return n, b.err
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}
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// Close blocks until another goroutine calls Release(error). Returns
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// error code if either writer fails or Release is called with an error.
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func (b *blockingWriteCloser) Close() error {
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err := b.writer.Close()
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if err != nil {
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b.mutex.Lock()
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b.err = err
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b.mutex.Unlock()
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}
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b.release.Wait()
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return b.err
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}
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// Release the Close, causing it to unblock. Only call this
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// once. Calling it multiple times results in a panic.
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func (b *blockingWriteCloser) Release(err error) {
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b.release.Done()
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if err != nil {
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b.mutex.Lock()
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b.err = err
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b.mutex.Unlock()
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}
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return
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}
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// newBlockingWriteCloser Creates a new write closer that must be
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// released by the read consumer.
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func newBlockingWriteCloser(writer io.WriteCloser) *blockingWriteCloser {
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// Wait group for the go-routine.
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wg := &sync.WaitGroup{}
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// Add to the wait group to wait for.
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wg.Add(1)
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return &blockingWriteCloser{
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writer: writer,
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mutex: &sync.Mutex{},
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release: wg,
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}
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}
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