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75 lines
2.1 KiB
Go
75 lines
2.1 KiB
Go
/*
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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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// waitCloser implements a Closer that blocks until released, this
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// prevents the writer closing one end of a pipe while making sure
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// that all data is written and committed to disk on the end.
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// Additionally this also implements Write().
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type waitCloser struct {
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wg *sync.WaitGroup // Waitgroup for atomicity.
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writer io.WriteCloser // Embedded writer.
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}
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// Write to the underlying writer.
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func (b *waitCloser) Write(data []byte) (int, error) {
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return b.writer.Write(data)
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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 *waitCloser) Close() error {
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err := b.writer.Close()
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b.wg.Wait()
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return err
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}
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// CloseWithError closes the writer; subsequent read to the read
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// half of the pipe will return the error err.
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func (b *waitCloser) CloseWithError(err error) error {
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w, ok := b.writer.(*io.PipeWriter)
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if ok {
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return w.CloseWithError(err)
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}
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return 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 *waitCloser) release() {
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b.wg.Done()
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return
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}
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// newWaitCloser creates a new write closer that must be
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// released by the read consumer.
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func newWaitCloser(writer io.WriteCloser) *waitCloser {
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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 &waitCloser{
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wg: wg,
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writer: writer,
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}
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}
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