minio/xl-v1-blockingwriter.go

63 lines
1.7 KiB
Go

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