103 lines
2.8 KiB
Go
103 lines
2.8 KiB
Go
/*
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Copyright The containerd Authors.
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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 ioutil
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import (
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"io"
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"sync"
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)
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// writeCloseInformer wraps passed in write closer with a close channel.
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// Caller could wait on the close channel for the write closer to be
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// closed.
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type writeCloseInformer struct {
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close chan struct{}
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wc io.WriteCloser
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}
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// NewWriteCloseInformer creates the writeCloseInformer from a write closer.
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func NewWriteCloseInformer(wc io.WriteCloser) (io.WriteCloser, <-chan struct{}) {
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close := make(chan struct{})
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return &writeCloseInformer{
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close: close,
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wc: wc,
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}, close
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}
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// Write passes through the data into the internal write closer.
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func (w *writeCloseInformer) Write(p []byte) (int, error) {
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return w.wc.Write(p)
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}
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// Close closes the internal write closer and inform the close channel.
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func (w *writeCloseInformer) Close() error {
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err := w.wc.Close()
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close(w.close)
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return err
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}
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// nopWriteCloser wraps passed in writer with a nop close function.
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type nopWriteCloser struct {
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w io.Writer
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}
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// NewNopWriteCloser creates the nopWriteCloser from a writer.
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func NewNopWriteCloser(w io.Writer) io.WriteCloser {
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return &nopWriteCloser{w: w}
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}
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// Write passes through the data into the internal writer.
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func (n *nopWriteCloser) Write(p []byte) (int, error) {
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return n.w.Write(p)
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}
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// Close is a nop close function.
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func (n *nopWriteCloser) Close() error {
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return nil
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}
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// serialWriteCloser wraps a write closer and makes sure all writes
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// are done in serial.
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// Parallel write won't intersect with each other. Use case:
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// 1) Pipe: Write content longer than PIPE_BUF.
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// See http://man7.org/linux/man-pages/man7/pipe.7.html
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// 2) <3.14 Linux Kernel: write is not atomic
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// See http://man7.org/linux/man-pages/man2/write.2.html
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type serialWriteCloser struct {
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mu sync.Mutex
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wc io.WriteCloser
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}
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// NewSerialWriteCloser creates a SerialWriteCloser from a write closer.
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func NewSerialWriteCloser(wc io.WriteCloser) io.WriteCloser {
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return &serialWriteCloser{wc: wc}
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}
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// Write writes a group of byte arrays in order atomically.
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func (s *serialWriteCloser) Write(data []byte) (int, error) {
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s.mu.Lock()
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defer s.mu.Unlock()
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return s.wc.Write(data)
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}
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// Close closes the write closer.
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func (s *serialWriteCloser) Close() error {
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s.mu.Lock()
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defer s.mu.Unlock()
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return s.wc.Close()
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}
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