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package request
import (
"io"
"sync"
)
// offsetReader is a thread-safe io.ReadCloser to prevent racing
// with retrying requests
type offsetReader struct {
buf io.ReadSeeker
lock sync.RWMutex
closed bool
}
func newOffsetReader(buf io.ReadSeeker, offset int64) *offsetReader {
reader := &offsetReader{}
buf.Seek(offset, 0)
reader.buf = buf
return reader
}
// Close is a thread-safe close. Uses the write lock.
func (o *offsetReader) Close() error {
o.lock.Lock()
defer o.lock.Unlock()
o.closed = true
return nil
}
// Read is a thread-safe read using a read lock.
func (o *offsetReader) Read(p []byte) (int, error) {
o.lock.RLock()
defer o.lock.RUnlock()
if o.closed {
return 0, io.EOF
}
return o.buf.Read(p)
}
// CloseAndCopy will return a new offsetReader with a copy of the old buffer
// and close the old buffer.
func (o *offsetReader) CloseAndCopy(offset int64) *offsetReader {
o.Close()
return newOffsetReader(o.buf, offset)
}
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