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// Package chunkedreader provides functionality for reading a stream in chunks.
package chunkedreader
import (
"context"
"errors"
"io"
"github.com/rclone/rclone/fs"
)
// io related errors returned by ChunkedReader
var (
ErrorFileClosed = errors.New("file already closed")
ErrorInvalidSeek = errors.New("invalid seek position")
)
// ChunkedReader describes what a chunked reader can do.
type ChunkedReader interface {
io.Reader
io.Seeker
io.Closer
fs.RangeSeeker
Open() (ChunkedReader, error)
}
// New returns a ChunkedReader for the Object.
//
// An initialChunkSize of <= 0 will disable chunked reading.
// If maxChunkSize is greater than initialChunkSize, the chunk size will be
// doubled after each chunk read with a maximum of maxChunkSize.
// A Seek or RangeSeek will reset the chunk size to it's initial value
func New(ctx context.Context, o fs.Object, initialChunkSize int64, maxChunkSize int64, streams int) ChunkedReader {
if initialChunkSize <= 0 {
initialChunkSize = -1
}
if maxChunkSize != -1 && maxChunkSize < initialChunkSize {
maxChunkSize = initialChunkSize
}
if streams < 0 {
streams = 0
}
if streams <= 1 || o.Size() < 0 {
return newSequential(ctx, o, initialChunkSize, maxChunkSize)
}
return newParallel(ctx, o, initialChunkSize, streams)
}
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