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readerctx.go
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/
readerctx.go
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package lib
import (
"context"
"io"
)
type readerAtCtx struct {
ctx context.Context
r io.ReaderAt
}
type readerCtx struct {
ctx context.Context
io.ReadCloser
}
type WithContextReaderAt interface {
WithContext(context.Context) interface{}
io.ReaderAt
}
type WithContextReader interface {
WithContext(context.Context) interface{}
io.Reader
}
type ReaderAtCloser interface {
io.ReaderAt
io.ReadCloser
}
func (r *readerAtCtx) ReadAt(p []byte, off int64) (n int, err error) {
if err := r.ctx.Err(); err != nil {
return 0, err
}
withContext, ok := r.r.(WithContextReader)
if ok {
r.r = withContext.WithContext(r.ctx).(io.ReaderAt)
}
return r.r.ReadAt(p, off)
}
func (r *readerCtx) Read(p []byte) (n int, err error) {
if err := r.ctx.Err(); err != nil {
return 0, err
}
withContext, ok := r.ReadCloser.(WithContextReader)
if ok {
r.ReadCloser = withContext.WithContext(r.ctx).(io.ReadCloser)
}
return r.ReadCloser.Read(p)
}
// NewReader gets a context-aware io.Reader.
func NewReaderAt(ctx context.Context, r io.ReaderAt) io.ReaderAt {
return &readerAtCtx{ctx: ctx, r: r}
}
// NewReader gets a context-aware io.Reader.
func NewReader(ctx context.Context, r io.ReadCloser) io.ReadCloser {
return &readerCtx{ctx: ctx, ReadCloser: r}
}