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A cancelable reader for Go

This package is based on the fantastic work of Erik Geiser
in Charm’s Bubble Tea framework.


NewReader returns a reader with a Cancel function. If the input reader is an
*os.File, the cancel function can be used to interrupt a blocking Read call.
In this case, the cancel function returns true if the call was canceled
successfully. If the input reader is not an *os.File, the cancel function does
nothing and always returns false.

r, err := cancelreader.NewReader(file)
if err != nil {
    // handle error

// cancel after five seconds
go func() {
    time.Sleep(5 * time.Second)

// keep reading
for {
    var buf [1024]byte
    _, err := r.Read(buf[:])

    if errors.Is(err, cancelreader.ErrCanceled) {
    if err != nil {
        // handle other errors

    // handle data


  • The Linux implementation is based on the epoll mechanism
  • The BSD and macOS implementation is based on the kqueue mechanism
  • The generic Unix implementation is based on the posix select syscall.


The Windows implementation is based on WaitForMultipleObject with overlapping
reads from CONIN$. At this point it only supports canceling reads from


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