[bufferstream] readers would be canceled on stream close.

[cheatfate]

import chronos
import bufferstream

proc testReadCancellation(): Future[bool] {.async.} =
  var stream = newBufferStream()
  proc readMessage1(s: BufferStream): Future[seq[byte]] {.async.} =
    result = await s.read(10)
  proc readMessage2(s: BufferStream): Future[seq[byte]] {.async.} =
    var res = await readMessage1(s)
    res.add(@[0x00'u8, 0x00'u8])
  proc readMessage3(s: BufferStream): Future[seq[byte]] {.async.} =
    var res = await readMessage2(s)
    res.add(@[0x01'u8, 0x01'u8])

  var fut = stream.readMessage3()
  await stream.close()
  var c = await fut

when isMainModule:
  echo waitFor(testReadCancellation())

This code raises CancelledError, but it should not.

[dryajov]

This is by design, but perhaps we can raise an EOF instead of canceling the Future.

[cheatfate]

Raising one simple EOF is not enough, because different primitives has different behavior, for example read() should just returned all the data it gets before EOF received, while readUntil() should raise IncompleteError.

[arnetheduck]

obsolete