waitForIo() // Wait until we receive a WINDOW_UPDATE for this stream.
          }
        } finally {
          writeTimeout.exitAndThrowIfTimedOut()
        }

        checkOutNotClosed() // Kick out if the stream was reset or closed while waiting.
        toWrite = minOf(writeBytesMaximum - writeBytesTotal, sendBuffer.size)
        writeBytesTotal += toWrite