An example of how to use coroutines with IOStream.read and timeouts

stdin_byte_reader.py

import sys
import functools
import termios
import socket

from tornado import gen, ioloop, iostream
from datetime import timedelta


class StdinReader(object):
    def __init__(self):
        fd = sys.stdin.fileno()
        # Set stdin to non-cannonical and no echo mode
        # so we can read a byte at a time
        term = termios.tcgetattr(fd)
        term[3] &= ~termios.ICANON & ~termios.ECHO
        termios.tcsetattr(fd, termios.TCSANOW, term)

        self.stream = iostream.PipeIOStream(fd)

    @gen.coroutine
    def read(self, num_bytes, timeout=None):
        ioloop_timeout = None
        if timeout:
            def on_timeout():
                # We now have a scheduled read which is not deliverable.
                # I chose to ignore this for simplicity.
                raise socket.timeout
            ioloop_timeout = ioloop.IOLoop.current().add_timeout(timeout, callback=on_timeout)

        data = yield gen.Task(self.stream.read_bytes, num_bytes)
        if ioloop_timeout is not None:
            ioloop.IOLoop.current().remove_timeout(ioloop_timeout)
        raise gen.Return(data)


if __name__ == "__main__":
    r = StdinReader()
    read = functools.partial(r.read, num_bytes=1, timeout=timedelta(seconds=1))

    print ioloop.IOLoop.current().run_sync(read)

    @gen.coroutine
    def read3():
        for x in range(3):
            char = yield read()
            print char

    ioloop.IOLoop.current().run_sync(read3)