Initial checkin of asyncio package (== Tulip, == PEP 3156).

Lib/asyncio/__init__.py

+"""The asyncio package, tracking PEP 3156."""
+
+import sys
+
+# The selectors module is in the stdlib in Python 3.4 but not in 3.3.
+# Do this first, so the other submodules can use "from . import selectors".
+try:
+    import selectors  # Will also be exported.
+except ImportError:
+    from . import selectors
+
+# This relies on each of the submodules having an __all__ variable.
+from .futures import *
+from .events import *
+from .locks import *
+from .transports import *
+from .protocols import *
+from .streams import *
+from .tasks import *
+
+if sys.platform == 'win32':  # pragma: no cover
+    from .windows_events import *
+else:
+    from .unix_events import *  # pragma: no cover
+
+
+__all__ = (futures.__all__ +
+           events.__all__ +
+           locks.__all__ +
+           transports.__all__ +
+           protocols.__all__ +
+           streams.__all__ +
+           tasks.__all__)

Lib/asyncio/constants.py

+"""Constants."""
+
+
+LOG_THRESHOLD_FOR_CONNLOST_WRITES = 5

Lib/asyncio/log.py

+"""Logging configuration."""
+
+import logging
+
+
+asyncio_log = logging.getLogger("asyncio")

Lib/asyncio/protocols.py

+"""Abstract Protocol class."""
+
+__all__ = ['Protocol', 'DatagramProtocol']
+
+
+class BaseProtocol:
+    """ABC for base protocol class.
+
+    Usually user implements protocols that derived from BaseProtocol
+    like Protocol or ProcessProtocol.
+
+    The only case when BaseProtocol should be implemented directly is
+    write-only transport like write pipe
+    """
+
+    def connection_made(self, transport):
+        """Called when a connection is made.
+
+        The argument is the transport representing the pipe connection.
+        To receive data, wait for data_received() calls.
+        When the connection is closed, connection_lost() is called.
+        """
+
+    def connection_lost(self, exc):
+        """Called when the connection is lost or closed.
+
+        The argument is an exception object or None (the latter
+        meaning a regular EOF is received or the connection was
+        aborted or closed).
+        """
+
+
+class Protocol(BaseProtocol):
+    """ABC representing a protocol.
+
+    The user should implement this interface.  They can inherit from
+    this class but don't need to.  The implementations here do
+    nothing (they don't raise exceptions).
+
+    When the user wants to requests a transport, they pass a protocol
+    factory to a utility function (e.g., EventLoop.create_connection()).
+
+    When the connection is made successfully, connection_made() is
+    called with a suitable transport object.  Then data_received()
+    will be called 0 or more times with data (bytes) received from the
+    transport; finally, connection_lost() will be called exactly once
+    with either an exception object or None as an argument.
+
+    State machine of calls:
+
+      start -> CM [-> DR*] [-> ER?] -> CL -> end
+    """
+
+    def data_received(self, data):
+        """Called when some data is received.
+
+        The argument is a bytes object.
+        """
+
+    def eof_received(self):
+        """Called when the other end calls write_eof() or equivalent.
+
+        If this returns a false value (including None), the transport
+        will close itself.  If it returns a true value, closing the
+        transport is up to the protocol.
+        """
+
+
+class DatagramProtocol(BaseProtocol):
+    """ABC representing a datagram protocol."""
+
+    def datagram_received(self, data, addr):
+        """Called when some datagram is received."""
+
+    def connection_refused(self, exc):
+        """Connection is refused."""
+
+
+class SubprocessProtocol(BaseProtocol):
+    """ABC representing a protocol for subprocess calls."""
+
+    def pipe_data_received(self, fd, data):
+        """Called when subprocess write a data into stdout/stderr pipes.
+
+        fd is int file dascriptor.
+        data is bytes object.
+        """
+
+    def pipe_connection_lost(self, fd, exc):
+        """Called when a file descriptor associated with the child process is
+        closed.
+
+        fd is the int file descriptor that was closed.
+        """
+
+    def process_exited(self):
+        """Called when subprocess has exited.
+        """

Lib/asyncio/queues.py

+"""Queues"""
+
+__all__ = ['Queue', 'PriorityQueue', 'LifoQueue', 'JoinableQueue',
+           'Full', 'Empty']
+
+import collections
+import heapq
+import queue
+
+from . import events
+from . import futures
+from . import locks
+from .tasks import coroutine
+
+
+# Re-export queue.Full and .Empty exceptions.
+Full = queue.Full
+Empty = queue.Empty
+
+
+class Queue:
+    """A queue, useful for coordinating producer and consumer coroutines.
+
+    If maxsize is less than or equal to zero, the queue size is infinite. If it
+    is an integer greater than 0, then "yield from put()" will block when the
+    queue reaches maxsize, until an item is removed by get().
+
+    Unlike the standard library Queue, you can reliably know this Queue's size
+    with qsize(), since your single-threaded Tulip application won't be
+    interrupted between calling qsize() and doing an operation on the Queue.
+    """
+
+    def __init__(self, maxsize=0, *, loop=None):
+        if loop is None:
+            self._loop = events.get_event_loop()
+        else:
+            self._loop = loop
+        self._maxsize = maxsize
+
+        # Futures.
+        self._getters = collections.deque()
+        # Pairs of (item, Future).
+        self._putters = collections.deque()
+        self._init(maxsize)
+
+    def _init(self, maxsize):
+        self._queue = collections.deque()
+
+    def _get(self):
+        return self._queue.popleft()
+
+    def _put(self, item):
+        self._queue.append(item)
+
+    def __repr__(self):
+        return '<{} at {:#x} {}>'.format(
+            type(self).__name__, id(self), self._format())
+
+    def __str__(self):
+        return '<{} {}>'.format(type(self).__name__, self._format())
+
+    def _format(self):
+        result = 'maxsize={!r}'.format(self._maxsize)
+        if getattr(self, '_queue', None):
+            result += ' _queue={!r}'.format(list(self._queue))
+        if self._getters:
+            result += ' _getters[{}]'.format(len(self._getters))
+        if self._putters:
+            result += ' _putters[{}]'.format(len(self._putters))
+        return result
+
+    def _consume_done_getters(self):
+        # Delete waiters at the head of the get() queue who've timed out.
+        while self._getters and self._getters[0].done():
+            self._getters.popleft()
+
+    def _consume_done_putters(self):
+        # Delete waiters at the head of the put() queue who've timed out.
+        while self._putters and self._putters[0][1].done():
+            self._putters.popleft()
+
+    def qsize(self):
+        """Number of items in the queue."""
+        return len(self._queue)
+
+    @property
+    def maxsize(self):
+        """Number of items allowed in the queue."""
+        return self._maxsize
+
+    def empty(self):
+        """Return True if the queue is empty, False otherwise."""
+        return not self._queue
+
+    def full(self):
+        """Return True if there are maxsize items in the queue.
+
+        Note: if the Queue was initialized with maxsize=0 (the default),
+        then full() is never True.
+        """
+        if self._maxsize <= 0:
+            return False
+        else:
+            return self.qsize() == self._maxsize
+
+    @coroutine
+    def put(self, item):
+        """Put an item into the queue.
+
+        If you yield from put(), wait until a free slot is available
+        before adding item.
+        """
+        self._consume_done_getters()
+        if self._getters:
+            assert not self._queue, (
+                'queue non-empty, why are getters waiting?')
+
+            getter = self._getters.popleft()
+
+            # Use _put and _get instead of passing item straight to getter, in
+            # case a subclass has logic that must run (e.g. JoinableQueue).
+            self._put(item)
+            getter.set_result(self._get())
+
+        elif self._maxsize > 0 and self._maxsize == self.qsize():
+            waiter = futures.Future(loop=self._loop)
+
+            self._putters.append((item, waiter))
+            yield from waiter
+
+        else:
+            self._put(item)
+
+    def put_nowait(self, item):
+        """Put an item into the queue without blocking.
+
+        If no free slot is immediately available, raise Full.
+        """
+        self._consume_done_getters()
+        if self._getters:
+            assert not self._queue, (
+                'queue non-empty, why are getters waiting?')
+
+            getter = self._getters.popleft()
+
+            # Use _put and _get instead of passing item straight to getter, in
+            # case a subclass has logic that must run (e.g. JoinableQueue).
+            self._put(item)
+            getter.set_result(self._get())
+
+        elif self._maxsize > 0 and self._maxsize == self.qsize():
+            raise Full
+        else:
+            self._put(item)
+
+    @coroutine
+    def get(self):
+        """Remove and return an item from the queue.
+
+        If you yield from get(), wait until a item is available.
+        """
+        self._consume_done_putters()
+        if self._putters:
+            assert self.full(), 'queue not full, why are putters waiting?'
+            item, putter = self._putters.popleft()
+            self._put(item)
+
+            # When a getter runs and frees up a slot so this putter can
+            # run, we need to defer the put for a tick to ensure that
+            # getters and putters alternate perfectly. See
+            # ChannelTest.test_wait.
+            self._loop.call_soon(putter.set_result, None)
+
+            return self._get()
+
+        elif self.qsize():
+            return self._get()
+        else:
+            waiter = futures.Future(loop=self._loop)
+
+            self._getters.append(waiter)
+            return (yield from waiter)
+
+    def get_nowait(self):
+        """Remove and return an item from the queue.
+
+        Return an item if one is immediately available, else raise Full.
+        """
+        self._consume_done_putters()
+        if self._putters:
+            assert self.full(), 'queue not full, why are putters waiting?'
+            item, putter = self._putters.popleft()
+            self._put(item)
+            # Wake putter on next tick.
+            putter.set_result(None)
+
+            return self._get()
+
+        elif self.qsize():
+            return self._get()
+        else:
+            raise Empty
+
+
+class PriorityQueue(Queue):
+    """A subclass of Queue; retrieves entries in priority order (lowest first).
+
+    Entries are typically tuples of the form: (priority number, data).
+    """
+
+    def _init(self, maxsize):
+        self._queue = []
+
+    def _put(self, item, heappush=heapq.heappush):
+        heappush(self._queue, item)
+
+    def _get(self, heappop=heapq.heappop):
+        return heappop(self._queue)
+
+
+class LifoQueue(Queue):
+    """A subclass of Queue that retrieves most recently added entries first."""
+
+    def _init(self, maxsize):
+        self._queue = []
+
+    def _put(self, item):
+        self._queue.append(item)
+
+    def _get(self):
+        return self._queue.pop()
+
+
+class JoinableQueue(Queue):
+    """A subclass of Queue with task_done() and join() methods."""
+
+    def __init__(self, maxsize=0, *, loop=None):
+        super().__init__(maxsize=maxsize, loop=loop)
+        self._unfinished_tasks = 0
+        self._finished = locks.Event(loop=self._loop)
+        self._finished.set()
+
+    def _format(self):
+        result = Queue._format(self)
+        if self._unfinished_tasks:
+            result += ' tasks={}'.format(self._unfinished_tasks)
+        return result
+
+    def _put(self, item):
+        super()._put(item)
+        self._unfinished_tasks += 1
+        self._finished.clear()
+
+    def task_done(self):
+        """Indicate that a formerly enqueued task is complete.
+
+        Used by queue consumers. For each get() used to fetch a task,
+        a subsequent call to task_done() tells the queue that the processing
+        on the task is complete.
+
+        If a join() is currently blocking, it will resume when all items have
+        been processed (meaning that a task_done() call was received for every
+        item that had been put() into the queue).
+
+        Raises ValueError if called more times than there were items placed in
+        the queue.
+        """
+        if self._unfinished_tasks <= 0:
+            raise ValueError('task_done() called too many times')
+        self._unfinished_tasks -= 1
+        if self._unfinished_tasks == 0:
+            self._finished.set()
+
+    @coroutine
+    def join(self):
+        """Block until all items in the queue have been gotten and processed.
+
+        The count of unfinished tasks goes up whenever an item is added to the
+        queue. The count goes down whenever a consumer thread calls task_done()
+        to indicate that the item was retrieved and all work on it is complete.
+        When the count of unfinished tasks drops to zero, join() unblocks.
+        """
+        if self._unfinished_tasks > 0:
+            yield from self._finished.wait()

Lib/asyncio/streams.py

+"""Stream-related things."""
+
+__all__ = ['StreamReader', 'StreamReaderProtocol', 'open_connection']
+
+import collections
+
+from . import events
+from . import futures
+from . import protocols
+from . import tasks
+
+
+_DEFAULT_LIMIT = 2**16
+
+
+@tasks.coroutine
+def open_connection(host=None, port=None, *,
+                    loop=None, limit=_DEFAULT_LIMIT, **kwds):
+    """A wrapper for create_connection() returning a (reader, writer) pair.
+
+    The reader returned is a StreamReader instance; the writer is a
+    Transport.
+
+    The arguments are all the usual arguments to create_connection()
+    except protocol_factory; most common are positional host and port,
+    with various optional keyword arguments following.
+
+    Additional optional keyword arguments are loop (to set the event loop
+    instance to use) and limit (to set the buffer limit passed to the
+    StreamReader).
+
+    (If you want to customize the StreamReader and/or
+    StreamReaderProtocol classes, just copy the code -- there's
+    really nothing special here except some convenience.)
+    """
+    if loop is None:
+        loop = events.get_event_loop()
+    reader = StreamReader(limit=limit, loop=loop)
+    protocol = StreamReaderProtocol(reader)
+    transport, _ = yield from loop.create_connection(
+        lambda: protocol, host, port, **kwds)
+    return reader, transport  # (reader, writer)
+
+
+class StreamReaderProtocol(protocols.Protocol):
+    """Trivial helper class to adapt between Protocol and StreamReader.
+
+    (This is a helper class instead of making StreamReader itself a
+    Protocol subclass, because the StreamReader has other potential
+    uses, and to prevent the user of the StreamReader to accidentally
+    call inappropriate methods of the protocol.)
+    """
+
+    def __init__(self, stream_reader):
+        self.stream_reader = stream_reader
+
+    def connection_made(self, transport):
+        self.stream_reader.set_transport(transport)
+
+    def connection_lost(self, exc):
+        if exc is None:
+            self.stream_reader.feed_eof()
+        else:
+            self.stream_reader.set_exception(exc)
+
+    def data_received(self, data):
+        self.stream_reader.feed_data(data)
+
+    def eof_received(self):
+        self.stream_reader.feed_eof()
+
+
+class StreamReader:
+
+    def __init__(self, limit=_DEFAULT_LIMIT, loop=None):
+        # The line length limit is  a security feature;
+        # it also doubles as half the buffer limit.
+        self.limit = limit
+        if loop is None:
+            loop = events.get_event_loop()
+        self.loop = loop
+        self.buffer = collections.deque()  # Deque of bytes objects.
+        self.byte_count = 0  # Bytes in buffer.
+        self.eof = False  # Whether we're done.
+        self.waiter = None  # A future.
+        self._exception = None
+        self._transport = None
+        self._paused = False
+
+    def exception(self):
+        return self._exception
+
+    def set_exception(self, exc):
+        self._exception = exc
+
+        waiter = self.waiter
+        if waiter is not None:
+            self.waiter = None
+            if not waiter.cancelled():
+                waiter.set_exception(exc)
+
+    def set_transport(self, transport):
+        assert self._transport is None, 'Transport already set'
+        self._transport = transport
+
+    def _maybe_resume_transport(self):
+        if self._paused and self.byte_count <= self.limit:
+            self._paused = False
+            self._transport.resume()
+
+    def feed_eof(self):
+        self.eof = True
+        waiter = self.waiter
+        if waiter is not None:
+            self.waiter = None
+            if not waiter.cancelled():
+                waiter.set_result(True)
+
+    def feed_data(self, data):
+        if not data:
+            return
+
+        self.buffer.append(data)
+        self.byte_count += len(data)
+
+        waiter = self.waiter
+        if waiter is not None:
+            self.waiter = None
+            if not waiter.cancelled():
+                waiter.set_result(False)
+
+        if (self._transport is not None and
+            not self._paused and
+            self.byte_count > 2*self.limit):
+            try:
+                self._transport.pause()
+            except NotImplementedError:
+                # The transport can't be paused.
+                # We'll just have to buffer all data.
+                # Forget the transport so we don't keep trying.
+                self._transport = None
+            else:
+                self._paused = True
+
+    @tasks.coroutine
+    def readline(self):
+        if self._exception is not None:
+            raise self._exception
+
+        parts = []
+        parts_size = 0
+        not_enough = True
+
+        while not_enough:
+            while self.buffer and not_enough:
+                data = self.buffer.popleft()
+                ichar = data.find(b'\n')
+                if ichar < 0:
+                    parts.append(data)
+                    parts_size += len(data)
+                else:
+                    ichar += 1
+                    head, tail = data[:ichar], data[ichar:]
+                    if tail:
+                        self.buffer.appendleft(tail)
+                    not_enough = False
+                    parts.append(head)
+                    parts_size += len(head)
+
+                if parts_size > self.limit:
+                    self.byte_count -= parts_size
+                    self._maybe_resume_transport()
+                    raise ValueError('Line is too long')
+
+            if self.eof:
+                break
+
+            if not_enough:
+                assert self.waiter is None
+                self.waiter = futures.Future(loop=self.loop)
+                try:
+                    yield from self.waiter
+                finally:
+                    self.waiter = None
+
+        line = b''.join(parts)
+        self.byte_count -= parts_size
+        self._maybe_resume_transport()
+
+        return line
+
+    @tasks.coroutine
+    def read(self, n=-1):
+        if self._exception is not None:
+            raise self._exception
+
+        if not n:
+            return b''
+
+        if n < 0:
+            while not self.eof:
+                assert not self.waiter
+                self.waiter = futures.Future(loop=self.loop)
+                try:
+                    yield from self.waiter
+                finally:
+                    self.waiter = None
+        else:
+            if not self.byte_count and not self.eof:
+                assert not self.waiter
+                self.waiter = futures.Future(loop=self.loop)
+                try:
+                    yield from self.waiter
+                finally:
+                    self.waiter = None
+
+        if n < 0 or self.byte_count <= n:
+            data = b''.join(self.buffer)
+            self.buffer.clear()
+            self.byte_count = 0
+            self._maybe_resume_transport()
+            return data
+
+        parts = []
+        parts_bytes = 0
+        while self.buffer and parts_bytes < n:
+            data = self.buffer.popleft()
+            data_bytes = len(data)
+            if n < parts_bytes + data_bytes:
+                data_bytes = n - parts_bytes
+                data, rest = data[:data_bytes], data[data_bytes:]
+                self.buffer.appendleft(rest)
+
+            parts.append(data)
+            parts_bytes += data_bytes
+            self.byte_count -= data_bytes
+            self._maybe_resume_transport()
+
+        return b''.join(parts)
+
+    @tasks.coroutine
+    def readexactly(self, n):
+        if self._exception is not None:
+            raise self._exception
+
+        if n <= 0:
+            return b''
+
+        while self.byte_count < n and not self.eof:
+            assert not self.waiter
+            self.waiter = futures.Future(loop=self.loop)
+            try:
+                yield from self.waiter
+            finally:
+                self.waiter = None
+
+        return (yield from self.read(n))

Lib/asyncio/test_utils.py

+"""Utilities shared by tests."""
+
+import collections
+import contextlib
+import io
+import unittest.mock
+import os
+import sys
+import threading
+import unittest
+import unittest.mock
+from wsgiref.simple_server import make_server, WSGIRequestHandler, WSGIServer
+try:
+    import ssl
+except ImportError:  # pragma: no cover
+    ssl = None
+
+from . import tasks
+from . import base_events
+from . import events
+from . import selectors
+
+
+if sys.platform == 'win32':  # pragma: no cover
+    from .windows_utils import socketpair
+else:
+    from socket import socketpair  # pragma: no cover
+
+
+def dummy_ssl_context():
+    if ssl is None:
+        return None
+    else:
+        return ssl.SSLContext(ssl.PROTOCOL_SSLv23)
+
+
+def run_briefly(loop):
+    @tasks.coroutine
+    def once():
+        pass
+    gen = once()
+    t = tasks.Task(gen, loop=loop)
+    try:
+        loop.run_until_complete(t)
+    finally:
+        gen.close()
+
+
+def run_once(loop):
+    """loop.stop() schedules _raise_stop_error()
+    and run_forever() runs until _raise_stop_error() callback.
+    this wont work if test waits for some IO events, because
+    _raise_stop_error() runs before any of io events callbacks.
+    """
+    loop.stop()
+    loop.run_forever()
+
+
+@contextlib.contextmanager
+def run_test_server(*, host='127.0.0.1', port=0, use_ssl=False):
+
+    class SilentWSGIRequestHandler(WSGIRequestHandler):
+        def get_stderr(self):
+            return io.StringIO()
+
+        def log_message(self, format, *args):
+            pass
+
+    class SilentWSGIServer(WSGIServer):
+        def handle_error(self, request, client_address):
+            pass
+
+    class SSLWSGIServer(SilentWSGIServer):
+        def finish_request(self, request, client_address):
+            # The relative location of our test directory (which
+            # contains the sample key and certificate files) differs
+            # between the stdlib and stand-alone Tulip/asyncio.
+            # Prefer our own if we can find it.
+            here = os.path.join(os.path.dirname(__file__), '..', 'tests')
+            if not os.path.isdir(here):
+                here = os.path.join(os.path.dirname(os.__file__),
+                                    'test', 'test_asyncio')
+            keyfile = os.path.join(here, 'sample.key')
+            certfile = os.path.join(here, 'sample.crt')
+            ssock = ssl.wrap_socket(request,
+                                    keyfile=keyfile,
+                                    certfile=certfile,
+                                    server_side=True)
+            try:
+                self.RequestHandlerClass(ssock, client_address, self)
+                ssock.close()
+            except OSError:
+                # maybe socket has been closed by peer
+                pass
+
+    def app(environ, start_response):
+        status = '200 OK'
+        headers = [('Content-type', 'text/plain')]
+        start_response(status, headers)
+        return [b'Test message']
+
+    # Run the test WSGI server in a separate thread in order not to
+    # interfere with event handling in the main thread
+    server_class = SSLWSGIServer if use_ssl else SilentWSGIServer
+    httpd = make_server(host, port, app,
+                        server_class, SilentWSGIRequestHandler)
+    httpd.address = httpd.server_address
+    server_thread = threading.Thread(target=httpd.serve_forever)
+    server_thread.start()
+    try:
+        yield httpd
+    finally:
+        httpd.shutdown()
+        server_thread.join()
+
+
+def make_test_protocol(base):
+    dct = {}
+    for name in dir(base):
+        if name.startswith('__') and name.endswith('__'):
+            # skip magic names
+            continue
+        dct[name] = unittest.mock.Mock(return_value=None)
+    return type('TestProtocol', (base,) + base.__bases__, dct)()
+
+
+class TestSelector(selectors.BaseSelector):
+
+    def select(self, timeout):
+        return []
+
+
+class TestLoop(base_events.BaseEventLoop):
+    """Loop for unittests.
+
+    It manages self time directly.
+    If something scheduled to be executed later then
+    on next loop iteration after all ready handlers done
+    generator passed to __init__ is calling.
+
+    Generator should be like this:
+
+        def gen():
+            ...
+            when = yield ...
+            ... = yield time_advance
+
+    Value retuned by yield is absolute time of next scheduled handler.
+    Value passed to yield is time advance to move loop's time forward.
+    """
+
+    def __init__(self, gen=None):
+        super().__init__()
+
+        if gen is None:
+            def gen():
+                yield
+            self._check_on_close = False
+        else:
+            self._check_on_close = True
+
+        self._gen = gen()
+        next(self._gen)
+        self._time = 0
+        self._timers = []
+        self._selector = TestSelector()
+
+        self.readers = {}
+        self.writers = {}
+        self.reset_counters()
+
+    def time(self):
+        return self._time
+
+    def advance_time(self, advance):
+        """Move test time forward."""
+        if advance:
+            self._time += advance
+
+    def close(self):
+        if self._check_on_close:
+            try:
+                self._gen.send(0)
+            except StopIteration:
+                pass
+            else:  # pragma: no cover
+                raise AssertionError("Time generator is not finished")
+
+    def add_reader(self, fd, callback, *args):
+        self.readers[fd] = events.make_handle(callback, args)
+
+    def remove_reader(self, fd):
+        self.remove_reader_count[fd] += 1
+        if fd in self.readers:
+            del self.readers[fd]
+            return True
+        else:
+            return False
+
+    def assert_reader(self, fd, callback, *args):
+        assert fd in self.readers, 'fd {} is not registered'.format(fd)
+        handle = self.readers[fd]
+        assert handle._callback == callback, '{!r} != {!r}'.format(
+            handle._callback, callback)
+        assert handle._args == args, '{!r} != {!r}'.format(
+            handle._args, args)
+
+    def add_writer(self, fd, callback, *args):
+        self.writers[fd] = events.make_handle(callback, args)
+
+    def remove_writer(self, fd):
+        self.remove_writer_count[fd] += 1
+        if fd in self.writers:
+            del self.writers[fd]
+            return True
+        else:
+            return False
+
+    def assert_writer(self, fd, callback, *args):
+        assert fd in self.writers, 'fd {} is not registered'.format(fd)
+        handle = self.writers[fd]
+        assert handle._callback == callback, '{!r} != {!r}'.format(
+            handle._callback, callback)
+        assert handle._args == args, '{!r} != {!r}'.format(
+            handle._args, args)
+
+    def reset_counters(self):
+        self.remove_reader_count = collections.defaultdict(int)
+        self.remove_writer_count = collections.defaultdict(int)
+
+    def _run_once(self):
+        super()._run_once()
+        for when in self._timers:
+            advance = self._gen.send(when)
+            self.advance_time(advance)
+        self._timers = []
+
+    def call_at(self, when, callback, *args):
+        self._timers.append(when)
+        return super().call_at(when, callback, *args)
+
+    def _process_events(self, event_list):
+        return
+
+    def _write_to_self(self):
+        pass

Lib/asyncio/transports.py

+"""Abstract Transport class."""
+
+__all__ = ['ReadTransport', 'WriteTransport', 'Transport']
+
+
+class BaseTransport:
+    """Base ABC for transports."""
+
+    def __init__(self, extra=None):
+        if extra is None:
+            extra = {}
+        self._extra = extra
+
+    def get_extra_info(self, name, default=None):
+        """Get optional transport information."""
+        return self._extra.get(name, default)
+
+    def close(self):
+        """Closes the transport.
+
+        Buffered data will be flushed asynchronously.  No more data
+        will be received.  After all buffered data is flushed, the
+        protocol's connection_lost() method will (eventually) called
+        with None as its argument.
+        """
+        raise NotImplementedError
+
+
+class ReadTransport(BaseTransport):
+    """ABC for read-only transports."""
+
+    def pause(self):
+        """Pause the receiving end.
+
+        No data will be passed to the protocol's data_received()
+        method until resume() is called.
+        """
+        raise NotImplementedError
+
+    def resume(self):
+        """Resume the receiving end.
+
+        Data received will once again be passed to the protocol's
+        data_received() method.
+        """
+        raise NotImplementedError
+
+
+class WriteTransport(BaseTransport):
+    """ABC for write-only transports."""
+
+    def write(self, data):
+        """Write some data bytes to the transport.
+
+        This does not block; it buffers the data and arranges for it
+        to be sent out asynchronously.
+        """
+        raise NotImplementedError
+
+    def writelines(self, list_of_data):
+        """Write a list (or any iterable) of data bytes to the transport.
+
+        The default implementation just calls write() for each item in
+        the list/iterable.
+        """
+        for data in list_of_data:
+            self.write(data)
+
+    def write_eof(self):
+        """Closes the write end after flushing buffered data.
+
+        (This is like typing ^D into a UNIX program reading from stdin.)
+
+        Data may still be received.
+        """
+        raise NotImplementedError
+
+    def can_write_eof(self):
+        """Return True if this protocol supports write_eof(), False if not."""
+        raise NotImplementedError
+
+    def abort(self):
+        """Closes the transport immediately.
+
+        Buffered data will be lost.  No more data will be received.
+        The protocol's connection_lost() method will (eventually) be
+        called with None as its argument.
+        """
+        raise NotImplementedError
+
+
+class Transport(ReadTransport, WriteTransport):
+    """ABC representing a bidirectional transport.
+
+    There may be several implementations, but typically, the user does
+    not implement new transports; rather, the platform provides some
+    useful transports that are implemented using the platform's best
+    practices.
+
+    The user never instantiates a transport directly; they call a
+    utility function, passing it a protocol factory and other
+    information necessary to create the transport and protocol.  (E.g.
+    EventLoop.create_connection() or EventLoop.create_server().)
+
+    The utility function will asynchronously create a transport and a
+    protocol and hook them up by calling the protocol's
+    connection_made() method, passing it the transport.
+
+    The implementation here raises NotImplemented for every method
+    except writelines(), which calls write() in a loop.
+    """
+
+
+class DatagramTransport(BaseTransport):
+    """ABC for datagram (UDP) transports."""
+
+    def sendto(self, data, addr=None):
+        """Send data to the transport.
+
+        This does not block; it buffers the data and arranges for it
+        to be sent out asynchronously.
+        addr is target socket address.
+        If addr is None use target address pointed on transport creation.
+        """
+        raise NotImplementedError
+
+    def abort(self):
+        """Closes the transport immediately.
+
+        Buffered data will be lost.  No more data will be received.
+        The protocol's connection_lost() method will (eventually) be
+        called with None as its argument.
+        """
+        raise NotImplementedError
+
+
+class SubprocessTransport(BaseTransport):
+
+    def get_pid(self):
+        """Get subprocess id."""
+        raise NotImplementedError
+
+    def get_returncode(self):
+        """Get subprocess returncode.
+
+        See also
+        http://docs.python.org/3/library/subprocess#subprocess.Popen.returncode
+        """
+        raise NotImplementedError
+
+    def get_pipe_transport(self, fd):
+        """Get transport for pipe with number fd."""
+        raise NotImplementedError
+
+    def send_signal(self, signal):
+        """Send signal to subprocess.
+
+        See also:
+        docs.python.org/3/library/subprocess#subprocess.Popen.send_signal
+        """
+        raise NotImplementedError
+
+    def terminate(self):
+        """Stop the subprocess.
+
+        Alias for close() method.
+
+        On Posix OSs the method sends SIGTERM to the subprocess.
+        On Windows the Win32 API function TerminateProcess()
+         is called to stop the subprocess.
+
+        See also:
+        http://docs.python.org/3/library/subprocess#subprocess.Popen.terminate
+        """
+        raise NotImplementedError
+
+    def kill(self):
+        """Kill the subprocess.
+
+        On Posix OSs the function sends SIGKILL to the subprocess.
+        On Windows kill() is an alias for terminate().
+
+        See also:
+        http://docs.python.org/3/library/subprocess#subprocess.Popen.kill
+        """
+        raise NotImplementedError

Lib/test/test_asyncio/__main__.py

+from . import test_main
+
+
+if __name__ == '__main__':
+    test_main()

Lib/test/test_asyncio/echo.py

+import os
+
+if __name__ == '__main__':
+    while True:
+        buf = os.read(0, 1024)
+        os.write(1, buf)