Victor Stinner | 24f8ebf | 2014-01-23 11:05:01 +0100 | [diff] [blame] | 1 | .. currentmodule:: asyncio |
| 2 | |
Victor Stinner | 4b4f9eb | 2014-01-24 17:33:20 +0100 | [diff] [blame^] | 3 | .. _streams: |
| 4 | |
Victor Stinner | 1374bd4 | 2014-01-24 15:34:19 +0100 | [diff] [blame] | 5 | ++++++++++++++++++++++++ |
| 6 | Streams (high-level API) |
| 7 | ++++++++++++++++++++++++ |
Victor Stinner | 24f8ebf | 2014-01-23 11:05:01 +0100 | [diff] [blame] | 8 | |
| 9 | Stream functions |
| 10 | ================ |
| 11 | |
| 12 | .. function:: open_connection(host=None, port=None, *, loop=None, limit=_DEFAULT_LIMIT, **kwds) |
| 13 | |
| 14 | A wrapper for :meth:`~BaseEventLoop.create_connection()` returning a (reader, |
| 15 | writer) pair. |
| 16 | |
| 17 | The reader returned is a :class:`StreamReader` instance; the writer is |
| 18 | a :class:`StreamWriter` instance. |
| 19 | |
| 20 | The arguments are all the usual arguments to |
| 21 | :meth:`BaseEventLoop.create_connection` except *protocol_factory*; most |
| 22 | common are positional host and port, with various optional keyword arguments |
| 23 | following. |
| 24 | |
| 25 | Additional optional keyword arguments are *loop* (to set the event loop |
| 26 | instance to use) and *limit* (to set the buffer limit passed to the |
| 27 | :class:`StreamReader`). |
| 28 | |
| 29 | (If you want to customize the :class:`StreamReader` and/or |
| 30 | :class:`StreamReaderProtocol` classes, just copy the code -- there's really |
| 31 | nothing special here except some convenience.) |
| 32 | |
| 33 | This function returns a :ref:`coroutine object <coroutine>`. |
| 34 | |
| 35 | .. function:: start_server(client_connected_cb, host=None, port=None, *, loop=None, limit=_DEFAULT_LIMIT, **kwds) |
| 36 | |
| 37 | Start a socket server, call back for each client connected. |
| 38 | |
| 39 | The first parameter, *client_connected_cb*, takes two parameters: |
| 40 | *client_reader*, *client_writer*. *client_reader* is a |
| 41 | :class:`StreamReader` object, while *client_writer* is a |
| 42 | :class:`StreamWriter` object. This parameter can either be a plain callback |
| 43 | function or a :ref:`coroutine function <coroutine>`; if it is a coroutine |
| 44 | function, it will be automatically converted into a :class:`Task`. |
| 45 | |
| 46 | The rest of the arguments are all the usual arguments to |
| 47 | :meth:`~BaseEventLoop.create_server()` except *protocol_factory*; most |
| 48 | common are positional host and port, with various optional keyword arguments |
| 49 | following. The return value is the same as |
| 50 | :meth:`~BaseEventLoop.create_server()`. |
| 51 | |
| 52 | Additional optional keyword arguments are *loop* (to set the event loop |
| 53 | instance to use) and *limit* (to set the buffer limit passed to the |
| 54 | :class:`StreamReader`). |
| 55 | |
| 56 | The return value is the same as :meth:`~BaseEventLoop.create_server()`, i.e. |
| 57 | a :class:`AbstractServer` object which can be used to stop the service. |
| 58 | |
| 59 | This function returns a :ref:`coroutine object <coroutine>`. |
| 60 | |
| 61 | |
| 62 | StreamReader |
| 63 | ============ |
| 64 | |
| 65 | .. class:: StreamReader(limit=_DEFAULT_LIMIT, loop=None) |
| 66 | |
| 67 | .. method:: exception() |
| 68 | |
| 69 | Get the exception. |
| 70 | |
| 71 | .. method:: feed_eof() |
| 72 | |
| 73 | XXX |
| 74 | |
| 75 | .. method:: feed_data(data) |
| 76 | |
| 77 | XXX |
| 78 | |
| 79 | .. method:: set_exception(exc) |
| 80 | |
| 81 | Set the exception. |
| 82 | |
| 83 | .. method:: set_transport(transport) |
| 84 | |
| 85 | Set the transport. |
| 86 | |
| 87 | .. method:: read(n=-1) |
| 88 | |
| 89 | XXX |
| 90 | |
| 91 | This method returns a :ref:`coroutine object <coroutine>`. |
| 92 | |
| 93 | .. method:: readline() |
| 94 | |
| 95 | XXX |
| 96 | |
| 97 | This method returns a :ref:`coroutine object <coroutine>`. |
| 98 | |
| 99 | .. method:: readexactly(n) |
| 100 | |
| 101 | XXX |
| 102 | |
| 103 | This method returns a :ref:`coroutine object <coroutine>`. |
| 104 | |
| 105 | |
| 106 | StreamWriter |
| 107 | ============ |
| 108 | |
| 109 | .. class:: StreamWriter(transport, protocol, reader, loop) |
| 110 | |
| 111 | Wraps a Transport. |
| 112 | |
| 113 | This exposes :meth:`write`, :meth:`writelines`, :meth:`can_write_eof()`, |
| 114 | :meth:`write_eof`, :meth:`get_extra_info` and :meth:`close`. It adds |
| 115 | :meth:`drain` which returns an optional :class:`Future` on which you can |
| 116 | wait for flow control. It also adds a transport attribute which references |
| 117 | the :class:`Transport` directly. |
| 118 | |
| 119 | .. attribute:: transport |
| 120 | |
| 121 | Transport. |
| 122 | |
| 123 | .. method:: close() |
| 124 | |
| 125 | Close the transport: see :meth:`BaseTransport.close`. |
| 126 | |
| 127 | .. method:: drain() |
| 128 | |
| 129 | This method has an unusual return value. |
| 130 | |
| 131 | The intended use is to write:: |
| 132 | |
| 133 | w.write(data) |
| 134 | yield from w.drain() |
| 135 | |
| 136 | When there's nothing to wait for, :meth:`drain()` returns ``()``, and the |
| 137 | yield-from continues immediately. When the transport buffer is full (the |
| 138 | protocol is paused), :meth:`drain` creates and returns a |
| 139 | :class:`Future` and the yield-from will block until |
| 140 | that Future is completed, which will happen when the buffer is |
| 141 | (partially) drained and the protocol is resumed. |
| 142 | |
| 143 | .. method:: get_extra_info(name, default=None) |
| 144 | |
| 145 | Return optional transport information: see |
| 146 | :meth:`BaseTransport.get_extra_info`. |
| 147 | |
| 148 | .. method:: write(data) |
| 149 | |
| 150 | Write some *data* bytes to the transport: see |
| 151 | :meth:`WriteTransport.write`. |
| 152 | |
| 153 | .. method:: writelines(data) |
| 154 | |
| 155 | Write a list (or any iterable) of data bytes to the transport: |
| 156 | see :meth:`WriteTransport.writelines`. |
| 157 | |
| 158 | .. method:: can_write_eof() |
| 159 | |
| 160 | Return :const:`True` if the transport supports :meth:`write_eof`, |
| 161 | :const:`False` if not. See :meth:`WriteTransport.can_write_eof`. |
| 162 | |
| 163 | .. method:: write_eof() |
| 164 | |
| 165 | Close the write end of the transport after flushing buffered data: |
| 166 | see :meth:`WriteTransport.write_eof`. |
| 167 | |
| 168 | |
| 169 | StreamReaderProtocol |
| 170 | ==================== |
| 171 | |
| 172 | .. class:: StreamReaderProtocol(stream_reader, client_connected_cb=None, loop=None) |
| 173 | |
| 174 | Trivial helper class to adapt between :class:`Protocol` and |
| 175 | :class:`StreamReader`. Sublclass of :class:`Protocol`. |
| 176 | |
| 177 | *stream_reader* is a :class:`StreamReader` instance, *client_connected_cb* |
| 178 | is an optional function called with (stream_reader, stream_writer) when a |
| 179 | connection is made, *loop* is the event loop instance to use. |
| 180 | |
| 181 | (This is a helper class instead of making :class:`StreamReader` itself a |
| 182 | :class:`Protocol` subclass, because the :class:`StreamReader` has other |
| 183 | potential uses, and to prevent the user of the :class:`StreamReader` to |
| 184 | accidentally call inappropriate methods of the protocol.) |
| 185 | |
| 186 | .. method:: connection_made(transport) |
| 187 | |
| 188 | XXX |
| 189 | |
| 190 | .. method:: connection_lost(exc) |
| 191 | |
| 192 | XXX |
| 193 | |
| 194 | .. method:: data_received(data) |
| 195 | |
| 196 | XXX |
| 197 | |
| 198 | .. method:: eof_received() |
| 199 | |
| 200 | XXX |
| 201 | |
| 202 | .. method:: pause_writing() |
| 203 | |
| 204 | XXX |
| 205 | |
| 206 | .. method:: resume_writing() |
| 207 | |
| 208 | XXX |
| 209 | |
Victor Stinner | c520edc | 2014-01-23 11:25:48 +0100 | [diff] [blame] | 210 | |
| 211 | Example |
| 212 | ======= |
| 213 | |
| 214 | Simple example querying HTTP headers of the URL passed on the command line:: |
| 215 | |
| 216 | import asyncio |
| 217 | import urllib.parse |
| 218 | import sys |
| 219 | |
| 220 | @asyncio.coroutine |
| 221 | def print_http_headers(url): |
| 222 | url = urllib.parse.urlsplit(url) |
| 223 | reader, writer = yield from asyncio.open_connection(url.hostname, 80) |
| 224 | query = ('HEAD {url.path} HTTP/1.0\r\n' |
| 225 | 'Host: {url.hostname}\r\n' |
| 226 | '\r\n').format(url=url) |
| 227 | writer.write(query.encode('latin-1')) |
| 228 | while True: |
| 229 | line = yield from reader.readline() |
| 230 | if not line: |
| 231 | break |
| 232 | line = line.decode('latin1').rstrip() |
| 233 | if line: |
| 234 | print('HTTP header> %s' % line) |
| 235 | |
| 236 | url = sys.argv[1] |
| 237 | loop = asyncio.get_event_loop() |
| 238 | task = asyncio.async(print_http_headers(url)) |
| 239 | loop.run_until_complete(task) |
| 240 | |
| 241 | Usage:: |
| 242 | |
| 243 | python example.py http://example.com/path/page.html |
| 244 | |