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#
# Copyright (C) 2010 Anton Khirnov <wyskas@gmail.com>
# Copyright (C) 2008 J. Alexander Treuman <jat@spatialrift.net>
#
# Nephilim is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Nephilim is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with Nephilim. If not, see <http://www.gnu.org/licenses/>.
#
import logging
from PyQt4 import QtCore, QtNetwork
from PyQt4.QtCore import pyqtSignal as Signal
class MPDError(Exception):
pass
class ConnectionError(MPDError):
pass
class MPDSocket(QtCore.QObject):
"""
A dumb TCP/domain socket wrapper -- has a very basic understanding of MPD protocol.
The caller should make sure that all returned iterators are exhausted or
the world will explode.
"""
#### PUBLIC ####
# signals #
"""True is emitted when the socket succesfully connectes to MPD.
False is emitted when it's disconnected."""
connect_changed = Signal(bool)
"""Emitted whenever MPD signals that some of its subsystems have changed.
For a list of subsystems see MPD protocol documentation."""
subsystems_changed = Signal(list)
# read-only
"""A tuple of (major, minor, micro)."""
version = None
#### PRIVATE ####
_logger = None
_sock = None
"""A list of callbacks that are waiting for a response from MPD."""
_cmd_queue = None
_is_idle = False
# MPD strings
SEPARATOR = ': '
HELLO_PREFIX = "OK MPD "
ERROR_PREFIX = "ACK "
SUCCESS = "OK"
#### PUBLIC ####
def __init__(self, parent = None):
QtCore.QObject.__init__(self, parent)
self._logger = logging.getLogger('%smpdsocket'%(unicode(parent) + "." if parent else ""))
self._cmd_queue = []
self.version = (0, 0, 0)
def connect_mpd(self, host, port = None):
"""
Connect to MPD at given host:port. If port is omitted, then connection
using Unix domain sockets is used.
"""
self._logger.info('Connecting to MPD.')
if self._sock:
raise ConnectionError('Stale socket found.')
if not port:
#assume Unix domain socket
self._sock = QtNetwork.QLocalSocket(self)
c = lambda host, port: self._sock.connectToServer(host)
else:
self._sock = QtNetwork.QTcpSocket(self)
c = self._sock.connectToHost
self._sock.disconnected.connect(self._finish_disconnect)
self._sock.error.connect( self._handle_error)
self._sock.readyRead.connect( self._finish_connect)
c(host, port)
def disconnect_mpd(self):
"""
Disconnect from MPD.
"""
self._logger.info('Disconnecting from MPD.')
if self._sock:
try:
self._sock.disconnectFromHost()
except AttributeError:
self._sock.disconnectFromServer()
def write_command(self, *args, **kwargs):
"""
Send a command contained in args to MPD. If a response from
MPD is desired, then kwargs must contain a 'callback' memeber,
which shall be called with an iterator over response lines as
an argument. Otherwise the response is silently discarded.
"""
self._logger.debug('Executing command:' + ' '.join(map(unicode, args)))
if 'callback' in kwargs:
if callable(kwargs['callback']):
callback = kwargs['callback']
else:
self._logger.error('Supplied callback is not callable. Will discard data instead.')
callback = self._parse_discard
else:
callback = self._parse_discard
self._cmd_queue.append(callback)
if self._is_idle:
self._sock.write('noidle\n')
self._sock.write(args[0])
for arg in args[1:]:
self._sock.write((' "%s" '%self._escape(unicode(arg))).encode('utf-8'))
self._sock.write('\n')
def write_command_sync(self, *args):
"""
Send a command contained in args to MPD synchronously. An iterator over
response lines is returned.
"""
# XXX i don't really like this solution. can't it be done better?
self._logger.debug('Synchronously executing command:' + ' '.join(map(unicode, args)))
self._sock.blockSignals(True)
while not self._is_idle:
# finish all outstanding responses
if not self._sock.canReadLine():
self._sock.waitForReadyRead()
self._handle_response()
self._sock.write('noidle\n')
self._sock.waitForBytesWritten()
self._sock.waitForReadyRead()
self._parse_discard(self._read_response())
self._sock.write(args[0])
for arg in args[1:]:
self._sock.write((' "%s" '%self._escape(unicode(arg))).encode('utf-8'))
self._sock.write('\n')
self._sock.waitForBytesWritten()
while not self._sock.canReadLine():
self._sock.waitForReadyRead()
for line in self._read_response():
yield line
self._idle()
self._sock.blockSignals(False)
def state(self):
"""
Return a socket state as one of the values in QtNetwork.QAbstractSocket.SocketState enum.
"""
if self._sock:
return self._sock.state()
return QtNetwork.QAbstractSocket.UnconnectedState
#### PRIVATE ####
def _escape(self, text):
"""
Escape backslashes and quotes before sending.
"""
return text.replace('\\', '\\\\').replace('"', '\\"')
def _readline(self):
"""
Read from the socket one line and return it, unless it's an
error or end of response.
"""
line = str(self._sock.readLine()).decode('utf-8').rstrip('\n')
if line.startswith(self.ERROR_PREFIX):
self._logger.error('MPD returned error: %s'%line)
return
if line == self.SUCCESS:
return
return line
def _handle_error(self, error):
"""
Called on socket error signal, print it and disconnect.
"""
self._logger.error(self._sock.errorString())
self.disconnect_mpd()
def _finish_connect(self):
"""
Called when a connection is established. Read hello and emit
a corresponding signal.
"""
# wait until we can read MPD hello
if not self._sock.canReadLine():
return
line = str(self._sock.readLine())
if not line.startswith(self.HELLO_PREFIX):
self.logger.error('Got invalid MPD hello: %s' % line)
return self.disconnect_mpd()
self.version = tuple(map(int, line[len(self.HELLO_PREFIX):].strip().split('.')))
self._sock.readyRead.disconnect(self._finish_connect)
self._logger.debug('Successfully connected to MPD, protocol version %s.'%('.'.join(map(str,self.version))))
self._sock.readyRead.connect(self._handle_response)
self._idle()
self.connect_changed.emit(True)
def _finish_disconnect(self):
"""
Called when a socket has been disconnected. Reset the socket state and
emit corresponding signal.
"""
self._sock = None
self.version = None
self._logger.debug('Disconnected from MPD.')
self.connect_changed.emit(False)
def _idle(self):
"""
Enter idle mode.
"""
self._logger.debug('Entering idle mode.')
self._sock.write('idle\n')
self._is_idle = True
def _handle_response(self):
"""
Called when some data has arrived on the socket. Parse it according to
current state either as change subsystems or a response to a command.
Then reenter idle mode.
"""
if not self._sock.canReadLine():
return
if self._is_idle:
self._logger.debug('Exited idle mode, reading changed subsystems.')
self._is_idle = False
subsystems = []
line = self._readline()
while line:
parts = line.partition(self.SEPARATOR)
if parts[1]:
subsystems.append(parts[2])
self._logger.debug('Subsystem changed: %s'%parts[2])
else:
self._logger.error('Malformed line: %s.'%line)
if not self._sock.canReadLine() and not self._sock.waitForReadyRead():
raise MPDError
line = self._readline()
if subsystems:
self.subsystems_changed.emit(subsystems)
while self._cmd_queue:
# wait for more data
if not self._sock.canReadLine():
return
self._cmd_queue[0](self._read_response())
del self._cmd_queue[0]
self._idle()
def _read_response(self):
"""
An iterator over all lines in one response.
"""
while self._sock.canReadLine():
line = self._readline()
if not line:
raise StopIteration
yield line
if not self._sock.canReadLine() and not self._sock.waitForReadyRead():
raise MPDError
def _parse_discard(self, data):
"""
(Almost) silently discard response data.
"""
for line in data:
self._logger.debug('Ignoring line: %s.'%line)
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