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# Copyright (C) 2008 Canonical Ltd
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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from cStringIO import StringIO
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from bzrlib.trace import mutter
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class MessageHandler(object):
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"""Base class for handling messages received via the smart protocol.
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As parts of a message are received, the corresponding PART_received method
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def headers_received(self, headers):
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"""Called when message headers are received.
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This default implementation just stores them in self.headers.
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self.headers = headers
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def byte_part_received(self, byte):
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"""Called when a 'byte' part is received.
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Note that a 'byte' part is a message part consisting of exactly one
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raise NotImplementedError(self.byte_received)
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def bytes_part_received(self, bytes):
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"""Called when a 'bytes' part is received.
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A 'bytes' message part can contain any number of bytes. It should not
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be confused with a 'byte' part, which is always a single byte.
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raise NotImplementedError(self.bytes_received)
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def structure_part_received(self, structure):
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"""Called when a 'structure' part is received.
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:param structure: some structured data, which will be some combination
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of list, dict, int, and str objects.
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raise NotImplementedError(self.bytes_received)
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def protocol_error(self, exception):
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"""Called when there is a protocol decoding error.
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The default implementation just re-raises the exception.
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def end_received(self):
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"""Called when the end of the message is received."""
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class ConventionalRequestHandler(MessageHandler):
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"""A message handler for "conventional" requests.
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"Conventional" is used in the sense described in
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doc/developers/network-protocol.txt: a simple message with arguments and an
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* args: expecting args
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* body: expecting body (terminated by receiving a post-body status)
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* error: expecting post-body error
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* end: expecting end of message
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def __init__(self, request_handler, responder):
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MessageHandler.__init__(self)
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self.request_handler = request_handler
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self.responder = responder
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self.expecting = 'args'
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self._should_finish_body = False
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self._response_sent = False
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def protocol_error(self, exception):
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if self.responder.response_sent:
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# We can only send one response to a request, no matter how many
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# errors happen while processing it.
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self.responder.send_error(exception)
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def byte_part_received(self, byte):
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if self.expecting == 'body':
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# Success. Nothing more to come except the end of message.
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self.expecting = 'end'
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# Error. Expect an error structure.
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self.expecting = 'error'
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raise errors.SmartProtocolError(
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'Non-success status byte in request body: %r' % (byte,))
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raise errors.SmartProtocolError(
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'Unexpected message part: byte(%r)' % (byte,))
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def structure_part_received(self, structure):
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if self.expecting == 'args':
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self._args_received(structure)
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elif self.expecting == 'error':
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self._error_received(structure)
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raise errors.SmartProtocolError(
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'Unexpected message part: structure(%r)' % (structure,))
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def _args_received(self, args):
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self.expecting = 'body'
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self.request_handler.dispatch_command(args[0], args[1:])
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if self.request_handler.finished_reading:
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self._response_sent = True
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self.responder.send_response(self.request_handler.response)
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self.expecting = 'end'
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def _error_received(self, error_args):
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self.expecting = 'end'
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self.request_handler.post_body_error_received(error_args)
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def bytes_part_received(self, bytes):
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if self.expecting == 'body':
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self._should_finish_body = True
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self.request_handler.accept_body(bytes)
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raise errors.SmartProtocolError(
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'Unexpected message part: bytes(%r)' % (bytes,))
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def end_received(self):
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if self.expecting not in ['body', 'end']:
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raise errors.SmartProtocolError(
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'End of message received prematurely (while expecting %s)'
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self.expecting = 'nothing'
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self.request_handler.end_received()
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if not self.request_handler.finished_reading:
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raise errors.SmartProtocolError(
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"Complete conventional request was received, but request "
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"handler has not finished reading.")
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if not self._response_sent:
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self.responder.send_response(self.request_handler.response)
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class ResponseHandler(object):
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"""Abstract base class for an object that handles a smart response."""
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def read_response_tuple(self, expect_body=False):
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"""Reads and returns the response tuple for the current request.
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:keyword expect_body: a boolean indicating if a body is expected in the
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response. Some protocol versions needs this information to know
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when a response is finished. If False, read_body_bytes should
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*not* be called afterwards. Defaults to False.
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:returns: tuple of response arguments.
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raise NotImplementedError(self.read_response_tuple)
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def read_body_bytes(self, count=-1):
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"""Read and return some bytes from the body.
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:param count: if specified, read up to this many bytes. By default,
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reads the entire body.
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:returns: str of bytes from the response body.
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raise NotImplementedError(self.read_body_bytes)
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def read_streamed_body(self):
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"""Returns an iterable that reads and returns a series of body chunks.
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raise NotImplementedError(self.read_streamed_body)
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def cancel_read_body(self):
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"""Stop expecting a body for this response.
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If expect_body was passed to read_response_tuple, this cancels that
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expectation (and thus finishes reading the response, allowing a new
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request to be issued). This is useful if a response turns out to be an
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error rather than a normal result with a body.
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raise NotImplementedError(self.cancel_read_body)
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class ConventionalResponseHandler(MessageHandler, ResponseHandler):
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MessageHandler.__init__(self)
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self._bytes_parts = collections.deque()
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self._body_started = False
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self._body_stream_status = None
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self._body_error_args = None
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self.finished_reading = False
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def setProtoAndMediumRequest(self, protocol_decoder, medium_request):
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self._protocol_decoder = protocol_decoder
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self._medium_request = medium_request
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def byte_part_received(self, byte):
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if byte not in ['E', 'S']:
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raise errors.SmartProtocolError(
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'Unknown response status: %r' % (byte,))
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if self._body_started:
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if self._body_stream_status is not None:
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raise errors.SmartProtocolError(
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'Unexpected byte part received: %r' % (byte,))
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self._body_stream_status = byte
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if self.status is not None:
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raise errors.SmartProtocolError(
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'Unexpected byte part received: %r' % (byte,))
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def bytes_part_received(self, bytes):
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self._body_started = True
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self._bytes_parts.append(bytes)
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def structure_part_received(self, structure):
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if type(structure) is not tuple:
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raise errors.SmartProtocolError(
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'Args structure is not a sequence: %r' % (structure,))
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if not self._body_started:
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if self.args is not None:
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raise errors.SmartProtocolError(
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'Unexpected structure received: %r (already got %r)'
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% (structure, self.args))
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self.args = structure
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if self._body_stream_status != 'E':
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raise errors.SmartProtocolError(
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'Unexpected structure received after body: %r'
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self._body_error_args = structure
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def _wait_for_response_args(self):
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while self.args is None and not self.finished_reading:
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def _wait_for_response_end(self):
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while not self.finished_reading:
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def _read_more(self):
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next_read_size = self._protocol_decoder.next_read_size()
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if next_read_size == 0:
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# a complete request has been read.
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self.finished_reading = True
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self._medium_request.finished_reading()
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bytes = self._medium_request.read_bytes(next_read_size)
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# end of file encountered reading from server
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if 'hpss' in debug.debug_flags:
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'decoder state: buf[:10]=%r, state_accept=%s',
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self._protocol_decoder._get_in_buffer()[:10],
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self._protocol_decoder.state_accept.__name__)
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raise errors.ConnectionReset(
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"please check connectivity and permissions",
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"(and try -Dhpss if further diagnosis is required)")
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self._protocol_decoder.accept_bytes(bytes)
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def protocol_error(self, exception):
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# Whatever the error is, we're done with this request.
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self.finished_reading = True
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self._medium_request.finished_reading()
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def read_response_tuple(self, expect_body=False):
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"""Read a response tuple from the wire."""
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self._wait_for_response_args()
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self._wait_for_response_end()
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if 'hpss' in debug.debug_flags:
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mutter(' result: %r', self.args)
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if self.status == 'E':
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self._wait_for_response_end()
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_translate_error(self.args)
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return tuple(self.args)
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def read_body_bytes(self, count=-1):
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"""Read bytes from the body, decoding into a byte stream.
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We read all bytes at once to ensure we've checked the trailer for
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errors, and then feed the buffer back as read_body_bytes is called.
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Like the builtin file.read in Python, a count of -1 (the default) means
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read the entire body.
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# TODO: we don't necessarily need to buffer the full request if count
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# != -1. (2008/04/30, Andrew Bennetts)
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if self._body is None:
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self._wait_for_response_end()
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body_bytes = ''.join(self._bytes_parts)
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if 'hpss' in debug.debug_flags:
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mutter(' %d body bytes read', len(body_bytes))
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self._body = StringIO(body_bytes)
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self._bytes_parts = None
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return self._body.read(count)
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def read_streamed_body(self):
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while not self.finished_reading:
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while self._bytes_parts:
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bytes_part = self._bytes_parts.popleft()
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if 'hpss' in debug.debug_flags:
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mutter(' %d byte part read', len(bytes_part))
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if self._body_stream_status == 'E':
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_translate_error(self._body_error_args)
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def cancel_read_body(self):
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self._wait_for_response_end()
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def _translate_error(error_tuple):
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# Many exceptions need some state from the requestor to be properly
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# translated (e.g. they need a branch object). So this only translates a
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# few errors, and the rest are turned into a generic ErrorFromSmartServer.
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error_name = error_tuple[0]
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error_args = error_tuple[1:]
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if error_name == 'UnknownMethod':
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raise errors.UnknownSmartMethod(error_args[0])
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if error_name == 'LockContention':
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raise errors.LockContention('(remote lock)')
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elif error_name == 'LockFailed':
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raise errors.LockFailed(*error_args[:2])
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raise errors.ErrorFromSmartServer(error_tuple)
added
removed
bzrlib/smart/message.py
