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# -*- coding: utf-8 -*-
# fetch_protocol.py
# Copyright (C) 2016 LEAP
#
# This program 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.
#
# This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
import json
from functools import partial
from cStringIO import StringIO
from twisted.web._newclient import ResponseDone
from leap.soledad.common.l2db import errors
from leap.soledad.common.l2db.remote import utils
from .support import ReadBodyProtocol
from .support import readBody
class DocStreamReceiver(ReadBodyProtocol):
"""
A protocol implementation that can parse incoming data from server based
on a line format specified on u1db implementation. Except that we split doc
attributes from content to ease parsing and increment throughput for larger
documents.
[\r\n
{metadata},\r\n
{doc_info},\r\n
{content},\r\n
...
{doc_info},\r\n
{content},\r\n
]
"""
def __init__(self, response, deferred, doc_reader):
self.deferred = deferred
self.status = response.code if response else None
self.message = response.phrase if response else None
self.headers = response.headers if response else {}
self.delimiter = '\r\n'
self._doc_reader = doc_reader
self.reset()
def reset(self):
self._line = 0
self._buffer = StringIO()
self._properly_finished = False
def connectionLost(self, reason):
"""
Deliver the accumulated response bytes to the waiting L{Deferred}, if
the response body has been completely received without error.
"""
try:
if reason.check(ResponseDone):
self.dataBuffer = self.metadata
else:
self.dataBuffer = self.finish()
except errors.BrokenSyncStream, e:
return self.deferred.errback(e)
return ReadBodyProtocol.connectionLost(self, reason)
def consumeBufferLines(self):
"""
Consumes lines from buffer and rewind it, writing remaining data
that didn't formed a line back into buffer.
"""
content = self._buffer.getvalue()[0:self._buffer.tell()]
self._buffer.seek(0)
lines = content.split(self.delimiter)
self._buffer.write(lines.pop(-1))
return lines
def dataReceived(self, data):
"""
Buffer incoming data until a line breaks comes in. We check only
the incoming data for efficiency.
"""
self._buffer.write(data)
if '\n' not in data:
return
lines = self.consumeBufferLines()
while lines:
line, _ = utils.check_and_strip_comma(lines.pop(0))
self.lineReceived(line)
self._line += 1
def lineReceived(self, line):
"""
Protocol implementation.
0: [\r\n
1: {metadata},\r\n
(even): {doc_info},\r\n
(odd): {data},\r\n
(last): ]
"""
if self._properly_finished:
raise errors.BrokenSyncStream("Reading a finished stream")
if ']' == line:
self._properly_finished = True
elif self._line == 0:
if line is not '[':
raise errors.BrokenSyncStream("Invalid start")
elif self._line == 1:
self.metadata = line
if 'error' in self.metadata:
raise errors.BrokenSyncStream("Error from server: %s" % line)
self.total = json.loads(line).get('number_of_changes', -1)
elif (self._line % 2) == 0:
self.current_doc = json.loads(line)
if 'error' in self.current_doc:
raise errors.BrokenSyncStream("Error from server: %s" % line)
else:
self._doc_reader(
self.current_doc, line.strip() or None, self.total)
def finish(self):
"""
Checks that ']' came and stream was properly closed.
"""
if not self._properly_finished:
raise errors.BrokenSyncStream()
content = self._buffer.getvalue()[0:self._buffer.tell()]
self._buffer.close()
return content
def build_body_reader(doc_reader):
"""
Get the documents from a sync stream and call doc_reader on each
doc received.
@param doc_reader: Function to be called for processing an incoming doc.
Will be called with doc metadata (dict parsed from 1st line) and doc
content (string)
@type doc_reader: function
@return: A function that can be called by the http Agent to create and
configure the proper protocol.
"""
protocolClass = partial(DocStreamReceiver, doc_reader=doc_reader)
return partial(readBody, protocolClass=protocolClass)
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