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qreader.py
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#
# Copyright (c) 2011-2014 Exxeleron GmbH
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
import struct
import sys
if sys.version > '3':
from sys import intern
unicode = str
from qpython import MetaData, CONVERSION_OPTIONS
from qpython.qtype import * # @UnusedWildImport
from qpython.qcollection import qlist, QDictionary, qtable, QTable, QKeyedTable
from qpython.qtemporal import qtemporal, from_raw_qtemporal, array_from_raw_qtemporal
try:
from qpython.fastutils import uncompress
except:
from qpython.utils import uncompress
class QReaderException(Exception):
'''
Indicates an error raised during data deserialization.
'''
pass
class QMessage(object):
'''
Represents a single message parsed from q protocol.
Encapsulates data, message size, type, compression flag.
:Parameters:
- `data` - data payload
- `message_type` (one of the constants defined in :class:`.MessageType`) -
type of the message
- `message_size` (`integer`) - size of the message
- `is_compressed` (`boolean`) - indicates whether message is compressed
'''
@property
def data(self):
'''Parsed data.'''
return self._data
@data.setter
def data(self, value):
self._data = value
@property
def type(self):
'''Type of the message.'''
return self._type
@property
def is_compressed(self):
'''Indicates whether source message was compressed.'''
return self._is_compressed
@property
def size(self):
'''Size of the source message.'''
return self._size
def __init__(self, data, message_type, message_size, is_compressed):
self._data = data
self._type = message_type
self._size = message_size
self._is_compressed = is_compressed
def __str__(self, *args, **kwargs):
return 'QMessage: message type: %s, data size: %s, is_compressed: %s, data: %s' % (self._type, self._size, self._is_compressed, self._data)
class QReader(object):
'''
Provides deserialization from q IPC protocol.
:Parameters:
- `stream` (`file object` or `None`) - data input stream
- `encoding` (`string`) - encoding for characters parsing
:Attrbutes:
- `_reader_map` - stores mapping between q types and functions
responsible for parsing into Python objects
'''
_reader_map = {}
parse = Mapper(_reader_map)
def __init__(self, stream, encoding = 'latin-1'):
self._stream = stream
self._buffer = QReader.BytesBuffer()
self._encoding = encoding
def read(self, source = None, **options):
'''
Reads and optionally parses a single message.
:Parameters:
- `source` - optional data buffer to be read, if not specified data is
read from the wrapped stream
:Options:
- `raw` (`boolean`) - indicates whether read data should parsed or
returned in raw byte form
- `numpy_temporals` (`boolean`) - if ``False`` temporal vectors are
backed by raw q representation (:class:`.QTemporalList`,
:class:`.QTemporal`) instances, otherwise are represented as
`numpy datetime64`/`timedelta64` arrays and atoms,
**Default**: ``False``
:returns: :class:`.QMessage` - read data (parsed or raw byte form) along
with meta information
'''
message = self.read_header(source)
message.data = self.read_data(message.size, message.is_compressed, **options)
return message
def read_header(self, source = None):
'''
Reads and parses message header.
.. note:: :func:`.read_header` wraps data for further reading in internal
buffer
:Parameters:
- `source` - optional data buffer to be read, if not specified data is
read from the wrapped stream
:returns: :class:`.QMessage` - read meta information
'''
if self._stream:
header = self._read_bytes(8)
self._buffer.wrap(header)
else:
self._buffer.wrap(source)
self._buffer.endianness = '<' if self._buffer.get_byte() == 1 else '>'
self._is_native = self._buffer.endianness == ('<' if sys.byteorder == 'little' else '>')
message_type = self._buffer.get_byte()
message_compressed = self._buffer.get_byte() == 1
# skip 1 byte
self._buffer.skip()
message_size = self._buffer.get_int()
return QMessage(None, message_type, message_size, message_compressed)
def read_data(self, message_size, is_compressed = False, **options):
'''
Reads and optionally parses data part of a message.
.. note:: :func:`.read_header` is required to be called before executing
the :func:`.read_data`
:Parameters:
- `message_size` (`integer`) - size of the message to be read
- `is_compressed` (`boolean`) - indicates whether data is compressed
:Options:
- `raw` (`boolean`) - indicates whether read data should parsed or
returned in raw byte form
- `numpy_temporals` (`boolean`) - if ``False`` temporal vectors are
backed by raw q representation (:class:`.QTemporalList`,
:class:`.QTemporal`) instances, otherwise are represented as
`numpy datetime64`/`timedelta64` arrays and atoms,
**Default**: ``False``
:returns: read data (parsed or raw byte form)
'''
self._options = MetaData(**CONVERSION_OPTIONS.union_dict(**options))
if is_compressed:
if self._stream:
self._buffer.wrap(self._read_bytes(4))
uncompressed_size = -8 + self._buffer.get_int()
compressed_data = self._read_bytes(message_size - 12) if self._stream else self._buffer.raw(message_size - 12)
raw_data = numpy.fromstring(compressed_data, dtype = numpy.uint8)
if uncompressed_size <= 0:
raise QReaderException('Error while data decompression.')
raw_data = uncompress(raw_data, numpy.intc(uncompressed_size))
raw_data = numpy.ndarray.tostring(raw_data)
self._buffer.wrap(raw_data)
elif self._stream:
raw_data = self._read_bytes(message_size - 8)
self._buffer.wrap(raw_data)
if not self._stream and self._options.raw:
raw_data = self._buffer.raw(message_size - 8)
return raw_data if self._options.raw else self._read_object()
def _read_object(self):
qtype = self._buffer.get_byte()
reader = self._get_reader(qtype)
if reader:
return reader(self, qtype)
elif qtype >= QBOOL_LIST and qtype <= QTIME_LIST:
return self._read_list(qtype)
elif qtype <= QBOOL and qtype >= QTIME:
return self._read_atom(qtype)
raise QReaderException('Unable to deserialize q type: %s' % hex(qtype))
def _get_reader(self, qtype):
return self._reader_map.get(qtype, None)
@parse(QERROR)
def _read_error(self, qtype = QERROR):
raise QException(self._read_symbol())
@parse(QSTRING)
def _read_string(self, qtype = QSTRING):
self._buffer.skip() # ignore attributes
length = self._buffer.get_int()
return self._buffer.raw(length) if length > 0 else b''
@parse(QSYMBOL)
def _read_symbol(self, qtype = QSYMBOL):
return numpy.string_(self._buffer.get_symbol())
@parse(QCHAR)
def _read_char(self, qtype = QCHAR):
return chr(self._read_atom(QCHAR)).encode(self._encoding)
@parse(QGUID)
def _read_guid(self, qtype = QGUID):
return uuid.UUID(bytes = self._buffer.raw(16))
def _read_atom(self, qtype):
try:
fmt = STRUCT_MAP[qtype]
conversion = PY_TYPE[qtype]
return conversion(self._buffer.get(fmt))
except KeyError:
raise QReaderException('Unable to deserialize q type: %s' % hex(qtype))
@parse(QTIMESPAN, QTIMESTAMP, QTIME, QSECOND, QMINUTE, QDATE, QMONTH, QDATETIME)
def _read_temporal(self, qtype):
try:
fmt = STRUCT_MAP[qtype]
conversion = PY_TYPE[qtype]
temporal = from_raw_qtemporal(conversion(self._buffer.get(fmt)), qtype = qtype)
return temporal if self._options.numpy_temporals else qtemporal(temporal, qtype = qtype)
except KeyError:
raise QReaderException('Unable to deserialize q type: %s' % hex(qtype))
def _read_list(self, qtype):
self._buffer.skip() # ignore attributes
length = self._buffer.get_int()
conversion = PY_TYPE.get(-qtype, None)
if qtype == QSYMBOL_LIST:
symbols = self._buffer.get_symbols(length)
data = numpy.array(symbols, dtype = numpy.string_)
return qlist(data, qtype = qtype, adjust_dtype = False)
elif qtype == QGUID_LIST:
data = numpy.array([self._read_guid() for x in range(length)])
return qlist(data, qtype = qtype, adjust_dtype = False)
elif conversion:
raw = self._buffer.raw(length * ATOM_SIZE[qtype])
data = numpy.fromstring(raw, dtype = conversion)
if not self._is_native:
data.byteswap(True)
if qtype >= QTIMESTAMP_LIST and qtype <= QTIME_LIST and self._options.numpy_temporals:
data = array_from_raw_qtemporal(data, qtype)
return qlist(data, qtype = qtype, adjust_dtype = False)
else:
raise QReaderException('Unable to deserialize q type: %s' % hex(qtype))
@parse(QDICTIONARY)
def _read_dictionary(self, qtype = QDICTIONARY):
keys = self._read_object()
values = self._read_object()
if isinstance(keys, QTable):
return QKeyedTable(keys, values)
else:
return QDictionary(keys, values)
@parse(QTABLE)
def _read_table(self, qtype = QTABLE):
self._buffer.skip() # ignore attributes
self._buffer.skip() # ignore dict type stamp
columns = self._read_object()
data = self._read_object()
return qtable(columns, data, qtype = QTABLE)
@parse(QGENERAL_LIST)
def _read_general_list(self, qtype = QGENERAL_LIST):
self._buffer.skip() # ignore attributes
length = self._buffer.get_int()
return [self._read_object() for x in range(length)]
@parse(QNULL)
@parse(QUNARY_FUNC)
@parse(QBINARY_FUNC)
@parse(QTERNARY_FUNC)
def _read_function(self, qtype = QNULL):
code = self._buffer.get_byte()
return None if qtype == QNULL and code == 0 else QFunction(qtype)
@parse(QLAMBDA)
def _read_lambda(self, qtype = QLAMBDA):
self._buffer.get_symbol() # skip
expression = self._read_object()
return QLambda(expression.decode())
@parse(QCOMPOSITION_FUNC)
def _read_function_composition(self, qtype = QCOMPOSITION_FUNC):
self._read_projection(qtype) # skip
return QFunction(qtype)
@parse(QADVERB_FUNC_106)
@parse(QADVERB_FUNC_107)
@parse(QADVERB_FUNC_108)
@parse(QADVERB_FUNC_109)
@parse(QADVERB_FUNC_110)
@parse(QADVERB_FUNC_111)
def _read_adverb_function(self, qtype = QADVERB_FUNC_106):
self._read_object() # skip
return QFunction(qtype)
@parse(QPROJECTION)
def _read_projection(self, qtype = QPROJECTION):
length = self._buffer.get_int()
parameters = [ self._read_object() for x in range(length) ]
return QProjection(parameters)
def _read_bytes(self, length):
if not self._stream:
raise QReaderException('There is no input data. QReader requires either stream or data chunk')
if length == 0:
return b''
else:
data = self._stream.read(length)
if len(data) == 0:
raise QReaderException('Error while reading data')
return data
class BytesBuffer(object):
'''
Utility class for reading bytes from wrapped buffer.
'''
def __init__(self):
self._endianness = '@'
@property
def endianness(self):
'''
Gets the endianness.
'''
return self._endianness
@endianness.setter
def endianness(self, endianness):
'''
Sets the byte order (endianness) for reading from the buffer.
:Parameters:
- `endianness` (``<`` or ``>``) - byte order indicator
'''
self._endianness = endianness
def wrap(self, data):
'''
Wraps the data in the buffer.
:Parameters:
- `data` - data to be wrapped
'''
self._data = data
self._position = 0
self._size = len(data)
def skip(self, offset = 1):
'''
Skips reading of `offset` bytes.
:Parameters:
- `offset` (`integer`) - number of bytes to be skipped
'''
new_position = self._position + offset
if new_position > self._size:
raise QReaderException('Attempt to read data out of buffer bounds')
self._position = new_position
def raw(self, offset):
'''
Gets `offset` number of raw bytes.
:Parameters:
- `offset` (`integer`) - number of bytes to be retrieved
:returns: raw bytes
'''
new_position = self._position + offset
if new_position > self._size:
raise QReaderException('Attempt to read data out of buffer bounds')
raw = self._data[self._position : new_position]
self._position = new_position
return raw
def get(self, fmt, offset = None):
'''
Gets bytes from the buffer according to specified format or `offset`.
:Parameters:
- `fmt` (struct format) - conversion to be applied for reading
- `offset` (`integer`) - number of bytes to be retrieved
:returns: unpacked bytes
'''
fmt = self.endianness + fmt
offset = offset if offset else struct.calcsize(fmt)
return struct.unpack(fmt, self.raw(offset))[0]
def get_byte(self):
'''
Gets a single byte from the buffer.
:returns: single byte
'''
return self.get('b')
def get_int(self):
'''
Gets a single 32-bit integer from the buffer.
:returns: single integer
'''
return self.get('i')
def get_symbol(self):
'''
Gets a single, ``\\x00`` terminated string from the buffer.
:returns: ``\\x00`` terminated string
'''
new_position = self._data.find(b'\x00', self._position)
if new_position < 0:
raise QReaderException('Failed to read symbol from stream')
raw = self._data[self._position : new_position]
self._position = new_position + 1
return raw
def get_symbols(self, count):
'''
Gets ``count`` ``\\x00`` terminated strings from the buffer.
:Parameters:
- `count` (`integer`) - number of strings to be read
:returns: list of ``\\x00`` terminated string read from the buffer
'''
c = 0
new_position = self._position
if count == 0:
return []
while c < count:
new_position = self._data.find(b'\x00', new_position)
if new_position < 0:
raise QReaderException('Failed to read symbol from stream')
c += 1
new_position += 1
raw = self._data[self._position : new_position - 1]
self._position = new_position
return raw.split(b'\x00')