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"""
Tools for marshalling and unmarshalling data stored
in Cassandra.
"""
import uuid
import struct
import calendar
from datetime import datetime
from decimal import Decimal
import pycassa.util as util
_number_types = frozenset((int, long, float))
if hasattr(struct, 'Struct'): # new in Python 2.5
def make_packer(fmt_string):
return struct.Struct(fmt_string)
else:
def make_packer(fmt_string):
class Struct(object):
def pack(self, v):
return struct.pack(fmt_string, v)
def unpack(self, v):
return struct.unpack(fmt_string, v)
return Struct()
_bool_packer = make_packer('>B')
_float_packer = make_packer('>f')
_double_packer = make_packer('>d')
_long_packer = make_packer('>q')
_int_packer = make_packer('>i')
_short_packer = make_packer('>H')
_BASIC_TYPES = ('BytesType', 'LongType', 'IntegerType', 'UTF8Type',
'AsciiType', 'LexicalUUIDType', 'TimeUUIDType',
'CounterColumnType', 'FloatType', 'DoubleType',
'DateType', 'BooleanType', 'UUIDType', 'Int32Type',
'DecimalType')
def extract_type_name(typestr):
if typestr is None:
return 'BytesType'
if "CompositeType" in typestr:
return _get_composite_name(typestr)
if "ReversedType" in typestr:
return _get_inner_type(typestr)
index = typestr.rfind('.')
if index != -1:
typestr = typestr[index + 1:]
if typestr not in _BASIC_TYPES:
typestr = 'BytesType'
return typestr
def _get_inner_type(typestr):
""" Given a str like 'org.apache...ReversedType(LongType)',
return just 'LongType' """
first_paren = typestr.find('(')
return typestr[first_paren + 1:-1]
def _get_inner_types(typestr):
""" Given a str like 'org.apache...CompositeType(LongType, DoubleType)',
return a tuple of the inner types, like ('LongType', 'DoubleType') """
internal_str = _get_inner_type(typestr)
return map(str.strip, internal_str.split(','))
def _get_composite_name(typestr):
types = map(extract_type_name, _get_inner_types(typestr))
return "CompositeType(" + ", ".join(types) + ")"
def _to_timestamp(v):
# Expects Value to be either date or datetime
try:
converted = calendar.timegm(v.utctimetuple())
converted = converted * 1e3 + getattr(v, 'microsecond', 0) / 1e3
except AttributeError:
# Ints and floats are valid timestamps too
if type(v) not in _number_types:
raise TypeError('DateType arguments must be a datetime or timestamp')
converted = v * 1e3
return long(converted)
def get_composite_packer(typestr=None, composite_type=None):
assert (typestr or composite_type), "Must provide typestr or " + \
"CompositeType instance"
if typestr:
packers = map(packer_for, _get_inner_types(typestr))
elif composite_type:
packers = [c.pack for c in composite_type.components]
len_packer = _short_packer.pack
def pack_composite(items, slice_start=None):
last_index = len(items) - 1
s = ''
for i, (item, packer) in enumerate(zip(items, packers)):
eoc = '\x00'
if isinstance(item, tuple):
item, inclusive = item
if inclusive:
if slice_start:
eoc = '\xff'
elif slice_start is False:
eoc = '\x01'
else:
if slice_start:
eoc = '\x01'
elif slice_start is False:
eoc = '\xff'
elif i == last_index:
if slice_start:
eoc = '\xff'
elif slice_start is False:
eoc = '\x01'
packed = packer(item)
s += ''.join((len_packer(len(packed)), packed, eoc))
return s
return pack_composite
def get_composite_unpacker(typestr=None, composite_type=None):
assert (typestr or composite_type), "Must provide typestr or " + \
"CompositeType instance"
if typestr:
unpackers = map(unpacker_for, _get_inner_types(typestr))
elif composite_type:
unpackers = [c.unpack for c in composite_type.components]
len_unpacker = lambda v: _short_packer.unpack(v)[0]
def unpack_composite(bytestr):
# The composite format for each component is:
# <len> <value> <eoc>
# 2 bytes | ? bytes | 1 byte
components = []
i = iter(unpackers)
while bytestr:
unpacker = i.next()
length = len_unpacker(bytestr[:2])
components.append(unpacker(bytestr[2:2 + length]))
bytestr = bytestr[3 + length:]
return tuple(components)
return unpack_composite
def packer_for(typestr):
if typestr is None:
return lambda v: v
if "CompositeType" in typestr:
return get_composite_packer(typestr)
if "ReversedType" in typestr:
return packer_for(_get_inner_type(typestr))
data_type = extract_type_name(typestr)
if data_type == 'DateType':
def pack_date(v, _=None):
return _long_packer.pack(_to_timestamp(v))
return pack_date
elif data_type == 'BooleanType':
def pack_bool(v, _=None):
return _bool_packer.pack(bool(v))
return pack_bool
elif data_type == 'DoubleType':
def pack_double(v, _=None):
return _double_packer.pack(v)
return pack_double
elif data_type == 'FloatType':
def pack_float(v, _=None):
return _float_packer.pack(v)
return pack_float
elif data_type == 'DecimalType':
def pack_decimal(dec, _=None):
sign, digits, exponent = dec.as_tuple()
unscaled = int(''.join(map(str, digits)))
if sign:
unscaled *= -1
scale = _int_packer.pack(-exponent)
unscaled = encode_int(unscaled)
return scale + unscaled
return pack_decimal
elif data_type == 'LongType':
def pack_long(v, _=None):
return _long_packer.pack(v)
return pack_long
elif data_type == 'Int32Type':
def pack_int32(v, _=None):
return _int_packer.pack(v)
return pack_int32
elif data_type == 'IntegerType':
return encode_int
elif data_type == 'UTF8Type':
def pack_utf8(v, _=None):
try:
return v.encode('utf-8')
except UnicodeDecodeError:
# v is already utf-8 encoded
return v
return pack_utf8
elif 'UUIDType' in data_type:
def pack_uuid(value, slice_start=None):
if slice_start is None:
value = util.convert_time_to_uuid(value,
randomize=True)
else:
value = util.convert_time_to_uuid(value,
lowest_val=slice_start,
randomize=False)
if not hasattr(value, 'bytes'):
raise TypeError("%s is not valid for UUIDType" % value)
return value.bytes
return pack_uuid
elif data_type == "CounterColumnType":
def noop(value, slice_start=None):
return value
return noop
else: # data_type == 'BytesType' or something unknown
def pack_bytes(v, _=None):
if not isinstance(v, basestring):
raise TypeError("A str or unicode value was expected, " +
"but %s was received instead (%s)"
% (v.__class__.__name__, str(v)))
return v
return pack_bytes
def unpacker_for(typestr):
if typestr is None:
return lambda v: v
if "CompositeType" in typestr:
return get_composite_unpacker(typestr)
if "ReversedType" in typestr:
return unpacker_for(_get_inner_type(typestr))
data_type = extract_type_name(typestr)
if data_type == 'BytesType':
return lambda v: v
elif data_type == 'DateType':
return lambda v: datetime.utcfromtimestamp(
_long_packer.unpack(v)[0] / 1e3)
elif data_type == 'BooleanType':
return lambda v: bool(_bool_packer.unpack(v)[0])
elif data_type == 'DoubleType':
return lambda v: _double_packer.unpack(v)[0]
elif data_type == 'FloatType':
return lambda v: _float_packer.unpack(v)[0]
elif data_type == 'DecimalType':
def unpack_decimal(v):
scale = _int_packer.unpack(v[:4])[0]
unscaled = decode_int(v[4:])
return Decimal('%de%d' % (unscaled, -scale))
return unpack_decimal
elif data_type == 'LongType':
return lambda v: _long_packer.unpack(v)[0]
elif data_type == 'Int32Type':
return lambda v: _int_packer.unpack(v)[0]
elif data_type == 'IntegerType':
return decode_int
elif data_type == 'UTF8Type':
return lambda v: v.decode('utf-8')
elif 'UUIDType' in data_type:
return lambda v: uuid.UUID(bytes=v)
else:
return lambda v: v
def encode_int(x, *args):
if x >= 0:
out = []
while x >= 256:
out.append(struct.pack('B', 0xff & x))
x >>= 8
out.append(struct.pack('B', 0xff & x))
if x > 127:
out.append('\x00')
else:
x = -1 - x
out = []
while x >= 256:
out.append(struct.pack('B', 0xff & ~x))
x >>= 8
if x <= 127:
out.append(struct.pack('B', 0xff & ~x))
else:
out.append(struct.pack('>H', 0xffff & ~x))
return ''.join(reversed(out))
def decode_int(term, *args):
val = int(term.encode('hex'), 16)
if (ord(term[0]) & 128) != 0:
val = val - (1 << (len(term) * 8))
return val
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