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#
# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements. See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership. The ASF licenses this file
# to you 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.
#
from cStringIO import StringIO
from struct import pack,unpack
from thrift.Thrift import TException
class TTransportException(TException):
"""Custom Transport Exception class"""
UNKNOWN = 0
NOT_OPEN = 1
ALREADY_OPEN = 2
TIMED_OUT = 3
END_OF_FILE = 4
def __init__(self, type=UNKNOWN, message=None):
TException.__init__(self, message)
self.type = type
class TTransportBase:
"""Base class for Thrift transport layer."""
def isOpen(self):
pass
def open(self):
pass
def close(self):
pass
def read(self, sz):
pass
def readAll(self, sz):
buff = ''
have = 0
while (have < sz):
chunk = self.read(sz-have)
have += len(chunk)
buff += chunk
if len(chunk) == 0:
raise EOFError()
return buff
def write(self, buf):
pass
def flush(self):
pass
# This class should be thought of as an interface.
class CReadableTransport:
"""base class for transports that are readable from C"""
# TODO(dreiss): Think about changing this interface to allow us to use
# a (Python, not c) StringIO instead, because it allows
# you to write after reading.
# NOTE: This is a classic class, so properties will NOT work
# correctly for setting.
@property
def cstringio_buf(self):
"""A cStringIO buffer that contains the current chunk we are reading."""
pass
def cstringio_refill(self, partialread, reqlen):
"""Refills cstringio_buf.
Returns the currently used buffer (which can but need not be the same as
the old cstringio_buf). partialread is what the C code has read from the
buffer, and should be inserted into the buffer before any more reads. The
return value must be a new, not borrowed reference. Something along the
lines of self._buf should be fine.
If reqlen bytes can't be read, throw EOFError.
"""
pass
class TServerTransportBase:
"""Base class for Thrift server transports."""
def listen(self):
pass
def accept(self):
pass
def close(self):
pass
class TTransportFactoryBase:
"""Base class for a Transport Factory"""
def getTransport(self, trans):
return trans
class TBufferedTransportFactory:
"""Factory transport that builds buffered transports"""
def getTransport(self, trans):
buffered = TBufferedTransport(trans)
return buffered
class TBufferedTransport(TTransportBase,CReadableTransport):
"""Class that wraps another transport and buffers its I/O."""
DEFAULT_BUFFER = 4096
def __init__(self, trans):
self.__trans = trans
self.__wbuf = StringIO()
self.__rbuf = StringIO("")
def isOpen(self):
return self.__trans.isOpen()
def open(self):
return self.__trans.open()
def close(self):
return self.__trans.close()
def read(self, sz):
ret = self.__rbuf.read(sz)
if len(ret) != 0:
return ret
self.__rbuf = StringIO(self.__trans.read(max(sz, self.DEFAULT_BUFFER)))
return self.__rbuf.read(sz)
def write(self, buf):
self.__wbuf.write(buf)
def flush(self):
out = self.__wbuf.getvalue()
# reset wbuf before write/flush to preserve state on underlying failure
self.__wbuf = StringIO()
self.__trans.write(out)
self.__trans.flush()
# Implement the CReadableTransport interface.
@property
def cstringio_buf(self):
return self.__rbuf
def cstringio_refill(self, partialread, reqlen):
retstring = partialread
if reqlen < self.DEFAULT_BUFFER:
# try to make a read of as much as we can.
retstring += self.__trans.read(self.DEFAULT_BUFFER)
# but make sure we do read reqlen bytes.
if len(retstring) < reqlen:
retstring += self.__trans.readAll(reqlen - len(retstring))
self.__rbuf = StringIO(retstring)
return self.__rbuf
class TMemoryBuffer(TTransportBase, CReadableTransport):
"""Wraps a cStringIO object as a TTransport.
NOTE: Unlike the C++ version of this class, you cannot write to it
then immediately read from it. If you want to read from a
TMemoryBuffer, you must either pass a string to the constructor.
TODO(dreiss): Make this work like the C++ version.
"""
def __init__(self, value=None):
"""value -- a value to read from for stringio
If value is set, this will be a transport for reading,
otherwise, it is for writing"""
if value is not None:
self._buffer = StringIO(value)
else:
self._buffer = StringIO()
def isOpen(self):
return not self._buffer.closed
def open(self):
pass
def close(self):
self._buffer.close()
def read(self, sz):
return self._buffer.read(sz)
def write(self, buf):
self._buffer.write(buf)
def flush(self):
pass
def getvalue(self):
return self._buffer.getvalue()
# Implement the CReadableTransport interface.
@property
def cstringio_buf(self):
return self._buffer
def cstringio_refill(self, partialread, reqlen):
# only one shot at reading...
raise EOFError()
class TFramedTransportFactory:
"""Factory transport that builds framed transports"""
def getTransport(self, trans):
framed = TFramedTransport(trans)
return framed
class TFramedTransport(TTransportBase, CReadableTransport):
"""Class that wraps another transport and frames its I/O when writing."""
def __init__(self, trans,):
self.__trans = trans
self.__rbuf = StringIO()
self.__wbuf = StringIO()
def isOpen(self):
return self.__trans.isOpen()
def open(self):
return self.__trans.open()
def close(self):
return self.__trans.close()
def read(self, sz):
ret = self.__rbuf.read(sz)
if len(ret) != 0:
return ret
self.readFrame()
return self.__rbuf.read(sz)
def readFrame(self):
buff = self.__trans.readAll(4)
sz, = unpack('!i', buff)
self.__rbuf = StringIO(self.__trans.readAll(sz))
def write(self, buf):
self.__wbuf.write(buf)
def flush(self):
wout = self.__wbuf.getvalue()
wsz = len(wout)
# reset wbuf before write/flush to preserve state on underlying failure
self.__wbuf = StringIO()
# N.B.: Doing this string concatenation is WAY cheaper than making
# two separate calls to the underlying socket object. Socket writes in
# Python turn out to be REALLY expensive, but it seems to do a pretty
# good job of managing string buffer operations without excessive copies
buf = pack("!i", wsz) + wout
self.__trans.write(buf)
self.__trans.flush()
# Implement the CReadableTransport interface.
@property
def cstringio_buf(self):
return self.__rbuf
def cstringio_refill(self, prefix, reqlen):
# self.__rbuf will already be empty here because fastbinary doesn't
# ask for a refill until the previous buffer is empty. Therefore,
# we can start reading new frames immediately.
while len(prefix) < reqlen:
readFrame()
prefix += self.__rbuf.getvalue()
self.__rbuf = StringIO(prefix)
return self.__rbuf
class TFileObjectTransport(TTransportBase):
"""Wraps a file-like object to make it work as a Thrift transport."""
def __init__(self, fileobj):
self.fileobj = fileobj
def isOpen(self):
return True
def close(self):
self.fileobj.close()
def read(self, sz):
return self.fileobj.read(sz)
def write(self, buf):
self.fileobj.write(buf)
def flush(self):
self.fileobj.flush()
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