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erlproto.py
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/
erlproto.py
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# Copyright (c) 2009-2015, Dmitry Vasiliev <dima@hlabs.org>
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
# * Redistributions of source code must retain the above copyright notice,
# this list of conditions and the following disclaimer.
# * Redistributions in binary form must reproduce the above copyright notice,
# this list of conditions and the following disclaimer in the documentation
# and/or other materials provided with the distribution.
# * Neither the name of the copyright holders nor the names of its
# contributors may be used to endorse or promote products derived from this
# software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
"""Erlang port protocol."""
from __future__ import with_statement
__author__ = "Dmitry Vasiliev <dima@hlabs.org>"
import os
import errno
from struct import Struct
from threading import Lock
from erlport.erlterms import encode, decode
class Port(object):
"""Erlang port."""
_formats = {
1: Struct("B"),
2: Struct(">H"),
4: Struct(">I"),
}
def __init__(self, packet=4, use_stdio=True, compressed=False,
descriptors=None, buffer_size=65536):
if buffer_size < 1:
raise ValueError("invalid buffer size value: %s" % (buffer_size,))
struct = self._formats.get(packet)
if struct is None:
raise ValueError("invalid packet size value: %s" % (packet,))
self.__pack = struct.pack
self.__unpack = struct.unpack
self.packet = packet
self.compressed = compressed
if descriptors is not None:
self.in_d, self.out_d = descriptors
elif use_stdio:
self.in_d, self.out_d = 0, 1
else:
self.in_d, self.out_d = 3, 4
self.__buffer = ""
self.buffer_size = buffer_size
self.__read_lock = Lock()
self.__write_lock = Lock()
def _read_data(self):
try:
buf = os.read(self.in_d, self.buffer_size)
except OSError, why:
if why.errno in (errno.EPIPE, errno.EINVAL):
raise EOFError()
raise
if not buf:
raise EOFError()
return buf
def read(self):
"""Read incoming message."""
packet = self.packet
with self.__read_lock:
buffer = self.__buffer
while len(buffer) < packet:
buffer += self._read_data()
length = self.__unpack(buffer[:packet])[0] + packet
while len(buffer) < length:
buffer += self._read_data()
term, self.__buffer = decode(buffer[packet:])
return term
def write(self, message):
"""Write outgoing message."""
data = encode(message, compressed=self.compressed)
length = len(data)
data = self.__pack(length) + data
with self.__write_lock:
while data:
try:
n = os.write(self.out_d, data)
except OSError, why:
if why.errno in (errno.EPIPE, errno.EINVAL):
raise EOFError()
raise
if not n:
raise EOFError()
data = data[n:]
return length + self.packet
def close(self):
"""Close port."""
os.close(self.in_d)
os.close(self.out_d)