# *****************************************************************************
# * Copyright (c) 2011, 2013 Wind River Systems, Inc. and others.
# * All rights reserved. This program and the accompanying materials
# * are made available under the terms of the Eclipse Public License v1.0
# * which accompanies this distribution, and is available at
# * http://www.eclipse.org/legal/epl-v10.html
# *
# * Contributors:
# * Wind River Systems - initial API and implementation
# *****************************************************************************
import types
from .AbstractChannel import AbstractChannel, EOS, EOM
ESC = 3
class StreamChannel(AbstractChannel):
"""Abstract channel implementation for stream oriented transport protocols.
StreamChannel implements communication link connecting two end points
(peers).
The channel asynchronously transmits messages: commands, results and
events.
StreamChannel uses escape sequences to represent End-Of-Message and
End-Of-Stream markers.
Clients can subclass StreamChannel to support particular stream oriented
transport (wire) protocol.
Also, see ChannelTCP for a concrete IChannel implementation that works on
top of TCP sockets as a transport.
"""
def __init__(self, remote_peer, local_peer=None):
super(StreamChannel, self).__init__(remote_peer, local_peer=local_peer)
self.bin_data_size = 0
self.buf = bytearray(0x1000)
self.buf_pos = 0
self.buf_len = 0
def get(self):
pass
def put(self, n):
pass
def getBuf(self, buf):
i = 0
l = len(buf)
while i < l:
b = self.get()
if b < 0:
if i == 0:
return -1
break
buf[i] = b
i += 1
if i >= self.bin_data_size:
break
return i
def putBuf(self, buf):
for b in buf:
self.put(b & 0xff)
def read(self):
while True:
while self.buf_pos >= self.buf_len:
self.buf_len = self.getBuf(self.buf)
self.buf_pos = 0
if self.buf_len < 0:
return EOS
res = self.buf[self.buf_pos] & 0xff
self.buf_pos += 1
if self.bin_data_size > 0:
self.bin_data_size -= 1
return res
if res != ESC:
return res
while self.buf_pos >= self.buf_len:
self.buf_len = self.getBuf(self.buf)
self.buf_pos = 0
if self.buf_len < 0:
return EOS
n = self.buf[self.buf_pos] & 0xff
self.buf_pos += 1
if n == 0:
return ESC
elif n == 1:
return EOM
elif n == 2:
return EOS
elif n == 3:
for i in xrange(0, 100000, 7):
while self.buf_pos >= self.buf_len:
self.buf_len = self.getBuf(self.buf)
self.buf_pos = 0
if self.buf_len < 0:
return EOS
m = self.buf[self.buf_pos] & 0xff
self.buf_pos += 1
self.bin_data_size |= (m & 0x7f) << i
if (m & 0x80) == 0:
break
else:
if n < 0:
return EOS
assert False
def writeByte(self, n):
if n == ESC:
self.put(ESC)
self.put(0)
elif n == EOM:
self.put(ESC)
self.put(1)
elif n == EOS:
self.put(ESC)
self.put(2)
else:
assert n >= 0 and n <= 0xff
self.put(n)
def write(self, buf):
t = type(buf)
if t == types.IntType:
self.writeByte(buf)
return
elif t == types.StringType:
buf = bytearray(buf)
if len(buf) > 32 and self.isZeroCopySupported():
self.put(ESC)
self.put(3)
n = len(buf)
while True:
if n <= 0x7f:
self.put(n)
break
self.put((n & 0x7f) | 0x80)
n >>= 7
self.putBuf(buf)
else:
for b in buf:
n = b & 0xff
self.put(n)
if n == ESC:
self.put(0)
