/usr/share/pyshared/d_rats/sessions/stateful.py is in d-rats 0.3.3-3ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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#
# Copyright 2009 Dan Smith <dsmith@danplanet.com>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
import threading
import time
from d_rats import transport
from d_rats.ddt2 import DDT2EncodedFrame
from d_rats.sessions import base
T_SYN = 0
T_ACK = 1
T_NAK = 2
T_DAT = 4
T_REQACK = 5
class StatefulSession(base.Session):
stateless = False
type = base.T_GENERAL
IDLE_TIMEOUT = 90
def __init__(self, name, **kwargs):
base.Session.__init__(self, name)
self.outq = transport.BlockQueue()
self.oob_queue = {}
self.recv_list = []
self.outstanding = []
self.waiting_for_ack = []
self.enabled = True
self.bsize = kwargs.get("blocksize", 1024)
self.out_limit = kwargs.get("outlimit", 8)
self.iseq = -1
self.oseq = 0
self.data = transport.BlockQueue()
self.data_waiting = threading.Condition()
self.__attempts = 0
self.__ack_timeout = 0
self.__full_acks = 0
self._rtr = 0.0 # Round trip rate (bps)
self._xmt = 0.0 # Transmit rate (bps)
self._xms = 0.0 # Start of last transmit of self.outstanding[]
self._rtt_measure = {
"bnum" : -1,
"start" : 0,
"end" : 0,
"size" : 0,
}
self.event = threading.Event()
self.thread = threading.Thread(target=self.worker)
self.thread.setDaemon(True)
self.thread.start()
def notify(self):
self.event.set()
def close(self, force=False):
print "Got close request, joining thread..."
self.enabled = False
self.notify()
# Free up any block listeners
if isinstance(self.outstanding, list):
for b in self.outstanding:
b.sent_event.set()
b.sent_event.clear()
b.ackd_event.set()
elif self.outstanding:
b.sent_event.set()
self.thread.join()
print "Thread is done, continuing with close"
base.Session.close(self, force)
def queue_next(self):
if self.outstanding is None:
# This is a silly race condition because the worker thread is
# started in the init, which might run before we set our values
# after the superclass init
return
limit = self.out_limit
if self.__full_acks > 0:
limit += self.__full_acks
elif self.__full_acks < 0:
limit -= abs(self.__full_acks)
# Hard limit of 4KB outstanding (should be per-path!)
hardlimit = (1 << 12) / self.bsize
if limit < 2:
limit = 2
elif limit > hardlimit:
limit = hardlimit
count = limit - len(self.outstanding)
print "New limit is %i (%i/%i), queueing %i" % (limit,
self.out_limit,
hardlimit,
count)
if count < 0:
# Need to requeue some blocks to shrink our window
print "Need to requeue %i blocks to shrink window" % abs(count)
for i in range(abs(count)):
print " Requeuing block..."
b = self.outstanding[-1]
del self.outstanding[-1]
self.outq.requeue(b)
return
elif count > 0:
for i in range(count):
b = self.outq.dequeue()
if b:
if b.seq == 0 and self.outstanding:
print "### Pausing at rollover boundary ###"
self.outq.requeue(b)
break
print "Queuing %i for send (%i)" % (b.seq, count)
self.outstanding.append(b)
else:
break
def is_timeout(self):
if self._xms == 0:
return True
pending_size = 0
for block in self.outstanding:
pending_size += block._xmit_z
if pending_size == 0:
return True
if self._rtr != 0:
rate = self._rtr
else:
# No measured rate yet so assume the minimum rate
rate = 80
timeout = (pending_size / rate) * 1.5
if timeout < 12:
# Don't allow small outgoing buffers to fool us into thinking
# there is no turnaround delay
timeout = 12
print "## Timeout for %i bytes @ %i bps: %.1f sec" % (pending_size,
rate,
timeout)
print "## Remaining: %.1f sec" % (timeout - (time.time() - self._xms))
if self.__attempts:
print "## Waiting for ACK, timeout in %i" % (self.__ack_timeout -
time.time())
return (self.__ack_timeout - time.time()) <= 0
else:
return (timeout - (time.time() - self._xms)) <= 0
def send_reqack(self, blocks):
f = DDT2EncodedFrame()
f.seq = 0
f.type = T_REQACK
# FIXME: This needs to support 16-bit block numbers!
f.data = "".join([chr(x) for x in blocks])
print "Requesting ack of blocks %s" % blocks
self._sm.outgoing(self, f)
def send_blocks(self):
if self.outstanding and not self.is_timeout():
# Not time to try again yet
return
self.queue_next()
if not self.outstanding:
# nothing to send
return
if self.__attempts >= 10:
print "Too many retries, closing..."
self.set_state(base.ST_CLSD)
self.enabled = False
return
# Short circuit to just an ack for outstanding blocks, if
# we're still waiting for an ack from remote. Increase the timeout
# for the ack by four seconds each time to give some backoff
if self.waiting_for_ack:
print "Didn't get last ack, asking again"
self.send_reqack(self.waiting_for_ack)
if self.__full_acks > 0:
self.__full_acks = 0
else:
self.__full_acks -= 1
self.__attempts += 1
self.__ack_timeout = time.time() + 4 + (self.__attempts * 4)
return
toack = []
self._rtt_measure["start"] = time.time()
self._rtt_measure["end"] = self._rtt_measure["size"] = 0
self._xms = time.time()
last_block = None
for b in self.outstanding:
if b.sent_event.isSet():
self.stats["retries"] += 1
b.sent_event.clear()
print "Sending %i" % b.seq
self._sm.outgoing(self, b)
toack.append(b.seq)
t = time.time()
if last_block:
last_block.sent_event.wait()
self.update_xmt(last_block)
self.stats["sent_wire"] += len(last_block.data)
last_block = b
self.send_reqack(toack)
self.waiting_for_ack = toack
print "Waiting for block to be sent"
last_block.sent_event.wait()
self._xme = time.time()
self.update_xmt(last_block)
self.stats["sent_wire"] += len(last_block.data)
self.ts = time.time()
print "Block sent after: %f" % (self.ts - t)
def send_ack(self, blocks):
f = DDT2EncodedFrame()
f.seq = 0
f.type = T_ACK
f.data = "".join([chr(x) for x in blocks])
print "Acking blocks %s (%s)" % (blocks,
{"" : f.data})
self._sm.outgoing(self, f)
def recv_blocks(self):
blocks = self.inq.dequeue_all()
blocks.reverse()
def next(i):
# FIXME: For 16 bit blocks
return (i + 1) % 256
def enqueue(_block):
self.data_waiting.acquire()
self.data.enqueue(_block.data)
self.iseq = _block.seq
self.data_waiting.notify()
self.data_waiting.release()
for b in blocks:
self._rtt_measure["size"] += len(b.get_packed())
if b.type == T_ACK:
self.__attempts = 0
self._rtt_measure["end"] = time.time()
self.waiting_for_ack = False
acked = [ord(x) for x in b.data]
print "Acked blocks: %s (/%i)" % (acked, len(self.outstanding))
for block in self.outstanding[:]:
self._rtt_measure["size"] += block._xmit_z
if block.seq in acked:
block.ackd_event.set()
self.stats["sent_size"] += len(block.data)
self.outstanding.remove(block)
else:
print "Block %i outstanding, but not acked" % block.seq
if len(self.outstanding) == 0:
print "This ACKed every block"
if self.__full_acks >= 0:
self.__full_acks += 1
else:
self.__full_acks = 0
else:
print "This was not a full ACK"
if self.__full_acks > 0:
self.__full_acks = 0
else:
self.__full_acks -= 1
elif b.type == T_DAT:
print "Got block %i" % b.seq
# FIXME: For 16-bit blocks
if b.seq == 0 and self.iseq == 255:
# Reset received list, because remote will only send
# a block 0 following a block 255 if it has received
# our ack of the previous 0-255
self.recv_list = []
if b.seq not in self.recv_list:
self.recv_list.append(b.seq)
self.stats["recv_size"] += len(b.data)
self.oob_queue[b.seq] = b
elif b.type == T_REQACK:
toack = []
# FIXME: This needs to support 16-bit block numbers!
for i in [ord(x) for x in b.data]:
if i in self.recv_list:
print "Acking block %i" % i
toack.append(i)
else:
print "Naking block %i" % i
self.send_ack(toack)
else:
print "Got unknown type: %i" % b.type
if self.oob_queue:
print "Waiting OOO blocks: %s" % self.oob_queue.keys()
# Process any OOO blocks, if we should
while next(self.iseq) in self.oob_queue.keys():
block = self.oob_queue[next(self.iseq)]
print "Queuing now in-order block %i: %s" % (next(self.iseq),
block)
del self.oob_queue[next(self.iseq)]
enqueue(block)
def update_xmt(self, block):
self._xmt = (self._xmt + block.get_xmit_bps()) / 2.0
print "Average transmit rate: %i bps" % self._xmt
def calculate_rtt(self):
rtt = self._rtt_measure["end"] - self._rtt_measure["start"]
size = self._rtt_measure["size"]
if size > 300:
# Only calculate the rate if we had a reasonable amount of data
# queued. We can't reliably measure small quantities, so we either
# keep the last-known rate or leave it zero so that is_timeout()
# will use a worst-case estimation
self._rtr = size / rtt
print "## Calculated rate for session %i: %.1f bps" % (self._id,
self._rtr)
print "## %i bytes in %.1f sec" % (size,
self._rtt_measure["end"] - \
self._rtt_measure["start"])
self._rtt_measure["start"] = self._rtt_measure["end"] = 0
self._rtt_measure["size"] = 0
self._rtt_measure["bnum"] = -1
def worker(self):
while self.enabled:
self.send_blocks()
self.recv_blocks()
if self._rtt_measure["end"]:
self.calculate_rtt()
if not self.outstanding and self.outq.peek():
print "Short-circuit"
continue # Short circuit because we have things to send
print "Session loop (%s:%s)" % (self._id, self.name)
if self.outstanding:
print "Outstanding data, short sleep"
self.event.wait(1)
else:
print "Deep sleep"
self.event.wait(self.IDLE_TIMEOUT)
if not self.event.isSet():
print "Session timed out!"
self.set_state(base.ST_CLSD)
self.enabled = False
else:
print "Awoke from deep sleep to some data"
self.event.clear()
def _block_read_for(self, count):
waiting = self.data.peek_all()
if not count and not waiting:
self.data_waiting.wait(1)
return
if count > len("".join(waiting)):
self.data_waiting.wait(1)
return
def _read(self, count):
self.data_waiting.acquire()
self._block_read_for(count)
if count == None:
b = self.data.dequeue_all()
# BlockQueue.dequeue_all() returns the blocks in poppable order,
# which is newest first
b.reverse()
buf = "".join(b)
else:
buf = ""
i = 0
while True:
next = self.data.peek() or ''
if len(next) > 0 and (len(next) + i) < count:
buf += self.data.dequeue()
else:
break
self.data_waiting.release()
return buf
def read(self, count=None):
while self.get_state() == base.ST_SYNC:
print "Waiting for session to open"
self.wait_for_state_change(5)
if self.get_state() != base.ST_OPEN:
raise base.SessionClosedError("State is %i" % self.get_state())
buf = self._read(count)
if not buf and self.get_state() != base.ST_OPEN:
raise base.SessionClosedError()
return buf
def write(self, buf, timeout=0):
while self.get_state() == base.ST_SYNC:
print "Waiting for session to open"
self.wait_for_state_change(5)
if self.get_state() != base.ST_OPEN:
raise base.SessionClosedError("State is %s" % self.get_state())
blocks = []
while buf:
chunk = buf[:self.bsize]
buf = buf[self.bsize:]
f = DDT2EncodedFrame()
f.seq = self.oseq
f.type = T_DAT
f.data = chunk
f.sent_event.clear()
self.outq.enqueue(f)
blocks.append(f)
self.oseq = (self.oseq + 1) % 256
self.queue_next()
self.event.set()
while timeout is not None and \
blocks and \
self.get_state() != base.ST_CLSD:
block = blocks[0]
del blocks[0]
print "Waiting for block %i to be ack'd" % block.seq
block.sent_event.wait()
if block.sent_event.isSet():
print "Block %i is sent, waiting for ack" % block.seq
block.ackd_event.wait(timeout)
if block.ackd_event.isSet() and block.sent_event.isSet():
print "%i ACKED" % block.seq
else:
print "%i Not ACKED (probably canceled)" % block.seq
break
else:
print "Block %i not sent?" % block.seq
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