def __init__(self, name=None, buffer=1):
if name == None:
# Create unique name
name = str(random.random())+str(time.time())
self.name = name
self.__inChan = Channel(name=name+'inChan')
self.__outChan = Channel(name=name+'outChan')
self.__bufferProcess = self.Buffer(self.__inChan.reader(),
self.__outChan.writer(),
N=buffer)
# Retrieve channel ends
self.reader = self.__outChan.reader
self.writer = self.__inChan.writer
# Set buffer process as deamon to allow kill if mother process
# exists.
self.__bufferProcess.daemon = True
# Start buffer process
Spawn(self.__bufferProcess)
class BufferedChannel:
""" Channel class.
Blocking or buffered communication.
>>> from pycsp import *
>>> @process
... def P1(cout):
... while True:
... cout('Hello World')
>>> C = Channel()
>>> Spawn(P1(OUT(C)))
>>> cin = IN(C)
>>> cin()
'Hello World'
>>> retire(cin)
Buffered channels are semantically equivalent with a chain
of forwarding processes.
>>> B = Channel(buffer=5)
>>> cout = OUT(B)
>>> for i in range(5):
... cout(i)
Poison and retire are attached to final element of the buffer.
>>> poison(cout)
>>> @process
... def sink(cin, L):
... while True:
... L.append(cin())
>>> L = []
>>> Parallel(sink(IN(B), L))
>>> L
[0, 1, 2, 3, 4]
"""
def __init__(self, name=None, buffer=1):
if name == None:
# Create unique name
name = str(random.random())+str(time.time())
self.name = name
self.__inChan = Channel(name=name+'inChan')
self.__outChan = Channel(name=name+'outChan')
self.__bufferProcess = self.Buffer(self.__inChan.reader(),
self.__outChan.writer(),
N=buffer)
# Retrieve channel ends
self.reader = self.__outChan.reader
self.writer = self.__inChan.writer
# Set buffer process as deamon to allow kill if mother process
# exists.
self.__bufferProcess.daemon = True
# Start buffer process
Spawn(self.__bufferProcess)
def __pos__(self):
return self.reader()
def __neg__(self):
return self.writer()
def poison(self):
self.__inChan.poison()
self.__outChan.poison()
@process
def Buffer(self, cin, cout, N):
queue = deque()
poisoned = False
retired = False
while True:
try:
import pycsp.current
if pycsp.current.trace:
TraceMsg(len(queue))
# Handling poison / retire
if (poisoned or retired):
if len(queue):
try:
cout(queue.popleft())
except:
if poisoned:
poison(cin, cout)
if retired:
retire(cin, cout)
else:
try:
if poisoned:
poison(cin, cout)
if retired:
retire(cin, cout)
except:
pass
return # quit
# Queue empty
elif not len(queue):
queue.append(cin())
# Queue not full and not empty
elif len(queue) < N:
g, msg = Alternation([
(cout, queue[0], None),
(cin, None)
]).select()
if g == cin:
queue.append(msg)
else:
queue.popleft()
# Queue full
else:
cout(queue.popleft())
except ChannelPoisonException, e:
poisoned = True
except ChannelRetireException, e:
retired = True
