get-poetry-errback.py

# This is the Twisted Get Poetry Now! client, version 2.1.

# NOTE: This should not be used as the basis for production code.

import optparse,sys

from twisted.internet.protocol import Protocol, ClientFactory
from twisted.internet import reactor
from twisted.python.failure import Failure

def parse_args():
    usage = """usage: %prog [options] [hostname]:port ...

This is the Get Poetry Now! client, Twisted version 2.1.
Run it like this:

  python get-poetry-simple.py port1 port2 port3 ...

If you are in the base directory of the twisted-intro package,
you could run it like this:

  python twisted-client-2/get-poetry-simple.py 10001 10002 10003

to grab poetry from servers on ports 10001, 10002, and 10003.

Of course, there need to be servers listening on those ports
for that to work.
"""

    parser = optparse.OptionParser(usage)

    _, addresses = parser.parse_args()

    if not addresses:
        print(parser.format_help())
        parser.exit()

    def parse_address(addr):
        if ':' not in addr:
            host = '127.0.0.1'
            port = addr
        else:
            host, port = addr.split(':', 1)

        if not port.isdigit():
            parser.error('Ports must be integers.')

        return host, int(port)

    return map(parse_address, addresses)



class PoetryProtocol(Protocol):

    poem = ''
    timeout = None
    
    def dataReceived(self, data):
        self.poem += data.decode('utf-8')
        
    def connectionLost(self, reason):
        if self.delayedTimeout.active():
            self.delayedTimeout.cancel()
            self.poemReceived(self.poem)
        
    def poemReceived(self, poem):
        self.factory.poem_finished(poem)
    
    def connectionMade(self):
        self.delayedTimeout = reactor.callLater(1,self.timeouthandler,Failure(TimeoutException(),TimeoutException))

    def timeouthandler(self,failure):
        self.factory.errback(failure)
        self.transport.loseConnection()
        
class TimeoutException(Exception):
    def __init__(self):
        self.message = "timeout exception"
    def __str__(self):
        return repr(self.message)

class PoetryClientFactory(ClientFactory):

    protocol = PoetryProtocol # tell base class what proto to build

    def __init__(self, callback,errback,timeout):
        self.callback = callback
        self.errback = errback
        self.timeout = timeout

    def buildProtocol(self, addr):
        proto = ClientFactory.buildProtocol(self,addr)
        proto.timeout = self.timeout
        return proto
    def poem_finished(self, poem=None):
        self.callback(poem)

    def clientConnectionFailed(self, connector, reason):
        '''
        reason : A Failure object records Exception and possibly trackback
        '''
        self.errback(reason)
        print("invoke after get_poetry")

def get_poetry(host,port,callback,errback,timeout):
    from twisted.internet import reactor
    factory = PoetryClientFactory(callback,errback,timeout)
    reactor.connectTCP(host,port,factory)

def poetry_main():
    addresses = list(parse_args())

    from twisted.internet import reactor

    poems = []
    errs = []

    def get_poem(poem):
        poems.append(poem)
        poem_done()

    def poem_failed(err):
        from twisted.internet.error import ConnectionRefusedError
        r = err.trap(ConnectionRefusedError, TimeoutException)
        if r == TimeoutException:
            print('Timeout Now')
        else:
            print("Connection Problem")
        errs.append(err)
        print("Poem Failed:",err, file=sys.stderr)
        poem_done()

    def poem_done():
        if len(poems) + len(errs) == len(addresses):
            reactor.stop()
    
    for addr in addresses:
        host,port = addr
        get_poetry(host, port, get_poem,poem_failed, 2)
        print("exercise 3")
      
    reactor.run()

    for poem in poems:
        print(poem)


if __name__ == '__main__':
    poetry_main()