The code is in attachment.
I run it on Debian/Linux, twisted 10.0.0
When you run it on a terminal, it works by prefixing the data you enter with
"dataReceived: "
and outputting that back to terminal.
$ ./program.py
i: blabla
o: dataReceived: 'blabla
o: '
i: ^D
o: readConnectionLost(input is done)
i: ^C
o: OK
$
The same happens if you redirect output to a pipe (no matter if it a named FIFO
or an anonymous pipe).
But if you redirect output to a file or to a /dev/null, this happens:
$ ./program.py > /dev/null
<a short pause, no input>
o: StdioProtocol.connectionLost('[Failure instance: Traceback (failure with no
frames): <class 'twisted.internet.error.ConnectionLost'>: Connection to the
other side was lost in a non-clean fashion.
o: ]')OK
$
But I expected it to work the same way, regardless of redirections.
I haven't traced the source of that Failure, so just asking, whether that
behavior is
known, or maybe intended?
Or, perhaps, I do something incorrectly?
Well, right now I'm using the workaround with /bin/cat:
$ ./program.py > >(cat > file)
or with an extra shell process:
$ ./program.py | cat > file
#!/usr/bin/python
from twisted.internet.stdio import StandardIO
from twisted.internet.interfaces import IHalfCloseableProtocol
from twisted.internet import protocol, reactor
from zope.interface import implements
import sys
class StdioProtocol(protocol.Protocol):
implements(IHalfCloseableProtocol)
def __init__(self):
pass
# IBaseProtocol
def connectionMade(self):
pass
# IProtocol
def dataReceived(self, data):
sys.stderr.write("dataReceived: '%s'\n" %(data))
def connectionLost(self, reason):
# some error happened to stdio, like exception in my code
from twisted.internet.error import ConnectionDone
if isinstance(reason.value, ConnectionDone):
sys.stderr.write("ConnectionDone (clean)\n")
else:
sys.stderr.write("StdioProtocol.connectionLost('%s')" % (reason))
reactor.callLater(0, reactor.stop)
# IHalfCloseableProtocol
def writeConnectionLost(self, reason=SystemExit("output pipe is broken")):
# no more writing is possible, pipe is broken, output is closed
# This is the end.
sys.stderr.write("writeConnectionLost(%s)" %(reason))
self.transport.loseConnection()
def readConnectionLost(self, reason=EOFError("input is done")):
# EOF on stdin, congratulations, no more tasks will arrive!
sys.stderr.write("\nreadConnectionLost(%s)\n\n" %(reason))
p = StdioProtocol()
t = StandardIO(p)
reactor.run()
sys.stderr.write("OK\n")
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