70 lines
1.9 KiB
Python
70 lines
1.9 KiB
Python
# Copyright 2011 Florent Le Coz <louiz@louiz.org>
|
||
#
|
||
# This file is part of Poezio.
|
||
#
|
||
# Poezio is free software: you can redistribute it and/or modify
|
||
# it under the terms of the zlib license. See the COPYING file.
|
||
|
||
"""
|
||
Defines the Fifo class
|
||
"""
|
||
|
||
import logging
|
||
log = logging.getLogger(__name__)
|
||
|
||
import os
|
||
import threading
|
||
|
||
class OpenTrick(threading.Thread):
|
||
"""
|
||
A threaded trick to make the open for writing succeed.
|
||
A fifo cannot be opened for writing if it has not been
|
||
yet opened by the other hand for reading.
|
||
So, we just open the fifo for reading and close it
|
||
immediately afterwards.
|
||
Once that is done, we can freely keep the fifo open for
|
||
writing and write things in it. The writing can fail if
|
||
there’s still nothing reading that fifo, but we just yell
|
||
an error in that case.
|
||
"""
|
||
def __init__(self, path):
|
||
threading.Thread.__init__(self)
|
||
self.path = path
|
||
|
||
def run(self):
|
||
open(self.path, 'r', encoding='utf-8').close()
|
||
|
||
|
||
class Fifo(object):
|
||
"""
|
||
Just a simple file handler, writing and reading in a fifo.
|
||
Mode is either 'r' or 'w', just like the mode for the open()
|
||
function.
|
||
"""
|
||
def __init__(self, path, mode):
|
||
self.trick = None
|
||
if not os.path.exists(path):
|
||
os.mkfifo(path)
|
||
if mode == 'w':
|
||
self.trick = OpenTrick(path)
|
||
# that thread will wait until we open it for writing
|
||
self.trick.start()
|
||
self.fd = open(path, mode, encoding='utf-8')
|
||
|
||
def write(self, data):
|
||
"""
|
||
Try to write on the fifo. If that fails, this means
|
||
that nothing has that fifo opened, so the writing is useless,
|
||
so we just return (and display an error telling that, somewhere).
|
||
"""
|
||
self.fd.write(data)
|
||
self.fd.flush()
|
||
|
||
def readline(self):
|
||
return self.fd.readline()
|
||
|
||
def __del__(self):
|
||
try:
|
||
self.fd.close()
|
||
except:
|
||
pass
|