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author | Florent Le Coz <louiz@louiz.org> | 2011-11-09 01:23:35 +0100 |
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committer | Florent Le Coz <louiz@louiz.org> | 2011-11-09 01:23:35 +0100 |
commit | ad0b3b41ecc0003f3d5b4fdb9799b6e325127e1f (patch) | |
tree | 3f2bbf1be7f753f1c7495f0a60833f469e7f10a7 /src/fifo.py | |
parent | 7fadb35fe2e7932a0a4aa6a8184ab6b186669edc (diff) | |
parent | 03999f1ef08036b7ea25e2239cf7b6bcdb4d76cc (diff) | |
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Merge branch 'plugins'
Conflicts:
README
src/core.py
src/tabs.py
Diffstat (limited to 'src/fifo.py')
-rw-r--r-- | src/fifo.py | 70 |
1 files changed, 70 insertions, 0 deletions
diff --git a/src/fifo.py b/src/fifo.py new file mode 100644 index 00000000..8306e24b --- /dev/null +++ b/src/fifo.py @@ -0,0 +1,70 @@ +# 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').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) + + 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 |