_logs.py 文件源码

def _open_log_file():
    """Open a Porcupine log file.

    Usually this opens and overwrites log.txt. If another Porcupine
    process has it currently opened, this opens log1.txt instead, then
    log2.txt and so on.
    """
    # create an iterator 'log.txt', 'log2.txt', 'log3.txt', ...
    filenames = itertools.chain(
        ['log.txt'],
        map('log{}.txt'.format, itertools.count(start=2)),
    )

    for filename in filenames:
        path = os.path.join(dirs.cachedir, filename)
        # unfortunately there's not a mode that would open in write but
        # not truncate like 'w' or seek to end like 'a'
        fileno = os.open(path, os.O_WRONLY | os.O_CREAT, 0o644)

        if _lock(fileno):
            # now we can delete the old content, can't use os.truncate
            # here because it doesn't exist on windows
            file = open(fileno, 'w')
            file.truncate(0)
            return file
        else:
            os.close(fileno)


# FileHandler doesn't take already opened files and StreamHandler
# doesn't close the file :(