method: path.local.make_numbered_dir

 return unique directory with a number greater than the current
            maximum one.  The number is assumed to start directly after prefix.
            if keep is true directories with a number less than (maxnum-keep)
            will be removed.
        
    def make_numbered_dir(cls, prefix='session-', rootdir=None, keep=3,

origin: type

where:

exceptions that might appear during execution:

function source:

def make_numbered_dir(cls, prefix='session-', rootdir=None, keep=3,
                      lock_timeout = 172800):   # two days
    """ return unique directory with a number greater than the current
            maximum one.  The number is assumed to start directly after prefix.
            if keep is true directories with a number less than (maxnum-keep)
            will be removed.
        """
    if rootdir is None:
        rootdir = cls.get_temproot()

    def parse_num(path):
        """ parse the number out of a path (if it matches the prefix) """
        bn = path.basename
        if bn.startswith(prefix):
            try:
                return int(bn[len(prefix):])
            except ValueError:
                pass

    # compute the maximum number currently in use with the
    # prefix
    lastmax = None
    while True:
        maxnum = -1
        for path in rootdir.listdir():
            num = parse_num(path)
            if num is not None:
                maxnum = max(maxnum, num)

        # make the new directory
        try:
            udir = rootdir.mkdir(prefix + str(maxnum+1))
        except py.error.EEXIST:
            # race condition: another thread/process created the dir
            # in the meantime.  Try counting again
            if lastmax == maxnum:
                raise
            lastmax = maxnum
            continue
        break

    # put a .lock file in the new directory that will be removed at
    # process exit
    lockfile = udir.join('.lock')
    if hasattr(lockfile, 'mksymlinkto'):
        lockfile.mksymlinkto(str(os.getpid()))
    else:
        lockfile.write(str(os.getpid()))
    def try_remove_lockfile():
        try:
            lockfile.remove()
        except py.error.Error:
            pass
    atexit.register(try_remove_lockfile)

    # prune old directories
    if keep:
        for path in rootdir.listdir():
            num = parse_num(path)
            if num is not None and num <= (maxnum - keep):
                lf = path.join('.lock')
                try:
                    t1 = lf.lstat().mtime
                    t2 = lockfile.lstat().mtime
                    if abs(t2-t1) < lock_timeout:
                        continue   # skip directories still locked
                except py.error.Error:
                    pass   # assume that it means that there is no 'lf'
                try:
                    path.remove(rec=1)
                except py.error.Error:
                    pass
        
    # make link...
    try:
        username = os.environ['USER']           #linux, et al
    except KeyError:
        try:
            username = os.environ['USERNAME']   #windows
        except KeyError:
            username = 'current'

    src  = str(udir)
    dest = src[:src.rfind('-')] + '-' + username
    try:
        os.unlink(dest)
    except OSError:
        pass
    try:
        os.symlink(src, dest)
    except (OSError, AttributeError): # AttributeError on win32
        pass

    return udir

call sites:

called in /home/johnny/projects/merlinux/py/dist/py/test/config.py

traceback path.local.make_numbered_dir.0

called in /home/johnny/projects/merlinux/py/dist/py/path/local/testing/test_local.py

traceback path.local.make_numbered_dir.1

called in /home/johnny/projects/merlinux/py/dist/py/path/local/testing/test_local.py

traceback path.local.make_numbered_dir.2

called in /home/johnny/projects/merlinux/pypy-dist/pypy/tool/udir.py

traceback path.local.make_numbered_dir.3