Source

arigo / hack / stm / transactionmodule / transaction.py

import random


class TransactionError(Exception):
    pass


_running = False
_pending = {}

def add(callback, *args, **kwds):
    while True:
        prio = random.random()
        if prio not in _pending:
            break
    _pending[prio] = (callback, args, kwds)

def run():
    global _running
    if _running:
        raise TransactionError("recursive invocation of transaction.run()")
    _running = True
    try:
        while _pending:
            prio, (callback, args, kwds) = _pending.popitem()
            callback(*args, **kwds)      # exceptions propagate
    finally:
        _running = False