Synnefo

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from synnefo.lib.db.xctx import TransactionHandler

from time import sleep

class RetryException(Exception):

    pass

class RetryTransactionHandler(TransactionHandler):

    def __init__(self, retries=3, retry_wait=1.0, on_fail=None, **kwargs):

        self.retries    = retries

        self.retry_wait = retry_wait

        self.on_fail    = on_fail

        TransactionHandler.__init__(self, **kwargs)

    def __call__(self, func):

        def wrap(*args, **kwargs):

            while True:

                try:

                    f = TransactionHandler.__call__(self, func)

                    return f(*args, **kwargs)

                except RetryException:

                    self.retries -= 1

                    if self.retries <= 0:

                        f = self.on_fail

                        if not callable(f):

                            raise

                        return f(*args, **kwargs)

                    sleep(self.retry_wait)

        return wrap