def poll_all_received_events(self):
        """ This will be triggered once for each `echo_node_alarm_callback`.
        It polls all channels for `EventPaymentReceivedSuccess` events,
        adds all new events to the `self.received_transfers` queue and
        respawns `self.echo_node_worker`, if it died. """

        locked = False
        try:
            with Timeout(10):
                locked = self.lock.acquire(blocking=False)
                if not locked:
                    return
                else:
                    received_transfers = self.api.get_raiden_events_payment_history(
                        token_address=self.token_address,
                        offset=self.last_poll_offset,
                    )

                    # received transfer is a tuple of (block_number, event)
                    received_transfers = [
                        event
                        for event in received_transfers
                        if type(event) == EventPaymentReceivedSuccess
                    ]

                    for event in received_transfers:
                        transfer = copy.deepcopy(event)
                        self.received_transfers.put(transfer)

                    # set last_poll_block after events are enqueued (timeout safe)
                    if received_transfers:
                        self.last_poll_offset += len(received_transfers)

                    if not self.echo_worker_greenlet.started:
                        log.debug(
                            'restarting echo_worker_greenlet',
                            dead=self.echo_worker_greenlet.dead,
                            successful=self.echo_worker_greenlet.successful(),
                            exception=self.echo_worker_greenlet.exception,
                        )
                        self.echo_worker_greenlet = gevent.spawn(self.echo_worker)
        except Timeout:
            log.info('timeout while polling for events')
        finally:
            if locked:
                self.lock.release()
This will be triggered once for each `echo_node_alarm_callback`.
        It polls all channels for `EventPaymentReceivedSuccess` events,
        adds all new events to the `self.received_transfers` queue and
        respawns `self.echo_node_worker`, if it died.