Files
python-teos/pisa/watcher.py
Sergi Delgado Segura 1e18630ce2 Adds Cleaner tests. Fixes Cleaner, Watcher and Responder
There is no need to return the dictionaries modified by the client since they are "passed-by-reference" in Python.
2019-10-04 17:23:45 +01:00

121 lines
5.2 KiB
Python

from uuid import uuid4
from queue import Queue
from threading import Thread
from pisa import logging
from pisa.cleaner import Cleaner
from pisa.conf import EXPIRY_DELTA
from pisa.responder import Responder
from pisa.conf import MAX_APPOINTMENTS
from pisa.block_processor import BlockProcessor
from pisa.utils.zmq_subscriber import ZMQHandler
# WIP: MOVED BLOCKCHAIN RELATED TASKS TO BLOCK PROCESSOR IN AN AIM TO MAKE THE CODE MORE MODULAR. THIS SHOULD HELP
# WITH CODE REUSE WHEN MERGING THE DATA PERSISTENCE PART.
class Watcher:
def __init__(self, max_appointments=MAX_APPOINTMENTS):
self.appointments = dict()
self.locator_uuid_map = dict()
self.block_queue = None
self.asleep = True
self.max_appointments = max_appointments
self.zmq_subscriber = None
self.responder = Responder()
def add_appointment(self, appointment):
# Rationale:
# The Watcher will analyze every received block looking for appointment matches. If there is no work
# to do the watcher can go sleep (if appointments = {} then asleep = True) otherwise for every received block
# the watcher will get the list of transactions and compare it with the list of appointments.
# If the watcher is awake, every new appointment will just be added to the appointment list until
# max_appointments is reached.
if len(self.appointments) < self.max_appointments:
# Appointments are identified by the locator: the sha256 of commitment txid (H(tx_id)).
# Two different nodes may ask for appointments using the same commitment txid, what will result in a
# collision in our appointments structure (and may be an attack surface). In order to avoid such collisions
# we will identify every appointment with a uuid
uuid = uuid4().hex
self.appointments[uuid] = appointment
if appointment.locator in self.locator_uuid_map:
self.locator_uuid_map[appointment.locator].append(uuid)
else:
self.locator_uuid_map[appointment.locator] = [uuid]
if self.asleep:
self.asleep = False
self.block_queue = Queue()
zmq_thread = Thread(target=self.do_subscribe, args=[self.block_queue])
watcher = Thread(target=self.do_watch)
zmq_thread.start()
watcher.start()
logging.info("[Watcher] waking up!")
appointment_added = True
logging.info('[Watcher] new appointment accepted (locator = {})'.format(appointment.locator))
else:
appointment_added = False
logging.info('[Watcher] maximum appointments reached, appointment rejected (locator = {})'.format(
appointment.locator))
return appointment_added
def do_subscribe(self, block_queue):
self.zmq_subscriber = ZMQHandler(parent='Watcher')
self.zmq_subscriber.handle(block_queue)
def do_watch(self):
while len(self.appointments) > 0:
block_hash = self.block_queue.get()
logging.info("[Watcher] new block received {}".format(block_hash))
block = BlockProcessor.get_block(block_hash)
if block is not None:
txids = block.get('tx')
logging.info("[Watcher] list of transactions: {}".format(txids))
expired_appointments = [uuid for uuid, appointment in self.appointments.items()
if block["height"] > appointment.end_time + EXPIRY_DELTA]
Cleaner.delete_expired_appointment(expired_appointments, self.appointments, self.locator_uuid_map)
potential_matches = BlockProcessor.get_potential_matches(txids, self.locator_uuid_map)
matches = BlockProcessor.get_matches(potential_matches, self.locator_uuid_map, self.appointments)
for locator, uuid, dispute_txid, justice_txid, justice_rawtx in matches:
logging.info("[Watcher] notifying responder about {} and deleting appointment {} (uuid: {})"
.format(justice_txid, locator, uuid))
self.responder.add_response(uuid, dispute_txid, justice_txid, justice_rawtx,
self.appointments[uuid].end_time)
# Delete the appointment
self.appointments.pop(uuid)
# If there was only one appointment that matches the locator we can delete the whole list
if len(self.locator_uuid_map[locator]) == 1:
# ToDo: #9-add-data-persistence
self.locator_uuid_map.pop(locator)
else:
# Otherwise we just delete the appointment that matches locator:appointment_pos
# ToDo: #9-add-data-persistence
self.locator_uuid_map[locator].remove(uuid)
# Go back to sleep if there are no more appointments
self.asleep = True
self.zmq_subscriber.terminate = True
logging.error("[Watcher] no more pending appointments, going back to sleep")