cic-stack/apps/cic-eth/cic_eth/db/models/nonce.py
2021-03-06 17:55:51 +00:00

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# standard imports
import logging
import datetime
# third-party imports
from sqlalchemy import Column, String, Integer, DateTime
# local imports
from .base import SessionBase
from cic_eth.error import (
InitializationError,
IntegrityError,
)
logg = logging.getLogger()
class Nonce(SessionBase):
"""Provides thread-safe nonce increments.
"""
__tablename__ = 'nonce'
nonce = Column(Integer)
address_hex = Column(String(42))
@staticmethod
def get(address, session=None):
session = SessionBase.bind_session(session)
q = session.query(Nonce)
q = q.filter(Nonce.address_hex==address)
nonce = q.first()
nonce_value = None
if nonce != None:
nonce_value = nonce.nonce;
SessionBase.release_session(session)
return nonce_value
@staticmethod
def __get(conn, address):
r = conn.execute("SELECT nonce FROM nonce WHERE address_hex = '{}'".format(address))
nonce = r.fetchone()
if nonce == None:
return None
return nonce[0]
@staticmethod
def __set(conn, address, nonce):
conn.execute("UPDATE nonce set nonce = {} WHERE address_hex = '{}'".format(nonce, address))
@staticmethod
def __init(conn, address, nonce):
conn.execute("INSERT INTO nonce (nonce, address_hex) VALUES ({}, '{}')".format(nonce, address))
@staticmethod
def init(address, nonce=0, session=None):
session = SessionBase.bind_session(session)
q = session.query(Nonce)
q = q.filter(Nonce.address_hex==address)
o = q.first()
if o != None:
session.flush()
raise InitializationError('nonce on {} already exists ({})'.format(address, o.nonce))
session.flush()
Nonce.__init(session, address, nonce)
SessionBase.release_session(session)
# TODO: Incrementing nonce MUST be done by separate tasks.
@staticmethod
def next(address, initial_if_not_exists=0):
"""Generate next nonce for the given address.
If there is no previous nonce record for the address, the nonce may be initialized to a specified value, or 0 if no value has been given.
:param address: Associate Ethereum address
:type address: str, 0x-hex
:param initial_if_not_exists: Initial nonce value to set if no record exists
:type initial_if_not_exists: number
:returns: Nonce
:rtype: number
"""
#session = SessionBase.bind_session(session)
#session.begin_nested()
conn = Nonce.engine.connect()
if Nonce.transactional:
conn.execute('BEGIN')
conn.execute('LOCK TABLE nonce IN SHARE ROW EXCLUSIVE MODE')
logg.debug('locking nonce table for address {}'.format(address))
nonce = Nonce.__get(conn, address)
logg.debug('get nonce {} for address {}'.format(nonce, address))
if nonce == None:
nonce = initial_if_not_exists
logg.debug('setting default nonce to {} for address {}'.format(nonce, address))
Nonce.__init(conn, address, nonce)
Nonce.__set(conn, address, nonce+1)
if Nonce.transactional:
conn.execute('COMMIT')
logg.debug('unlocking nonce table for address {}'.format(address))
conn.close()
#session.commit()
#SessionBase.release_session(session)
return nonce
class NonceReservation(SessionBase):
__tablename__ = 'nonce_task_reservation'
nonce = Column(Integer)
key = Column(String)
date_created = Column(DateTime, default=datetime.datetime.utcnow)
@staticmethod
def peek(key, session=None):
session = SessionBase.bind_session(session)
q = session.query(NonceReservation)
q = q.filter(NonceReservation.key==key)
o = q.first()
nonce = None
if o != None:
nonce = o.nonce
session.flush()
SessionBase.release_session(session)
return nonce
@staticmethod
def release(key, session=None):
session = SessionBase.bind_session(session)
nonce = NonceReservation.peek(key, session=session)
q = session.query(NonceReservation)
q = q.filter(NonceReservation.key==key)
o = q.first()
if o == None:
raise IntegrityError('nonce for key {}'.format(nonce))
SessionBase.release_session(session)
session.delete(o)
session.flush()
SessionBase.release_session(session)
return nonce
@staticmethod
def next(address, key, session=None):
session = SessionBase.bind_session(session)
if NonceReservation.peek(key, session) != None:
raise IntegrityError('nonce for key {}'.format(key))
nonce = Nonce.next(address)
o = NonceReservation()
o.nonce = nonce
o.key = key
session.add(o)
SessionBase.release_session(session)
return nonce