cic-internal-integration/apps/cic-eth/cic_eth/db/models/nonce.py

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2021-02-01 18:12:51 +01:00
# standard imports
import logging
# third-party imports
from sqlalchemy import Column, String, Integer
# local imports
from .base import SessionBase
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):
localsession = session
if localsession == None:
localsession = SessionBase.create_session()
q = localsession.query(Nonce)
q = q.filter(Nonce.address_hex==address)
nonce = q.first()
nonce_value = None
if nonce != None:
nonce_value = nonce.nonce;
if session == None:
localsession.close()
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 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
"""
conn = Nonce.engine.connect()
if Nonce.transactional:
conn.execute('BEGIN')
conn.execute('LOCK TABLE nonce IN SHARE ROW EXCLUSIVE MODE')
nonce = Nonce.__get(conn, address)
logg.debug('get nonce {} for address {}'.format(nonce, address))
if nonce == None:
nonce = initial_if_not_exists
conn.execute("INSERT INTO nonce (nonce, address_hex) VALUES ({}, '{}')".format(nonce, address))
logg.debug('setting default nonce to {} for address {}'.format(nonce, address))
Nonce.__set(conn, address, nonce+1)
if Nonce.transactional:
conn.execute('COMMIT')
conn.close()
return nonce