87 lines
2.4 KiB
Python
87 lines
2.4 KiB
Python
# standard imports
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import logging
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# third-party imports
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from sqlalchemy import Column, String, Integer
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# local imports
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from .base import SessionBase
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logg = logging.getLogger()
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class Nonce(SessionBase):
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"""Provides thread-safe nonce increments.
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"""
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__tablename__ = 'nonce'
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nonce = Column(Integer)
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address_hex = Column(String(42))
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@staticmethod
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def get(address, session=None):
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localsession = session
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if localsession == None:
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localsession = SessionBase.create_session()
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q = localsession.query(Nonce)
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q = q.filter(Nonce.address_hex==address)
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nonce = q.first()
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nonce_value = None
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if nonce != None:
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nonce_value = nonce.nonce;
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if session == None:
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localsession.close()
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return nonce_value
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@staticmethod
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def __get(conn, address):
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r = conn.execute("SELECT nonce FROM nonce WHERE address_hex = '{}'".format(address))
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nonce = r.fetchone()
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if nonce == None:
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return None
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return nonce[0]
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@staticmethod
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def __set(conn, address, nonce):
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conn.execute("UPDATE nonce set nonce = {} WHERE address_hex = '{}'".format(nonce, address))
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@staticmethod
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def next(address, initial_if_not_exists=0):
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"""Generate next nonce for the given address.
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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.
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:param address: Associate Ethereum address
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:type address: str, 0x-hex
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:param initial_if_not_exists: Initial nonce value to set if no record exists
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:type initial_if_not_exists: number
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:returns: Nonce
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:rtype: number
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"""
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conn = Nonce.engine.connect()
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if Nonce.transactional:
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conn.execute('BEGIN')
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conn.execute('LOCK TABLE nonce IN SHARE ROW EXCLUSIVE MODE')
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nonce = Nonce.__get(conn, address)
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logg.debug('get nonce {} for address {}'.format(nonce, address))
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if nonce == None:
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nonce = initial_if_not_exists
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conn.execute("INSERT INTO nonce (nonce, address_hex) VALUES ({}, '{}')".format(nonce, address))
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logg.debug('setting default nonce to {} for address {}'.format(nonce, address))
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Nonce.__set(conn, address, nonce+1)
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if Nonce.transactional:
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conn.execute('COMMIT')
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conn.close()
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return nonce
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