chainsyncer/cic_syncer/backend.py

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2021-02-03 20:55:39 +01:00
# standard imports
import logging
# local imports
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from cic_syncer.db.models.sync import BlockchainSync
from cic_syncer.db.models.base import SessionBase
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logg = logging.getLogger()
class SyncerBackend:
"""Interface to block and transaction sync state.
:param chain_spec: Chain spec for the chain that syncer is running for.
:type chain_spec: cic_registry.chain.ChainSpec
:param object_id: Unique id for the syncer session.
:type object_id: number
"""
def __init__(self, chain_spec, object_id):
self.db_session = None
self.db_object = None
self.chain_spec = chain_spec
self.object_id = object_id
self.connect()
self.disconnect()
def connect(self):
"""Loads the state of the syncer session with the given id.
"""
self.db_session = SessionBase.create_session()
q = self.db_session.query(BlockchainSync)
q = q.filter(BlockchainSync.id==self.object_id)
self.db_object = q.first()
if self.db_object == None:
raise ValueError('sync entry with id {} not found'.format(self.object_id))
def disconnect(self):
"""Commits state of sync to backend.
"""
self.db_session.add(self.db_object)
self.db_session.commit()
self.db_session.close()
def chain(self):
"""Returns chain spec for syncer
:returns: Chain spec
:rtype chain_spec: cic_registry.chain.ChainSpec
"""
return self.chain_spec
def get(self):
"""Get the current state of the syncer cursor.
:returns: Block and block transaction height, respectively
:rtype: tuple
"""
self.connect()
pair = self.db_object.cursor()
self.disconnect()
return pair
def set(self, block_height, tx_height):
"""Update the state of the syncer cursor
:param block_height: Block height of cursor
:type block_height: number
:param tx_height: Block transaction height of cursor
:type tx_height: number
:returns: Block and block transaction height, respectively
:rtype: tuple
"""
self.connect()
pair = self.db_object.set(block_height, tx_height)
self.disconnect()
return pair
def start(self):
"""Get the initial state of the syncer cursor.
:returns: Initial block and block transaction height, respectively
:rtype: tuple
"""
self.connect()
pair = self.db_object.start()
self.disconnect()
return pair
def target(self):
"""Get the target state (upper bound of sync) of the syncer cursor.
:returns: Target block height
:rtype: number
"""
self.connect()
target = self.db_object.target()
self.disconnect()
return target
@staticmethod
def first(chain):
"""Returns the model object of the most recent syncer in backend.
:param chain: Chain spec of chain that syncer is running for.
:type chain: cic_registry.chain.ChainSpec
:returns: Last syncer object
:rtype: cic_eth.db.models.BlockchainSync
"""
return BlockchainSync.first(chain)
@staticmethod
def initial(chain, block_height):
"""Creates a new syncer session and commit its initial state to backend.
:param chain: Chain spec of chain that syncer is running for.
:type chain: cic_registry.chain.ChainSpec
:param block_height: Target block height
:type block_height: number
:returns: New syncer object
:rtype: cic_eth.db.models.BlockchainSync
"""
object_id = None
session = SessionBase.create_session()
o = BlockchainSync(chain, 0, 0, block_height)
session.add(o)
session.commit()
object_id = o.id
session.close()
return SyncerBackend(chain, object_id)
@staticmethod
def resume(chain, block_height):
"""Retrieves and returns all previously unfinished syncer sessions.
:param chain: Chain spec of chain that syncer is running for.
:type chain: cic_registry.chain.ChainSpec
:param block_height: Target block height
:type block_height: number
:returns: Syncer objects of unfinished syncs
:rtype: list of cic_eth.db.models.BlockchainSync
"""
syncers = []
session = SessionBase.create_session()
object_id = None
for object_id in BlockchainSync.get_unsynced(session=session):
logg.debug('block syncer resume added previously unsynced sync entry id {}'.format(object_id))
syncers.append(SyncerBackend(chain, object_id))
(block_resume, tx_resume) = BlockchainSync.get_last_live_height(block_height, session=session)
if block_height != block_resume:
o = BlockchainSync(chain, block_resume, tx_resume, block_height)
session.add(o)
session.commit()
object_id = o.id
syncers.append(SyncerBackend(chain, object_id))
logg.debug('block syncer resume added new sync entry from previous run id {}, start{}:{} target {}'.format(object_id, block_resume, tx_resume, block_height))
session.close()
return syncers
@staticmethod
def live(chain, block_height):
"""Creates a new open-ended syncer session starting at the given block height.
:param chain: Chain spec of chain that syncer is running for.
:type chain: cic_registry.chain.ChainSpec
:param block_height: Target block height
:type block_height: number
:returns: "Live" syncer object
:rtype: cic_eth.db.models.BlockchainSync
"""
object_id = None
session = SessionBase.create_session()
o = BlockchainSync(chain, block_height, 0, None)
session.add(o)
session.commit()
object_id = o.id
session.close()
return SyncerBackend(chain, object_id)