cic-stack/apps/cic-eth/cic_eth/sync/history.py

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# standard imports
import logging
# third-party imports
from web3.exceptions import BlockNotFound
from .error import LoopDone
# local imports
from .mined import MinedSyncer
from .base import Syncer
from cic_eth.db.models.base import SessionBase
logg = logging.getLogger()
class HistorySyncer(MinedSyncer):
"""Implements the get method in Syncer for retrieving all blocks between last processed block before previous shutdown and block height at time of syncer start.
:param bc_cache: Retrieves block cache cursors for chain head and latest processed block.
:type bc_cache: Object implementing methods from cic_eth.sync.SyncerBackend
:param mx: Maximum number of blocks to return in one call
:type mx: int
"""
def __init__(self, bc_cache, mx=20):
super(HistorySyncer, self).__init__(bc_cache)
self.max = mx
self.target = bc_cache.target()
logg.info('History syncer target block number {}'.format(self.target))
session_offset = self.bc_cache.get()
self.block_offset = session_offset[0]
self.tx_offset = session_offset[1]
logg.info('History syncer starting at {}:{}'.format(session_offset[0], session_offset[1]))
self.filter = []
"""Implements Syncer.get
BUG: Should also raise LoopDone when block array is empty after loop.
:param w3: Web3 object
:type w3: web3.Web3
:raises LoopDone: If a block is not found.
:return: Return a batch of blocks to process
:rtype: list of str, 0x-hex
"""
def get(self, w3):
sync_db = self.bc_cache
height = self.bc_cache.get()
logg.debug('height {}'.format(height))
block_last = height[0]
tx_last = height[1]
if not self.running:
raise LoopDone((block_last, tx_last))
b = []
block_target = block_last + self.max
if block_target > self.target:
block_target = self.target
logg.debug('target {} last {} max {}'.format(block_target, block_last, self.max))
for i in range(block_last, block_target):
if i == self.target:
logg.info('reached target {}, exiting'.format(i))
self.running = False
break
bhash = w3.eth.getBlock(i).hash
b.append(bhash)
logg.debug('appending block {} {}'.format(i, bhash.hex()))
if block_last == block_target:
logg.info('aleady reached target {}, exiting'.format(self.target))
self.running = False
return b