57 lines
1.9 KiB
Python
57 lines
1.9 KiB
Python
# standard imports
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import logging
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# external imports
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from chainlib.error import RPCException
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# local imports
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from .head import HeadSyncer
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from chainsyncer.error import SyncDone
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from chainlib.error import RPCException
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logg = logging.getLogger(__name__)
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class HistorySyncer(HeadSyncer):
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"""Bounded syncer implementation of the block poller. Reuses the head syncer process method implementation.
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"""
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name = 'history'
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def __init__(self, backend, chain_interface, pre_callback=None, block_callback=None, post_callback=None):
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super(HeadSyncer, self).__init__(backend, chain_interface, pre_callback, block_callback, post_callback)
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self.block_target = None
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(block_number, flags) = self.backend.target()
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if block_number == None:
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raise AttributeError('backend has no future target. Use HeadSyner instead')
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self.block_target = block_number
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def get(self, conn):
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"""Retrieve the block currently defined by the syncer cursor from the RPC provider.
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:param conn: RPC connection
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:type conn: chainlib.connectin.RPCConnection
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:raises SyncDone: Block target reached (at which point the syncer should terminate).
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:rtype: chainlib.block.Block
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:returns: Block object
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:todo: DRY against HeadSyncer
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"""
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(height, flags) = self.backend.get()
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if self.block_target < height[0]:
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raise SyncDone(self.block_target)
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block_number = height[0]
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block_hash = []
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o = self.chain_interface.block_by_number(block_number, include_tx=True)
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try:
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r = conn.do(o)
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# TODO: Disambiguate whether error is temporary or permanent, if permanent, SyncDone should be raised, because a historical sync is attempted into the future
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except RPCException:
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r = None
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if r == None:
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raise SyncDone()
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b = self.chain_interface.block_from_src(r)
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return b
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