192 lines
5.7 KiB
Python
192 lines
5.7 KiB
Python
"""This module takes care of all the logic related to block creation.
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The logic is encapsulated in the ``BlockPipeline`` class, while the sequence
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of actions to do on transactions is specified in the ``create_pipeline``
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function.
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"""
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import logging
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import rethinkdb as r
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from multipipes import Pipeline, Node
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from bigchaindb.models import Transaction
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from bigchaindb.pipelines.utils import ChangeFeed
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from bigchaindb import Bigchain
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logger = logging.getLogger(__name__)
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class BlockPipeline:
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"""This class encapsulates the logic to create blocks.
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Note:
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Methods of this class will be executed in different processes.
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"""
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def __init__(self):
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"""Initialize the BlockPipeline creator"""
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self.bigchain = Bigchain()
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self.txs = []
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def filter_tx(self, tx):
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"""Filter a transaction.
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Args:
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tx (dict): the transaction to process.
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Returns:
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dict: The transaction if assigned to the current node,
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``None`` otherwise.
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"""
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if tx['assignee'] == self.bigchain.me:
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tx.pop('assignee')
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tx.pop('assignment_timestamp')
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return tx
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def validate_tx(self, tx):
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"""Validate a transaction.
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Also checks if the transaction already exists in the blockchain. If it
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does, or it's invalid, it's deleted from the backlog immediately.
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Args:
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tx (dict): the transaction to validate.
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Returns:
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:class:`~bigchaindb.models.Transaction`: The transaction if valid,
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``None`` otherwise.
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"""
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tx = Transaction.from_dict(tx)
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if self.bigchain.transaction_exists(tx.id):
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# if the transaction already exists, we must check whether
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# it's in a valid or undecided block
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tx, status = self.bigchain.get_transaction(tx.id,
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include_status=True)
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if status == self.bigchain.TX_VALID \
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or status == self.bigchain.TX_UNDECIDED:
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# if the tx is already in a valid or undecided block,
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# then it no longer should be in the backlog, or added
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# to a new block. We can delete and drop it.
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r.table('backlog').get(tx.id) \
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.delete(durability='hard') \
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.run(self.bigchain.conn)
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return None
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tx_validated = self.bigchain.is_valid_transaction(tx)
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if tx_validated:
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return tx
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else:
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# if the transaction is not valid, remove it from the
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# backlog
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r.table('backlog').get(tx.id) \
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.delete(durability='hard') \
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.run(self.bigchain.conn)
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return None
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def create(self, tx, timeout=False):
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"""Create a block.
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This method accumulates transactions to put in a block and outputs
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a block when one of the following conditions is true:
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- the size limit of the block has been reached, or
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- a timeout happened.
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Args:
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tx (:class:`~bigchaindb.models.Transaction`): the transaction
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to validate, might be None if a timeout happens.
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timeout (bool): ``True`` if a timeout happened
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(Default: ``False``).
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Returns:
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:class:`~bigchaindb.models.Block`: The block,
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if a block is ready, or ``None``.
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"""
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if tx:
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self.txs.append(tx)
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if len(self.txs) == 1000 or (timeout and self.txs):
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block = self.bigchain.create_block(self.txs)
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self.txs = []
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return block
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def write(self, block):
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"""Write the block to the Database.
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Args:
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block (:class:`~bigchaindb.models.Block`): the block of
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transactions to write to the database.
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Returns:
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:class:`~bigchaindb.models.Block`: The Block.
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"""
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logger.info('Write new block {} with {} transactions'.format(block.id,
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len(block.transactions)))
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self.bigchain.write_block(block)
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return block
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def delete_tx(self, block):
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"""Delete transactions.
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Args:
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block (:class:`~bigchaindb.models.Block`): the block
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containg the transactions to delete.
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Returns:
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:class:`~bigchaindb.models.Block`: The block.
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"""
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r.table('backlog')\
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.get_all(*[tx.id for tx in block.transactions])\
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.delete(durability='hard')\
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.run(self.bigchain.conn)
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return block
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def initial():
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"""Return old transactions from the backlog."""
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b = Bigchain()
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rs = b.connection.run(
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r.table('backlog')
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.between(
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[b.me, r.minval],
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[b.me, r.maxval],
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index='assignee__transaction_timestamp')
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.order_by(index=r.asc('assignee__transaction_timestamp')))
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return rs
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def get_changefeed():
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"""Create and return the changefeed for the backlog."""
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return ChangeFeed('backlog', ChangeFeed.INSERT | ChangeFeed.UPDATE,
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prefeed=initial())
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def create_pipeline():
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"""Create and return the pipeline of operations to be distributed
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on different processes."""
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block_pipeline = BlockPipeline()
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pipeline = Pipeline([
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Node(block_pipeline.filter_tx),
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Node(block_pipeline.validate_tx, fraction_of_cores=1),
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Node(block_pipeline.create, timeout=1),
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Node(block_pipeline.write),
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Node(block_pipeline.delete_tx),
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])
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return pipeline
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def start():
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"""Create, start, and return the block pipeline."""
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pipeline = create_pipeline()
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pipeline.setup(indata=get_changefeed())
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pipeline.start()
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return pipeline
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