Repository: bitcoin/bitcoin
File: test/functional/mempool_updatefromblock.py (Python)

Code before:
#!/usr/bin/env python3
# Copyright (c) 2020-2022 The Bitcoin Core developers
# Distributed under the MIT software license, see the accompanying
# file COPYING or http://www.opensource.org/licenses/mit-license.php.
"""Test mempool descendants/ancestors information update.

Test mempool update of transaction descendants/ancestors information (count, size)
when transactions have been re-added from a disconnected block to the mempool.
"""
from math import ceil
import time

from test_framework.test_framework import BitcoinTestFramework
from test_framework.util import assert_equal
from test_framework.wallet import MiniWallet


class MempoolUpdateFromBlockTest(BitcoinTestFramework):
    def set_test_params(self):
        self.num_nodes = 1
        self.extra_args = [['-limitdescendantsize=1000', '-limitancestorsize=1000', '-limitancestorcount=100']]

    def transaction_graph_test(self, size, n_tx_to_mine=None, fee=100_000):
        """Create an acyclic tournament (a type of directed graph) of transactions and use it for testing.

        Keyword arguments:
        size -- the order N of the tournament which is equal to the number of the created transactions
        n_tx_to_mine -- the number of transaction that should be mined into a block

        If all of the N created transactions tx[0]..tx[N-1] reside in the mempool,
        the following holds:
            the tx[K] transaction:
            - has N-K descendants (including this one), and
            - has K+1 ancestors (including this one)

        More details: https://en.wikipedia.org/wiki/Tournament_(graph_theory)
        """
        wallet = MiniWallet(self.nodes[0])
        first_block_hash = ''
        tx_id = []
        tx_size = []
        self.log.info('Creating {} transactions...'.format(size))
        for i in range(0, size):
            self.log.debug('Preparing transaction #{}...'.format(i))
            # Prepare inputs.
            if i == 0:
                inputs = [wallet.get_utxo()]  # let MiniWallet provide a start UTXO
            else:
                inputs = []
                for j, tx in enumerate(tx_id[0:i]):
                    # Transaction tx[K] is a child of each of previous transactions tx[0]..tx[K-1] at their output K-1.
                    vout = i - j - 1
                    inputs.append(wallet.get_utxo(txid=tx_id[j], vout=vout))

            # Prepare outputs.
            tx_count = i + 1
            if tx_count < size:
                # Transaction tx[K] is an ancestor of each of subsequent transactions tx[K+1]..tx[N-1].
                n_outputs = size - tx_count
            else:
                n_outputs = 1

            # Create a new transaction.
            new_tx = wallet.send_self_transfer_multi(
                from_node=self.nodes[0],
                utxos_to_spend=inputs,
                num_outputs=n_outputs,
                fee_per_output=ceil(fee / n_outputs)
            )
            tx_id.append(new_tx['txid'])
            tx_size.append(new_tx['tx'].get_vsize())

            if tx_count in n_tx_to_mine:
                # The created transactions are mined into blocks by batches.
                self.log.info('The batch of {} transactions has been accepted into the mempool.'.format(len(self.nodes[0].getrawmempool())))
                block_hash = self.generate(self.nodes[0], 1)[0]
                if not first_block_hash:
                    first_block_hash = block_hash
                assert_equal(len(self.nodes[0].getrawmempool()), 0)
                self.log.info('All of the transactions from the current batch have been mined into a block.')
            elif tx_count == size:
                # At the end all of the mined blocks are invalidated, and all of the created
                # transactions should be re-added from disconnected blocks to the mempool.
                self.log.info('The last batch of {} transactions has been accepted into the mempool.'.format(len(self.nodes[0].getrawmempool())))
                start = time.time()
                self.nodes[0].invalidateblock(first_block_hash)
                end = time.time()
                assert_equal(len(self.nodes[0].getrawmempool()), size)
                self.log.info('All of the recently mined transactions have been re-added into the mempool in {} seconds.'.format(end - start))

        self.log.info('Checking descendants/ancestors properties of all of the in-mempool transactions...')
        for k, tx in enumerate(tx_id):
            self.log.debug('Check transaction #{}.'.format(k))
            entry = self.nodes[0].getmempoolentry(tx)
            assert_equal(entry['descendantcount'], size - k)
            assert_equal(entry['descendantsize'], sum(tx_size[k:size]))
            assert_equal(entry['ancestorcount'], k + 1)
            assert_equal(entry['ancestorsize'], sum(tx_size[0:(k + 1)]))

    def run_test(self):
        # Use batch size limited by DEFAULT_ANCESTOR_LIMIT = 25 to not fire "too many unconfirmed parents" error.
        self.transaction_graph_test(size=100, n_tx_to_mine=[25, 50, 75])


if __name__ == '__main__':
    MempoolUpdateFromBlockTest(__file__).main()


Review comment (suggestion):
This comment is outdated, because `DEFAULT_ANCESTOR_LIMIT = 25` is no longer after the last commit. Not sure about the reason why it was used before, is it no longer valid?

Also, changing DEFAULT_ANCESTOR_LIMIT to 100 could be mentioned in the commit message, it also affects the other subtests.


Code after:

        assert_equal(self.nodes[0].getmempoolinfo()["size"], len(small_child_txs))

        # Reorg back before the first block in the series, should drop something
        # but not all, and any time parent is dropped, child is also removed
        for block in fork_blocks:
            self.nodes[0].submitblock(block.serialize().hex())
        mempool = self.nodes[0].getrawmempool()
        expected_parent_count = len(large_std_txs) - 2
        assert_equal(len(mempool), expected_parent_count * 2)

        # The txns at the end of the list, or most recently confirmed, should have been trimmed
        assert_equal([tx["txid"] in mempool for tx in large_std_txs], [tx["txid"] in mempool for tx in small_child_txs])
        assert_equal([tx["txid"] in mempool for tx in large_std_txs], [True] * expected_parent_count + [False] * 2)

    def test_chainlimits_exceeded(self):
        self.log.info('Check that too long chains on reorg are handled')

        wallet = MiniWallet(self.nodes[0])
        self.generate(wallet, 101)

        assert_equal(self.nodes[0].getrawmempool(), [])

        # Prep fork
        fork_blocks = self.create_empty_fork(fork_length=10)

        # Two higher than descendant count
        chain = wallet.create_self_transfer_chain(chain_length=CUSTOM_DESCENDANT_COUNT + 2)
        for tx in chain[:-2]:
            self.nodes[0].sendrawtransaction(tx["hex"])

        assert_raises_rpc_error(-26, "too-long-mempool-chain, too many unconfirmed ancestors [limit: 100]", self.nodes[0].sendrawtransaction, chain[-2]["hex"])

        # Mine a block with all but last transaction, non-standardly long chain
        self.generateblock(self.nodes[0], output="raw(42)", transactions=[tx["hex"] for tx in chain[:-1]])
        assert_equal(self.nodes[0].getrawmempool(), [])

        # Last tx fits now
        self.nodes[0].sendrawtransaction(chain[-1]["hex"])

        # Finally, reorg to empty chain kick everything back into mempool
        # at normal chain limits
        for block in fork_blocks:
            self.nodes[0].submitblock(block.serialize().hex())
        mempool = self.nodes[0].getrawmempool()
        assert_equal(set(mempool), set([tx["txid"] for tx in chain[:-2]]))

    def run_test(self):
        # Mine in batches of 25 to test multi-block reorg under chain limits
        self.transaction_graph_test(size=CUSTOM_ANCESTOR_COUNT, n_tx_to_mine=[25, 50, 75])