#!/usr/bin/env python3 # Copyright (c) 2014-2022 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 limiting together/eviction with the wallet.""" from decimal import Decimal from test_framework.mempool_util import ( fill_mempool, ) from test_framework.p2p import P2PTxInvStore from test_framework.test_framework import BitcoinTestFramework from test_framework.util import ( assert_equal, assert_fee_amount, assert_greater_than, assert_raises_rpc_error, ) from test_framework.wallet import ( COIN, DEFAULT_FEE, MiniWallet, ) class MempoolLimitTest(BitcoinTestFramework): def set_test_params(self): self.setup_clean_chain = True self.num_nodes = 1 self.extra_args = [[ "-datacarriersize=100000", "-maxmempool=5", ]] self.supports_cli = False def test_rbf_carveout_disallowed(self): node = self.nodes[0] self.log.info("Check that individually-evaluated transactions in a package don't increase package limits for other subpackage parts") # We set chain limits to 2 ancestors, 1 descendant, then try to get a parents-and-child chain of 2 in mempool # # A: Solo transaction to be RBF'd (to bump descendant limit for package later) # B: First transaction in package, RBFs A by itself under individual evaluation, which would give it +1 descendant limit # C: Second transaction in package, spends B. If the +1 descendant limit persisted, would make it into mempool self.restart_node(0, extra_args=self.extra_args[0] + ["-limitancestorcount=2", "-limitdescendantcount=1"]) # Generate a confirmed utxo we will double-spend rbf_utxo = self.wallet.send_self_transfer( from_node=node, confirmed_only=True )["new_utxo"] self.generate(node, 1) # tx_A needs to be RBF'd, set minfee at set size A_weight = 1000 mempoolmin_feerate = node.getmempoolinfo()["mempoolminfee"] tx_A = self.wallet.send_self_transfer( from_node=node, fee_rate=mempoolmin_feerate, target_weight=A_weight, utxo_to_spend=rbf_utxo, confirmed_only=True ) # RBF's tx_A, is not yet submitted tx_B = self.wallet.create_self_transfer( fee=tx_A["fee"] * 4, target_weight=A_weight, utxo_to_spend=rbf_utxo, confirmed_only=True ) # Spends tx_B's output, too big for cpfp carveout (because that would also increase the descendant limit by 1) non_cpfp_carveout_weight = 40001 # EXTRA_DESCENDANT_TX_SIZE_LIMIT + 1 tx_C = self.wallet.create_self_transfer( target_weight=non_cpfp_carveout_weight, fee_rate=mempoolmin_feerate, utxo_to_spend=tx_B["new_utxo"], confirmed_only=True ) res = node.submitpackage([tx_B["hex"], tx_C["hex"]]) assert_equal(res["package_msg"], "transaction failed") assert "too-long-mempool-chain" in res["tx-results"][tx_C["wtxid"]]["error"] def test_mid_package_eviction(self): node = self.nodes[0] self.log.info("Check a package where each parent passes the current mempoolminfee but would cause eviction before package submission terminates") self.restart_node(0, extra_args=self.extra_args[0]) # Restarting the node resets mempool minimum feerate assert_equal(node.getmempoolinfo()['minrelaytxfee'], Decimal('0.00001000')) assert_equal(node.getmempoolinfo()['mempoolminfee'], Decimal('0.00001000')) fill_mempool(self, node) current_info = node.getmempoolinfo() mempoolmin_feerate = current_info["mempoolminfee"] package_hex = [] # UTXOs to be spent by the ultimate child transaction parent_utxos = [] evicted_weight = 8000 # Mempool transaction which is evicted due to being at the "bottom" of the mempool when the # mempool overflows and evicts by descendant score. It's important that the eviction doesn't # happen in the middle of package evaluation, as it can invalidate the coins cache. mempool_evicted_tx = self.wallet.send_self_transfer( from_node=node, fee_rate=mempoolmin_feerate, target_weight=evicted_weight, confirmed_only=True ) # Already in mempool when package is submitted. assert mempool_evicted_tx["txid"] in node.getrawmempool() # This parent spends the above mempool transaction that exists when its inputs are first # looked up, but disappears later. It is rejected for being too low fee (but eligible for # reconsideration), and its inputs are cached. When the mempool transaction is evicted, its # coin is no longer available, but the cache could still contains the tx. cpfp_parent = self.wallet.create_self_transfer( utxo_to_spend=mempool_evicted_tx["new_utxo"], fee_rate=mempoolmin_feerate - Decimal('0.00001'), confirmed_only=True) package_hex.append(cpfp_parent["hex"]) parent_utxos.append(cpfp_parent["new_utxo"]) assert_equal(node.testmempoolaccept([cpfp_parent["hex"]])[0]["reject-reason"], "mempool min fee not met") self.wallet.rescan_utxos() # Series of parents that don't need CPFP and are submitted individually. Each one is large and # high feerate, which means they should trigger eviction but not be evicted. parent_weight = 100000 num_big_parents = 3 assert_greater_than(parent_weight * num_big_parents, current_info["maxmempool"] - current_info["bytes"]) parent_feerate = 100 * mempoolmin_feerate big_parent_txids = [] for i in range(num_big_parents): parent = self.wallet.create_self_transfer(fee_rate=parent_feerate, target_weight=parent_weight, confirmed_only=True) parent_utxos.append(parent["new_utxo"]) package_hex.append(parent["hex"]) big_parent_txids.append(parent["txid"]) # There is room for each of these transactions independently assert node.testmempoolaccept([parent["hex"]])[0]["allowed"] # Create a child spending everything, bumping cpfp_parent just above mempool minimum # feerate. It's important not to bump too much as otherwise mempool_evicted_tx would not be # evicted, making this test much less meaningful. approx_child_vsize = self.wallet.create_self_transfer_multi(utxos_to_spend=parent_utxos)["tx"].get_vsize() cpfp_fee = (mempoolmin_feerate / 1000) * (cpfp_parent["tx"].get_vsize() + approx_child_vsize) - cpfp_parent["fee"] # Specific number of satoshis to fit within a small window. The parent_cpfp + child package needs to be # - When there is mid-package eviction, high enough feerate to meet the new mempoolminfee # - When there is no mid-package eviction, low enough feerate to be evicted immediately after submission. magic_satoshis = 1200 cpfp_satoshis = int(cpfp_fee * COIN) + magic_satoshis child = self.wallet.create_self_transfer_multi(utxos_to_spend=parent_utxos, fee_per_output=cpfp_satoshis) package_hex.append(child["hex"]) # Package should be submitted, temporarily exceeding maxmempool, and then evicted. with node.assert_debug_log(expected_msgs=["rolling minimum fee bumped"]): assert_equal(node.submitpackage(package_hex)["package_msg"], "transaction failed") # Maximum size must never be exceeded. assert_greater_than(node.getmempoolinfo()["maxmempool"], node.getmempoolinfo()["bytes"]) # Evicted transaction and its descendants must not be in mempool. resulting_mempool_txids = node.getrawmempool() assert mempool_evicted_tx["txid"] not in resulting_mempool_txids assert cpfp_parent["txid"] not in resulting_mempool_txids assert child["txid"] not in resulting_mempool_txids for txid in big_parent_txids: assert txid in resulting_mempool_txids def test_mid_package_replacement(self): node = self.nodes[0] self.log.info("Check a package where an early tx depends on a later-replaced mempool tx") self.restart_node(0, extra_args=self.extra_args[0]) # Restarting the node resets mempool minimum feerate assert_equal(node.getmempoolinfo()['minrelaytxfee'], Decimal('0.00001000')) assert_equal(node.getmempoolinfo()['mempoolminfee'], Decimal('0.00001000')) fill_mempool(self, node) current_info = node.getmempoolinfo() mempoolmin_feerate = current_info["mempoolminfee"] # Mempool transaction which is evicted due to being at the "bottom" of the mempool when the # mempool overflows and evicts by descendant score. It's important that the eviction doesn't # happen in the middle of package evaluation, as it can invalidate the coins cache. double_spent_utxo = self.wallet.get_utxo(confirmed_only=True) replaced_tx = self.wallet.send_self_transfer( from_node=node, utxo_to_spend=double_spent_utxo, fee_rate=mempoolmin_feerate, confirmed_only=True ) # Already in mempool when package is submitted. assert replaced_tx["txid"] in node.getrawmempool() # This parent spends the above mempool transaction that exists when its inputs are first # looked up, but disappears later. It is rejected for being too low fee (but eligible for # reconsideration), and its inputs are cached. When the mempool transaction is evicted, its # coin is no longer available, but the cache could still contain the tx. cpfp_parent = self.wallet.create_self_transfer( utxo_to_spend=replaced_tx["new_utxo"], fee_rate=mempoolmin_feerate - Decimal('0.00001'), confirmed_only=True) self.wallet.rescan_utxos() # Parent that replaces the parent of cpfp_parent. replacement_tx = self.wallet.create_self_transfer( utxo_to_spend=double_spent_utxo, fee_rate=10*mempoolmin_feerate, confirmed_only=True ) parent_utxos = [cpfp_parent["new_utxo"], replacement_tx["new_utxo"]] # Create a child spending everything, CPFPing the low-feerate parent. approx_child_vsize = self.wallet.create_self_transfer_multi(utxos_to_spend=parent_utxos)["tx"].get_vsize() cpfp_fee = (2 * mempoolmin_feerate / 1000) * (cpfp_parent["tx"].get_vsize() + approx_child_vsize) - cpfp_parent["fee"] child = self.wallet.create_self_transfer_multi(utxos_to_spend=parent_utxos, fee_per_output=int(cpfp_fee * COIN)) # It's very important that the cpfp_parent is before replacement_tx so that its input (from # replaced_tx) is first looked up *before* replacement_tx is submitted. package_hex = [cpfp_parent["hex"], replacement_tx["hex"], child["hex"]] # Package should be submitted, temporarily exceeding maxmempool, and then evicted. res = node.submitpackage(package_hex) assert_equal(res["package_msg"], "transaction failed") assert len([tx_res for _, tx_res in res["tx-results"].items() if "error" in tx_res and tx_res["error"] == "bad-txns-inputs-missingorspent"]) # Maximum size must never be exceeded. assert_greater_than(node.getmempoolinfo()["maxmempool"], node.getmempoolinfo()["bytes"]) resulting_mempool_txids = node.getrawmempool() # The replacement should be successful. assert replacement_tx["txid"] in resulting_mempool_txids # The replaced tx and all of its descendants must not be in mempool. assert replaced_tx["txid"] not in resulting_mempool_txids assert cpfp_parent["txid"] not in resulting_mempool_txids assert child["txid"] not in resulting_mempool_txids def run_test(self): node = self.nodes[0] self.wallet = MiniWallet(node) miniwallet = self.wallet # Generate coins needed to create transactions in the subtests (excluding coins used in fill_mempool). self.generate(miniwallet, 20) relayfee = node.getnetworkinfo()['relayfee'] self.log.info('Check that mempoolminfee is minrelaytxfee') assert_equal(node.getmempoolinfo()['minrelaytxfee'], Decimal('0.00001000')) assert_equal(node.getmempoolinfo()['mempoolminfee'], Decimal('0.00001000')) fill_mempool(self, node) # Deliberately try to create a tx with a fee less than the minimum mempool fee to assert that it does not get added to the mempool self.log.info('Create a mempool tx that will not pass mempoolminfee') assert_raises_rpc_error(-26, "mempool min fee not met", miniwallet.send_self_transfer, from_node=node, fee_rate=relayfee) self.log.info("Check that submitpackage allows cpfp of a parent below mempool min feerate") node = self.nodes[0] peer = node.add_p2p_connection(P2PTxInvStore()) # Package with 2 parents and 1 child. One parent has a high feerate due to modified fees, # another is below the mempool minimum feerate but bumped by the child. tx_poor = miniwallet.create_self_transfer(fee_rate=relayfee) tx_rich = miniwallet.create_self_transfer(fee=0, fee_rate=0) node.prioritisetransaction(tx_rich["txid"], 0, int(DEFAULT_FEE * COIN)) package_txns = [tx_rich, tx_poor] coins = [tx["new_utxo"] for tx in package_txns] tx_child = miniwallet.create_self_transfer_multi(utxos_to_spend=coins, fee_per_output=10000) #DEFAULT_FEE package_txns.append(tx_child) submitpackage_result = node.submitpackage([tx["hex"] for tx in package_txns]) assert_equal(submitpackage_result["package_msg"], "success") rich_parent_result = submitpackage_result["tx-results"][tx_rich["wtxid"]] poor_parent_result = submitpackage_result["tx-results"][tx_poor["wtxid"]] child_result = submitpackage_result["tx-results"][tx_child["tx"].getwtxid()] assert_fee_amount(poor_parent_result["fees"]["base"], tx_poor["tx"].get_vsize(), relayfee) assert_equal(rich_parent_result["fees"]["base"], 0) assert_equal(child_result["fees"]["base"], DEFAULT_FEE) # The "rich" parent does not require CPFP so its effective feerate is just its individual feerate. assert_fee_amount(DEFAULT_FEE, tx_rich["tx"].get_vsize(), rich_parent_result["fees"]["effective-feerate"]) assert_equal(rich_parent_result["fees"]["effective-includes"], [tx_rich["wtxid"]]) # The "poor" parent and child's effective feerates are the same, composed of their total # fees divided by their combined vsize. package_fees = poor_parent_result["fees"]["base"] + child_result["fees"]["base"] package_vsize = tx_poor["tx"].get_vsize() + tx_child["tx"].get_vsize() assert_fee_amount(package_fees, package_vsize, poor_parent_result["fees"]["effective-feerate"]) assert_fee_amount(package_fees, package_vsize, child_result["fees"]["effective-feerate"]) assert_equal([tx_poor["wtxid"], tx_child["tx"].getwtxid()], poor_parent_result["fees"]["effective-includes"]) assert_equal([tx_poor["wtxid"], tx_child["tx"].getwtxid()], child_result["fees"]["effective-includes"]) # The node will broadcast each transaction, still abiding by its peer's fee filter peer.wait_for_broadcast([tx["tx"].getwtxid() for tx in package_txns]) self.log.info("Check a package that passes mempoolminfee but is evicted immediately after submission") mempoolmin_feerate = node.getmempoolinfo()["mempoolminfee"] current_mempool = node.getrawmempool(verbose=False) worst_feerate_btcvb = Decimal("21000000") for txid in current_mempool: entry = node.getmempoolentry(txid) worst_feerate_btcvb = min(worst_feerate_btcvb, entry["fees"]["descendant"] / entry["descendantsize"]) # Needs to be large enough to trigger eviction target_weight_each = 200000 assert_greater_than(target_weight_each * 2, node.getmempoolinfo()["maxmempool"] - node.getmempoolinfo()["bytes"]) # Should be a true CPFP: parent's feerate is just below mempool min feerate parent_feerate = mempoolmin_feerate - Decimal("0.000001") # 0.1 sats/vbyte below min feerate # Parent + child is above mempool minimum feerate child_feerate = (worst_feerate_btcvb * 1000) - Decimal("0.000001") # 0.1 sats/vbyte below worst feerate # However, when eviction is triggered, these transactions should be at the bottom. # This assertion assumes parent and child are the same size. miniwallet.rescan_utxos() tx_parent_just_below = miniwallet.create_self_transfer(fee_rate=parent_feerate, target_weight=target_weight_each) tx_child_just_above = miniwallet.create_self_transfer(utxo_to_spend=tx_parent_just_below["new_utxo"], fee_rate=child_feerate, target_weight=target_weight_each) # This package ranks below the lowest descendant package in the mempool package_fee = tx_parent_just_below["fee"] + tx_child_just_above["fee"] package_vsize = tx_parent_just_below["tx"].get_vsize() + tx_child_just_above["tx"].get_vsize() assert_greater_than(worst_feerate_btcvb, package_fee / package_vsize) assert_greater_than(mempoolmin_feerate, tx_parent_just_below["fee"] / (tx_parent_just_below["tx"].get_vsize())) assert_greater_than(package_fee / package_vsize, mempoolmin_feerate / 1000) res = node.submitpackage([tx_parent_just_below["hex"], tx_child_just_above["hex"]]) for wtxid in [tx_parent_just_below["wtxid"], tx_child_just_above["wtxid"]]: assert_equal(res["tx-results"][wtxid]["error"], "mempool full") self.log.info('Test passing a value below the minimum (5 MB) to -maxmempool throws an error') self.stop_node(0) self.nodes[0].assert_start_raises_init_error(["-maxmempool=4"], "Error: -maxmempool must be at least 5 MB") self.test_mid_package_replacement() self.test_mid_package_eviction() self.test_rbf_carveout_disallowed() if __name__ == '__main__': MempoolLimitTest().main()