#!/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(__file__).main()