Merge bitcoin/bitcoin#22378: test: remove confusing `MAX_BLOCK_BASE_SIZE`

607076d01bf23c69ac21950c17b01fb4e1130774 test: remove confusing `MAX_BLOCK_BASE_SIZE` (Sebastian Falbesoner)
4af97c74edcda56cd15523bf3a335adea2bad14a test: introduce `get_weight()` helper for CBlock (Sebastian Falbesoner)
a084ebe1330bcec15715e08b0f65319142927ad1 test: introduce `get_weight()` helper for CTransaction (Sebastian Falbesoner)

Pull request description:

  This is a very late follow-up PR to #10618, which removed the constant `MAX_BLOCK_BASE_SIZE` from the core implementation about four years ago (see also #10608 in why it was considered confusing and superfluous).
  Since there is also no point in still keeping it in the functional test framework, the PR switches to weight-based accounting on the relevant test code parts and use `MAX_BLOCK_WEIGHT` instead for the block limit checks. To prepare that, the first two commits introduce `get_weight()` helpers for the classes CTransaction and CBlock, respectively.

ACKs for top commit:
  MarcoFalke:
    review ACK 607076d01bf23c69ac21950c17b01fb4e1130774 🚴

Tree-SHA512: d59aa0b6b3dfd0a849b8063e66de275d252f705f99e25cd3bf6daec028b47d946777ee5b42a060f5283cb18e917ac073119c2c0e11bbc21211f69ef0a6ed335a

1 files changed, 11 insertions, 26 deletions

diff --git a/test/functional/p2p_segwit.py b/test/functional/p2p_segwit.py
index c53feaf0c6..e5093855ff 100755
--- a/test/functional/p2p_segwit.py
+++ b/test/functional/p2p_segwit.py
@@ -4,7 +4,6 @@
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 """Test segwit transactions and blocks on P2P network."""
 from decimal import Decimal
-import math
 import random
 import struct
 import time
@@ -21,7 +20,7 @@ from test_framework.messages import (
     CTxInWitness,
     CTxOut,
     CTxWitness,
-    MAX_BLOCK_BASE_SIZE,
+    MAX_BLOCK_WEIGHT,
     MSG_BLOCK,
     MSG_TX,
     MSG_WITNESS_FLAG,
@@ -106,16 +105,6 @@ def sign_p2pk_witness_input(script, tx_to, in_idx, hashtype, value, key):
     tx_to.wit.vtxinwit[in_idx].scriptWitness.stack = [signature, script]
     tx_to.rehash()
 
-def get_virtual_size(witness_block):
-    """Calculate the virtual size of a witness block.
-
-    Virtual size is base + witness/4."""
-    base_size = len(witness_block.serialize(with_witness=False))
-    total_size = len(witness_block.serialize())
-    # the "+3" is so we round up
-    vsize = int((3 * base_size + total_size + 3) / 4)
-    return vsize
-
 def test_transaction_acceptance(node, p2p, tx, with_witness, accepted, reason=None):
     """Send a transaction to the node and check that it's accepted to the mempool
 
@@ -437,8 +426,7 @@ class SegWitTest(BitcoinTestFramework):
             rpc_details = self.nodes[0].getblock(block.hash, True)
             assert_equal(rpc_details["size"], len(block.serialize()))
             assert_equal(rpc_details["strippedsize"], len(block.serialize(False)))
-            weight = 3 * len(block.serialize(False)) + len(block.serialize())
-            assert_equal(rpc_details["weight"], weight)
+            assert_equal(rpc_details["weight"], block.get_weight())
 
             # Upgraded node should not ask for blocks from unupgraded
             block4 = self.build_next_block(version=4)
@@ -849,7 +837,7 @@ class SegWitTest(BitcoinTestFramework):
         block.solve()
 
         block.vtx[0].wit.vtxinwit[0].scriptWitness.stack.append(b'a' * 5000000)
-        assert get_virtual_size(block) > MAX_BLOCK_BASE_SIZE
+        assert block.get_weight() > MAX_BLOCK_WEIGHT
 
         # We can't send over the p2p network, because this is too big to relay
         # TODO: repeat this test with a block that can be relayed
@@ -858,7 +846,7 @@ class SegWitTest(BitcoinTestFramework):
         assert self.nodes[0].getbestblockhash() != block.hash
 
         block.vtx[0].wit.vtxinwit[0].scriptWitness.stack.pop()
-        assert get_virtual_size(block) < MAX_BLOCK_BASE_SIZE
+        assert block.get_weight() < MAX_BLOCK_WEIGHT
         assert_equal(None, self.nodes[0].submitblock(block.serialize().hex()))
 
         assert self.nodes[0].getbestblockhash() == block.hash
@@ -920,11 +908,10 @@ class SegWitTest(BitcoinTestFramework):
         child_tx.rehash()
         self.update_witness_block_with_transactions(block, [parent_tx, child_tx])
 
-        vsize = get_virtual_size(block)
-        additional_bytes = (MAX_BLOCK_BASE_SIZE - vsize) * 4
+        additional_bytes = MAX_BLOCK_WEIGHT - block.get_weight()
         i = 0
         while additional_bytes > 0:
-            # Add some more bytes to each input until we hit MAX_BLOCK_BASE_SIZE+1
+            # Add some more bytes to each input until we hit MAX_BLOCK_WEIGHT+1
             extra_bytes = min(additional_bytes + 1, 55)
             block.vtx[-1].wit.vtxinwit[int(i / (2 * NUM_DROPS))].scriptWitness.stack[i % (2 * NUM_DROPS)] = b'a' * (195 + extra_bytes)
             additional_bytes -= extra_bytes
@@ -933,8 +920,7 @@ class SegWitTest(BitcoinTestFramework):
         block.vtx[0].vout.pop()  # Remove old commitment
         add_witness_commitment(block)
         block.solve()
-        vsize = get_virtual_size(block)
-        assert_equal(vsize, MAX_BLOCK_BASE_SIZE + 1)
+        assert_equal(block.get_weight(), MAX_BLOCK_WEIGHT + 1)
         # Make sure that our test case would exceed the old max-network-message
         # limit
         assert len(block.serialize()) > 2 * 1024 * 1024
@@ -947,7 +933,7 @@ class SegWitTest(BitcoinTestFramework):
         block.vtx[0].vout.pop()
         add_witness_commitment(block)
         block.solve()
-        assert get_virtual_size(block) == MAX_BLOCK_BASE_SIZE
+        assert block.get_weight() == MAX_BLOCK_WEIGHT
 
         test_witness_block(self.nodes[0], self.test_node, block, accepted=True)
 
@@ -1304,10 +1290,9 @@ class SegWitTest(BitcoinTestFramework):
         raw_tx = self.nodes[0].getrawtransaction(tx3.hash, 1)
         assert_equal(int(raw_tx["hash"], 16), tx3.calc_sha256(True))
         assert_equal(raw_tx["size"], len(tx3.serialize_with_witness()))
-        weight = len(tx3.serialize_with_witness()) + 3 * len(tx3.serialize_without_witness())
-        vsize = math.ceil(weight / 4)
+        vsize = tx3.get_vsize()
         assert_equal(raw_tx["vsize"], vsize)
-        assert_equal(raw_tx["weight"], weight)
+        assert_equal(raw_tx["weight"], tx3.get_weight())
         assert_equal(len(raw_tx["vin"][0]["txinwitness"]), 1)
         assert_equal(raw_tx["vin"][0]["txinwitness"][0], witness_script.hex())
         assert vsize != raw_tx["size"]
@@ -1663,7 +1648,7 @@ class SegWitTest(BitcoinTestFramework):
             block.vtx.append(tx)
 
             # Test the block periodically, if we're close to maxblocksize
-            if (get_virtual_size(block) > MAX_BLOCK_BASE_SIZE - 1000):
+            if block.get_weight() > MAX_BLOCK_WEIGHT - 4000:
                 self.update_witness_block_with_transactions(block, [])
                 test_witness_block(self.nodes[0], self.test_node, block, accepted=True)
                 block = self.build_next_block()