`PartiallyDownloadedBlock::FillBlock()` computed the block header hash and summed missing transaction sizes for debug logging unconditionally, including when cmpctblock debug logging is disabled.
Guard the debug-only hash and size computations with `LogAcceptCategory`.
Since `txn_available` is invalidated after the first loop (needed for efficient moving), we compute `tx_missing_size` by iterating `vtx_missing` directly. This is safe because the later `tx_missing_offset` check guarantees `vtx_missing` was fully consumed during reconstruction.
Use `block.GetHash()` instead of `header.GetHash()`, since header is cleared before logging.
No behavior change when debug logging is enabled: the reported counts, hashes, and byte totals remain the same.
Transaction hashes are cached, it may not be intuitive that their sizes are actually recalculated every time.
This is done before the other refactors to clarify why we want to avoid calling this method;
Co-authored-by: maflcko <6399679+maflcko@users.noreply.github.com>
Replaces separate `shorttxidk0`/`shorttxidk1` members with a cached `PresaltedSipHasher`, so `GetShortID()` reuses the precomputed `SipHash` state instead of rebuilding it on every call.
`CBlockHeaderAndShortTxIDs` was never intended to be used before `FillShortTxIDSelector()` runs; doing so already relied on indeterminate salt values.
The new `Assert(m_hasher)` just makes this invariant explicit and fails fast if the object is used in an uninitialized state.
Replaces standalone `SipHashUint256` with an `operator()` overload in `PresaltedSipHasher`.
Updates all hasher classes (`SaltedUint256Hasher`, `SaltedTxidHasher`, `SaltedWtxidHasher`) to use `PresaltedSipHasher` internally, enabling the same constant-state caching optimization while keeping behavior unchanged.
Benchmark was also adjusted to cache the salting part.
These remaining miscellaneous changes were identified by commenting out
the `operator const uint256&` conversion and the `Compare(const uint256&)`
method from `transaction_identifier.h`.
Since #29412, we have not allowed mutated blocks to continue
being processed immediately the block is received, but this
is only done for the legacy BLOCK message.
Extend these checks as belt-and-suspenders to not allow
similar mutation strategies to affect relay by honest peers
by applying the check inside
PartiallyDownloadedBlock::FillBlock, immediately before
returning READ_STATUS_OK.
This also removes the extraneous CheckBlock call.
refactor: CBlockHeaderAndShortTxIDs constructor now always takes an explicit nonce.
test: Make blockencodings_tests deterministic using fixed seed providing deterministic
CBlockHeaderAndShortTxID nonces and dummy transaction IDs.
Fixes very rare flaky test failures, where the ShortIDs of test transactions collide, leading to
`READ_STATUS_FAILED` from PartiallyDownloadedBlock::InitData and/or `IsTxAvailable` giving `false`
when the transaction should actually be available.
* Use a new `FastRandomContext` with a fixed seed in each test, to ensure 'random' uint256s
used as fake prevouts are deterministic, so in-turn test txids and short IDs are deterministic
and don't collide causing very rare but flaky test failures.
* Add new test-only/internal initializer for `CBlockHeaderAndShortTxIDs` that takes a specified
nonce to further ensure determinism and avoid rare but undesireable short ID collisions.
In a test context this nonce is set to a fixed known-good value. Normally it is random, as
previously.
Flaky test failures can be reproduced with:
```patch
diff --git a/src/blockencodings.cpp b/src/blockencodings.cpp
index 695e8d806a..64d635a97a 100644
--- a/src/blockencodings.cpp
+++ b/src/blockencodings.cpp
@@ -44,7 +44,8 @@ void CBlockHeaderAndShortTxIDs::FillShortTxIDSelector() const {
uint64_t CBlockHeaderAndShortTxIDs::GetShortID(const Wtxid& wtxid) const {
static_assert(SHORTTXIDS_LENGTH == 6, "shorttxids calculation assumes 6-byte shorttxids");
- return SipHashUint256(shorttxidk0, shorttxidk1, wtxid) & 0xffffffffffffL;
+ // return SipHashUint256(shorttxidk0, shorttxidk1, wtxid) & 0xffffffffffffL;
+ return SipHashUint256(shorttxidk0, shorttxidk1, wtxid) & 0x0f;
}
```
to increase the likelihood of a short ID collision; and running
```shell
set -e;
n=0;
while (( n++ < 5000 )); do
src/test/test_bitcoin --run_test=blockencodings_tests;
done
```
All `CTransactionRef` have `.GetWitnessHash()` that returns a cached `const Wtxid` (since fac1223a56),
so we don't need to pass transaction refs around with their IDs as they're easy to get from a ref.
Since the kernel library no longer depends on the system file, move it
to the common library instead in accordance to the diagram in
doc/design/libraries.md.
All uses of CBlockHeaderAndShortTxIDs in the product code are
constructed with fUseWTXID=true, so remove the parameter.
There is one use of the CBlockHeaderAndShortTxIDs constructor with
fUseWTXID=false in the unit tests. This is used to construct a
CBlockHeaderAndShortTxIDs for a block with only the coinbase
transaction, so setting fUseWTXID to true or false makes no difference.
Suggested in https://github.com/bitcoin/bitcoin/pull/20799#pullrequestreview-963480278
Some people keep thinking that MAX_BLOCK_BASE_SIZE is a separate
size limit from the weight limit when it fact it is superfluous,
and used in early tests before the witness data has been
validated or just to compute worst case sizes. The size checks
that use it would not behave any differently consensus wise
if they were eliminated completely.
Its correct value is not independently settable but is a function
of the weight limit and weight formula.
This patch just eliminates it and uses the scale factor as
required to compute the worse case constants.
It also moves the weight factor out of primitives into consensus,
which is a more logical place for it.
This changes the logging categories to boolean flags instead of strings.
This simplifies the acceptance testing by avoiding accessing a scoped
static thread local pointer to a thread local set of strings. It
eliminates the only use of boost::thread_specific_ptr outside of
lockorder debugging.
This change allows log entries to be directed to multiple categories
and makes it easy to change the logging flags at runtime (e.g. via
an RPC, though that isn't done by this commit.)
It also eliminates the fDebug global.
Configuration of unknown logging categories now produces a warning.
