This adds a new CuckooCache in validation, caching whether all of a
transaction's scripts were valid with a given set of script flags.
Unlike previous attempts at caching an entire transaction's
validity, which have nearly universally introduced consensus
failures, this only caches the validity of a transaction's
scriptSigs. As these are pure functions of the transaction and
data it commits to, this should be much safer.
This is somewhat duplicative with the sigcache, as entries in the
new cache will also have several entries in the sigcache. However,
the sigcache is kept both as ATMP relies on it and because it
prevents malleability-based DoS attacks on the new higher-level
cache. Instead, the -sigcachesize option is re-used - cutting the
sigcache size in half and using the newly freed memory for the
script execution cache.
Transactions which match the script execution cache never even have
entries in the script check thread's workqueue created.
Note that the cache is indexed only on the script execution flags
and the transaction's witness hash. While this is sufficient to
make the CScriptCheck() calls pure functions, this introduces
dependancies on the mempool calculating things such as the
PrecomputedTransactionData object, filling the CCoinsViewCache, etc
in the exact same way as ConnectBlock. I belive this is a reasonable
assumption, but should be noted carefully.
In a rather naive benchmark (reindex-chainstate up to block 284k
with cuckoocache always returning true for contains(),
-assumevalid=0 and a very large dbcache), this connected blocks
~1.7x faster.
Prior to per-utxo CCoins, we checked that no other in-mempool tx
spent any of the given transaction's outputs, as we don't want to
uncache that entire tx in such a case. However, we now are checking
only that there exists no other mempool spends of the same output,
which should clearly be impossible after we removed the transaction
which was spending said output (barring massive mempool
inconsistency).
Thanks to @sdaftuar for the suggestion.
At startup, we choose one peer to serve us the headers chain, until
our best header is close to caught up. Disconnect this peer if more
than 15 minutes + 1ms/expected_header passes and our best header
is still more than 1 day away from current time.
This change has no effect on wallet behavior.
On wallet startup, the transaction scan avoids reading any blocks with
timestamps older than the wallet birthday (less than nTimeFirstKey -
TIMESTAMP_WINDOW). This block skipping code currently resides in
CWallet::ScanForWalletTransactions but it doesn't really belong there because
it makes the implementation unnecessarily fragile and hard to understand, and
it never has any effect except at startup (because all other callers do their
rescans based on timestamps other than, but always greater or equal to,
nTimeFirstKey).
This adds the listening address on which incoming connections were received to the
CNode and CNodeStats structures.
The address is reported in `getpeerinfo`.
This can be useful for distinguishing connections received on different listening ports
(e.g. when using a different listening port for Tor hidden service connections)
or different networks.
Matt Corallo