In Olaoluwa Osuntokun's recent protocol proposal they were using a
mod in an inner loop. I wanted to suggest a normative protocol
change to use the trick we use here, but to find an explanation
of it I had to dig up the PR on github. After I posted about it
several other developers commented that it was very interesting
and they were unaware of it.
I think ideally the code should be self documenting and help
educate other contributors about non-obvious techniques that
we use. So I've written a description of the technique with
citations for future reference.
3ff1fa8 Use override keyword on CCoinsView overrides (Russell Yanofsky)
24e44c3 Don't return stale data from CCoinsViewCache::Cursor() (Russell Yanofsky)
Tree-SHA512: 08699dae0925ffb9c018f02612ac6b7eaf73ec331e2f4f934f1fe25a2ce120735fa38596926e924897c203f7470e99f0a99cf70d2ce31ff428b105e16583a861
c237bd7 wallet: Update formatting (Luke Dashjr)
9cbe8c8 wallet: Forbid -salvagewallet, -zapwallettxes, and -upgradewallet with multiple wallets (Luke Dashjr)
a2a5f3f wallet: Base backup filenames on original wallet filename (Luke Dashjr)
b823a4c wallet: Include actual backup filename in recovery warning message (Luke Dashjr)
84dcb45 Bugfix: wallet: Fix warningStr, errorStr argument order (Luke Dashjr)
008c360 Wallet: Move multiwallet sanity checks to CWallet::Verify, and do other checks on all wallets (Luke Dashjr)
0f08575 Wallet: Support loading multiple wallets if -wallet used more than once (Luke Dashjr)
b124cf0 Wallet: Replace pwalletMain with a vector of wallet pointers (Luke Dashjr)
19b3648 CWalletDB: Store the update counter per wallet (Luke Dashjr)
74e8738 Bugfix: ForceSetArg should replace entr(ies) in mapMultiArgs, not append (Luke Dashjr)
23fb9ad wallet: Move nAccountingEntryNumber from static/global to CWallet (Luke Dashjr)
9d15d55 Bugfix: wallet: Increment "update counter" when modifying account stuff (Luke Dashjr)
f28eb80 Bugfix: wallet: Increment "update counter" only after actually making the applicable db changes to avoid potential races (Luke Dashjr)
Tree-SHA512: 23f5dda58477307bc07997010740f1dc729164cdddefd2f9a2c9c7a877111eb1516d3e2ad4f9b104621f0b7f17369c69fcef13d28b85cb6c01d35f09a8845f23
40796e1 Remove references to priority that snuck back in in 870824e9. (Matt Corallo)
Tree-SHA512: fd6f772a9fdf14b3b125e84a79059d7ab34b3571b35dc48f8d4b9f22ea71c6cdd4ae88c2e135ae317a16744c28dd23cf7f7dd88ea9d8b2d408e57845ef87d03b
While the current implementation is pretty free, there is a lot
of possibility for this to blow up in our face with future changes,
especially as the backing map gets tweaked.
There are some similar asserts which are left removed in policy
and ATMP (policy code being broken isn't a huge deal, but if we
fail to verify some consensus rules, we should most definitely
crash).
Previously it was possible for HaveCoinInCache to return true for a spent
coin. It is more clear to keep the semantics the same. HaveCoinInCache is
used for two reasons:
- tracking coins we may want to uncache, in which case it is unlikely there
would be spent coins we could uncache (not dirty)
- optimistically checking whether we have already included a tx in the
blockchain, in which case a spent coin is not a reliable indicator that we have.
3fb81a8 Use list initialization (C++11) for maps/vectors instead of boost::assign::map_list_of/list_of (practicalswift)
Tree-SHA512: 63a9ac9ec5799472943dce1cd92a4b14e7f1fe12758a5fc4b1efceaf2c85a4ba71dad5ccc50813527f18b192e7714c076e2478ecd6ca0d452b24e88416f872f7
246a02f Use std::unordered_{map,set} (C++11) instead of boost::unordered_{map,set} (practicalswift)
Tree-SHA512: 35cd42012248174751e4b87efbc78689957f731d7710dea7e369974c6ec31b15b32d1537fb0d875c94c7ffb5046d9784735e218e5baeed96d525861dab6d4252
227ae9b [tests] Use FastRandomContext instead of boost::random::{mt19937,uniform_int_distribution} (practicalswift)
Tree-SHA512: 1bde6c8b9498051fa2eae4913eb1f5411adea8dea1511c0df859aea57a2a7db6f5839945ddf2eccdddfa322bceacad35a5d875742db7d15e40dbea83185307bb
e94584858 scripted-diff: Use new naming style for insecure_rand* functions (Pieter Wuille)
2fcd9cc86 scripted-diff: Use randbits/bool instead of randrange where possible (Pieter Wuille)
2ada67852 Use randbits instead of ad-hoc emulation in prevector tests (Pieter Wuille)
5f0b04eed Replace rand() & ((1 << N) - 1) with randbits(N) (Pieter Wuille)
3ecabae36 Replace more rand() % NUM by randranges (Pieter Wuille)
efee1db21 scripted-diff: use insecure_rand256/randrange more (Pieter Wuille)
1119927df Add various insecure_rand wrappers for tests (Pieter Wuille)
124d13a58 Merge test_random.h into test_bitcoin.h (Pieter Wuille)
90620d66c scripted-diff: Rename cuckoo tests' local rand context (Pieter Wuille)
37e864eb9 Add FastRandomContext::rand256() and ::randbytes() (Pieter Wuille)
Tree-SHA512: d09705a3ec718ae792f7d66a75401903ba7b9c9d3fc36669d6e3b9242f0194738106be26baefc8a8e3fa6df7c9a35978c71c0c430278a028b331df23a3ea3070
We can call gettxoutproof() with a list of transactions. Currently, if
the first transaction is unspent (and all other transactions are in the
same block), then the call will succeed. If the first transaction has
been spent, then the call will fail. The means that the following two
calls will return different results:
gettxoutproof(unspent_tx1, spent_tx1)
gettxoutproof(spent_tx1, unspent_tx1)
This commit makes behaviour independent of transaction ordering by looping
through all transactions provided and trying to find which block they're in.
This commit also increases the test coverage and tests more failure
cases for gettxoutproof()
Added an option to configure to allow for branch coverage statistics gathering.
Disabled logprint macro when coverage testing is on so that unnecessary branches are not analyzed.
The implementation of base_uint::operator++(int) and base_uint::operator--(int) is now safer.
Array pn is accessed via index i after bounds checking has been performed on the index, rather than before.
The logic of the while loops has also been made more clear.
A compile time assertion has been added in the class constructors to ensure that BITS is a positive multiple of 32.
CCoinsViewCache doesn't actually support cursor iteration returning the
current contents of the cache, so raise an error when the cursor method is
called instead of returning a cursor that iterates over stale data.
Also update the gettxoutsetinfo RPC which was relying on the old behavior to be
explicit about which view it is returning data about.
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.
9a5a1d7 RPC/rawtransaction: createrawtransaction: Check opt_into_rbf when provided with either value (Luke Dashjr)
23b0fe3 bitcoin-tx: rbfoptin: Avoid touching nSequence if the value is already opting in (Luke Dashjr)
b005bf2 Introduce MAX_BIP125_RBF_SEQUENCE constant (Luke Dashjr)
575cde4 [bitcoin-tx] add rbfoptin command (Jonas Schnelli)
5d26244 [Tests] extend the replace-by-fee test to cover RPC rawtx features (Jonas Schnelli)
36bcab2 RPC/Wallet: Add RBF support for fundrawtransaction (Luke Dashjr)
891c5ee Wallet: Refactor FundTransaction to accept parameters via CCoinControl (Luke Dashjr)
578ec80 RPC: rawtransaction: Add RBF support for createrawtransaction (Luke Dashjr)
Tree-SHA512: 446e37c617c188cc3b3fd1e2841c98eda6f4869e71cb3249c4a9e54002607d0f1e6bef92187f7894d4e0746ab449cfee89be9f6a1a8831e25c70cf912eac1570
656dbd871 Perform member initialization in initialization lists where possible (practicalswift)
Tree-SHA512: 048380f4da23ab1eaaf471801a01dbd76f2235afb686c1489b30a6bac109195134afc83414b8378d3482a9042d537ec62d30136dadb9347cf06b07fb5c693208
8ad5bde Merge bctest.py into bitcoin-util-test.py (John Newbery)
95836c5 Use shared config file for functional and util tests (John Newbery)
89fcd35 Use an .ini config file for environment vars in bitcoin-util-test.py (John Newbery)
e9265df Change help_text in bitcoin-util-test.py to a docstring. (John Newbery)
ce58e93 Change bitcoin-util-test.py to use Python3 (John Newbery)
Tree-SHA512: 66dab0b4a8546aee0dfaef134a165f1447aff4c0ec335754bbc7d9e55909721c62f09cdbf4b22d02ac1fcd5a9b66780f91e1cc4d8687fae7288cc9072a23a78f
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.
8906a9a0d Fix bumpfee test after #10449 (Russell Yanofsky)
Tree-SHA512: 0838c7696499baf0fb5ee6edf0b081752d6c37578360a7f24a7e9c700598cbc14ff95826f2f5124cca805d2609470a052bc7309211874b13be7ac1ff9e911a34
589827975 scripted-diff: various renames for per-utxo consistency (Pieter Wuille)
a5e02bc7f Increase travis unit test timeout (Pieter Wuille)
73de2c1ff Rename CCoinsCacheEntry::coins to coin (Pieter Wuille)
119e552f7 Merge CCoinsViewCache's GetOutputFor and AccessCoin (Pieter Wuille)
580b02309 [MOVEONLY] Move old CCoins class to txdb.cpp (Pieter Wuille)
8b25d2c0c Upgrade from per-tx database to per-txout (Pieter Wuille)
b2af357f3 Reduce reserved memory space for flushing (Pieter Wuille)
41aa5b79a Pack Coin more tightly (Pieter Wuille)
97072d668 Remove unused CCoins methods (Pieter Wuille)
ce23efaa5 Extend coins_tests (Pieter Wuille)
508307968 Switch CCoinsView and chainstate db from per-txid to per-txout (Pieter Wuille)
4ec0d9e79 Refactor GetUTXOStats in preparation for per-COutPoint iteration (Pieter Wuille)
13870b56f Replace CCoins-based CTxMemPool::pruneSpent with isSpent (Pieter Wuille)
05293f3cb Remove ModifyCoins/ModifyNewCoins (Pieter Wuille)
961e48397 Switch tests from ModifyCoins to AddCoin/SpendCoin (Pieter Wuille)
8b3868c1b Switch CScriptCheck to use Coin instead of CCoins (Pieter Wuille)
c87b957a3 Only pass things committed to by tx's witness hash to CScriptCheck (Matt Corallo)
f68cdfe92 Switch from per-tx to per-txout CCoinsViewCache methods in some places (Pieter Wuille)
000391132 Introduce new per-txout CCoinsViewCache functions (Pieter Wuille)
bd83111a0 Optimization: Coin&& to ApplyTxInUndo (Pieter Wuille)
cb2c7fdac Replace CTxInUndo with Coin (Pieter Wuille)
422634e2f Introduce Coin, a single unspent output (Pieter Wuille)
7d991b55d Store/allow tx metadata in all undo records (Pieter Wuille)
c3aa0c119 Report on-disk size in gettxoutsetinfo (Pieter Wuille)
d34242430 Remove/ignore tx version in utxo and undo (Pieter Wuille)
7e0032290 Add specialization of SipHash for 256 + 32 bit data (Pieter Wuille)
e484652fc Introduce CHashVerifier to hash read data (Pieter Wuille)
f54580e7e error() in disconnect for disk corruption, not inconsistency (Pieter Wuille)
e66dbde6d Add SizeEstimate to CDBBatch (Pieter Wuille)
Tree-SHA512: ce1fb1e40c77d38915cd02189fab7a8b125c7f44d425c85579d872c3bede3a437760997907c99d7b3017ced1c2de54b2ac7223d99d83a6658fe5ef61edef1de3
As the maximum amount of data that can be pulled into the cache due to
a block validation is much lower now (at most one CCoin entry per input
and per output), reduce the conservative estimate used to determine
flushing time.
This patch makes several related changes:
* Changes the CCoinsView virtual methods (GetCoins, HaveCoins, ...)
to be COutPoint/Coin-based rather than txid/CCoins-based.
* Changes the chainstate db to a new incompatible format that is also
COutPoint/Coin based.
* Implements reconstruction code for hash_serialized_2.
* Adapts the coins_tests unit tests (thanks to Russell Yanofsky).
A side effect of the new CCoinsView model is that we can no longer
use the (unreliable) test for transaction outputs in the UTXO set
to determine whether we already have a particular transaction.
This clarifies a bit more the ways in which the new script execution
cache could break consensus in the future if additional data from
the CCoins object were to be used as a part of script execution.
After this change, any such consensus breaks should be very visible
to reviewers, hopefully ensuring no such changes can be made.
The new functions are:
* CCoinsViewCache::AddCoin: Add a single COutPoint/Coin pair.
* CCoinsViewCache::SpendCoin: Remove a single COutPoint.
* AddCoins: utility function that invokes CCoinsViewCache::AddCoin for
each output in a CTransaction.
* AccessByTxid: utility function that searches for any output with
a given txid.
* CCoinsViewCache::AccessCoin: retrieve the Coin for a COutPoint.
* CCoinsViewCache::HaveCoins: check whether a non-empty Coin exists
for a given COutPoint.
The AddCoin and SpendCoin methods will eventually replace ModifyCoins
and ModifyNewCoins, AddCoins will replace CCoins::FromTx, and the new
AccessCoins and HaveCoins functions will replace their per-txid
counterparts.
Note that AccessCoin for now returns a copy of the Coin object. In a
later commit it will be change to returning a const reference (which
keeps working in all call sites).
The earlier CTxInUndo class now holds the same information as the Coin
class. Instead of duplicating functionality, replace CTxInUndo with a
serialization adapter for Coin.
6d7104c99 [Qt] make sure transaction table entry gets updated after bump (Jonas Schnelli)
32325a3f5 [Qt] hide bump context menu action if tx already has been bumped (Jonas Schnelli)
Tree-SHA512: d3e5991145879b7f6b212d9d9c6f423609dc8e6fa7f6feb7df931691f1dec2acb6ab162c2fb7e758d3ca3f3fb14363df2f50f0e83e83068da5cc7e6de35e69d2
b6fbfc2 net: only enforce the services required to connect (Cory Fields)
Tree-SHA512: 88943bff63213a734f3c96c45760cadaeb9ba18287c8a20c279851ebaf058a334c969028fb2180f155508e3eea4b838147382e4f2b655e7a9aa098eadc81d53e
cd5622d Make bitcoind invalid argument error message specific (Wladimir J. van der Laan)
Tree-SHA512: 78999b9359685c4090f9a112e1d02bdddac22173f5f04600773b042acb9481ebb54d0f73d9d6d74249f845f497927a58d59de69bf33e3dccf096c3c80c7ebf6b
