Using the zmq notifications to avoid excessive mempool polling can be difficult
given the current notifications available. It announces all transactions
being added to mempool or included in blocks, but announces no evictions
and gives no indication if the transaction is in the mempool or a block.
Block notifications for zmq are also substandard, in that it only announces
block tips, while all block transactions are still announced.
This commit adds a unified stream which can be used to closely track mempool:
1) getrawmempool to fill out mempool knowledge
2) if txhash is announced, add or remove from set
based on add/remove flag
3) if blockhash is announced, get block txn list,
remove from those transactions local view of mempool
4) if we drop a sequence number, go to (1)
The mempool sequence number starts at the value 1, and
increments each time a transaction enters the mempool,
or is evicted from the mempool for any reason, including
block inclusion. The mempool sequence number is published
via ZMQ for any transaction-related notification.
These features allow for ZMQ/RPC consumer to track mempool
state in a more exacting way, without unnecesarily polling
getrawmempool. See interface_zmq.py::test_mempool_sync for
example usage.
This fix is a based on the fix by Antoine Riard <ariard@student.42.fr> in
https://github.com/bitcoin/bitcoin/pull/18600.
Unlike that PR, which implements some new behavior, this just restores previous
wallet notification and status behavior for transactions removed from the
mempool because they conflict with transactions in a block. The behavior was
accidentally changed in two `CWallet::BlockConnected` updates:
a31be09bfd and
7e89994133 from
https://github.com/bitcoin/bitcoin/pull/16624, causing issue
https://github.com/bitcoin/bitcoin/issues/18325.
The change here could be improved and replaced with a more comprehensive
cleanup, so it includes a detailed comment explaining future considerations.
Fixes#18325
Co-authored-by: Antoine Riard <ariard@student.42.fr>
50fc4df6c4 [mempool] Persist unbroadcast set to mempool.dat (Amiti Uttarwar)
297a178536 [test] Integration tests for unbroadcast functionality (Amiti Uttarwar)
6851502472 [refactor/test] Extract P2PTxInvStore into test framework (Amiti Uttarwar)
dc1da48dc5 [wallet] Update the rebroadcast frequency to be ~1/day. (Amiti Uttarwar)
e25e42f20a [p2p] Reattempt initial send of unbroadcast transactions (Amiti Uttarwar)
7e93eecce3 [util] Add method that returns random time in milliseconds (Amiti Uttarwar)
89eeb4a333 [mempool] Track "unbroadcast" transactions (Amiti Uttarwar)
Pull request description:
This PR introduces mempool tracking of unbroadcast transactions and periodic reattempts at initial broadcast. This is a part of the rebroadcast project, and a standalone privacy win.
The current rebroadcast logic is terrible for privacy because 1. only the source wallet rebroadcasts transactions and 2. it does so quite frequently. In the current system, if a user submits a transaction that does not immediately get broadcast to the network (eg. they are offline), this "rebroadcast" behavior is the safety net that can actually serve as the initial broadcast. So, keeping the attempts frequent is important for initial delivery within a reasonable timespan.
This PR aims to improve # 2 by reducing the wallet rebroadcast frequency to ~1/day from ~1/15 min. It achieves this by separating the notion of initial broadcast from rebroadcasts. With these changes, the mempool tracks locally submitted transactions & periodically reattempts initial broadcast. Transactions submitted via the wallet or RPC are added to an "unbroadcast" set & are removed when a peer sends a `getdata` request, or the transaction is removed from the mempool. Every 10-15 minutes, the node reattempts an initial broadcast. This enables reducing the wallet rebroadcast frequency while ensuring the transactions will be propagated to the network.
For privacy improvements around # 1, please see #16698.
Thank you to gmaxwell for the idea of how to break out this subset of functionality (https://github.com/bitcoin/bitcoin/pull/16698#issuecomment-571399346)
ACKs for top commit:
fjahr:
Code review ACK 50fc4df6c4
MarcoFalke:
ACK 50fc4df6c4, I think this is ready for merge now 👻
amitiuttarwar:
The current tip `50fc4df` currently has 6 ACKs on it, so I've opened #18807 to address the last bits.
jnewbery:
utACK 50fc4df6c4.
ariard:
Code Review ACK 50fc4df (minor points no need to invalid other ACKs)
robot-visions:
ACK 50fc4df6c4
sipa:
utACK 50fc4df6c4
naumenkogs:
utACK 50fc4df
Tree-SHA512: 2dd935d645d5e209f8abf87bfaa3ef0e4492705ce7e89ea64279cb27ffd37f4727fa94ad62d41be331177332f8edbebf3c7f4972f8cda10dd951b80a28ab3c0f
- Mempool tracks locally submitted transactions (wallet or rpc)
- Transactions are removed from set when the node receives a GETDATA request
from a peer, or if the transaction is removed from the mempool.
NotifyEntryAdded never had any subscribers so can be removed.
Since ConnectTrace no longer subscribes to NotifyEntryRemoved, there are
now no subscribers.
The CValidationInterface TransactionAddedToMempool and
TransactionRemovedFromMempool methods can now provide this
functionality. There's no need for a special notifications framework for
the mempool.
The only CValidationInterface client that cares about transactions that
are removed from the mempool because of CONFLICT is the wallet.
Start using the TransactionRemovedFromMempool method to notify about
conflicted transactions instead of using the vtxConflicted vector in
BlockConnected.
d314e8a818 refactor: Replace all uses of boost::optional with our own Optional type (Wladimir J. van der Laan)
Pull request description:
Replace all uses of boost::optional with our own Optional type. Luckily, there aren't so many.
After this:
- `boost::optional` is no longer used directly (only through `Optional` which is an alias for it)
- `boost/optional.hpp` is only included in one place
ACKs for top commit:
MarcoFalke:
ACK d314e8a818
practicalswift:
ACK d314e8a818 -- diff looks correct + satisfying to see incremental progress towards the goal of a Boost free future :)
jtimon:
ACK d314e8a818
fanquake:
ACK d314e8a818
Tree-SHA512: b43e0017af81b07b5851377cd09624f114510ac5b9018d037664b58ad0fc8e893e30946b61f8f5e21e39125925bf9998a81f2226b468aab2df653ee57ed3213d
After this:
- `boost::optional` is no longer used directly (only through `Optional`
which is an alias for it)
- `boost/optional.hpp` is only included in one place
effe81f750 Move g_is_mempool_loaded into CTxMemPool::m_is_loaded (Ben Woosley)
bb8ae2c419 rpc: Expose g_is_mempool_loaded via getmempoolinfo and /rest/mempool/info.json (Ben Woosley)
Pull request description:
And use it to fix a race condition in mempool_persist.py:
https://travis-ci.org/Empact/bitcoin/jobs/487577243
Since e.g. getrawmempool returns errors based on this status, this
enables users to test it for readiness.
Fixes#12863
ACKs for commit effe81:
MarcoFalke:
utACK effe81f750
jnewbery:
utACK effe81f750
Tree-SHA512: 74328b0c17a97efb8a000d4ee49b9a673c2b6dde7ea30c43a6a2eff961a233351c9471f9a42344412135786c02bdf2ee1b2526651bb8fed68bd94d2120c4ef86
This moves the following policy settings functions and globals to a new
src/policy/settings unit in lib_server:
- `incrementalRelayFee`
- `dustRelayFee`
- `nBytesPerSigOp`
- `fIsBareMultisigStd`
These settings are only required by the node and should not be accessed
by other libraries.
f34c8c466a Make objects in range declarations immutable by default. Avoid unnecessary copying of objects in range declarations. (practicalswift)
Pull request description:
Make objects in range declarations immutable by default.
Rationale:
* Immutable objects are easier to reason about.
* Prevents accidental or hard-to-notice change of value.
Tree-SHA512: cad69d35f0cf8a938b848e65dd537c621d96fe3369be306b65ef0cd1baf6cc0a9f28bc230e1e383d810c555a6743d08cb6b2b0bd51856d4611f537a12e5abb8b
fa587773e5 scripted-diff: Remove unused first argument to addUnchecked (MarcoFalke)
fe5c49766c tx pool: Use the entry's hash instead of the one passed to addUnchecked (MarcoFalke)
ddd395f968 Mark CTxMemPoolEntry members that should not be modified const (MarcoFalke)
Pull request description:
Several years ago the transaction hash was not cached. For optimization the hash was instead passed into `addUnchecked` to avoid re-calculating it. See f77654a0e9
Passing in the hash is now redundant and the argument can safely be removed.
Tree-SHA512: 0206b65c7a014295f67574120e8c5397bf1b1bd70c918ae1360ab093676f7f89a6f084fd2c7000a141baebfe63fe6f515559e38c4ac71810ba64f949f9c0467f
3fc20632a3 qt: Set BLOCK_CHAIN_SIZE = 220 (DrahtBot)
2b6a2f4a28 Regenerate manpages (DrahtBot)
eb7daf4d60 Update copyright headers to 2018 (DrahtBot)
Pull request description:
Some trivial maintenance to avoid having to do it again after the 0.17 branch off.
(The scripts to do this are in `./contrib/`)
Tree-SHA512: 16b2af45e0351b1c691c5311d48025dc6828079e98c2aa2e600dc5910ee8aa01858ca6c356538150dc46fe14c8819ed8ec8e4ec9a0f682b9950dd41bc50518fa
01a06d6686 Avoid locking mutexes that are already held by the same thread (practicalswift)
Pull request description:
Avoid locking mutexes that are already held by the same thread. These are reentrant mutexes, but still no need to lock them more than once per thread :-)
Tree-SHA512: e2fb85882e8800892fd8e8170f3c13128d6acfeb14d7b69fb9555f2b7ad0884fb201cf945b8144ffaf6fb1253c28af7c8c6c435319a7ae30ca003f28aa645a98
f77e1d34fd test: Add MempoolAncestryTests (Karl-Johan Alm)
a08d76bcfe mempool: Calculate descendant maximum thoroughly (Karl-Johan Alm)
6d3568371e wallet: Switch to using ancestor/descendant limits (Karl-Johan Alm)
6888195b06 wallet: Strictly greater than for ancestor caps (Karl-Johan Alm)
322b12ac4e Remove deprecated TransactionWithinChainLimit (Karl-Johan Alm)
4784751547 Switch to GetTransactionAncestry() in OutputEligibleForSpending (Karl-Johan Alm)
475a385a80 Add GetTransactionAncestry to CTxMemPool for general purpose chain limit checking (Karl-Johan Alm)
46847d69d2 mempool: Fix max descendants check (Karl-Johan Alm)
b9ef21dd72 mempool: Add explicit max_descendants (Karl-Johan Alm)
Pull request description:
Currently, `TransactionWithinChainLimit` is restricted to single-output use, and needs to be called every time for different limits. If it is replaced with a chain limit value calculator, that can be called once and reused, and is generally more flexible (see e.g. #12257).
Update: this PR now corrects usage of max ancestors / max descendants, including calculating the correct max descendant value, as advertised for the two limits.
~~This change also makes `nMaxAncestors` signed, as the replacement method will return `-1` for "not in the mempool", which is different from "0", which means "no ancestors/descendants in mempool".~~
~~This is a subset of #12257.~~
Tree-SHA512: aa59c849360542362b3126c0e29d44d3d58f11898e277d38c034dc4b86a5b4500f77ac61767599ce878c876b5c446fec9c02699797eb2fa41e530ec863a00cf9
The chain limits check for max descendants would check the descendants of the transaction itself even though the description for -limitdescendantcount says 'any ancestor'. This commit corrects the descendant count check by finding the top parent transaction in the mempool and comparing against that.
TransactionWithinChainLimits would take a 'limit' and check it against ascendants and descendants. This is changed to take an explicit
max ancestors and max descendants value, and to test the corresponding value against its corresponding max.
b55555d rpc: Add testmempoolaccept (MarcoFalke)
Pull request description:
To check if a single raw transaction makes it into the current transaction pool, one had to call `sendrawtransaction`. However, on success, this adds the transaction to the mempool with no easy way to undo.
The call `testmempoolaccept` is introduced to provide a way to solely check the result without changing the mempool state.
Tree-SHA512: 5afd9311190135cee8fc1f229c7d39bf893f1028f29e28d34f70df820198ff97b4bf86b41cbbd6e6c36a5c30073cefa92d541c74a4939c7a2a6fa283dfd41b63
203a4aa31 Fix CTxMemPoolEntry::UpdateAncestorState: modifySigOps param type int -> int64_t (donaloconnor)
Pull request description:
CTxMemPoolEntry::CTxMemPoolEntry's modifySigOps parameter is int while update_ancestor_state::modifySigOpsCost is int64_t. This issue was raised in #11165. It looks like the function paramaters were not changed in commit 72abd2c
This will avoid unexpected truncation of int64_t -> int
Tree-SHA512: 314c703f217e104336456859066d18fb0d12c4f9f32835e17490a6f29eb05951184095039e4e57edacef8ad35dd75c6d97d9af656a52209dd0c3779b4ffa0914
4e955c5 Near-Bugfix: Reestablish consensus check removed in 8d7849b (Jorge Timón)
3e8c916 Introduce CheckInputsAndUpdateCoins static wrapper in txmempool.cpp (Jorge Timón)
832e074 Optimization: Minimize the number of times it is checked that no money is created (Jorge Timón)
3f0ee3e Proper indentation for CheckTxInputs and other minor fixes (Jorge Timón)
Pull request description:
...is created by individual transactions to 2 places (but call only once in each):
- ConnectBlock ( before calculated fees per txs twice )
- AcceptToMemoryPoolWorker ( before called CheckTxInputs 4 times and calculated
fees per tx one extra time )
Also call tx.GetValueOut() only once per call of CheckTxInputs (instead of 2)
For more motivation:
~~https://github.com/bitcoin/bitcoin/blob/master/src/main.cpp#L1493~~https://github.com/jtimon/bitcoin/compare/0.13-consensus-inputs...jtimon:0.13-consensus-inputs-comments
EDIT: partially replaces #6445
Near-Bugfix as pointed out in https://github.com/bitcoin/bitcoin/pull/8498#discussion_r124346132
Tree-SHA512: c71188e7c7c2425c9170ed7b803896755a92fd22f43b136eedaa6e554106696f0b10271d0ef0d0127c1eaafbc31d12eb19143df4f1b6882feecedf6ef05ea346
by individual transactions to 2 places (but call only once in each):
- ConnectBlock ( before calculated fees per txs twice )
- AcceptToMemoryPoolWorker ( before called CheckTxInputs 4 times and calculated
fees per tx one extra time )
Also call tx.GetValueOut() only once per call of CheckTxInputs (instead of 2)
This resolves an issue where estimatesmartfee would return 999
sat/byte instead of 1000, due to floating point loss of precision
Thanks to sipa for suggesting is_integral.
CFeeRate and CTxMemPoolEntry have explicitly defined copy ctors which has the same functionality as the implicit default copy ctors which would have been generated otherwise.
Besides being redundant, it violates the rule of three (see https://en.wikipedia.org/wiki/Rule_of_three_(C%2B%2B_programming) ).
(Of course, the rule of three doesn't -really- cause a resource management issue here, but the reason for that is exactly that there is no need for an explicit copy ctor in the first place since no resources are being managed).
CFeeRate has an explicitly defined copy ctor which has the same functionality as the implicit default copy ctor which would h
ave been generated otherwise.
This removes the possibility for GetCoin/HaveCoin/HaveCoinInCache to return
true while the respective coin is spent. By doing it across all calls, some
extra checks can be eliminated.
coins_tests is modified to call HaveCoin sometimes before and sometimes
after AccessCoin. A further change is needed because the semantics for
GetCoin slightly changed, causing a pruned entry in the parent cache to not
be pulled into the child in FetchCoin.
5a9b508 [trivial] Add end of namespace comments (practicalswift)
Tree-SHA512: 92b0fcae4d1d3f4da9e97569ae84ef2d6e09625a5815cd0e5f0eb6dd2ecba9852fa85c184c5ae9de5117050330ce995e9867b451fa8cd5512169025990541a2b
A few "a->an" and "an->a".
"Shows, if the supplied default SOCKS5 proxy" -> "Shows if the supplied default SOCKS5 proxy". Change made on 3 occurrences.
"without fully understanding the ramification of a command" -> "without fully understanding the ramifications of a command".
Removed duplicate words such as "the the".
9417d7a33 Be much more agressive in AccessCoin docs. (Matt Corallo)
f58349ca8 Restore some assert semantics in sigop cost calculations (Matt Corallo)
3533fb4d3 Return a bool in SpendCoin to restore pre-per-utxo assert semantics (Matt Corallo)
ec1271f2b Remove useless mapNextTx lookup in CTxMemPool::TrimToSize. (Matt Corallo)
Tree-SHA512: 158a4bce063eac93e1d50709500a10a7cb1fb3271f10ed445d701852fce713e2bf0da3456088e530ab005f194ef4a2adf0c7cb23226b160cecb37a79561f29ca
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.
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
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 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.
This a breaking API change to the prioritisetransaction RPC call which previously required exactly three arguments and now requires exactly two (hash and feeDelta). The function prioritiseTransaction is also updated.
Add notification signals to make it possible to subscribe to mempool
changes:
- NotifyEntryAdded(CTransactionRef)>
- NotifyEntryRemoved(CTransactionRef, MemPoolRemovalReason)>
Also add a mempool removal reason enumeration, which is passed to the
removed notification based on why the transaction was removed from
the mempool.
All decisions about whether the transactions are valid data points are made at the time the transaction arrives. Updating on blocks all the time will now cause stale fee estimates to decay quickly when we restart a node.
Fee estimation can just check its own mapMemPoolTxs to determine the same information. Note that now fee estimation for block processing must happen before those transactions are removed, but this shoudl be a speedup.
f8d43b8 Avoid rollingMinimumFeeRate never being able to decay below half (Alex Morcos)
eab8e1b fix a bug if the min fee is 0 for FeeFilterRounder (Alex Morcos)
cee1612 reduce number of lookups in TransactionWithinChainLimit (Gregory Sanders)
af9bedb Test for fix of txn chaining in wallet (Gregory Sanders)
5882c09 CreateTransaction: Don't return success with too-many-ancestor txn (Gregory Sanders)
0b2294a SelectCoinsMinConf: Prefer coins with fewer ancestors (Gregory Sanders)
There are only a few uses of `insecure_random` outside the tests.
This PR replaces uses of insecure_random (and its accompanying global
state) in the core code with an FastRandomContext that is automatically
seeded on creation.
This is meant to be used for inner loops. The FastRandomContext
can be in the outer scope, or the class itself, then rand32() is used
inside the loop. Useful e.g. for pushing addresses in CNode or the fee
rounding, or randomization for coin selection.
As a context is created per purpose, thus it gets rid of
cross-thread unprotected shared usage of a single set of globals, this
should also get rid of the potential race conditions.
- I'd say TxMempool::check is not called enough to warrant using a special
fast random context, this is switched to GetRand() (open for
discussion...)
- The use of `insecure_rand` in ConnectThroughProxy has been replaced by
an atomic integer counter. The only goal here is to have a different
credentials pair for each connection to go on a different Tor circuit,
it does not need to be random nor unpredictable.
- To avoid having a FastRandomContext on every CNode, the context is
passed into PushAddress as appropriate.
There remains an insecure_random for test usage in `test_random.h`.
Saves about 10% of application memory usage once the mempool warms up. Since the
mempool is DynamicUsage-regulated, this will translate to a larger mempool in
the same amount of space.
Map value type: eliminate the vin index; no users of the map need to know which
input of the transaction is spending the prevout.
Map key type: replace the COutPoint with a pointer to a COutPoint. A COutPoint
is 36 bytes, but each COutPoint is accessible from the same map entry's value.
A trivial DereferencingComparator functor allows indirect map keys, but the
resulting syntax is misleading: `map.find(&outpoint)`. Implement an indirectmap
that acts as a wrapper to a map that uses a DereferencingComparator, supporting
a syntax that accurately reflect the container's semantics: inserts and
iterators use pointers since they store pointers and need them to remain
constant and dereferenceable, but lookup functions take const references.
The ability to GETDATA a transaction which has not (yet) been relayed
is a privacy loss vector.
The use of the mempool for this was added as part of the mempool p2p
message and is only needed to fetch transactions returned by it.
b559914 Move bloom and feerate filtering to just prior to tx sending. (Gregory Maxwell)
4578215 Return mempool queries in dependency order (Pieter Wuille)
ed70683 Handle mempool requests in send loop, subject to trickle (Pieter Wuille)
dc13dcd Split up and optimize transaction and block inv queues (Pieter Wuille)
f2d3ba7 Eliminate TX trickle bypass, sort TX invs for privacy and priority. (Gregory Maxwell)
Previously Bitcoin would send 1/4 of transactions out to all peers
instantly. This causes high overhead because it makes >80% of
INVs size 1. Doing so harms privacy, because it limits the
amount of source obscurity a transaction can receive.
These randomized broadcasts also disobeyed transaction dependencies
and required use of the orphan pool. Because the orphan pool is
so small this leads to poor propagation for dependent transactions.
When the bypass wasn't in effect, transactions were sent in the
order they were received. This avoided creating orphans but
undermines privacy fairly significantly.
This commit:
Eliminates the bypass. The bypass is replaced by halving the
average delay for outbound peers.
Sorts candidate transactions for INV by their topological
depth then by their feerate (then hash); removing the
information leakage and providing priority service to
higher fee transactions.
Limits the amount of transactions sent in a single INV to
7tx/sec (and twice that for outbound); this limits the
harm of low fee transaction floods, gives faster relay
service to higher fee transactions. The 7 sounds lower
than it really is because received advertisements need
not be sent, and because the aggregate rate is multipled
by the number of peers.
The "feefilter" p2p message is used to inform other nodes of your mempool min fee which is the feerate that any new transaction must meet to be accepted to your mempool. This will allow them to filter invs to you according to this feerate.
This implements caching of ancestor state to each mempool entry, similar to
descendant tracking, but also including caching sigops-with-ancestors (as that
metric will be helpful to future code that implements better transaction
selection in CreatenewBlock).
The work limit served to prevent the descendant walking algorithm from doing
too much work by marking the parent transaction as dirty. However to implement
ancestor tracking, it's not possible to similarly mark those descendant
transactions as dirty without having to calculate them to begin with.
This commit removes the work limit altogether. With appropriate
chain limits (-limitdescendantcount) the concern about doing too much
work inside this function should be mitigated.
SequenceLocks functions are used to evaluate sequence lock times or heights per BIP 68.
The majority of this code is copied from maaku in #6312
Further credit: btcdrak, sipa, NicolasDorier
Redo the feerate index to be based on mining score, rather than fee.
Update mempool_packages.py to test prioritisetransaction's effect on
package scores.
The score index is meant to represent the order of priority for being included in a block for miners. Initially this is set to the transactions modified (by any feeDelta) fee rate. Index improvements and unit tests by sdaftuar.
Store sum of legacy and P2SH sig op counts. This is calculated in AcceptToMemory pool and storing it saves redoing the expensive calculation in block template creation.
Compute the value of inputs that already are in the chain at time of mempool entry and only increase priority due to aging for those inputs. This effectively changes the CTxMemPoolEntry's GetPriority calculation from an upper bound to a lower bound.
These are more useful fee and priority estimation functions. If there is no fee/pri high enough for the target you are aiming for, it will give you the estimate for the lowest target that you can reliably obtain. This is better than defaulting to the minimum. It will also pass back the target for which it returned an answer.
After each transaction which is added to mempool, we first call
Expire() to remove old transactions, then throwing away the
lowest-feerate transactions.
After throwing away transactions by feerate, we set the minimum
relay fee to the maximum fee transaction-and-dependant-set we
removed, plus the default minimum relay fee.
After the next block is received, the minimum relay fee is allowed
to decrease exponentially. Its halflife defaults to 12 hours, but
is decreased to 6 hours if the mempool is smaller than half its
maximum size, and 3 hours if the mempool is smaller than a quarter
its maximum size.
The minimum -maxmempool size is 40*-limitdescendantsize, as it is
easy for an attacker to play games with the cheapest
-limitdescendantsize transactions. -maxmempool defaults to 300MB.
This disables high-priority transaction relay when the min relay
fee adjustment is >0 (ie when the mempool is full). When the relay
fee adjustment drops below the default minimum relay fee / 2 it is
set to 0 (re-enabling priority-based free relay).
