75f51f2a introduced asynchronous processing for blocks, where reject messages
and DoS scoring could be applied outside of ProcessBlock, because block
validation may happen later.
However, some types of errors are still detected immediately (in particular,
CheckBlock violations), which need acting after ProcessBlock returns.
The wallet now uses the mempool fee estimator with a new
command-line option: -txconfirmtarget (default: 1) instead
of using hard-coded fees or priorities.
A new bitcoind that hasn't seen enough transactions to estimate
will fall back to the old hard-coded minimum priority or
transaction fee.
-paytxfee option overrides -txconfirmtarget.
Relaying and mining code isn't changed.
For Qt, the coin control dialog now uses priority estimates to
label transaction priority (instead of hard-coded constants);
unspent outputs were consistently labeled with a much higher
priority than is justified by the free transactions actually
being accepted into blocks.
I did not implement any GUI for setting -txconfirmtarget; I would
suggest getting rid of the "Pay transaction fee" GUI and replace
it with either "target number of confirmations" or maybe
a "faster confirmation <--> lower fee" slider or select box.
The original comment forgets to account for the script push which will
need an OP_PUSHDATA2 + 2-bytes for the 513 script bytes.
props davecgh
fixes#4224
Allows network wallets and other clients to see transactions that respend
a prevout already spent in an unconfirmed transaction in this node's mempool.
Knowledge of an attempted double-spend is of interest to recipients of the
first spend. In some cases, it will allow these recipients to withhold
goods or services upon being alerted of a double-spend that deprives them
of payment.
As before, respends are not added to the mempool.
Anti-Denial-of-Service-Attack provisions:
- Use a bloom filter to relay only one respend per mempool prevout
- Rate-limit respend relays to a default of 100 thousand bytes/minute
- Define tx2.IsEquivalentTo(tx1): equality when scriptSigs are not considered
- Do not relay these equivalent transactions
Remove an unused variable declaration in txmempool.cpp.
Relax the AreInputsStandard() tests for P2SH transactions --
allow any Script in a P2SH transaction to be relayed/mined,
as long as it has 15 or fewer signature operations.
Rationale: https://gist.github.com/gavinandresen/88be40c141bc67acb247
I don't have an easy way to test this, but the code changes are
straightforward and I've updated the AreInputsStandard unit tests.
... instead of after 30 minutes of no sending, for latency measurement
and keep-alive. Also, disconnect if no reply arrives within 20 minutes,
instead of 90 of inactivity (for peers supporting the 'pong' message).
New RPC methods: return an estimate of the fee (or priority) a
transaction needs to be likely to confirm in a given number of
blocks.
Mike Hearn created the first version of this method for estimating fees.
It works as follows:
For transactions that took 1 to N (I picked N=25) blocks to confirm,
keep N buckets with at most 100 entries in each recording the
fees-per-kilobyte paid by those transactions.
(separate buckets are kept for transactions that confirmed because
they are high-priority)
The buckets are filled as blocks are found, and are saved/restored
in a new fee_estiamtes.dat file in the data directory.
A few variations on Mike's initial scheme:
To estimate the fee needed for a transaction to confirm in X buckets,
all of the samples in all of the buckets are used and a median of
all of the data is used to make the estimate. For example, imagine
25 buckets each containing the full 100 entries. Those 2,500 samples
are sorted, and the estimate of the fee needed to confirm in the very
next block is the 50'th-highest-fee-entry in that sorted list; the
estimate of the fee needed to confirm in the next two blocks is the
150'th-highest-fee-entry, etc.
That algorithm has the nice property that estimates of how much fee
you need to pay to get confirmed in block N will always be greater
than or equal to the estimate for block N+1. It would clearly be wrong
to say "pay 11 uBTC and you'll get confirmed in 3 blocks, but pay
12 uBTC and it will take LONGER".
A single block will not contribute more than 10 entries to any one
bucket, so a single miner and a large block cannot overwhelm
the estimates.
Use CFeeRate instead of an int64_t for quantities that are
fee-per-size.
Helps prevent unit-conversion mismatches between the wallet,
relaying, and mining code.
Removes the limits on number of pubkeys for P2SH CHECKMULTISIG outputs.
Previously with the 500 byte scriptSig limit there were odd restrictions
where even a 1-of-12 P2SH could be spent in a standard transaction(1),
yet multisig scriptPubKey's requiring more signatures quickly ran out of
scriptSig space.
From a "stuff-data-in-the-blockchain" point of view not much has changed
as with the prior commit now only allowing the dummy value to be null
the newly allowed scriptSig space can only be used for signatures. In
any case, just using more outputs is trivial and doesn't cost much.
1) See 779b519480d8c5346de6e635119c7ee772e97ec872240c45e558f582a37b4b73
Mined by BTC Guild.
Size specifiers are no longer needed now that we use typesafe tinyformat
for string formatting, instead of the system's sprintf.
No functional changes.
This continues the work in #3735.
Generally useless information. Only updates on connect time, not after
that. Peers can easily lie and the median filter is not effective in
preventing that.
In the past it was used for progress display in the GUI but
`CheckPoints::guessVerificationProgress` provides a better way that is now used.
It was too easy to mislead it. Peers do lie about it in practice, see issue #4065.
From the RPC, `getpeerinfo` gives the peer raw values, which are more
useful.
jtimon