Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Use worst-case fee estimates #681

Merged
merged 1 commit into from
Oct 20, 2022
Merged

Use worst-case fee estimates #681

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
55 changes: 31 additions & 24 deletions src/subcommand/wallet/transaction_builder.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -25,9 +25,10 @@

use {
super::*,
bitcoin::blockdata::locktime::PackedLockTime,
bitcoin::blockdata::witness::Witness,
bitcoin::util::amount::Amount,
bitcoin::{
blockdata::{locktime::PackedLockTime, script, witness::Witness},
util::amount::Amount,
},
std::collections::{BTreeMap, BTreeSet},
};

Expand Down Expand Up @@ -235,16 +236,25 @@ impl TransactionBuilder {
self
}

fn estimate_fee(&self) -> Amount {
let dummy_transaction = Transaction {
/// Estimate the size in virtual bytes of the transaction being built. Since
/// we don't know the size of the input script sigs and witnesses, assume
/// they are P2PKH, so that we get a worst case estimate, since it's probably
/// better to pay too overestimate and pay too much in fees than to
/// underestimate and never get the transaction confirmed, or, even worse, be
/// under the minimum relay fee and never even get relayed.
fn estimate_vsize(&self) -> usize {
Transaction {
version: 1,
lock_time: PackedLockTime::ZERO,
input: self
.inputs
.iter()
.map(|_| TxIn {
previous_output: OutPoint::null(),
script_sig: Script::new(),
script_sig: script::Builder::new()
.push_slice(&[0; 71])
.push_slice(&[0; 65])
.into_script(),
sequence: Sequence::ENABLE_RBF_NO_LOCKTIME,
witness: Witness::new(),
})
Expand All @@ -257,9 +267,12 @@ impl TransactionBuilder {
script_pubkey: address.script_pubkey(),
})
.collect(),
};
}
.vsize()
}

Self::TARGET_FEE_RATE * dummy_transaction.vsize().try_into().unwrap()
fn estimate_fee(&self) -> Amount {
Self::TARGET_FEE_RATE * self.estimate_vsize().try_into().unwrap()
}

fn build(self) -> Transaction {
Expand Down Expand Up @@ -377,7 +390,7 @@ impl TransactionBuilder {
fee -= Amount::from_sat(output.value);
}

let fee_rate = fee.to_sat() as f64 / transaction.vsize() as f64;
let fee_rate = fee.to_sat() as f64 / self.estimate_vsize() as f64;
let target_fee_rate = Self::TARGET_FEE_RATE.to_sat() as f64;
assert!(
fee_rate == target_fee_rate,
Expand Down Expand Up @@ -536,7 +549,7 @@ mod tests {
outputs: vec![
(recipient(), Amount::from_sat(5_000)),
(change(0), Amount::from_sat(5_000)),
(change(1), Amount::from_sat(1_774)),
(change(1), Amount::from_sat(1_360)),
],
};

Expand All @@ -549,7 +562,7 @@ mod tests {
output: vec![
tx_out(5_000, recipient()),
tx_out(5_000, change(0)),
tx_out(1_774, change(1))
tx_out(1_360, change(1))
],
}
)
Expand All @@ -570,7 +583,7 @@ mod tests {
version: 1,
lock_time: PackedLockTime::ZERO,
input: vec![tx_in(outpoint(1))],
output: vec![tx_out(5_000 - 82, recipient())],
output: vec![tx_out(4780, recipient())],
})
)
}
Expand Down Expand Up @@ -611,7 +624,7 @@ mod tests {
version: 1,
lock_time: PackedLockTime::ZERO,
input: vec![tx_in(outpoint(1)), tx_in(outpoint(2))],
output: vec![tx_out(4_950, change(1)), tx_out(4_896, recipient())],
output: vec![tx_out(4_950, change(1)), tx_out(4_620, recipient())],
})
)
}
Expand Down Expand Up @@ -670,7 +683,7 @@ mod tests {
output: vec![
tx_out(4_950, change(1)),
tx_out(TransactionBuilder::TARGET_POSTAGE.to_sat(), recipient()),
tx_out(9_865, change(0)),
tx_out(9_589, change(0)),
],
})
)
Expand Down Expand Up @@ -753,10 +766,7 @@ mod tests {
input: vec![tx_in(outpoint(1))],
output: vec![
tx_out(TransactionBuilder::TARGET_POSTAGE.to_sat(), recipient()),
tx_out(
1_000_000 - TransactionBuilder::TARGET_POSTAGE.to_sat() - 113,
change(1)
)
tx_out(989_749, change(1))
],
})
)
Expand Down Expand Up @@ -793,10 +803,7 @@ mod tests {
version: 1,
lock_time: PackedLockTime::ZERO,
input: vec![tx_in(outpoint(1))],
output: vec![
tx_out(3_333, change(1)),
tx_out(10_000 - 3_333 - 113, recipient())
],
output: vec![tx_out(3_333, change(1)), tx_out(6_416, recipient())],
})
)
}
Expand All @@ -819,7 +826,7 @@ mod tests {
version: 1,
lock_time: PackedLockTime::ZERO,
input: vec![tx_in(outpoint(2)), tx_in(outpoint(1))],
output: vec![tx_out(10_001, change(1)), tx_out(9_845, recipient())],
output: vec![tx_out(10_001, change(1)), tx_out(9_569, recipient())],
})
)
}
Expand Down Expand Up @@ -923,7 +930,7 @@ mod tests {
version: 1,
lock_time: PackedLockTime::ZERO,
input: vec![tx_in(outpoint(1)), tx_in(outpoint(3))],
output: vec![tx_out(4_950, change(1)), tx_out(4_896, recipient())],
output: vec![tx_out(4_950, change(1)), tx_out(4_620, recipient())],
})
)
}
Expand Down