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Add total_weight to Input Weight Prediction

This commit is contained in:
yancy 2024-11-25 11:07:24 -06:00
parent cc4c36e8ac
commit 261c8d8ae6
1 changed files with 17 additions and 16 deletions
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33
bitcoin/src/blockdata/transaction.rs
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@ -851,19 +851,13 @@ where
I: IntoIterator<Item = InputWeightPrediction>,
O: IntoIterator<Item = usize>,
{
// This fold() does three things:
// 1) Counts the inputs and returns the sum as `input_count`.
// 2) Sums all of the input weights and returns the sum as `partial_input_weight`
// For every input: script_size * 4 + witness_size
// Since script_size is non-witness data, it gets a 4x multiplier.
// 3) Counts the number of inputs that have a witness data and returns the count as
// `num_inputs_with_witnesses`.
let (input_count, partial_input_weight, inputs_with_witnesses) = inputs.into_iter().fold(
// sum input_weights, input_count and count of inputs with witness data
let (input_count, input_weight, inputs_with_witnesses) = inputs.into_iter().fold(
(0, 0, 0),
|(count, partial_input_weight, inputs_with_witnesses), prediction| {
|(count, input_weight, inputs_with_witnesses), prediction| {
(
count + 1,
partial_input_weight + prediction.witness_weight().to_wu() as usize,
input_weight + prediction.total_weight().to_wu() as usize,
inputs_with_witnesses + (prediction.witness_size > 0) as usize,
)
},
@ -882,7 +876,7 @@ where
);
predict_weight_internal(
input_count,
partial_input_weight,
input_weight,
inputs_with_witnesses,
output_count,
output_scripts_size,
@ -891,15 +885,11 @@ where
const fn predict_weight_internal(
input_count: usize,
partial_input_weight: usize,
input_weight: usize,
inputs_with_witnesses: usize,
output_count: usize,
output_scripts_size: usize,
) -> Weight {
// Lengths of txid, index and sequence: (32, 4, 4).
// Multiply the lengths by 4 since the fields are all non-witness fields.
let input_weight = partial_input_weight + input_count * 4 * (32 + 4 + 4);
// The value field of a TxOut is 8 bytes.
let output_size = 8 * output_count + output_scripts_size;
let non_input_size =
@ -1147,6 +1137,17 @@ impl InputWeightPrediction {
Self::witness_weight(self)
}
/// Computes the signature, prevout (txid, index), and sequence weights of this weight
/// prediction.
///
/// See also [`InputWeightPrediction::witness_weight`]
pub const fn total_weight(&self) -> Weight {
// `impl const Trait` is currently unavailable: rust/issues/67792
// Convert to u64s because we can't use `Add` in const context.
let weight = TX_IN_BASE_WEIGHT.to_wu() + Self::witness_weight(self).to_wu();
Weight::from_wu(weight)
}
/// Computes the **signature weight** added to a transaction by an input with this weight prediction,
/// not counting the prevout (txid, index), sequence, potential witness flag bytes or the witness count varint.
///