diff --git a/bitcoin/src/blockdata/transaction.rs b/bitcoin/src/blockdata/transaction.rs index 7815e038..e608cd26 100644 --- a/bitcoin/src/blockdata/transaction.rs +++ b/bitcoin/src/blockdata/transaction.rs @@ -318,18 +318,40 @@ impl Sequence { /// BIP-68 relative lock time type flag mask. const LOCK_TYPE_MASK: u32 = 0x00400000; - /// Retuns `true` if the sequence number indicates that the transaction is finalised. + /// Returns `true` if the sequence number enables absolute lock-time ([`Transaction::lock_time`]). + #[inline] + pub fn enables_absolute_lock_time(&self) -> bool { + *self != Sequence::MAX + } + + /// Returns `true` if the sequence number indicates that the transaction is finalized. /// - /// The sequence number being equal to 0xffffffff on all txin sequences indicates - /// that the transaction is finalised. + /// Instead of this method please consider using `!enables_absolute_lock_time` because it + /// is equivalent and improves readability for those not steeped in Bitcoin folklore. + /// + /// ## Historical note + /// + /// The term 'final' is an archaic Bitcoin term, it may have come about because the sequence + /// number in the original Bitcoin code was intended to be incremented in order to replace a + /// transaction, so once the sequence number got to `u64::MAX` it could no longer be increased, + /// hence it was 'final'. + /// + /// + /// Some other references to the term: + /// - `CTxIn::SEQUENCE_FINAL` in the Bitcoin Core code. + /// - [BIP-112]: "BIP 68 prevents a non-final transaction from being selected for inclusion in a + /// block until the corresponding input has reached the specified age" + /// + /// [BIP-112]: #[inline] pub fn is_final(&self) -> bool { - *self == Sequence::MAX + !self.enables_absolute_lock_time() } /// Returns true if the transaction opted-in to BIP125 replace-by-fee. /// - /// Replace by fee is signaled by the sequence being less than 0xfffffffe which is checked by this method. + /// Replace by fee is signaled by the sequence being less than 0xfffffffe which is checked by + /// this method. Note, this is the highest "non-final" value (see [`Sequence::is_final`]). #[inline] pub fn is_rbf(&self) -> bool { *self < Sequence::MIN_NO_RBF @@ -394,12 +416,6 @@ impl Sequence { } } - /// Returns `true` if the sequence number enables absolute lock-time ([`Transaction::lock_time`]). - #[inline] - pub fn enables_absolute_lock_time(&self) -> bool { - !self.is_final() - } - /// Creates a sequence from a u32 value. #[inline] pub fn from_consensus(n: u32) -> Self {