Enum LockTime 

pub enum LockTime {
    Blocks(NumberOfBlocks),
    Time(NumberOf512Seconds),
}

A relative lock time value, representing either a count of blocks or time (512 second intervals).

Used for sequence numbers (nSequence in Bitcoin Core and TxIn::sequence in rust-bitcoin) and also for the argument to opcode OP_CHECKSEQUENCEVERIFY.

Note on ordering

Locktimes may be block- or time-based, and these metrics are incommensurate; there is no total ordering on locktimes. In order to compare locktimes, instead of using < or > we provide the LockTime::is_satisfied_by API.

Relevant BIPs

• BIP-0068 Relative lock-time using consensus-enforced sequence numbers
• BIP-0112 CHECKSEQUENCEVERIFY

Variants

Blocks(NumberOfBlocks)

A lock time measured in number of blocks.

Time(NumberOf512Seconds)

A 512 second time interval value.

Implementations

impl LockTime

pub const ZERO: Self

A relative locktime of 0 is always valid, and is assumed valid for inputs that are not yet confirmed.

pub const SIZE: usize = 4

The number of bytes that the locktime contributes to the size of a transaction.

pub fn from_consensus(n: u32) -> Result<Self, DisabledLockTimeError>

Constructs a new LockTime from an nSequence value or the argument to OP_CHECKSEQUENCEVERIFY.

This method will not round-trip with Self::to_consensus_u32, because relative locktimes only use some bits of the underlying u32 value and discard the rest. If you want to preserve the full value, you should use the Sequence type instead.

Errors

If n, interpreted as a Sequence number does not encode a relative lock time.

Examples

// Values with bit 22 set to 0 will be interpreted as block-based lock times.
let blocks: u32 = 144; // 144 blocks, approx 24h.
let lock_time = relative::LockTime::from_consensus(blocks)?;
assert!(lock_time.is_block_count());
assert_eq!(lock_time.to_consensus_u32(), blocks);

// Values with bit 22 set to 1 will be interpreted as time-based lock times.
let time: u32 = 168 | (1 << 22) ; // Bit 22 is 1 with time approx 24h.
let lock_time = relative::LockTime::from_consensus(time)?;
assert!(lock_time.is_block_time());
assert_eq!(lock_time.to_consensus_u32(), time);

pub fn to_consensus_u32(self) -> u32

Returns the u32 value used to encode this locktime in an nSequence field or argument to OP_CHECKSEQUENCEVERIFY.

Warning

Locktimes are not ordered by the natural ordering on u32. If you want to compare locktimes, use Self::is_implied_by or similar methods.

pub fn from_sequence(n: Sequence) -> Result<Self, DisabledLockTimeError>

Constructs a new LockTime from the sequence number of a Bitcoin input.

This method will not round-trip with Self::to_sequence. See the docs for Self::from_consensus for more information.

Errors

If n does not encode a relative lock time.

Examples

// Interpret a sequence number from a Bitcoin transaction input as a relative lock time
let sequence_number = Sequence::from_consensus(144); // 144 blocks, approx 24h.
let lock_time = relative::LockTime::from_sequence(sequence_number)?;
assert!(lock_time.is_block_count());

pub fn to_sequence(self) -> Sequence

Encodes the locktime as a sequence number.

pub const fn from_block_count(n: u16) -> Self

Constructs a new LockTime from n, expecting n to be a 16-bit count of blocks.

pub const fn from_512_second_intervals(intervals: u16) -> Self

Constructs a new LockTime from n, expecting n to be a count of 512-second intervals.

This function is a little awkward to use, and users may wish to instead use Self::from_seconds_floor or Self::from_seconds_ceil.

pub const fn from_seconds_floor(seconds: u32) -> Result<Self, TimeOverflowError>

Constructs a new LockTime from seconds, converting the seconds into 512 second interval with truncating division.

Errors

Will return an error if the input cannot be encoded in 16 bits.

pub const fn from_seconds_ceil(seconds: u32) -> Result<Self, TimeOverflowError>

Constructs a new LockTime from seconds, converting the seconds into 512 second interval with ceiling division.

Errors

Will return an error if the input cannot be encoded in 16 bits.

pub const fn is_same_unit(self, other: Self) -> bool

Returns true if both lock times use the same unit i.e., both height based or both time based.

pub const fn is_block_count(self) -> bool

Returns true if this lock time value is in units of blocks.

pub const fn is_block_time(self) -> bool

Returns true if this lock time value is in units of time.

pub fn is_satisfied_by( self, chain_tip_height: BlockHeight, chain_tip_mtp: BlockMtp, utxo_mined_at_height: Option<BlockHeight>, utxo_mined_at_mtp: Option<BlockMtp>, ) -> Result<bool, IsSatisfiedByError>

Returns true if this relative::LockTime is satisfied by the given chain state.

If this function returns true then an output with this locktime can be spent in the next block.

Arguments

• chain_tip_height: The current height of the blockchain.
• chain_tip_mtp: The current MTP (i.e. median of the 11 latest blocks).
• utxo_mined_at_height: Some height if mined, None if UTXO may go in the next block.
• utxo_mined_at_mtp: Some MTP if mined, None if UTXO may go in the next block.

Errors

If chain_tip is not after utxo_mined_at i.e., if you get the args mixed up.

pub fn is_satisfied_by_height( self, chain_tip: BlockHeight, utxo_mined_at: Option<BlockHeight>, ) -> Result<bool, IsSatisfiedByHeightError>

Returns true if an output with this locktime can be spent in the next block.

Arguments

• chain_tip: The current height of the blockchain.
• utxo_mined_at: Some height if mined, None if UTXO may go in the next block.

Errors

Returns an error if this lock is not lock-by-block-count.

pub fn is_satisfied_by_time( self, chain_tip: BlockMtp, utxo_mined_at: Option<BlockMtp>, ) -> Result<bool, IsSatisfiedByTimeError>

Returns true if an output with this locktime can be spent in the next block.

Arguments

• chain_tip: The current MTP (i.e. median of the 11 latest blocks).
• utxo_mined_at: Some MTP if mined, None if UTXO may go in the next block.

Errors

Returns an error if this lock is not lock-by-time.

pub fn is_implied_by(self, other: Self) -> bool

Returns true if satisfaction of other lock time implies satisfaction of this relative::LockTime.

A lock time can only be satisfied by n blocks being mined or n seconds passing. If you have two lock times (same unit) then the larger lock time being satisfied implies (in a mathematical sense) the smaller one being satisfied.

This function is useful when checking sequence values against a lock, first one checks the sequence represents a relative lock time by converting to LockTime then use this function to see if satisfaction of the newly created lock time would imply satisfaction of self.

Can also be used to remove the smaller value of two OP_CHECKSEQUENCEVERIFY operations within one branch of the script.

Examples

let satisfied = match test_sequence.to_relative_lock_time() {
    None => false, // Handle non-lock-time case.
    Some(test_lock) => lock.is_implied_by(test_lock),
};
assert!(satisfied);

pub fn is_implied_by_sequence(self, other: Sequence) -> bool

Returns true if satisfaction of the sequence number implies satisfaction of this lock time.

When deciding whether an instance of <n> CHECKSEQUENCEVERIFY will pass, this method can be used by parsing n as a LockTime and calling this method with the sequence number of the input which spends the script.

Examples

let sequence = Sequence::from_consensus(1 << 22 | 168); // Bit 22 is 1 with time approx 24h.
let lock_time = relative::LockTime::from_sequence(sequence)?;
let input_sequence = Sequence::from_consensus(1 << 22 | 336); // Approx 48h.
assert!(lock_time.is_block_time());

assert!(lock_time.is_implied_by_sequence(input_sequence));

Trait Implementations

impl<'a> Arbitrary<'a> for LockTime

Available on crate feature arbitrary only.

fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self>

Generate an arbitrary value of Self from the given unstructured data.

fn arbitrary_take_rest(u: Unstructured<'a>) -> Result<Self, Error>

Generate an arbitrary value of Self from the entirety of the given unstructured data.

fn size_hint(depth: usize) -> (usize, Option<usize>)

Get a size hint for how many bytes out of an Unstructured this type needs to construct itself.

fn try_size_hint( depth: usize, ) -> Result<(usize, Option<usize>), MaxRecursionReached>

Get a size hint for how many bytes out of an Unstructured this type needs to construct itself.

impl Clone for LockTime

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for LockTime

impl Debug for LockTime

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for LockTime

Available on crate feature serde only.

fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Display for LockTime

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for LockTime

impl From<LockTime> for Sequence

fn from(lt: LockTime) -> Self

Converts to this type from the input type.

impl From<NumberOf512Seconds> for LockTime

fn from(t: NumberOf512Seconds) -> Self

Converts to this type from the input type.

impl From<NumberOfBlocks> for LockTime

fn from(h: NumberOfBlocks) -> Self

Converts to this type from the input type.

impl Hash for LockTime

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for LockTime

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl Serialize for LockTime

Available on crate feature serde only.

fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>

where S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for LockTime

impl TryFrom<Sequence> for LockTime

type Error = DisabledLockTimeError

The type returned in the event of a conversion error.

fn try_from(seq: Sequence) -> Result<Self, DisabledLockTimeError>

Performs the conversion.