rust-lightning/lightning/src/chain/chaininterface.rs

// This file is Copyright its original authors, visible in version control
// history.
//
// This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
// or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
// You may not use this file except in accordance with one or both of these
// licenses.

//! Traits and utility impls which allow other parts of rust-lightning to interact with the
//! blockchain.
//!
//! Includes traits for monitoring and receiving notifications of new blocks and block
//! disconnections, transaction broadcasting, and feerate information requests.

use bitcoin::blockdata::transaction::Transaction;

/// An interface to send a transaction to the Bitcoin network.
pub trait BroadcasterInterface {
	/// Sends a transaction out to (hopefully) be mined.
	fn broadcast_transaction(&self, tx: &Transaction);
}

/// An enum that represents the speed at which we want a transaction to confirm used for feerate
/// estimation.
#[derive(Clone, Copy, PartialEq, Eq)]
pub enum ConfirmationTarget {
	/// We are happy with this transaction confirming slowly when feerate drops some.
	Background,
	/// We'd like this transaction to confirm without major delay, but 12-18 blocks is fine.
	Normal,
	/// We'd like this transaction to confirm in the next few blocks.
	HighPriority,
}

/// A trait which should be implemented to provide feerate information on a number of time
/// horizons.
///
/// Note that all of the functions implemented here *must* be reentrant-safe (obviously - they're
/// called from inside the library in response to chain events, P2P events, or timer events).
pub trait FeeEstimator {
	/// Gets estimated satoshis of fee required per 1000 Weight-Units.
	///
	/// Must return a value no smaller than 253 (ie 1 satoshi-per-byte rounded up to ensure later
	/// round-downs don't put us below 1 satoshi-per-byte).
	///
	/// This method can be implemented with the following unit conversions:
	///  * max(satoshis-per-byte * 250, 253)
	///  * max(satoshis-per-kbyte / 4, 253)
	fn get_est_sat_per_1000_weight(&self, confirmation_target: ConfirmationTarget) -> u32;
}

/// Minimum relay fee as required by bitcoin network mempool policy.
pub const MIN_RELAY_FEE_SAT_PER_1000_WEIGHT: u64 = 4000;