diff --git a/crates/chain/src/chain_data.rs b/crates/chain/src/chain_data.rs index 537f0bf7e9..20c8ebff8e 100644 --- a/crates/chain/src/chain_data.rs +++ b/crates/chain/src/chain_data.rs @@ -147,6 +147,8 @@ impl From<(&u32, &BlockHash)> for BlockId { /// An [`Anchor`] implementation that also records the exact confirmation height of the transaction. /// +/// Note that the confirmation block and the anchor block can be different here. +/// /// Refer to [`Anchor`] for more details. #[derive(Debug, Default, Clone, PartialEq, Eq, Copy, PartialOrd, Ord, core::hash::Hash)] #[cfg_attr( @@ -186,6 +188,8 @@ impl AnchorFromBlockPosition for ConfirmationHeightAnchor { /// An [`Anchor`] implementation that also records the exact confirmation time and height of the /// transaction. /// +/// Note that the confirmation block and the anchor block can be different here. +/// /// Refer to [`Anchor`] for more details. #[derive(Debug, Default, Clone, PartialEq, Eq, Copy, PartialOrd, Ord, core::hash::Hash)] #[cfg_attr( diff --git a/crates/chain/src/chain_oracle.rs b/crates/chain/src/chain_oracle.rs index e736be0354..cb5155724e 100644 --- a/crates/chain/src/chain_oracle.rs +++ b/crates/chain/src/chain_oracle.rs @@ -3,7 +3,7 @@ use crate::BlockId; /// Represents a service that tracks the blockchain. /// /// The main method is [`is_block_in_chain`] which determines whether a given block of [`BlockId`] -/// is an ancestor of another "static block". +/// is an ancestor of the `chain_tip`. /// /// [`is_block_in_chain`]: Self::is_block_in_chain pub trait ChainOracle { diff --git a/crates/chain/src/indexed_tx_graph.rs b/crates/chain/src/indexed_tx_graph.rs index 0e2620e0d1..504ce3cf28 100644 --- a/crates/chain/src/indexed_tx_graph.rs +++ b/crates/chain/src/indexed_tx_graph.rs @@ -1,7 +1,5 @@ -//! Contains the [`IndexedTxGraph`] structure and associated types. -//! -//! This is essentially a [`TxGraph`] combined with an indexer. - +//! Contains the [`IndexedTxGraph`] structure and associated types. Refer to the +//! [`IndexedTxGraph`] documentation for more. use alloc::vec::Vec; use bitcoin::{Block, OutPoint, Transaction, TxOut, Txid}; diff --git a/crates/chain/src/lib.rs b/crates/chain/src/lib.rs index ed167ebf6c..04ca62c4c6 100644 --- a/crates/chain/src/lib.rs +++ b/crates/chain/src/lib.rs @@ -12,9 +12,8 @@ //! you do it synchronously or asynchronously. If you know a fact about the blockchain, you can just //! tell `bdk_chain`'s APIs about it, and that information will be integrated, if it can be done //! consistently. -//! 2. Error-free APIs. -//! 3. Data persistence agnostic -- `bdk_chain` does not care where you cache on-chain data, what you -//! cache or how you fetch it. +//! 2. Data persistence agnostic -- `bdk_chain` does not care where you cache on-chain data, what you +//! cache or how you retrieve it from persistent storage. //! //! [Bitcoin Dev Kit]: https://bitcoindevkit.org/ diff --git a/crates/chain/src/tx_data_traits.rs b/crates/chain/src/tx_data_traits.rs index c957a3e57e..31935c475c 100644 --- a/crates/chain/src/tx_data_traits.rs +++ b/crates/chain/src/tx_data_traits.rs @@ -5,13 +5,17 @@ use alloc::vec::Vec; /// Trait that "anchors" blockchain data to a specific block of height and hash. /// -/// [`Anchor`] implementations must be [`Ord`] by the anchor block's [`BlockId`] first. -/// -/// I.e. If transaction A is anchored in block B, then if block B is in the best chain, we can +/// If transaction A is anchored in block B, and block B is in the best chain, we can /// assume that transaction A is also confirmed in the best chain. This does not necessarily mean /// that transaction A is confirmed in block B. It could also mean transaction A is confirmed in a /// parent block of B. /// +/// Every [`Anchor`] implementation must contain a [`BlockId`] parameter, and must implement +/// [`Ord`]. When implementing [`Ord`], the anchors' [`BlockId`]s should take precedence +/// over other elements inside the [`Anchor`]s for comparison purposes, i.e., you should first +/// compare the anchors' [`BlockId`]s and then care about the rest. +/// [`BlockId`]s. +/// /// ``` /// # use bdk_chain::local_chain::LocalChain; /// # use bdk_chain::tx_graph::TxGraph; @@ -19,7 +23,6 @@ use alloc::vec::Vec; /// # use bdk_chain::ConfirmationHeightAnchor; /// # use bdk_chain::example_utils::*; /// # use bitcoin::hashes::Hash; -/// /// // Initialize the local chain with two blocks. /// let chain = LocalChain::from_blocks( /// [ diff --git a/crates/chain/src/tx_graph.rs b/crates/chain/src/tx_graph.rs index 1f7bcdb122..5440c143c7 100644 --- a/crates/chain/src/tx_graph.rs +++ b/crates/chain/src/tx_graph.rs @@ -1,12 +1,30 @@ //! Module for structures that store and traverse transactions. //! -//! [`TxGraph`] is a monotone structure that inserts transactions and indexes the spends. The -//! [`ChangeSet`] structure reports changes of [`TxGraph`] but can also be applied to a -//! [`TxGraph`] as well. Lastly, [`TxDescendants`] is an [`Iterator`] that traverses descendants of -//! a given transaction. +//! [`TxGraph`] contains transactions and indexes them so you can easily traverse the graph of those transactions. +//! `TxGraph` is *monotone* in that you can always insert a transaction -- it doesn't care whether that +//! transaction is in the current best chain or whether it conflicts with any of the +//! existing transactions or what order you insert the transactions. +//! Furthermore, there is currently no way to delete a transaction. +//! +//! Transactions can be either whole or partial (i.e., transactions for which we only +//! know some outputs, which we usually call "floating outputs"). +//! +//! The graph contains transactions in the form of [`TxNode`]s. Each node contains the +//! txid, the transaction (whole or partial), the blocks it's anchored in (see the [`Anchor`] +//! documentation for more details), and the timestamp of the last time we saw +//! the transaction as unconfirmed. //! //! Conflicting transactions are allowed to coexist within a [`TxGraph`]. This is useful for -//! identifying and traversing conflicts and descendants of a given transaction. +//! identifying and traversing conflicts and descendants of a given transaction. Some [`TxGraph`] +//! methods only consider "canonical" (i.e., in the best chain or in mempool) transactions, +//! we decide which transactions are canonical based on anchors `last_seen_unconfirmed`; +//! see the [`try_get_chain_position`] documentation for more details. +//! +//! The [`ChangeSet`] reports changes made to a [`TxGraph`]; it can be used to either save to +//! persistent storage, or to be applied to another [`TxGraph`]. +//! +//! Lastly, you can use [`TxAncestors`]/[`TxDescendants`] to traverse ancestors and descendants of +//! a given transaction, respectively. //! //! # Applying changes //! @@ -49,6 +67,7 @@ //! let changeset = graph.apply_update(update); //! assert!(changeset.is_empty()); //! ``` +//! [`try_get_chain_position`]: TxGraph::try_get_chain_position use crate::{ collections::*, keychain::Balance, local_chain::LocalChain, Anchor, Append, BlockId, @@ -90,7 +109,7 @@ impl Default for TxGraph { } } -/// An outward-facing view of a (transaction) node in the [`TxGraph`]. +/// A transaction node in the [`TxGraph`]. #[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord)] pub struct TxNode<'a, T, A> { /// Txid of the transaction. @@ -127,7 +146,7 @@ impl Default for TxNodeInternal { } } -/// An outwards-facing view of a transaction that is part of the *best chain*'s history. +/// A transaction that is included in a certain chain. #[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord)] pub struct CanonicalTx<'a, T, A> { /// How the transaction is observed as (confirmed or unconfirmed). @@ -454,7 +473,7 @@ impl TxGraph { /// Batch insert unconfirmed transactions. /// /// Items of `txs` are tuples containing the transaction and a *last seen* timestamp. The - /// *last seen* communicates when the transaction is last seen in the mempool which is used for + /// *last seen* communicates when the transaction is last seen in mempool which is used for /// conflict-resolution (refer to [`TxGraph::insert_seen_at`] for details). pub fn batch_insert_unconfirmed( &mut self, @@ -687,8 +706,21 @@ impl TxGraph { /// Get the position of the transaction in `chain` with tip `chain_tip`. /// - /// If the given transaction of `txid` does not exist in the chain of `chain_tip`, `None` is - /// returned. + /// If the given `txid` does not exist in the chain of `chain_tip`, and + /// we believe that the transaction is not in mempool anymore, `None` is returned. + /// + /// There are two factors that we use to approximate whether an unconfirmed + /// transaction currently exists in mempool: + /// 1. Conflicts with confirmed txs. If the transaction `tx` or any of its unconfirmed + /// ancestors conflict with a confirmed transaction, then `tx` can't be in mempool. + /// 2. The `last_seen_unconfirmed` parameter. Given two conflicting transactions, we say + /// that the one with a higher `last_seen_unconfirmed` (i.e., we saw it later) has a higher + /// chance of still being in mempool. When trying to figure out if `tx` + /// is still in mempool, we first of all calculate `tx`'s `max_last_seen_unconfirmed`, + /// which is the max `last_seen_unconfirmed` between `tx` and all its descendants. + /// We then look at all the conflicts of `tx`, and if for all of them + /// `last_seen_unconfirmed` < `max_last_seen_unconfirmed` holds, + /// then we consider `tx` to be still in mempool. /// /// # Error /// @@ -714,7 +746,7 @@ impl TxGraph { } } - // The tx is not anchored to a block which is in the best chain, which means that it + // The tx is not anchored to a block in the best chain, which means that it // might be in mempool, or it might have been dropped already. // Let's check conflicts to find out! let tx = match tx_node { @@ -911,7 +943,8 @@ impl TxGraph { /// (`OI`) for convenience. If `OI` is not necessary, the caller can use `()`, or /// [`Iterator::enumerate`] over a list of [`OutPoint`]s. /// - /// Floating outputs are ignored. + /// Floating outputs (i.e., outputs for which we don't have the full transaction in the graph) + /// are ignored. /// /// # Error ///