Introduce IntentTracker
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| //! Unbroadcasted transaction queue. | ||
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| use alloc::vec::Vec; | ||
| use chain::tx_graph; | ||
| use chain::Anchor; | ||
| use chain::TxGraph; | ||
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| use crate::collections::HashSet; | ||
| use crate::collections::VecDeque; | ||
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| use bitcoin::Txid; | ||
| use chain::Merge; | ||
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| /// An ordered unbroadcasted list. | ||
| /// | ||
| /// It is ordered in case of RBF txs. | ||
| #[derive(Debug, Clone, Default)] | ||
| pub struct BroadcastQueue { | ||
| queue: VecDeque<Txid>, | ||
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| /// Enforces that we do not have duplicates in `queue`. | ||
| dedup: HashSet<Txid>, | ||
|
There was a problem hiding this comment. I wonder if it's worth having this separate set? How many unbroadcasted transactions are we expecting at any given time? Maybe it would just be quicker to simply iterate over the queue itself, also saving the heap allocations/memory footprint? There was a problem hiding this comment. That is a good point. Maybe premature optimization here. |
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| } | ||
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| /// Represents a single mutation to [`BroadcastQueue`]. | ||
| #[derive(Debug, Clone, PartialEq, serde::Deserialize, serde::Serialize)] | ||
| pub enum Mutation { | ||
| /// A push to the back of the queue. | ||
| Push(Txid), | ||
| /// A removal from the queue. | ||
| Remove(Txid), | ||
| } | ||
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| /// A list of mutations made to [`BroadcastQueue`]. | ||
| #[must_use] | ||
| #[derive(Debug, Clone, Default, PartialEq, serde::Deserialize, serde::Serialize)] | ||
| pub struct ChangeSet { | ||
| /// Mutations. | ||
| pub mutations: Vec<Mutation>, | ||
| } | ||
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| impl Merge for ChangeSet { | ||
| fn merge(&mut self, other: Self) { | ||
| self.mutations.extend(other.mutations); | ||
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| } | ||
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| fn is_empty(&self) -> bool { | ||
| self.mutations.is_empty() | ||
| } | ||
| } | ||
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| impl BroadcastQueue { | ||
| /// Construct [`Unbroadcasted`] from the given `changeset`. | ||
| pub fn from_changeset(changeset: ChangeSet) -> Self { | ||
| let mut out = BroadcastQueue::default(); | ||
| out.apply_changeset(changeset); | ||
| out | ||
| } | ||
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| /// Apply the given `changeset`. | ||
| pub fn apply_changeset(&mut self, changeset: ChangeSet) { | ||
| for mutation in changeset.mutations { | ||
| match mutation { | ||
| Mutation::Push(txid) => self._push(txid), | ||
| Mutation::Remove(txid) => self._remove(txid), | ||
| }; | ||
| } | ||
| } | ||
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| /// Whether the `txid` exists in the queue. | ||
| pub fn contains(&self, txid: Txid) -> bool { | ||
| self.dedup.contains(&txid) | ||
| } | ||
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| /// Push a `txid` to the queue if it does not already exist. | ||
| /// | ||
| /// # Warning | ||
| /// | ||
| /// This does not get rid of conflicting transactions already in the queue. | ||
| pub fn push(&mut self, txid: Txid) -> ChangeSet { | ||
| let mut changeset = ChangeSet::default(); | ||
| if self._push(txid) { | ||
| changeset.mutations.push(Mutation::Push(txid)); | ||
| } | ||
| changeset | ||
| } | ||
| fn _push(&mut self, txid: Txid) -> bool { | ||
| if self.dedup.insert(txid) { | ||
| self.queue.push_back(txid); | ||
| return true; | ||
| } | ||
| false | ||
| } | ||
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| /// Push a `txid` to the broadcast queue (if it does not exist already) and displaces all | ||
| /// coflicting txids in the queue. | ||
| pub fn push_and_displace_conflicts<A>(&mut self, tx_graph: &TxGraph<A>, txid: Txid) -> ChangeSet | ||
| where | ||
| A: Anchor, | ||
| { | ||
| let mut changeset = ChangeSet::default(); | ||
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| let tx = match tx_graph.get_tx(txid) { | ||
| Some(tx) => tx, | ||
| None => { | ||
| debug_assert!( | ||
|
There was a problem hiding this comment. Would it be better to throw and I also don't understand why you only panic if the There was a problem hiding this comment. Sorry this was never meant to be in the public API. The idea is that we should only add txids into the |
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| !self.dedup.contains(&txid), | ||
| "Cannot have txid in queue which has no corresponding tx in graph" | ||
| ); | ||
| return changeset; | ||
| } | ||
| }; | ||
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| if self._push(txid) { | ||
| changeset.mutations.push(Mutation::Push(txid)); | ||
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| for txid in tx_graph.walk_conflicts(&tx, |_, conflict_txid| Some(conflict_txid)) { | ||
| if self._remove(txid) { | ||
| changeset.mutations.push(Mutation::Remove(txid)); | ||
| } | ||
| } | ||
| } | ||
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| changeset | ||
| } | ||
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| /// Returns the next `txid` of the queue to broadcast which has no dependencies to other | ||
| /// transactions in the queue. | ||
| pub fn next_to_broadcast<A>(&self, tx_graph: &TxGraph<A>) -> Option<Txid> | ||
| where | ||
| A: Anchor, | ||
| { | ||
| self.queue.iter().copied().find(|&txid| { | ||
| let tx = match tx_graph.get_tx(txid) { | ||
| Some(tx) => tx, | ||
| None => return false, | ||
| }; | ||
| if tx | ||
| .input | ||
| .iter() | ||
| .any(|txin| self.dedup.contains(&txin.previous_output.txid)) | ||
| { | ||
| return false; | ||
| } | ||
| true | ||
| }) | ||
| } | ||
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| /// Returns unbroadcasted dependencies of the given `txid`. | ||
| /// | ||
| /// The returned `Vec` is in broadcast order. | ||
| pub fn unbroadcasted_dependencies<A>(&self, tx_graph: &TxGraph<A>, txid: Txid) -> Vec<Txid> | ||
| where | ||
| A: Anchor, | ||
| { | ||
| let tx = match tx_graph.get_tx(txid) { | ||
| Some(tx) => tx, | ||
| None => return Vec::new(), | ||
| }; | ||
| let mut txs = tx_graph | ||
| .walk_ancestors(tx, |_depth, ancestor_tx| { | ||
| let ancestor_txid = ancestor_tx.compute_txid(); | ||
| if self.dedup.contains(&ancestor_txid) { | ||
| Some(ancestor_txid) | ||
| } else { | ||
| None | ||
| } | ||
| }) | ||
| .collect::<Vec<_>>(); | ||
| txs.reverse(); | ||
| txs | ||
| } | ||
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| /// Untracks and removes a transaction from the broadcast queue. | ||
| /// | ||
| /// Transactions are automatically removed from the queue upon successful broadcast, so calling | ||
| /// this method directly is typically not required. | ||
| pub fn remove(&mut self, txid: Txid) -> ChangeSet { | ||
| let mut changeset = ChangeSet::default(); | ||
| if self._remove(txid) { | ||
| changeset.mutations.push(Mutation::Remove(txid)); | ||
| } | ||
| changeset | ||
| } | ||
| fn _remove(&mut self, txid: Txid) -> bool { | ||
| if self.dedup.remove(&txid) { | ||
| let i = (0..self.queue.len()) | ||
| .zip(self.queue.iter().copied()) | ||
| .find_map(|(i, queue_txid)| if queue_txid == txid { Some(i) } else { None }) | ||
| .expect("must exist in queue to exist in `queue`"); | ||
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| let _removed = self.queue.remove(i); | ||
| debug_assert_eq!(_removed, Some(txid)); | ||
| return true; | ||
| } | ||
| false | ||
| } | ||
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| /// Untracks and removes a transaction and it's descendants from the broadcast queue. | ||
| pub fn remove_and_displace_dependants<A>( | ||
| &mut self, | ||
| tx_graph: &TxGraph<A>, | ||
| txid: Txid, | ||
| ) -> ChangeSet | ||
| where | ||
| A: Anchor, | ||
| { | ||
| let mut changeset = ChangeSet::default(); | ||
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| if self._remove(txid) { | ||
| changeset.mutations.push(Mutation::Remove(txid)); | ||
| for txid in tx_graph.walk_descendants(txid, |_depth, txid| Some(txid)) { | ||
| if self._remove(txid) { | ||
| changeset.mutations.push(Mutation::Remove(txid)); | ||
| } | ||
| } | ||
| } | ||
| changeset | ||
| } | ||
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| /// Untrack transactions that are given anchors and/or mempool timestamps. | ||
| pub fn filter_from_graph_changeset<A>( | ||
| &mut self, | ||
| graph_changeset: &tx_graph::ChangeSet<A>, | ||
| ) -> ChangeSet { | ||
| let mut changeset = ChangeSet::default(); | ||
| let s_txids = graph_changeset.last_seen.keys().copied(); | ||
| let a_txids = graph_changeset.anchors.iter().map(|(_, txid)| *txid); | ||
| let e_txids = graph_changeset.last_evicted.keys().copied(); | ||
| for txid in s_txids.chain(a_txids).chain(e_txids) { | ||
| changeset.merge(self.remove(txid)); | ||
| } | ||
| changeset | ||
| } | ||
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| /// Txids ordered by precedence. | ||
| /// | ||
| /// Transactions with greater precedence will appear later in this list. | ||
| pub fn txids(&self) -> impl ExactSizeIterator<Item = Txid> + '_ { | ||
| self.queue.iter().copied() | ||
| } | ||
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| /// Initial changeset. | ||
| pub fn initial_changeset(&self) -> ChangeSet { | ||
| ChangeSet { | ||
| mutations: self.queue.iter().copied().map(Mutation::Push).collect(), | ||
| } | ||
| } | ||
| } | ||
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Maybe an enum
statefield with something like:UNSPENT,ON_QUEUE,SPENT,BROADCASTEDwill avoid keep adding new boolean fields here, and provide a better path for update on future occasions, taking advantage of non exhaustive patters.is_spentcould be marked for deprecation and be used along the new field in the meantime.There was a problem hiding this comment.
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I like this idea if done as a non-exhaustive enum to help reduce future API breaking changes. If we include a "LOCKED" variant could this also support #259?