feat(chain): add sync/full-scan structures for spk-based syncing

These structures allows spk-based chain-sources to have a universal API.

Co-authored-by: Steve Myers <[email protected]>

crates/chain/src/lib.rs

@@ -51,6 +51,7 @@ pub use descriptor_ext::DescriptorExt;
 mod spk_iter;
 #[cfg(feature = "miniscript")]
 pub use spk_iter::*;
+pub mod spk_client;
 
 #[allow(unused_imports)]
 #[macro_use]

crates/chain/src/spk_client.rs

@@ -0,0 +1,315 @@
+//! Helper types for spk-based blockchain clients.
+
+use core::{fmt::Debug, ops::RangeBounds};
+
+use alloc::{boxed::Box, collections::BTreeMap, vec::Vec};
+use bitcoin::{OutPoint, Script, ScriptBuf, Txid};
+
+use crate::{local_chain::CheckPoint, ConfirmationTimeHeightAnchor, TxGraph};
+
+/// Data required to perform a spk-based blockchain client sync.
+///
+/// A client sync fetches relevant chain data for a known list of scripts, transaction ids and
+/// outpoints. The sync process also updates the chain from the given [`CheckPoint`].
+pub struct SyncRequest {
+    /// A checkpoint for the current chain [`LocalChain::tip`].
+    /// The sync process will return a new chain update that extends this tip.
+    ///
+    /// [`LocalChain::tip`]: crate::local_chain::LocalChain::tip
+    pub chain_tip: CheckPoint,
+    /// Transactions that spend from or to these indexed script pubkeys.
+    pub spks: Box<dyn Iterator<Item = ScriptBuf> + Send>,
+    /// Transactions with these txids.
+    pub txids: Box<dyn Iterator<Item = Txid> + Send>,
+    /// Transactions with these outpoints or spent from these outpoints.
+    pub outpoints: Box<dyn Iterator<Item = OutPoint> + Send>,
+}
+
+impl SyncRequest {
+    /// Construct a new [`SyncRequest`] from a given `cp` tip.
+    pub fn from_chain_tip(cp: CheckPoint) -> Self {
+        Self {
+            chain_tip: cp,
+            spks: Box::new(core::iter::empty()),
+            txids: Box::new(core::iter::empty()),
+            outpoints: Box::new(core::iter::empty()),
+        }
+    }
+
+    /// Set the [`Script`]s that will be synced against.
+    ///
+    /// This consumes the [`SyncRequest`] and returns the updated one.
+    #[must_use]
+    pub fn set_spks(
+        mut self,
+        spks: impl IntoIterator<IntoIter = impl Iterator<Item = ScriptBuf> + Send + 'static>,
+    ) -> Self {
+        self.spks = Box::new(spks.into_iter());
+        self
+    }
+
+    /// Set the [`Txid`]s that will be synced against.
+    ///
+    /// This consumes the [`SyncRequest`] and returns the updated one.
+    #[must_use]
+    pub fn set_txids(
+        mut self,
+        txids: impl IntoIterator<IntoIter = impl Iterator<Item = Txid> + Send + 'static>,
+    ) -> Self {
+        self.txids = Box::new(txids.into_iter());
+        self
+    }
+
+    /// Set the [`OutPoint`]s that will be synced against.
+    ///
+    /// This consumes the [`SyncRequest`] and returns the updated one.
+    #[must_use]
+    pub fn set_outpoints(
+        mut self,
+        outpoints: impl IntoIterator<IntoIter = impl Iterator<Item = OutPoint> + Send + 'static>,
+    ) -> Self {
+        self.outpoints = Box::new(outpoints.into_iter());
+        self
+    }
+
+    /// Chain on additional [`Script`]s that will be synced against.
+    ///
+    /// This consumes the [`SyncRequest`] and returns the updated one.
+    #[must_use]
+    pub fn chain_spks(
+        mut self,
+        spks: impl IntoIterator<
+            IntoIter = impl Iterator<Item = ScriptBuf> + Send + 'static,
+            Item = ScriptBuf,
+        >,
+    ) -> Self {
+        self.spks = Box::new(self.spks.chain(spks));
+        self
+    }
+
+    /// Chain on additional [`Txid`]s that will be synced against.
+    ///
+    /// This consumes the [`SyncRequest`] and returns the updated one.
+    #[must_use]
+    pub fn chain_txids(
+        mut self,
+        txids: impl IntoIterator<IntoIter = impl Iterator<Item = Txid> + Send + 'static, Item = Txid>,
+    ) -> Self {
+        self.txids = Box::new(self.txids.chain(txids));
+        self
+    }
+
+    /// Chain on additional [`OutPoint`]s that will be synced against.
+    ///
+    /// This consumes the [`SyncRequest`] and returns the updated one.
+    #[must_use]
+    pub fn chain_outpoints(
+        mut self,
+        outpoints: impl IntoIterator<
+            IntoIter = impl Iterator<Item = OutPoint> + Send + 'static,
+            Item = OutPoint,
+        >,
+    ) -> Self {
+        self.outpoints = Box::new(self.outpoints.chain(outpoints));
+        self
+    }
+
+    /// Add a closure that will be called for each [`Script`] synced in this request.
+    ///
+    /// This consumes the [`SyncRequest`] and returns the updated one.
+    #[must_use]
+    pub fn inspect_spks(mut self, inspect: impl Fn(&Script) + Send + Sync + 'static) -> Self {
+        self.spks = Box::new(self.spks.inspect(move |spk| inspect(spk)));
+        self
+    }
+
+    /// Add a closure that will be called for each [`Txid`] synced in this request.
+    ///
+    /// This consumes the [`SyncRequest`] and returns the updated one.
+    #[must_use]
+    pub fn inspect_txids(mut self, inspect: impl Fn(&Txid) + Send + Sync + 'static) -> Self {
+        self.txids = Box::new(self.txids.inspect(move |txid| inspect(txid)));
+        self
+    }
+
+    /// Add a closure that will be called for each [`OutPoint`] synced in this request.
+    ///
+    /// This consumes the [`SyncRequest`] and returns the updated one.
+    #[must_use]
+    pub fn inspect_outpoints(
+        mut self,
+        inspect: impl Fn(&OutPoint) + Send + Sync + 'static,
+    ) -> Self {
+        self.outpoints = Box::new(self.outpoints.inspect(move |op| inspect(op)));
+        self
+    }
+
+    /// Populate the request with revealed script pubkeys from `index` with the given `spk_range`.
+    ///
+    /// This consumes the [`SyncRequest`] and returns the updated one.
+    #[cfg(feature = "miniscript")]
+    #[must_use]
+    pub fn populate_with_revealed_spks<K: Clone + Ord + Debug + Send + Sync>(
+        self,
+        index: &crate::keychain::KeychainTxOutIndex<K>,
+        spk_range: impl RangeBounds<K>,
+    ) -> Self {
+        use alloc::borrow::ToOwned;
+        self.chain_spks(
+            index
+                .revealed_spks(spk_range)
+                .map(|(_, _, spk)| spk.to_owned())
+                .collect::<Vec<_>>(),
+        )
+    }
+}
+
+/// Data returned from a spk-based blockchain client sync.
+///
+/// See also [`SyncRequest`].
+pub struct SyncResult<A = ConfirmationTimeHeightAnchor> {
+    /// The update to apply to the receiving [`TxGraph`].
+    pub graph_update: TxGraph<A>,
+    /// The update to apply to the receiving [`LocalChain`](crate::local_chain::LocalChain).
+    pub chain_update: CheckPoint,
+}
+
+/// Data required to perform a spk-based blockchain client full scan.
+///
+/// A client full scan iterates through all the scripts for the given keychains, fetching relevant
+/// data until some stop gap number of scripts is found that have no data. This operation is
+/// generally only used when importing or restoring previously used keychains in which the list of
+/// used scripts is not known. The full scan process also updates the chain from the given [`CheckPoint`].
+pub struct FullScanRequest<K> {
+    /// A checkpoint for the current [`LocalChain::tip`].
+    /// The full scan process will return a new chain update that extends this tip.
+    ///
+    /// [`LocalChain::tip`]: crate::local_chain::LocalChain::tip
+    pub chain_tip: CheckPoint,
+    /// Iterators of script pubkeys indexed by the keychain index.
+    pub spks_by_keychain: BTreeMap<K, Box<dyn Iterator<Item = (u32, ScriptBuf)> + Send>>,
+}
+
+impl<K: Ord + Clone> FullScanRequest<K> {
+    /// Construct a new [`FullScanRequest`] from a given `chain_tip`.
+    #[must_use]
+    pub fn from_chain_tip(chain_tip: CheckPoint) -> Self {
+        Self {
+            chain_tip,
+            spks_by_keychain: BTreeMap::new(),
+        }
+    }
+
+    /// Construct a new [`FullScanRequest`] from a given `chain_tip` and `index`.
+    ///
+    /// Unbounded script pubkey iterators for each keychain (`K`) are extracted using
+    /// [`KeychainTxOutIndex::all_unbounded_spk_iters`] and is used to populate the
+    /// [`FullScanRequest`].
+    ///
+    /// [`KeychainTxOutIndex::all_unbounded_spk_iters`]: crate::keychain::KeychainTxOutIndex::all_unbounded_spk_iters
+    #[cfg(feature = "miniscript")]
+    #[must_use]
+    pub fn from_keychain_txout_index(
+        chain_tip: CheckPoint,
+        index: &crate::keychain::KeychainTxOutIndex<K>,
+    ) -> Self
+    where
+        K: Debug,
+    {
+        let mut req = Self::from_chain_tip(chain_tip);
+        for (keychain, spks) in index.all_unbounded_spk_iters() {
+            req = req.set_spks_for_keychain(keychain, spks);
+        }
+        req
+    }
+
+    /// Set the [`Script`]s for a given `keychain`.
+    ///
+    /// This consumes the [`FullScanRequest`] and returns the updated one.
+    #[must_use]
+    pub fn set_spks_for_keychain(
+        mut self,
+        keychain: K,
+        spks: impl IntoIterator<IntoIter = impl Iterator<Item = (u32, ScriptBuf)> + Send + 'static>,
+    ) -> Self {
+        self.spks_by_keychain
+            .insert(keychain, Box::new(spks.into_iter()));
+        self
+    }
+
+    /// Chain on additional [`Script`]s that will be synced against.
+    ///
+    /// This consumes the [`FullScanRequest`] and returns the updated one.
+    #[must_use]
+    pub fn chain_spks_for_keychain(
+        mut self,
+        keychain: K,
+        spks: impl IntoIterator<IntoIter = impl Iterator<Item = (u32, ScriptBuf)> + Send + 'static>,
+    ) -> Self {
+        match self.spks_by_keychain.remove(&keychain) {
+            Some(keychain_spks) => self
+                .spks_by_keychain
+                .insert(keychain, Box::new(keychain_spks.chain(spks.into_iter()))),
+            None => self
+                .spks_by_keychain
+                .insert(keychain, Box::new(spks.into_iter())),
+        };
+        self
+    }
+
+    /// Add a closure that will be called for every [`Script`] previously added to any keychain in
+    /// this request.
+    ///
+    /// This consumes the [`SyncRequest`] and returns the updated one.
+    #[must_use]
+    pub fn inspect_spks_for_all_keychains(
+        mut self,
+        inspect: impl FnMut(K, u32, &Script) + Send + Sync + Clone + 'static,
+    ) -> Self
+    where
+        K: Send + 'static,
+    {
+        for (keychain, spks) in core::mem::take(&mut self.spks_by_keychain) {
+            let mut inspect = inspect.clone();
+            self.spks_by_keychain.insert(
+                keychain.clone(),
+                Box::new(spks.inspect(move |(i, spk)| inspect(keychain.clone(), *i, spk))),
+            );
+        }
+        self
+    }
+
+    /// Add a closure that will be called for every [`Script`] previously added to a given
+    /// `keychain` in this request.
+    ///
+    /// This consumes the [`SyncRequest`] and returns the updated one.
+    #[must_use]
+    pub fn inspect_spks_for_keychain(
+        mut self,
+        keychain: K,
+        mut inspect: impl FnMut(u32, &Script) + Send + Sync + 'static,
+    ) -> Self
+    where
+        K: Send + 'static,
+    {
+        if let Some(spks) = self.spks_by_keychain.remove(&keychain) {
+            self.spks_by_keychain.insert(
+                keychain,
+                Box::new(spks.inspect(move |(i, spk)| inspect(*i, spk))),
+            );
+        }
+        self
+    }
+}
+
+/// Data returned from a spk-based blockchain client full scan.
+///
+/// See also [`FullScanRequest`].
+pub struct FullScanResult<K> {
+    /// The update to apply to the receiving [`LocalChain`](crate::local_chain::LocalChain).
+    pub graph_update: TxGraph<ConfirmationTimeHeightAnchor>,
+    /// The update to apply to the receiving [`TxGraph`].
+    pub chain_update: CheckPoint,
+    /// Last active indices for the corresponding keychains (`K`).
+    pub last_active_indices: BTreeMap<K, u32>,
+}