Differentiate BlockHeader from Block

processor/primitives/src/lib.rs

@@ -5,7 +5,7 @@
 use core::fmt::Debug;
 use std::io;
 
-use group::GroupEncoding;
+use group::{Group, GroupEncoding};
 
 use serai_primitives::Balance;
 
@@ -137,9 +137,8 @@ pub trait ReceivedOutput<K: GroupEncoding, A>:
   fn read<R: io::Read>(reader: &mut R) -> io::Result<Self>;
 }
 
-/// A block from an external network.
-#[async_trait::async_trait]
-pub trait Block: Send + Sync + Sized + Clone + Debug {
+/// A block header from an external network.
+pub trait BlockHeader: Send + Sync + Sized + Clone + Debug {
   /// The type used to identify blocks.
   type Id: 'static + Id;
   /// The ID of this block.
@@ -148,6 +147,31 @@ pub trait Block: Send + Sync + Sized + Clone + Debug {
   fn parent(&self) -> Self::Id;
 }
 
+/// A block from an external network.
+///
+/// A block is defined as a consensus event associated with a set of transactions. It is not
+/// necessary to literally define it as whatever the external network defines as a block. For
+/// external networks which finalize block(s), this block type should be a representation of all
+/// transactions within a period finalization (whether block or epoch).
+#[async_trait::async_trait]
+pub trait Block: Send + Sync + Sized + Clone + Debug {
+  /// The type used for this block's header.
+  type Header: BlockHeader;
+
+  /// The type used to represent keys on this external network.
+  type Key: Group + GroupEncoding;
+  /// The type used to represent addresses on this external network.
+  type Address;
+  /// The type used to represent received outputs on this external network.
+  type Output: ReceivedOutput<Self::Key, Self::Address>;
+
+  /// The ID of this block.
+  fn id(&self) -> <Self::Header as BlockHeader>::Id;
+
+  /// Scan all outputs within this block to find the outputs spendable by this key.
+  fn scan_for_outputs(&self, key: Self::Key) -> Vec<Self::Output>;
+}
+
 /// A wrapper for a group element which implements the borsh traits.
 #[derive(Clone, Copy, PartialEq, Eq, Debug)]
 pub struct BorshG<G: GroupEncoding>(pub G);

processor/scanner/src/db.rs

@@ -5,7 +5,7 @@ use serai_db::{Get, DbTxn, create_db};
 
 use primitives::{Id, ReceivedOutput, Block, BorshG};
 
-use crate::ScannerFeed;
+use crate::{ScannerFeed, BlockIdFor, KeyFor, OutputFor};
 
 // The DB macro doesn't support `BorshSerialize + BorshDeserialize` as a bound, hence this.
 trait Borshy: BorshSerialize + BorshDeserialize {}
@@ -64,25 +64,25 @@ create_db!(
 
 pub(crate) struct ScannerDb<S: ScannerFeed>(PhantomData<S>);
 impl<S: ScannerFeed> ScannerDb<S> {
-  pub(crate) fn set_block(txn: &mut impl DbTxn, number: u64, id: <S::Block as Block>::Id) {
+  pub(crate) fn set_block(txn: &mut impl DbTxn, number: u64, id: BlockIdFor<S>) {
     BlockId::set(txn, number, &id);
     BlockNumber::set(txn, id, &number);
   }
-  pub(crate) fn block_id(getter: &impl Get, number: u64) -> Option<<S::Block as Block>::Id> {
+  pub(crate) fn block_id(getter: &impl Get, number: u64) -> Option<BlockIdFor<S>> {
     BlockId::get(getter, number)
   }
-  pub(crate) fn block_number(getter: &impl Get, id: <S::Block as Block>::Id) -> Option<u64> {
+  pub(crate) fn block_number(getter: &impl Get, id: BlockIdFor<S>) -> Option<u64> {
     BlockNumber::get(getter, id)
   }
 
   // activation_block_number is inclusive, so the key will be scanned for starting at the specified
   // block
-  pub(crate) fn queue_key(txn: &mut impl DbTxn, activation_block_number: u64, key: S::Key) {
+  pub(crate) fn queue_key(txn: &mut impl DbTxn, activation_block_number: u64, key: KeyFor<S>) {
     // Set this block as notable
     NotableBlock::set(txn, activation_block_number, &());
 
     // Push the key
-    let mut keys: Vec<SeraiKey<BorshG<S::Key>>> = ActiveKeys::get(txn).unwrap_or(vec![]);
+    let mut keys: Vec<SeraiKey<BorshG<KeyFor<S>>>> = ActiveKeys::get(txn).unwrap_or(vec![]);
     for key_i in &keys {
       if key == key_i.key.0 {
         panic!("queueing a key prior queued");
@@ -97,8 +97,8 @@ impl<S: ScannerFeed> ScannerDb<S> {
   }
   // retirement_block_number is inclusive, so the key will no longer be scanned for as of the
   // specified block
-  pub(crate) fn retire_key(txn: &mut impl DbTxn, retirement_block_number: u64, key: S::Key) {
-    let mut keys: Vec<SeraiKey<BorshG<S::Key>>> =
+  pub(crate) fn retire_key(txn: &mut impl DbTxn, retirement_block_number: u64, key: KeyFor<S>) {
+    let mut keys: Vec<SeraiKey<BorshG<KeyFor<S>>>> =
       ActiveKeys::get(txn).expect("retiring key yet no active keys");
 
     assert!(keys.len() > 1, "retiring our only key");
@@ -118,15 +118,11 @@ impl<S: ScannerFeed> ScannerDb<S> {
     }
     panic!("retiring key yet not present in keys")
   }
-  pub(crate) fn keys(getter: &impl Get) -> Option<Vec<SeraiKey<BorshG<S::Key>>>> {
+  pub(crate) fn keys(getter: &impl Get) -> Option<Vec<SeraiKey<BorshG<KeyFor<S>>>>> {
     ActiveKeys::get(getter)
   }
 
-  pub(crate) fn set_start_block(
-    txn: &mut impl DbTxn,
-    start_block: u64,
-    id: <S::Block as Block>::Id,
-  ) {
+  pub(crate) fn set_start_block(txn: &mut impl DbTxn, start_block: u64, id: BlockIdFor<S>) {
     Self::set_block(txn, start_block, id);
     LatestFinalizedBlock::set(txn, &start_block);
     LatestScannableBlock::set(txn, &start_block);
@@ -189,11 +185,7 @@ impl<S: ScannerFeed> ScannerDb<S> {
     HighestAcknowledgedBlock::get(getter)
   }
 
-  pub(crate) fn set_outputs(
-    txn: &mut impl DbTxn,
-    block_number: u64,
-    outputs: Vec<impl ReceivedOutput<S::Key, S::Address>>,
-  ) {
+  pub(crate) fn set_outputs(txn: &mut impl DbTxn, block_number: u64, outputs: Vec<OutputFor<S>>) {
     if outputs.is_empty() {
       return;
     }

processor/scanner/src/index.rs

@@ -1,6 +1,6 @@
 use serai_db::{Db, DbTxn};
 
-use primitives::{Id, Block};
+use primitives::{Id, BlockHeader};
 
 // TODO: Localize to IndexDb?
 use crate::{db::ScannerDb, ScannerFeed, ContinuallyRan};
@@ -43,7 +43,7 @@ impl<D: Db, S: ScannerFeed> ContinuallyRan for IndexFinalizedTask<D, S> {
 
     // Index the hashes of all blocks until the latest finalized block
     for b in (our_latest_finalized + 1) ..= latest_finalized {
-      let block = match self.feed.block_by_number(b).await {
+      let block = match self.feed.block_header_by_number(b).await {
         Ok(block) => block,
         Err(e) => Err(format!("couldn't fetch block {b}: {e:?}"))?,
       };

processor/scanner/src/lib.rs

@@ -2,7 +2,7 @@ use core::{fmt::Debug, time::Duration};
 
 use tokio::sync::mpsc;
 
-use primitives::{ReceivedOutput, Block};
+use primitives::{ReceivedOutput, BlockHeader, Block};
 
 mod db;
 mod index;
@@ -21,15 +21,6 @@ pub trait ScannerFeed: Send + Sync {
   /// This value must be at least `1`.
   const CONFIRMATIONS: u64;
 
-  /// The type of the key used to receive coins on this blockchain.
-  type Key: group::Group + group::GroupEncoding;
-
-  /// The type of the address used to specify who to send coins to on this blockchain.
-  type Address;
-
-  /// The type representing a received (and spendable) output.
-  type Output: ReceivedOutput<Self::Key, Self::Address>;
-
   /// The representation of a block for this blockchain.
   ///
   /// A block is defined as a consensus event associated with a set of transactions. It is not
@@ -58,17 +49,20 @@ pub trait ScannerFeed: Send + Sync {
     Ok(self.latest_block_number().await? - Self::CONFIRMATIONS)
   }
 
+  /// Fetch a block header by its number.
+  async fn block_header_by_number(
+    &self,
+    number: u64,
+  ) -> Result<<Self::Block as Block>::Header, Self::EphemeralError>;
+
   /// Fetch a block by its number.
   async fn block_by_number(&self, number: u64) -> Result<Self::Block, Self::EphemeralError>;
-
-  /// Scan a block for its outputs.
-  async fn scan_for_outputs(
-    &self,
-    block: &Self::Block,
-    key: Self::Key,
-  ) -> Result<Vec<Self::Output>, Self::EphemeralError>;
 }
 
+type BlockIdFor<S> = <<<S as ScannerFeed>::Block as Block>::Header as BlockHeader>::Id;
+type KeyFor<S> = <<S as ScannerFeed>::Block as Block>::Key;
+type OutputFor<S> = <<S as ScannerFeed>::Block as Block>::Output;
+
 /// A handle to immediately run an iteration of a task.
 #[derive(Clone)]
 pub(crate) struct RunNowHandle(mpsc::Sender<()>);

processor/scanner/src/scan.rs

@@ -60,12 +60,7 @@ impl<D: Db, S: ScannerFeed> ContinuallyRan for ScanForOutputsTask<D, S> {
           continue;
         }
 
-        for output in self
-          .feed
-          .scan_for_outputs(&block, key.key.0)
-          .await
-          .map_err(|e| format!("failed to scan block {b}: {e:?}"))?
-        {
+        for output in block.scan_for_outputs(key.key.0) {
           assert_eq!(output.key(), key.key.0);
           // TODO: Check for dust
           outputs.push(output);