for_blocks apply closure in parallel

requires changing the signature of the function from FnMut -> Fn and return
data instead of relying on mutating the context

src/daemon.rs

@@ -229,10 +229,11 @@ impl Daemon {
         self.p2p.lock().get_new_headers(chain)
     }
 
-    pub(crate) fn for_blocks<B, F>(&self, blockhashes: B, func: F) -> Result<()>
+    pub(crate) fn for_blocks<B, F, R>(&self, blockhashes: B, func: F) -> Result<Vec<R>>
     where
         B: IntoIterator<Item = BlockHash>,
-        F: FnMut(BlockHash, SerBlock),
+        F: Fn(BlockHash, SerBlock) -> R + Send + Sync,
+        R: Send + Sync,
     {
         self.p2p.lock().for_blocks(blockhashes, func)
     }

src/db.rs

@@ -8,6 +8,7 @@ pub(crate) type Row = Box<[u8]>;
 
 #[derive(Default)]
 pub(crate) struct WriteBatch {
+    pub(crate) height: usize,
     pub(crate) tip_row: Row,
     pub(crate) header_rows: Vec<Row>,
     pub(crate) funding_rows: Vec<Row>,
@@ -22,6 +23,16 @@ impl WriteBatch {
         self.spending_rows.sort_unstable();
         self.txid_rows.sort_unstable();
     }
+    pub(crate) fn merge(mut self, other: WriteBatch) -> Self {
+        self.header_rows.extend(other.header_rows.into_iter());
+        self.funding_rows.extend(other.funding_rows.into_iter());
+        self.spending_rows.extend(other.spending_rows.into_iter());
+        self.txid_rows.extend(other.txid_rows.into_iter());
+        if self.height < other.height {
+            self.tip_row = other.tip_row
+        }
+        self
+    }
 }
 
 /// RocksDB wrapper for index storage

src/index.rs

@@ -2,6 +2,7 @@ use anyhow::{Context, Result};
 use bitcoin::consensus::{deserialize, serialize, Decodable};
 use bitcoin::{BlockHash, OutPoint, Txid};
 use bitcoin_slices::{bsl, Visit, Visitor};
+use std::collections::HashMap;
 use std::ops::ControlFlow;
 
 use crate::{
@@ -199,29 +200,33 @@ impl Index {
     }
 
     fn sync_blocks(&mut self, daemon: &Daemon, chunk: &[NewHeader]) -> Result<()> {
-        let blockhashes: Vec<BlockHash> = chunk.iter().map(|h| h.hash()).collect();
-        let mut heights = chunk.iter().map(|h| h.height());
+        let hash_height: HashMap<_, _> = chunk.iter().map(|h| (h.hash(), h.height())).collect();
 
-        let mut batch = WriteBatch::default();
+        let batches = daemon.for_blocks(hash_height.keys().cloned(), |blockhash, block| {
+            let height = *hash_height.get(&blockhash).expect("some by construnction");
+            let mut batch = WriteBatch::default();
 
-        daemon.for_blocks(blockhashes, |blockhash, block| {
-            let height = heights.next().expect("unexpected block");
             self.stats.observe_duration("block", || {
                 index_single_block(blockhash, block, height, &mut batch);
             });
             self.stats.height.set("tip", height as f64);
+            batch
         })?;
-        let heights: Vec<_> = heights.collect();
-        assert!(
-            heights.is_empty(),
-            "some blocks were not indexed: {:?}",
-            heights
+        assert_eq!(
+            hash_height.len(),
+            batches.len(),
+            "some blocks were not indexed",
         );
+        let mut batch = batches
+            .into_iter()
+            .fold(WriteBatch::default(), |a, b| a.merge(b));
+
         batch.sort();
         self.stats.observe_batch(&batch);
         self.stats
             .observe_duration("write", || self.store.write(&batch));
         self.stats.observe_db(&self.store);
+
         Ok(())
     }
 
@@ -287,4 +292,5 @@ fn index_single_block(
     let mut index_block = IndexBlockVisitor { batch, height };
     bsl::Block::visit(&block, &mut index_block).expect("core returned invalid block");
     batch.tip_row = serialize(&block_hash).into_boxed_slice();
+    batch.height = height;
 }

src/p2p.rs

@@ -18,6 +18,8 @@ use bitcoin::{
 };
 use bitcoin_slices::{bsl, Parse};
 use crossbeam_channel::{bounded, select, Receiver, Sender};
+use rayon::iter::ParallelIterator;
+use rayon::prelude::IntoParallelIterator;
 
 use std::io::{self, ErrorKind, Write};
 use std::net::{IpAddr, Ipv4Addr, SocketAddr, TcpStream};
@@ -90,18 +92,20 @@ impl Connection {
             .collect())
     }
 
-    /// Request and process the specified blocks (in the specified order).
+    /// Request and process the specified blocks.
     /// See https://en.bitcoin.it/wiki/Protocol_documentation#getblocks for details.
     /// Defined as `&mut self` to prevent concurrent invocations (https://github.com/romanz/electrs/pull/526#issuecomment-934685515).
-    pub(crate) fn for_blocks<B, F>(&mut self, blockhashes: B, mut func: F) -> Result<()>
+    pub(crate) fn for_blocks<B, F, R>(&mut self, blockhashes: B, func: F) -> Result<Vec<R>>
     where
         B: IntoIterator<Item = BlockHash>,
-        F: FnMut(BlockHash, SerBlock),
+        F: Fn(BlockHash, SerBlock) -> R + Send + Sync,
+        R: Send + Sync,
     {
         self.blocks_duration.observe_duration("total", || {
+            let mut result = vec![];
             let blockhashes: Vec<BlockHash> = blockhashes.into_iter().collect();
             if blockhashes.is_empty() {
-                return Ok(());
+                return Ok(vec![]);
             }
             self.blocks_duration.observe_duration("request", || {
                 debug!("loading {} blocks", blockhashes.len());
@@ -123,10 +127,16 @@ impl Connection {
                     );
                     Ok(block)
                 })?;
-                self.blocks_duration
-                    .observe_duration("process", || func(hash, block));
+                result.push((hash, block));
             }
-            Ok(())
+
+            Ok(result
+                .into_par_iter()
+                .map(|(hash, block)| {
+                    self.blocks_duration
+                        .observe_duration("process", || func(hash, block))
+                })
+                .collect())
         })
     }
 

src/status.rs

@@ -308,10 +308,11 @@ impl ScriptHashStatus {
     }
 
     /// Apply func only on the new blocks (fetched from daemon).
-    fn for_new_blocks<B, F>(&self, blockhashes: B, daemon: &Daemon, func: F) -> Result<()>
+    fn for_new_blocks<B, F, R>(&self, blockhashes: B, daemon: &Daemon, func: F) -> Result<Vec<R>>
     where
         B: IntoIterator<Item = BlockHash>,
-        F: FnMut(BlockHash, SerBlock),
+        F: Fn(BlockHash, SerBlock) -> R + Send + Sync,
+        R: Send + Sync,
     {
         daemon.for_blocks(
             blockhashes
@@ -331,37 +332,54 @@ impl ScriptHashStatus {
         outpoints: &mut HashSet<OutPoint>,
     ) -> Result<HashMap<BlockHash, Vec<TxEntry>>> {
         let scripthash = self.scripthash;
-        let mut result = HashMap::<BlockHash, HashMap<usize, TxEntry>>::new();
 
         let funding_blockhashes = index.limit_result(index.filter_by_funding(scripthash))?;
-        self.for_new_blocks(funding_blockhashes, daemon, |blockhash, block| {
-            let block_entries = result.entry(blockhash).or_default();
-            for filtered_outputs in filter_block_txs_outputs(block, scripthash) {
-                cache.add_tx(filtered_outputs.txid, move || filtered_outputs.tx);
-                outpoints.extend(make_outpoints(
-                    filtered_outputs.txid,
-                    &filtered_outputs.result,
-                ));
-                block_entries
-                    .entry(filtered_outputs.pos)
-                    .or_insert_with(|| TxEntry::new(filtered_outputs.txid))
-                    .outputs = filtered_outputs.result;
-            }
-        })?;
+        let outputs_filtering =
+            self.for_new_blocks(funding_blockhashes, daemon, |blockhash, block| {
+                let mut block_entries: HashMap<usize, TxEntry> = HashMap::new();
+                let mut outpoints = vec![];
+                for filtered_outputs in filter_block_txs_outputs(block, scripthash) {
+                    cache.add_tx(filtered_outputs.txid, move || filtered_outputs.tx);
+                    outpoints.extend(make_outpoints(
+                        filtered_outputs.txid,
+                        &filtered_outputs.result,
+                    ));
+                    block_entries
+                        .entry(filtered_outputs.pos)
+                        .or_insert_with(|| TxEntry::new(filtered_outputs.txid))
+                        .outputs = filtered_outputs.result;
+                }
+                (blockhash, outpoints, block_entries)
+            })?;
+
+        outpoints.extend(outputs_filtering.iter().flat_map(|(_, o, _)| o).cloned());
+
+        let mut result: HashMap<_, _> = outputs_filtering
+            .into_iter()
+            .map(|(a, _, b)| (a, b))
+            .collect();
+
         let spending_blockhashes: HashSet<BlockHash> = outpoints
             .par_iter()
             .flat_map_iter(|outpoint| index.filter_by_spending(*outpoint))
             .collect();
-        self.for_new_blocks(spending_blockhashes, daemon, |blockhash, block| {
-            let block_entries = result.entry(blockhash).or_default();
-            for filtered_inputs in filter_block_txs_inputs(&block, outpoints) {
-                cache.add_tx(filtered_inputs.txid, move || filtered_inputs.tx);
-                block_entries
-                    .entry(filtered_inputs.pos)
-                    .or_insert_with(|| TxEntry::new(filtered_inputs.txid))
-                    .spent = filtered_inputs.result;
-            }
-        })?;
+        let inputs_filtering =
+            self.for_new_blocks(spending_blockhashes, daemon, |blockhash, block| {
+                let mut block_entries: HashMap<usize, TxEntry> = HashMap::new();
+
+                for filtered_inputs in filter_block_txs_inputs(&block, outpoints) {
+                    cache.add_tx(filtered_inputs.txid, move || filtered_inputs.tx);
+                    block_entries
+                        .entry(filtered_inputs.pos)
+                        .or_insert_with(|| TxEntry::new(filtered_inputs.txid))
+                        .spent = filtered_inputs.result;
+                }
+                (blockhash, block_entries)
+            })?;
+        for (b, h) in inputs_filtering {
+            let e = result.entry(b).or_default();
+            e.extend(h);
+        }
 
         Ok(result
             .into_iter()

src/tracker.rs

@@ -105,17 +105,18 @@ impl Tracker {
     ) -> Result<Option<(BlockHash, Transaction)>> {
         // Note: there are two blocks with coinbase transactions having same txid (see BIP-30)
         let blockhashes = self.index.filter_by_txid(txid);
-        let mut result = None;
-        daemon.for_blocks(blockhashes, |blockhash, block| {
-            if result.is_some() {
-                return; // keep first matching transaction
-            }
-            let mut visitor = FindTransaction::new(txid);
-            result = match bsl::Block::visit(&block, &mut visitor) {
-                Ok(_) | Err(VisitBreak) => visitor.tx_found().map(|tx| (blockhash, tx)),
-                Err(e) => panic!("core returned invalid block: {:?}", e),
-            };
-        })?;
+        let result = daemon
+            .for_blocks(blockhashes, |blockhash, block| {
+                let mut visitor = FindTransaction::new(txid);
+                match bsl::Block::visit(&block, &mut visitor) {
+                    Ok(_) | Err(VisitBreak) => (),
+                    Err(e) => panic!("core returned invalid block: {:?}", e),
+                }
+                visitor.tx_found().map(|tx| (blockhash, tx))
+            })?
+            .first()
+            .cloned()
+            .flatten();
         Ok(result)
     }
 }