From f3a13e7c3c626c86c9709952651a2c90a9df0a70 Mon Sep 17 00:00:00 2001
From: Nadav Ivgi <nadav@shesek.info>
Date: Tue, 6 Aug 2024 05:16:10 +0300
Subject: [PATCH] Avoid recomputing txids when possible

Following https://github.com/Blockstream/electrs/pull/89#discussion_r1632848608
and https://github.com/Blockstream/electrs/pull/89#discussion_r1632919266
---
 src/daemon.rs            | 11 ++++++-----
 src/new_index/mempool.rs | 14 ++++++--------
 src/new_index/query.rs   |  2 +-
 3 files changed, 13 insertions(+), 14 deletions(-)

diff --git a/src/daemon.rs b/src/daemon.rs
index 6ebf2dcaa..4fb24af69 100644
--- a/src/daemon.rs
+++ b/src/daemon.rs
@@ -11,7 +11,7 @@ use std::time::Duration;
 use base64::prelude::{Engine, BASE64_STANDARD};
 use error_chain::ChainedError;
 use hex::FromHex;
-use rayon::iter::{IntoParallelIterator, ParallelIterator};
+use rayon::iter::{IndexedParallelIterator, IntoParallelIterator, ParallelIterator};
 use serde_json::{from_str, from_value, Value};
 
 #[cfg(not(feature = "liquid"))]
@@ -461,7 +461,7 @@ impl Daemon {
         &'a self,
         method: &'a str,
         params_list: Vec<Value>,
-    ) -> impl ParallelIterator<Item = Result<Value>> + 'a {
+    ) -> impl ParallelIterator<Item = Result<Value>> + IndexedParallelIterator + 'a {
         self.rpc_threads.install(move || {
             params_list.into_par_iter().map(move |params| {
                 // Store a local per-thread Daemon, each with its own TCP connection. These will
@@ -537,7 +537,7 @@ impl Daemon {
 
     /// Fetch the given transactions in parallel over multiple threads and RPC connections,
     /// ignoring any missing ones and returning whatever is available.
-    pub fn gettransactions_available(&self, txids: &[&Txid]) -> Result<Vec<Transaction>> {
+    pub fn gettransactions_available(&self, txids: &[&Txid]) -> Result<Vec<(Txid, Transaction)>> {
         const RPC_INVALID_ADDRESS_OR_KEY: i64 = -5;
 
         let params_list: Vec<Value> = txids
@@ -546,8 +546,9 @@ impl Daemon {
             .collect();
 
         self.requests_iter("getrawtransaction", params_list)
-            .filter_map(|res| match res {
-                Ok(val) => Some(tx_from_value(val)),
+            .zip(txids)
+            .filter_map(|(res, txid)| match res {
+                Ok(val) => Some(tx_from_value(val).map(|tx| (**txid, tx))),
                 // Ignore 'tx not found' errors
                 Err(Error(ErrorKind::RpcError(code, _, _), _))
                     if code == RPC_INVALID_ADDRESS_OR_KEY =>
diff --git a/src/new_index/mempool.rs b/src/new_index/mempool.rs
index 8dae5bc62..374dcafeb 100644
--- a/src/new_index/mempool.rs
+++ b/src/new_index/mempool.rs
@@ -288,14 +288,12 @@ impl Mempool {
         self.backlog_stats = (BacklogStats::new(&self.feeinfo), Instant::now());
     }
 
-    pub fn add_by_txid(&mut self, daemon: &Daemon, txid: &Txid) -> Result<()> {
-        if self.txstore.get(txid).is_none() {
+    pub fn add_by_txid(&mut self, daemon: &Daemon, txid: Txid) -> Result<()> {
+        if self.txstore.get(&txid).is_none() {
             if let Ok(tx) = daemon.getmempooltx(&txid) {
-                self.add({
-                    let mut txs_map = HashMap::new();
-                    txs_map.insert(tx.txid(), tx);
-                    txs_map
-                })
+                let mut txs_map = HashMap::new();
+                txs_map.insert(txid, tx);
+                self.add(txs_map)
             } else {
                 bail!("add_by_txid cannot find {}", txid);
             }
@@ -528,7 +526,7 @@ impl Mempool {
             }
 
             let fetched_count = new_txs.len();
-            fetched_txs.extend(&mut new_txs.into_iter().map(|tx| (tx.txid(), tx)));
+            fetched_txs.extend(new_txs);
 
             // Retry if any transactions were evicted form the mempool before we managed to get them
             if fetched_count != new_txids.len() {
diff --git a/src/new_index/query.rs b/src/new_index/query.rs
index e178bec49..26d983734 100644
--- a/src/new_index/query.rs
+++ b/src/new_index/query.rs
@@ -75,7 +75,7 @@ impl Query {
             .mempool
             .write()
             .unwrap()
-            .add_by_txid(&self.daemon, &txid);
+            .add_by_txid(&self.daemon, txid);
         Ok(txid)
     }