From d4244e315017dfe570220f34f75b34e60a7fa8dd Mon Sep 17 00:00:00 2001
From: Matthew <ramsden@hey.com>
Date: Mon, 29 Sep 2025 16:00:47 -0500
Subject: [PATCH] refactor(esplora): clear remaining panic paths

---
 crates/esplora/src/async_ext.rs    | 24 ++++++++++++------------
 crates/esplora/src/blocking_ext.rs | 17 +++++++----------
 2 files changed, 19 insertions(+), 22 deletions(-)

diff --git a/crates/esplora/src/async_ext.rs b/crates/esplora/src/async_ext.rs
index c9cb17c1e..a450585c2 100644
--- a/crates/esplora/src/async_ext.rs
+++ b/crates/esplora/src/async_ext.rs
@@ -314,8 +314,9 @@ where
     type TxsOfSpkIndex = (u32, Vec<esplora_client::Tx>, HashSet<Txid>);
 
     let mut update = TxUpdate::<ConfirmationBlockTime>::default();
-    let mut last_index = Option::<u32>::None;
     let mut last_active_index = Option::<u32>::None;
+    let mut consecutive_unused = 0usize;
+    let gap_limit = stop_gap.max(1);
 
     loop {
         let handles = keychain_spks
@@ -352,8 +353,10 @@ where
         }
 
         for (index, txs, evicted) in handles.try_collect::<Vec<TxsOfSpkIndex>>().await? {
-            last_index = Some(index);
-            if !txs.is_empty() {
+            if txs.is_empty() {
+                consecutive_unused = consecutive_unused.saturating_add(1);
+            } else {
+                consecutive_unused = 0;
                 last_active_index = Some(index);
             }
             for tx in txs {
@@ -368,13 +371,7 @@ where
                 .extend(evicted.into_iter().map(|txid| (txid, start_time)));
         }
 
-        let last_index = last_index.expect("Must be set since handles wasn't empty.");
-        let gap_limit_reached = if let Some(i) = last_active_index {
-            last_index >= i.saturating_add(stop_gap as u32)
-        } else {
-            last_index + 1 >= stop_gap as u32
-        };
-        if gap_limit_reached {
+        if consecutive_unused >= gap_limit {
             break;
         }
     }
@@ -594,9 +591,12 @@ mod test {
 
         let anchors = BTreeSet::new();
         let res = chain_update(&client, &latest_blocks, &cp, &anchors).await;
-        use esplora_client::Error;
+        use esplora_client::Error as ClientError;
         assert!(
-            matches!(*res.unwrap_err(), Error::HeaderHashNotFound(hash) if hash == genesis_hash),
+            matches!(
+                *res.unwrap_err(),
+                ClientError::HeaderHashNotFound(hash) if hash == genesis_hash
+            ),
             "`chain_update` should error if it can't connect to the local CP",
         );
 
diff --git a/crates/esplora/src/blocking_ext.rs b/crates/esplora/src/blocking_ext.rs
index 5f8ab531c..2eeda0b25 100644
--- a/crates/esplora/src/blocking_ext.rs
+++ b/crates/esplora/src/blocking_ext.rs
@@ -282,8 +282,9 @@ fn fetch_txs_with_keychain_spks<I: Iterator<Item = Indexed<SpkWithExpectedTxids>
     type TxsOfSpkIndex = (u32, Vec<esplora_client::Tx>, HashSet<Txid>);
 
     let mut update = TxUpdate::<ConfirmationBlockTime>::default();
-    let mut last_index = Option::<u32>::None;
     let mut last_active_index = Option::<u32>::None;
+    let mut consecutive_unused = 0usize;
+    let gap_limit = stop_gap.max(1);
 
     loop {
         let handles = keychain_spks
@@ -321,8 +322,10 @@ fn fetch_txs_with_keychain_spks<I: Iterator<Item = Indexed<SpkWithExpectedTxids>
 
         for handle in handles {
             let (index, txs, evicted) = handle.join().expect("thread must not panic")?;
-            last_index = Some(index);
-            if !txs.is_empty() {
+            if txs.is_empty() {
+                consecutive_unused = consecutive_unused.saturating_add(1);
+            } else {
+                consecutive_unused = 0;
                 last_active_index = Some(index);
             }
             for tx in txs {
@@ -337,13 +340,7 @@ fn fetch_txs_with_keychain_spks<I: Iterator<Item = Indexed<SpkWithExpectedTxids>
                 .extend(evicted.into_iter().map(|txid| (txid, start_time)));
         }
 
-        let last_index = last_index.expect("Must be set since handles wasn't empty.");
-        let gap_limit_reached = if let Some(i) = last_active_index {
-            last_index >= i.saturating_add(stop_gap as u32)
-        } else {
-            last_index + 1 >= stop_gap as u32
-        };
-        if gap_limit_reached {
+        if consecutive_unused >= gap_limit {
             break;
         }
     }