From adfa0a562e23809027a8c3c121fc8855466a8e2e Mon Sep 17 00:00:00 2001
From: hanabi1224 <harlowmoo@gmail.com>
Date: Thu, 9 Apr 2026 09:06:47 +0800
Subject: [PATCH 1/2] fix: use smaller skip length for `tipset_by_height` cache

---
 src/chain/store/index.rs | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/src/chain/store/index.rs b/src/chain/store/index.rs
index 1d08857834b3..0cbbbcecb5b3 100644
--- a/src/chain/store/index.rs
+++ b/src/chain/store/index.rs
@@ -51,8 +51,8 @@ impl<DB: Blockstore> ChainIndex<DB> {
         let ts_height_cache: SizeTrackingLruCache<ChainEpoch, TipsetKey> =
             SizeTrackingLruCache::new_with_metrics(
                 "tipset_by_height".into(),
-                // 20480 * 900 = 18432000 which is sufficient for mainnet
-                nonzero!(20480_usize),
+                // 1048576 * 20 = 20971520 which is sufficient for mainnet
+                nonzero!(1048576_usize),
             );
         Self {
             ts_cache,
@@ -152,8 +152,9 @@ impl<DB: Blockstore> ChainIndex<DB> {
     ) -> Result<Tipset, Error> {
         use crate::shim::policy::policy_constants::CHAIN_FINALITY;
 
-        // use `CHAIN_FINALITY` as checkpoint interval
-        const CHECKPOINT_INTERVAL: ChainEpoch = CHAIN_FINALITY;
+        // use `20` as checkpoint interval to match Lotus:
+        // <https://github.com/filecoin-project/lotus/blob/006da4c7e1c1c29ac02b32112c0d205e4085ba35/chain/store/index.go#L52>
+        const CHECKPOINT_INTERVAL: ChainEpoch = 20;
         fn next_checkpoint(epoch: ChainEpoch) -> ChainEpoch {
             epoch - epoch.mod_floor(&CHECKPOINT_INTERVAL) + CHECKPOINT_INTERVAL
         }

From 74bbc5cc94715fe07fbdb26c4021f92234514b0d Mon Sep 17 00:00:00 2001
From: hanabi1224 <harlowmoo@gmail.com>
Date: Thu, 9 Apr 2026 18:47:58 +0800
Subject: [PATCH 2/2] resolve comments

---
 src/chain/store/index.rs | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/chain/store/index.rs b/src/chain/store/index.rs
index 0cbbbcecb5b3..aa4cb1f95d5c 100644
--- a/src/chain/store/index.rs
+++ b/src/chain/store/index.rs
@@ -52,6 +52,7 @@ impl<DB: Blockstore> ChainIndex<DB> {
             SizeTrackingLruCache::new_with_metrics(
                 "tipset_by_height".into(),
                 // 1048576 * 20 = 20971520 which is sufficient for mainnet
+                // Maximum ~32MiB RAM usage
                 nonzero!(1048576_usize),
             );
         Self {
@@ -153,7 +154,7 @@ impl<DB: Blockstore> ChainIndex<DB> {
         use crate::shim::policy::policy_constants::CHAIN_FINALITY;
 
         // use `20` as checkpoint interval to match Lotus:
-        // <https://github.com/filecoin-project/lotus/blob/006da4c7e1c1c29ac02b32112c0d205e4085ba35/chain/store/index.go#L52>
+        // <https://github.com/filecoin-project/lotus/blob/v1.35.1/chain/store/index.go#L52>
         const CHECKPOINT_INTERVAL: ChainEpoch = 20;
         fn next_checkpoint(epoch: ChainEpoch) -> ChainEpoch {
             epoch - epoch.mod_floor(&CHECKPOINT_INTERVAL) + CHECKPOINT_INTERVAL