From 152b2765bdbe3674abd6a4af626916fd55086e36 Mon Sep 17 00:00:00 2001
From: Darshan Kathiriya <8559992+lakshya-sky@users.noreply.github.com>
Date: Wed, 19 Jun 2024 13:09:25 -0400
Subject: [PATCH] use watch channels instead of rwlock (#8950)

---
 .../provider/src/providers/chain_info.rs      | 27 ++++++++++++-------
 1 file changed, 17 insertions(+), 10 deletions(-)

diff --git a/crates/storage/provider/src/providers/chain_info.rs b/crates/storage/provider/src/providers/chain_info.rs
index 2e53a78ac..c696fefea 100644
--- a/crates/storage/provider/src/providers/chain_info.rs
+++ b/crates/storage/provider/src/providers/chain_info.rs
@@ -8,6 +8,7 @@ use std::{
     },
     time::Instant,
 };
+use tokio::sync::watch;
 
 /// Tracks the chain info: canonical head, safe block, finalized block.
 #[derive(Debug, Clone)]
@@ -18,14 +19,16 @@ pub(crate) struct ChainInfoTracker {
 impl ChainInfoTracker {
     /// Create a new chain info container for the given canonical head.
     pub(crate) fn new(head: SealedHeader) -> Self {
+        let (finalized_block, _) = watch::channel(None);
+        let (safe_block, _) = watch::channel(None);
         Self {
             inner: Arc::new(ChainInfoInner {
                 last_forkchoice_update: RwLock::new(None),
                 last_transition_configuration_exchange: RwLock::new(None),
                 canonical_head_number: AtomicU64::new(head.number),
                 canonical_head: RwLock::new(head),
-                safe_block: RwLock::new(None),
-                finalized_block: RwLock::new(None),
+                safe_block,
+                finalized_block,
             }),
         }
     }
@@ -63,12 +66,12 @@ impl ChainInfoTracker {
 
     /// Returns the safe header of the chain.
     pub(crate) fn get_safe_header(&self) -> Option<SealedHeader> {
-        self.inner.safe_block.read().clone()
+        self.inner.safe_block.borrow().clone()
     }
 
     /// Returns the finalized header of the chain.
     pub(crate) fn get_finalized_header(&self) -> Option<SealedHeader> {
-        self.inner.finalized_block.read().clone()
+        self.inner.finalized_block.borrow().clone()
     }
 
     /// Returns the canonical head of the chain.
@@ -85,14 +88,14 @@ impl ChainInfoTracker {
     /// Returns the safe header of the chain.
     #[allow(dead_code)]
     pub(crate) fn get_safe_num_hash(&self) -> Option<BlockNumHash> {
-        let h = self.inner.safe_block.read();
+        let h = self.inner.safe_block.borrow();
         h.as_ref().map(|h| h.num_hash())
     }
 
     /// Returns the finalized header of the chain.
     #[allow(dead_code)]
     pub(crate) fn get_finalized_num_hash(&self) -> Option<BlockNumHash> {
-        let h = self.inner.finalized_block.read();
+        let h = self.inner.finalized_block.borrow();
         h.as_ref().map(|h| h.num_hash())
     }
 
@@ -107,12 +110,16 @@ impl ChainInfoTracker {
 
     /// Sets the safe header of the chain.
     pub(crate) fn set_safe(&self, header: SealedHeader) {
-        self.inner.safe_block.write().replace(header);
+        self.inner.safe_block.send_modify(|h| {
+            let _ = h.replace(header);
+        });
     }
 
     /// Sets the finalized header of the chain.
     pub(crate) fn set_finalized(&self, header: SealedHeader) {
-        self.inner.finalized_block.write().replace(header);
+        self.inner.finalized_block.send_modify(|h| {
+            let _ = h.replace(header);
+        });
     }
 }
 
@@ -132,7 +139,7 @@ struct ChainInfoInner {
     /// The canonical head of the chain.
     canonical_head: RwLock<SealedHeader>,
     /// The block that the beacon node considers safe.
-    safe_block: RwLock<Option<SealedHeader>>,
+    safe_block: watch::Sender<Option<SealedHeader>>,
     /// The block that the beacon node considers finalized.
-    finalized_block: RwLock<Option<SealedHeader>>,
+    finalized_block: watch::Sender<Option<SealedHeader>>,
 }