From 5f72b3c7347b8c8c9c783573ab3fb58eb97841e1 Mon Sep 17 00:00:00 2001
From: Ashwin Sekar <ashwin@solana.com>
Date: Wed, 25 Sep 2024 13:37:27 +0000
Subject: [PATCH] gossip: reduce votes stored per validator from 32 to 12

---
 gossip/src/cluster_info.rs | 25 ++++++++++++++-----------
 gossip/src/crds_value.rs   |  5 ++---
 2 files changed, 16 insertions(+), 14 deletions(-)

diff --git a/gossip/src/cluster_info.rs b/gossip/src/cluster_info.rs
index 67a587825d5843..dc2c18b1fbeee4 100644
--- a/gossip/src/cluster_info.rs
+++ b/gossip/src/cluster_info.rs
@@ -27,7 +27,7 @@ use {
         },
         crds_value::{
             self, CrdsData, CrdsValue, CrdsValueLabel, EpochSlotsIndex, LowestSlot, NodeInstance,
-            SnapshotHashes, Version, Vote, MAX_WALLCLOCK,
+            SnapshotHashes, Version, Vote, MAX_VOTES, MAX_WALLCLOCK,
         },
         duplicate_shred::DuplicateShred,
         epoch_slots::EpochSlots,
@@ -77,7 +77,6 @@ use {
         streamer::{PacketBatchReceiver, PacketBatchSender},
     },
     solana_vote::vote_parser,
-    solana_vote_program::vote_state::MAX_LOCKOUT_HISTORY,
     std::{
         borrow::{Borrow, Cow},
         collections::{HashMap, HashSet, VecDeque},
@@ -1054,7 +1053,7 @@ impl ClusterInfo {
     }
 
     pub fn push_vote_at_index(&self, vote: Transaction, vote_index: u8) {
-        assert!((vote_index as usize) < MAX_LOCKOUT_HISTORY);
+        assert!(vote_index < MAX_VOTES);
         let self_pubkey = self.id();
         let now = timestamp();
         let vote = Vote::new(self_pubkey, vote, now).unwrap();
@@ -1080,7 +1079,7 @@ impl ClusterInfo {
         let vote_index = {
             let gossip_crds =
                 self.time_gossip_read_lock("gossip_read_push_vote", &self.stats.push_vote_read);
-            (0..MAX_LOCKOUT_HISTORY as u8)
+            (0..MAX_VOTES)
                 .filter_map(|ix| {
                     let vote = CrdsValueLabel::Vote(ix, self_pubkey);
                     let vote: &CrdsData = gossip_crds.get(&vote)?;
@@ -1102,7 +1101,7 @@ impl ClusterInfo {
         if exists_newer_vote {
             return None;
         }
-        if num_crds_votes < MAX_LOCKOUT_HISTORY as u8 {
+        if num_crds_votes < MAX_VOTES {
             // Do not evict if there is space in crds
             Some(num_crds_votes)
         } else {
@@ -1127,7 +1126,7 @@ impl ClusterInfo {
                 tower
             );
         };
-        debug_assert!(vote_index < MAX_LOCKOUT_HISTORY as u8);
+        debug_assert!(vote_index < MAX_VOTES);
         self.push_vote_at_index(vote, vote_index);
     }
 
@@ -1136,7 +1135,7 @@ impl ClusterInfo {
             let self_pubkey = self.id();
             let gossip_crds =
                 self.time_gossip_read_lock("gossip_read_push_vote", &self.stats.push_vote_read);
-            (0..MAX_LOCKOUT_HISTORY as u8).find(|ix| {
+            (0..MAX_VOTES).find(|ix| {
                 let vote = CrdsValueLabel::Vote(*ix, self_pubkey);
                 let Some(vote) = gossip_crds.get::<&CrdsData>(&vote) else {
                     return false;
@@ -1168,7 +1167,7 @@ impl ClusterInfo {
                 );
                 return;
             };
-            debug_assert!(vote_index < MAX_LOCKOUT_HISTORY as u8);
+            debug_assert!(vote_index < MAX_VOTES);
             self.push_vote_at_index(refresh_vote, vote_index);
         }
     }
@@ -3413,10 +3412,14 @@ mod tests {
             duplicate_shred::{self, tests::new_rand_shred, MAX_DUPLICATE_SHREDS},
             socketaddr,
         },
+        crds_value::MAX_VOTES,
         itertools::izip,
         solana_ledger::shred::Shredder,
         solana_sdk::signature::{Keypair, Signer},
-        solana_vote_program::{vote_instruction, vote_state::Vote},
+        solana_vote_program::{
+            vote_instruction,
+            vote_state::{Vote, MAX_LOCKOUT_HISTORY},
+        },
         std::{
             iter::repeat_with,
             net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddrV4},
@@ -3966,7 +3969,7 @@ mod tests {
         }
 
         let initial_votes = cluster_info.get_votes(&mut Cursor::default());
-        assert_eq!(initial_votes.len(), MAX_LOCKOUT_HISTORY);
+        assert_eq!(initial_votes.len(), MAX_VOTES as usize);
 
         // Trying to refresh a vote less than all votes in gossip should do nothing
         let refresh_slot = lowest_vote_slot - 1;
@@ -4001,7 +4004,7 @@ mod tests {
 
         // This should evict the latest vote since it's for a slot less than refresh_slot
         let votes = cluster_info.get_votes(&mut Cursor::default());
-        assert_eq!(votes.len(), MAX_LOCKOUT_HISTORY);
+        assert_eq!(votes.len(), MAX_VOTES as usize);
         assert!(votes.contains(&refresh_tx));
         assert!(!votes.contains(&first_vote.unwrap()));
     }
diff --git a/gossip/src/crds_value.rs b/gossip/src/crds_value.rs
index 50061fe4df2c9c..19becaebff7575 100644
--- a/gossip/src/crds_value.rs
+++ b/gossip/src/crds_value.rs
@@ -33,9 +33,8 @@ pub const MAX_WALLCLOCK: u64 = 1_000_000_000_000_000;
 pub const MAX_SLOT: u64 = 1_000_000_000_000_000;
 
 pub type VoteIndex = u8;
-// TODO: Remove this in favor of vote_state::MAX_LOCKOUT_HISTORY once
-// the fleet is updated to the new ClusterInfo::push_vote code.
-pub const MAX_VOTES: VoteIndex = 32;
+/// Number of votes per validator to store.
+pub const MAX_VOTES: VoteIndex = 12;
 
 pub type EpochSlotsIndex = u8;
 pub const MAX_EPOCH_SLOTS: EpochSlotsIndex = 255;