From 8ba6454e21834061cdc90986e71690d64cbabbe0 Mon Sep 17 00:00:00 2001
From: Alex Auvolat <lx@deuxfleurs.fr>
Date: Tue, 25 Mar 2025 13:11:11 +0100
Subject: [PATCH] reduce anti-entropy interval for fullcopy tables

---
 src/table/replication/fullcopy.rs   | 7 +++++++
 src/table/replication/parameters.rs | 4 ++++
 src/table/replication/sharded.rs    | 4 ++++
 src/table/sync.rs                   | 5 +----
 4 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/src/table/replication/fullcopy.rs b/src/table/replication/fullcopy.rs
index 938fe954..63ca5181 100644
--- a/src/table/replication/fullcopy.rs
+++ b/src/table/replication/fullcopy.rs
@@ -1,4 +1,5 @@
 use std::sync::Arc;
+use std::time::Duration;
 
 use garage_rpc::layout::*;
 use garage_rpc::system::System;
@@ -26,6 +27,12 @@ pub struct TableFullReplication {
 impl TableReplication for TableFullReplication {
 	type WriteSets = Vec<Vec<Uuid>>;
 
+	// Do anti-entropy every 10 seconds.
+	// Compared to sharded tables, anti-entropy is much less costly as there is
+	// a single partition hash to exchange.
+	// Also, it's generally a much bigger problem for fullcopy tables to be out of sync.
+	const ANTI_ENTROPY_INTERVAL: Duration = Duration::from_secs(10);
+
 	fn storage_nodes(&self, _hash: &Hash) -> Vec<Uuid> {
 		self.system.cluster_layout().all_nodes().to_vec()
 	}
diff --git a/src/table/replication/parameters.rs b/src/table/replication/parameters.rs
index 3649fad3..327f2cbf 100644
--- a/src/table/replication/parameters.rs
+++ b/src/table/replication/parameters.rs
@@ -1,3 +1,5 @@
+use std::time::Duration;
+
 use garage_rpc::layout::*;
 use garage_util::data::*;
 
@@ -5,6 +7,8 @@ use garage_util::data::*;
 pub trait TableReplication: Send + Sync + 'static {
 	type WriteSets: AsRef<Vec<Vec<Uuid>>> + AsMut<Vec<Vec<Uuid>>> + Send + Sync + 'static;
 
+	const ANTI_ENTROPY_INTERVAL: Duration;
+
 	// See examples in table_sharded.rs and table_fullcopy.rs
 	// To understand various replication methods
 
diff --git a/src/table/replication/sharded.rs b/src/table/replication/sharded.rs
index 17a848fe..e1041174 100644
--- a/src/table/replication/sharded.rs
+++ b/src/table/replication/sharded.rs
@@ -1,4 +1,5 @@
 use std::sync::Arc;
+use std::time::Duration;
 
 use garage_rpc::layout::*;
 use garage_rpc::system::System;
@@ -25,6 +26,9 @@ pub struct TableShardedReplication {
 }
 
 impl TableReplication for TableShardedReplication {
+	// Do anti-entropy every 10 minutes
+	const ANTI_ENTROPY_INTERVAL: Duration = Duration::from_secs(10 * 60);
+
 	type WriteSets = WriteLock<Vec<Vec<Uuid>>>;
 
 	fn storage_nodes(&self, hash: &Hash) -> Vec<Uuid> {
diff --git a/src/table/sync.rs b/src/table/sync.rs
index 2d43b9fc..6c8ddb1d 100644
--- a/src/table/sync.rs
+++ b/src/table/sync.rs
@@ -27,9 +27,6 @@ use crate::merkle::*;
 use crate::replication::*;
 use crate::*;
 
-// Do anti-entropy every 10 minutes
-const ANTI_ENTROPY_INTERVAL: Duration = Duration::from_secs(10 * 60);
-
 pub struct TableSyncer<F: TableSchema, R: TableReplication> {
 	system: Arc<System>,
 	data: Arc<TableData<F, R>>,
@@ -514,7 +511,7 @@ impl<F: TableSchema, R: TableReplication> SyncWorker<F, R> {
 
 		partitions.partitions.shuffle(&mut thread_rng());
 		self.todo = Some(partitions);
-		self.next_full_sync = Instant::now() + ANTI_ENTROPY_INTERVAL;
+		self.next_full_sync = Instant::now() + R::ANTI_ENTROPY_INTERVAL;
 	}
 }