From bfb1845fdc981a370539d641a5d80f438f184f07 Mon Sep 17 00:00:00 2001
From: Alex Auvolat <alex@adnab.me>
Date: Thu, 9 Nov 2023 14:12:05 +0100
Subject: layout: refactor to use a RwLock on LayoutHistory

---
 src/table/sync.rs | 21 ++++++++++-----------
 1 file changed, 10 insertions(+), 11 deletions(-)

(limited to 'src/table/sync.rs')

diff --git a/src/table/sync.rs b/src/table/sync.rs
index 2da1bfe7..4355bd9e 100644
--- a/src/table/sync.rs
+++ b/src/table/sync.rs
@@ -10,7 +10,7 @@ use rand::Rng;
 use serde::{Deserialize, Serialize};
 use serde_bytes::ByteBuf;
 use tokio::select;
-use tokio::sync::{mpsc, watch};
+use tokio::sync::{mpsc, watch, Notify};
 
 use garage_util::background::*;
 use garage_util::data::*;
@@ -91,8 +91,8 @@ impl<F: TableSchema, R: TableReplication> TableSyncer<F, R> {
 
 		bg.spawn_worker(SyncWorker {
 			syncer: self.clone(),
-			layout_watch: self.system.layout_watch(),
-			layout: self.system.cluster_layout().clone(),
+			layout_notify: self.system.layout_notify(),
+			layout_version: self.system.cluster_layout().current().version,
 			add_full_sync_rx,
 			todo: vec![],
 			next_full_sync: Instant::now() + Duration::from_secs(20),
@@ -492,8 +492,8 @@ impl<F: TableSchema, R: TableReplication> EndpointHandler<SyncRpc> for TableSync
 
 struct SyncWorker<F: TableSchema, R: TableReplication> {
 	syncer: Arc<TableSyncer<F, R>>,
-	layout_watch: watch::Receiver<Arc<LayoutHistory>>,
-	layout: Arc<LayoutHistory>,
+	layout_notify: Arc<Notify>,
+	layout_version: u64,
 	add_full_sync_rx: mpsc::UnboundedReceiver<()>,
 	todo: Vec<TodoPartition>,
 	next_full_sync: Instant,
@@ -593,12 +593,11 @@ impl<F: TableSchema, R: TableReplication> Worker for SyncWorker<F, R> {
 					self.add_full_sync();
 				}
 			},
-			_ = self.layout_watch.changed() => {
-				let new_layout = self.layout_watch.borrow();
-				if !Arc::ptr_eq(&new_layout, &self.layout) {
-					self.layout = new_layout.clone();
-					drop(new_layout);
-					debug!("({}) Ring changed, adding full sync to syncer todo list", F::TABLE_NAME);
+			_ = self.layout_notify.notified() => {
+				let new_version = self.syncer.system.cluster_layout().current().version;
+				if new_version > self.layout_version {
+					self.layout_version = new_version;
+					debug!("({}) Layout changed, adding full sync to syncer todo list", F::TABLE_NAME);
 					self.add_full_sync();
 				}
 			},
-- 
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