From aa59059a910eb6e1e824b84413a66909d697ef8a Mon Sep 17 00:00:00 2001
From: Alex Auvolat <alex@adnab.me>
Date: Thu, 7 Dec 2023 11:50:00 +0100
Subject: [PATCH] layout cli: safer skip-dead-nodes command

---
 src/garage/cli/cmd.rs     | 23 ++++++++++++++++-------
 src/garage/cli/layout.rs  | 35 +++++++++++++++++++++++++----------
 src/garage/cli/structs.rs | 12 ++++++++----
 3 files changed, 49 insertions(+), 21 deletions(-)

diff --git a/src/garage/cli/cmd.rs b/src/garage/cli/cmd.rs
index c7f0ad2b..196c0cb3 100644
--- a/src/garage/cli/cmd.rs
+++ b/src/garage/cli/cmd.rs
@@ -49,13 +49,7 @@ pub async fn cli_command_dispatch(
 }
 
 pub async fn cmd_status(rpc_cli: &Endpoint<SystemRpc, ()>, rpc_host: NodeID) -> Result<(), Error> {
-	let status = match rpc_cli
-		.call(&rpc_host, SystemRpc::GetKnownNodes, PRIO_NORMAL)
-		.await??
-	{
-		SystemRpc::ReturnKnownNodes(nodes) => nodes,
-		resp => return Err(Error::Message(format!("Invalid RPC response: {:?}", resp))),
-	};
+	let status = fetch_status(rpc_cli, rpc_host).await?;
 	let layout = fetch_layout(rpc_cli, rpc_host).await?;
 
 	println!("==== HEALTHY NODES ====");
@@ -268,3 +262,18 @@ pub async fn cmd_admin(
 	}
 	Ok(())
 }
+
+// ---- utility ----
+
+pub async fn fetch_status(
+	rpc_cli: &Endpoint<SystemRpc, ()>,
+	rpc_host: NodeID,
+) -> Result<Vec<KnownNodeInfo>, Error> {
+	match rpc_cli
+		.call(&rpc_host, SystemRpc::GetKnownNodes, PRIO_NORMAL)
+		.await??
+	{
+		SystemRpc::ReturnKnownNodes(nodes) => Ok(nodes),
+		resp => Err(Error::Message(format!("Invalid RPC response: {:?}", resp))),
+	}
+}
diff --git a/src/garage/cli/layout.rs b/src/garage/cli/layout.rs
index 3c7843bd..cdf77c04 100644
--- a/src/garage/cli/layout.rs
+++ b/src/garage/cli/layout.rs
@@ -33,8 +33,8 @@ pub async fn cli_layout_command_dispatch(
 			cmd_config_layout(system_rpc_endpoint, rpc_host, config_opt).await
 		}
 		LayoutOperation::History => cmd_layout_history(system_rpc_endpoint, rpc_host).await,
-		LayoutOperation::AssumeSync(assume_sync_opt) => {
-			cmd_layout_assume_sync(system_rpc_endpoint, rpc_host, assume_sync_opt).await
+		LayoutOperation::SkipDeadNodes(assume_sync_opt) => {
+			cmd_layout_skip_dead_nodes(system_rpc_endpoint, rpc_host, assume_sync_opt).await
 		}
 	}
 }
@@ -388,13 +388,21 @@ pub async fn cmd_layout_history(
 	Ok(())
 }
 
-pub async fn cmd_layout_assume_sync(
+pub async fn cmd_layout_skip_dead_nodes(
 	rpc_cli: &Endpoint<SystemRpc, ()>,
 	rpc_host: NodeID,
-	opt: AssumeSyncOpt,
+	opt: SkipDeadNodesOpt,
 ) -> Result<(), Error> {
+	let status = fetch_status(rpc_cli, rpc_host).await?;
 	let mut layout = fetch_layout(rpc_cli, rpc_host).await?;
 
+	if layout.versions.len() == 1 {
+		return Err(Error::Message(
+			"This command cannot be called when there is only one live cluster layout version"
+				.into(),
+		));
+	}
+
 	let min_v = layout.min_stored();
 	if opt.version <= min_v || opt.version > layout.current().version {
 		return Err(Error::Message(format!(
@@ -408,12 +416,19 @@ pub async fn cmd_layout_assume_sync(
 
 	let all_nodes = layout.get_all_nodes();
 	for node in all_nodes.iter() {
-		layout.update_trackers.ack_map.set_max(*node, opt.version);
-		layout.update_trackers.sync_map.set_max(*node, opt.version);
-		layout
-			.update_trackers
-			.sync_ack_map
-			.set_max(*node, opt.version);
+		if status.iter().any(|x| x.id == *node && x.is_up) {
+			continue;
+		}
+
+		if layout.update_trackers.ack_map.set_max(*node, opt.version) {
+			println!("Increased the ACK tracker for node {:?}", node);
+		}
+
+		if opt.allow_missing_data {
+			if layout.update_trackers.sync_map.set_max(*node, opt.version) {
+				println!("Increased the SYNC tracker for node {:?}", node);
+			}
+		}
 	}
 
 	send_layout(rpc_cli, rpc_host, layout).await?;
diff --git a/src/garage/cli/structs.rs b/src/garage/cli/structs.rs
index c4b400f4..6bc3da22 100644
--- a/src/garage/cli/structs.rs
+++ b/src/garage/cli/structs.rs
@@ -117,9 +117,9 @@ pub enum LayoutOperation {
 	#[structopt(name = "history", version = garage_version())]
 	History,
 
-	/// Assume all nodes are synchronized up to a certain layout version
-	#[structopt(name = "assume-sync", version = garage_version())]
-	AssumeSync(AssumeSyncOpt),
+	/// Skip dead nodes when awaiting for a new layout version to be synchronized
+	#[structopt(name = "skip-dead-nodes", version = garage_version())]
+	SkipDeadNodes(SkipDeadNodesOpt),
 }
 
 #[derive(StructOpt, Debug)]
@@ -178,11 +178,15 @@ pub struct RevertLayoutOpt {
 }
 
 #[derive(StructOpt, Debug)]
-pub struct AssumeSyncOpt {
+pub struct SkipDeadNodesOpt {
 	/// Version number of the layout to assume is currently up-to-date.
 	/// This will generally be the current layout version.
 	#[structopt(long = "version")]
 	pub(crate) version: u64,
+	/// Allow the skip even if a quorum of ndoes could not be found for
+	/// the data among the remaining nodes
+	#[structopt(long = "allow-missing-data")]
+	pub(crate) allow_missing_data: bool,
 }
 
 #[derive(Serialize, Deserialize, StructOpt, Debug)]