From 041b60ed1dc48563ad297a6a30230655555c9a20 Mon Sep 17 00:00:00 2001
From: Alex Auvolat <alex@adnab.me>
Date: Tue, 13 Dec 2022 15:54:03 +0100
Subject: Add block.rc_size, table.size and table.merkle_tree_size metrics

---
 src/block/manager.rs |  3 ++-
 src/block/metrics.rs | 12 +++++++++++-
 src/table/data.rs    |  8 +++++++-
 src/table/metrics.rs | 38 +++++++++++++++++++++++++++++++++++++-
 4 files changed, 57 insertions(+), 4 deletions(-)

diff --git a/src/block/manager.rs b/src/block/manager.rs
index c23d7a59..28523a93 100644
--- a/src/block/manager.rs
+++ b/src/block/manager.rs
@@ -123,7 +123,8 @@ impl BlockManager {
 			.netapp
 			.endpoint("garage_block/manager.rs/Rpc".to_string());
 
-		let metrics = BlockManagerMetrics::new(resync.queue.clone(), resync.errors.clone());
+		let metrics =
+			BlockManagerMetrics::new(rc.rc.clone(), resync.queue.clone(), resync.errors.clone());
 
 		let (scrub_tx, scrub_rx) = mpsc::channel(1);
 
diff --git a/src/block/metrics.rs b/src/block/metrics.rs
index 477add66..fbef95af 100644
--- a/src/block/metrics.rs
+++ b/src/block/metrics.rs
@@ -1,9 +1,11 @@
 use opentelemetry::{global, metrics::*};
 
+use garage_db as db;
 use garage_db::counted_tree_hack::CountedTree;
 
 /// TableMetrics reference all counter used for metrics
 pub struct BlockManagerMetrics {
+	pub(crate) _rc_size: ValueObserver<u64>,
 	pub(crate) _resync_queue_len: ValueObserver<u64>,
 	pub(crate) _resync_errored_blocks: ValueObserver<u64>,
 
@@ -23,9 +25,17 @@ pub struct BlockManagerMetrics {
 }
 
 impl BlockManagerMetrics {
-	pub fn new(resync_queue: CountedTree, resync_errors: CountedTree) -> Self {
+	pub fn new(rc_tree: db::Tree, resync_queue: CountedTree, resync_errors: CountedTree) -> Self {
 		let meter = global::meter("garage_model/block");
 		Self {
+			_rc_size: meter
+				.u64_value_observer("block.rc_size", move |observer| {
+					if let Ok(Some(v)) = rc_tree.fast_len() {
+						observer.observe(v as u64, &[])
+					}
+				})
+				.with_description("Number of blocks known to the reference counter")
+				.init(),
 			_resync_queue_len: meter
 				.u64_value_observer("block.resync_queue_length", move |observer| {
 					observer.observe(resync_queue.len() as u64, &[])
diff --git a/src/table/data.rs b/src/table/data.rs
index 3212e82b..93da2110 100644
--- a/src/table/data.rs
+++ b/src/table/data.rs
@@ -58,7 +58,13 @@ where
 			.expect("Unable to open DB tree");
 		let gc_todo = CountedTree::new(gc_todo).expect("Cannot count gc_todo_v2");
 
-		let metrics = TableMetrics::new(F::TABLE_NAME, merkle_todo.clone(), gc_todo.clone());
+		let metrics = TableMetrics::new(
+			F::TABLE_NAME,
+			store.clone(),
+			merkle_tree.clone(),
+			merkle_todo.clone(),
+			gc_todo.clone(),
+		);
 
 		Arc::new(Self {
 			system,
diff --git a/src/table/metrics.rs b/src/table/metrics.rs
index 3a1783e0..8318a84f 100644
--- a/src/table/metrics.rs
+++ b/src/table/metrics.rs
@@ -5,6 +5,8 @@ use garage_db::counted_tree_hack::CountedTree;
 
 /// TableMetrics reference all counter used for metrics
 pub struct TableMetrics {
+	pub(crate) _table_size: ValueObserver<u64>,
+	pub(crate) _merkle_tree_size: ValueObserver<u64>,
 	pub(crate) _merkle_todo_len: ValueObserver<u64>,
 	pub(crate) _gc_todo_len: ValueObserver<u64>,
 
@@ -20,9 +22,43 @@ pub struct TableMetrics {
 	pub(crate) sync_items_received: Counter<u64>,
 }
 impl TableMetrics {
-	pub fn new(table_name: &'static str, merkle_todo: db::Tree, gc_todo: CountedTree) -> Self {
+	pub fn new(
+		table_name: &'static str,
+		store: db::Tree,
+		merkle_tree: db::Tree,
+		merkle_todo: db::Tree,
+		gc_todo: CountedTree,
+	) -> Self {
 		let meter = global::meter(table_name);
 		TableMetrics {
+			_table_size: meter
+				.u64_value_observer(
+					"table.size",
+					move |observer| {
+						if let Ok(Some(v)) = store.fast_len() {
+							observer.observe(
+								v as u64,
+								&[KeyValue::new("table_name", table_name)],
+							);
+						}
+					},
+				)
+				.with_description("Number of items in table")
+				.init(),
+			_merkle_tree_size: meter
+				.u64_value_observer(
+					"table.merkle_tree_size",
+					move |observer| {
+						if let Ok(Some(v)) = merkle_tree.fast_len() {
+							observer.observe(
+								v as u64,
+								&[KeyValue::new("table_name", table_name)],
+							);
+						}
+					},
+				)
+				.with_description("Number of nodes in table's Merkle tree")
+				.init(),
 			_merkle_todo_len: meter
 				.u64_value_observer(
 					"table.merkle_updater_todo_queue_length",
-- 
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