Add block.rc_size, table.size and table.merkle_tree_size metrics

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);
 

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, &[])