From 37961d36882564a0460562aee8d0c1553f6b251c Mon Sep 17 00:00:00 2001
From: Victor Allombert <victor.allombert@nomadic-labs.com>
Date: Mon, 12 Aug 2024 11:17:56 +0200
Subject: [PATCH] Store: introduce metric for delayed storage maintenance
 target

---
 src/lib_store/unix/store.ml         | 29 +++++++++++++++++++++++++++++
 src/lib_store/unix/store_metrics.ml |  9 +++++++++
 2 files changed, 38 insertions(+)

diff --git a/src/lib_store/unix/store.ml b/src/lib_store/unix/store.ml
index eaa6c770aeb1..105b66d5042d 100644
--- a/src/lib_store/unix/store.ml
+++ b/src/lib_store/unix/store.ml
@@ -1695,6 +1695,9 @@ module Chain = struct
       Store_events.(emit delay_store_merging)
         (chain_store.storage_maintenance.maintenance_delay, new_target)
     in
+    Prometheus.Gauge.set
+      Store_metrics.metrics.maintenance_target
+      (Int32.to_float new_target) ;
     return_unit
 
   (* Returns whether or not we should proceed to the merge. True upon
@@ -1704,6 +1707,13 @@ module Chain = struct
     let level_to_merge_reached = target <= Block.level new_head in
     let* () =
       if level_to_merge_reached then
+        let () =
+          (* Set the storage maintenance target to -1 to notify that
+             no target is set. *)
+          Prometheus.Gauge.set
+            Store_metrics.metrics.maintenance_target
+            Float.minus_one
+        in
         Stored_data.write
           chain_store.storage_maintenance.scheduled_maintenance
           None
@@ -1920,6 +1930,11 @@ module Chain = struct
                       chain_store.storage_maintenance.scheduled_maintenance
                       None
                   in
+                  (* Set the storage maintenance target to -1 to notify that no
+                     target is set. *)
+                  Prometheus.Gauge.set
+                    Store_metrics.metrics.maintenance_target
+                    Float.minus_one ;
                   return_true
               | Custom delay ->
                   custom_delayed_maintenance chain_store new_head delay
@@ -2366,6 +2381,11 @@ module Chain = struct
         (Naming.scheduled_maintenance chain_dir)
         ~initial_data:None
     in
+    (* Set the storage maintenance target to -1 to notify that no
+       target is set. *)
+    Prometheus.Gauge.set
+      Store_metrics.metrics.maintenance_target
+      Float.minus_one ;
     let chain_store : chain_store =
       {
         global_store;
@@ -2419,6 +2439,15 @@ module Chain = struct
             (Naming.scheduled_maintenance chain_dir)
             ~initial_data:None
         in
+        let*! scheduled_maintenance_value =
+          Stored_data.get scheduled_maintenance
+        in
+        (* Set the storage maintenance target to -1, if no value
+           found, to notify that no target is set. *)
+        Prometheus.Gauge.set
+          Store_metrics.metrics.maintenance_target
+          (Option.value ~default:Int32.minus_one scheduled_maintenance_value
+          |> Int32.to_float) ;
         let chain_store =
           {
             global_store;
diff --git a/src/lib_store/unix/store_metrics.ml b/src/lib_store/unix/store_metrics.ml
index f1247e4614d5..57d7ffe6b130 100644
--- a/src/lib_store/unix/store_metrics.ml
+++ b/src/lib_store/unix/store_metrics.ml
@@ -30,6 +30,7 @@ type metrics = {
   alternate_heads_count : Prometheus.Gauge.t;
   last_written_block_size : Prometheus.Gauge.t;
   last_store_merge_time : Prometheus.Gauge.t;
+  maintenance_target : Prometheus.Gauge.t;
 }
 
 let namespace = Tezos_version.Octez_node_version.namespace
@@ -67,6 +68,13 @@ let metrics =
     let help = "Time, in seconds, for the completion of the last store merge" in
     Prometheus.Gauge.v ~help ~namespace ~subsystem "last_merge_time"
   in
+  let maintenance_target =
+    let help =
+      "The level at which the storage maintenance is expected to be triggered. \
+       Set to -1 if no target is set"
+    in
+    Prometheus.Gauge.v ~help ~namespace ~subsystem "maintenance_target"
+  in
   let invalid_blocks_info =
     Prometheus.MetricInfo.
       {
@@ -94,4 +102,5 @@ let metrics =
     alternate_heads_count;
     last_written_block_size;
     last_store_merge_time;
+    maintenance_target;
   }
-- 
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