From aa8e95419744f209f3bf4a90e71e6fdb18a67cab Mon Sep 17 00:00:00 2001
From: Joonas Koivunen <joonas@neon.tech>
Date: Wed, 16 Aug 2023 12:30:05 +0300
Subject: [PATCH] layer_manager, layer_access_stats: remove witness sidequest

it was interfering with me moving responsibilities back and forth
---
 pageserver/src/tenant/timeline.rs             |  4 +--
 .../src/tenant/timeline/layer_manager.rs      | 28 ++++++++++++-------
 2 files changed, 20 insertions(+), 12 deletions(-)

diff --git a/pageserver/src/tenant/timeline.rs b/pageserver/src/tenant/timeline.rs
index 3080f942ac..3be999211c 100644
--- a/pageserver/src/tenant/timeline.rs
+++ b/pageserver/src/tenant/timeline.rs
@@ -13,7 +13,7 @@ use fail::fail_point;
 use itertools::Itertools;
 use pageserver_api::models::{
     DownloadRemoteLayersTaskInfo, DownloadRemoteLayersTaskSpawnRequest, LayerMapInfo,
-    LayerResidenceStatus, TimelineState,
+    LayerResidenceEventReason, LayerResidenceStatus, TimelineState,
 };
 use remote_storage::GenericRemoteStorage;
 use serde_with::serde_as;
@@ -2782,10 +2782,10 @@ impl Timeline {
         let mut guard = self.layers.write().await;
 
         for l in &image_layers {
+            // FIXME: these should be in guard
             self.metrics
                 .resident_physical_size_gauge
                 .add(l.layer_desc().file_size);
-            let l = Arc::new(l);
             l.access_stats().record_residence_event(
                 LayerResidenceStatus::Resident,
                 LayerResidenceEventReason::LayerCreate,
diff --git a/pageserver/src/tenant/timeline/layer_manager.rs b/pageserver/src/tenant/timeline/layer_manager.rs
index 63cba5e7f3..85355c29d7 100644
--- a/pageserver/src/tenant/timeline/layer_manager.rs
+++ b/pageserver/src/tenant/timeline/layer_manager.rs
@@ -1,4 +1,5 @@
 use anyhow::{bail, ensure, Context, Result};
+use pageserver_api::models::{LayerResidenceEventReason, LayerResidenceStatus};
 use std::{collections::HashMap, sync::Arc};
 use tracing::trace;
 use utils::{
@@ -167,6 +168,10 @@ impl LayerManager {
     pub(crate) fn track_new_image_layers(&mut self, image_layers: &[ResidentLayer]) {
         let mut updates = self.layer_map.batch_update();
         for layer in image_layers {
+            layer.access_stats().record_residence_event(
+                LayerResidenceStatus::Resident,
+                LayerResidenceEventReason::LayerCreate,
+            );
             Self::insert_historic_layer(layer.as_ref().clone(), &mut updates, &mut self.layer_fmgr);
         }
         updates.flush();
@@ -178,20 +183,24 @@ impl LayerManager {
         delta_layer: Option<&ResidentLayer>,
         frozen_layer_for_check: &Arc<InMemoryLayer>,
     ) {
-        let l = self.layer_map.frozen_layers.pop_front();
+        let inmem = self
+            .layer_map
+            .frozen_layers
+            .pop_front()
+            .expect("there must be a inmem layer to flush");
         let mut updates = self.layer_map.batch_update();
 
-        // Only one thread may call this function at a time (for this
-        // timeline). If two threads tried to flush the same frozen
+        // Only one task may call this function at a time (for this
+        // timeline). If two tasks tried to flush the same frozen
         // layer to disk at the same time, that would not work.
-        assert!(compare_arced_layers(&l.unwrap(), frozen_layer_for_check));
+        assert_eq!(Arc::as_ptr(&inmem), Arc::as_ptr(frozen_layer_for_check));
 
-        if let Some(delta_layer) = delta_layer {
-            Self::insert_historic_layer(
-                delta_layer.as_ref().clone(),
-                &mut updates,
-                &mut self.layer_fmgr,
+        if let Some(l) = delta_layer {
+            l.access_stats().record_residence_event(
+                LayerResidenceStatus::Resident,
+                LayerResidenceEventReason::LayerCreate,
             );
+            Self::insert_historic_layer(l.as_ref().clone(), &mut updates, &mut self.layer_fmgr);
         }
         updates.flush();
     }
@@ -207,7 +216,6 @@ impl LayerManager {
         let mut updates = self.layer_map.batch_update();
         for l in compact_to {
             l.access_stats().record_residence_event(
-                &guard,
                 LayerResidenceStatus::Resident,
                 LayerResidenceEventReason::LayerCreate,
             );