From 42d63270a57b89a520a1f78bac961764a1623ba4 Mon Sep 17 00:00:00 2001
From: Christian Schwarz <christian@neon.tech>
Date: Tue, 28 Mar 2023 11:42:47 +0200
Subject: [PATCH] doc: add comment on extend_lru_candidates

---
 pageserver/src/disk_usage_eviction_task.rs | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/pageserver/src/disk_usage_eviction_task.rs b/pageserver/src/disk_usage_eviction_task.rs
index 607898c6f5..9dc1340d2e 100644
--- a/pageserver/src/disk_usage_eviction_task.rs
+++ b/pageserver/src/disk_usage_eviction_task.rs
@@ -486,6 +486,11 @@ enum Mode {
     GlobalLru,
 }
 
+/// Figure out eviction candidates for the given tenant and append them to `lru_candidates`.
+///
+/// The `scratch` vector is temporary storage and taken as an argument to avoid allocations.
+/// It must be empty when calling this function. It is guaranteed to be empty when we
+/// return `ControlFlow::Continue`.
 #[instrument(skip_all, fields(?mode, %tenant_id))]
 async fn extend_lru_candidates(
     mode: Mode,