From 5c877c95ece99c6e7daf0df35a39d4caeffc97fc Mon Sep 17 00:00:00 2001
From: Christian Schwarz <christian@neon.tech>
Date: Thu, 17 Jul 2025 14:54:23 +0000
Subject: [PATCH] Revert "fetch apply_lsn as part of monitor (can have a
 separate task at a later point, but this will do)"

This reverts commit c8aab69ef1851d0235eefa223e60579faf32c8dc.
---
 Cargo.lock                     |  1 -
 compute_tools/Cargo.toml       |  1 -
 compute_tools/src/compute.rs   |  5 +----
 compute_tools/src/lsn_lease.rs | 18 ----------------
 compute_tools/src/monitor.rs   | 38 +---------------------------------
 5 files changed, 2 insertions(+), 61 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 40f8b04463..893932fb9d 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1348,7 +1348,6 @@ dependencies = [
  "p256 0.13.2",
  "pageserver_page_api",
  "postgres",
- "postgres-types",
  "postgres_initdb",
  "postgres_versioninfo",
  "regex",
diff --git a/compute_tools/Cargo.toml b/compute_tools/Cargo.toml
index c0e67851a4..1a03022d89 100644
--- a/compute_tools/Cargo.toml
+++ b/compute_tools/Cargo.toml
@@ -67,7 +67,6 @@ uuid.workspace = true
 walkdir.workspace = true
 x509-cert.workspace = true
 
-postgres-types.workspace = true
 postgres_versioninfo.workspace = true
 postgres_initdb.workspace = true
 compute_api.workspace = true
diff --git a/compute_tools/src/compute.rs b/compute_tools/src/compute.rs
index b263182e8b..ec6e6c1634 100644
--- a/compute_tools/src/compute.rs
+++ b/compute_tools/src/compute.rs
@@ -43,7 +43,7 @@ use crate::configurator::launch_configurator;
 use crate::disk_quota::set_disk_quota;
 use crate::installed_extensions::get_installed_extensions;
 use crate::logger::startup_context_from_env;
-use crate::lsn_lease::{self, launch_lsn_lease_bg_task_for_static};
+use crate::lsn_lease::launch_lsn_lease_bg_task_for_static;
 use crate::metrics::COMPUTE_CTL_UP;
 use crate::monitor::launch_monitor;
 use crate::pg_helpers::*;
@@ -131,8 +131,6 @@ pub struct ComputeNode {
     pub ext_download_progress: RwLock<HashMap<String, (DateTime<Utc>, bool)>>,
     pub compute_ctl_config: ComputeCtlConfig,
 
-    pub(crate) lsn_lease_state: Arc<lsn_lease::State>,
-
     /// Handle to the extension stats collection task
     extension_stats_task: TaskHandle,
     lfc_offload_task: TaskHandle,
@@ -440,7 +438,6 @@ impl ComputeNode {
             compute_ctl_config: config.compute_ctl_config,
             extension_stats_task: Mutex::new(None),
             lfc_offload_task: Mutex::new(None),
-            lsn_lease_state: Arc::new(lsn_lease::State::default()),
         })
     }
 
diff --git a/compute_tools/src/lsn_lease.rs b/compute_tools/src/lsn_lease.rs
index d6ebce38ba..bb0828429d 100644
--- a/compute_tools/src/lsn_lease.rs
+++ b/compute_tools/src/lsn_lease.rs
@@ -15,24 +15,6 @@ use utils::shard::{ShardCount, ShardNumber, TenantShardId};
 
 use crate::compute::ComputeNode;
 
-#[derive(Default)]
-pub(crate) struct State {
-    desired_lease_lsn: tokio::sync::watch::Sender<Option<Lsn>>,
-}
-
-impl State {
-    pub fn update_desired_lease_lsn(&self, update: Lsn) {
-        self.desired_lease_lsn.send_if_modified(|value| {
-            let modified = *value != Some(update);
-            if let Some(value) = *value && value > update {
-                warn!(current=%value, new=%update, "desired lease lsn moving backwards, this shouldn't happen");
-            }
-            *value = Some(update);
-            modified
-        });
-    }
-}
-
 /// Spawns a background thread to periodically renew LSN leases for static compute.
 /// Do nothing if the compute is not in static mode.
 pub fn launch_lsn_lease_bg_task_for_static(compute: &Arc<ComputeNode>) {
diff --git a/compute_tools/src/monitor.rs b/compute_tools/src/monitor.rs
index cc3b3adf7f..8a2f6addad 100644
--- a/compute_tools/src/monitor.rs
+++ b/compute_tools/src/monitor.rs
@@ -4,10 +4,9 @@ use std::time::Duration;
 
 use chrono::{DateTime, Utc};
 use compute_api::responses::ComputeStatus;
-use compute_api::spec::{ComputeFeature, ComputeMode};
+use compute_api::spec::ComputeFeature;
 use postgres::{Client, NoTls};
 use tracing::{Level, error, info, instrument, span};
-use utils::lsn::Lsn;
 
 use crate::compute::ComputeNode;
 use crate::metrics::{PG_CURR_DOWNTIME_MS, PG_TOTAL_DOWNTIME_MS};
@@ -345,41 +344,6 @@ impl ComputeMonitor {
             }
         }
 
-        let mode: ComputeMode = self
-            .compute
-            .state
-            .lock()
-            .unwrap()
-            .pspec
-            .as_ref()
-            .expect("we launch ComputeMonitor only after we received a spec")
-            .spec
-            .mode;
-        match mode {
-            // TODO: can the .spec.mode ever change? if it can (e.g. secondary promote to primary)
-            // then we should make sure that lsn_lease_state transitions back to None so we stop renewing it.
-            ComputeMode::Primary => (),
-            ComputeMode::Static(lsn) => {
-                self.compute.lsn_lease_state.update_desired_lease_lsn(lsn);
-            }
-            ComputeMode::Replica => {
-                match cli.query_one("SELECT pg_last_wal_replay_lsn() as apply_lsn", &[]) {
-                    Ok(r) => match r.try_get::<&str, postgres_types::PgLsn>("apply_lsn") {
-                        Ok(apply_lsn) => {
-                            let apply_lsn = Lsn(apply_lsn.into());
-                            self.compute.lsn_lease_state.update_desired_lease_lsn(apply_lsn);
-                        }
-                        Err(e) => {
-                            anyhow::bail!("parse apply_lsn: {e}");
-                        }
-                    },
-                    Err(e) => {
-                        anyhow::bail!("query apply_lsn: {e}");
-                    }
-                }
-            }
-        }
-
         Ok(())
     }
 }