some notes

safekeeper/src/send_wal.rs

@@ -1019,6 +1019,8 @@ impl<IO: AsyncRead + AsyncWrite + Unpin> ReplyReader<IO> {
                 self.ws_guard
                     .walsenders
                     .record_ps_feedback(self.ws_guard.id, &ps_feedback);
+                // This here is the principal spot that updates remote_consistent_lsn.
+                // The other spot where it's updated from peers will go away.
                 self.tli
                     .update_remote_consistent_lsn(ps_feedback.remote_consistent_lsn)
                     .await;

safekeeper/src/timeline.rs

@@ -222,11 +222,13 @@ impl StateSK {
         state.inmem.backup_lsn = max(Lsn(sk_info.backup_lsn), state.inmem.backup_lsn);
         sync_control_file |= state.backup_lsn + wal_seg_size < state.inmem.backup_lsn;
 
+        // This will go away in the new world.
         state.inmem.remote_consistent_lsn = max(
             Lsn(sk_info.remote_consistent_lsn),
             state.inmem.remote_consistent_lsn,
         );
         sync_control_file |=
+            // WTF is this criteria?
             state.remote_consistent_lsn + wal_seg_size < state.inmem.remote_consistent_lsn;
 
         state.inmem.peer_horizon_lsn =

safekeeper/src/timeline_manager.rs

@@ -503,7 +503,8 @@ impl Manager {
     ) {
         let is_active = is_wal_backup_required
             || num_computes > 0
-            || state.remote_consistent_lsn < state.commit_lsn;
+            // state.remote_consistent_lsn is the inmemo remote consistent lsn
+            || state.remote_consistent_lsn < state.commit_lsn; // this here changes with the design;
 
         // update the broker timeline set
         if self.tli_broker_active.set(is_active) {
@@ -516,7 +517,7 @@ impl Manager {
             MANAGER_ACTIVE_CHANGES.inc();
         }
 
-        // update the state in Arc<Timeline>
+        // update the state in Arc<Timeline> (which is only used for informational APIs)
         self.tli
             .broker_active
             .store(is_active, std::sync::atomic::Ordering::Relaxed);