From 66956ef86729320bed14e8420749eb7e55e20faf Mon Sep 17 00:00:00 2001
From: zzstoatzz <thrast36@gmail.com>
Date: Fri, 7 Aug 2026 21:53:18 -0500
Subject: [PATCH] compact: announce and progress-log the startup tombstone
 rebuild
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

The rebuild runs before ingest dials (upstream ordering) and scales with
the watermark backlog — hours on a large archive with a low watermark.
It previously logged only on completion, making a long rebuild
indistinguishable from a hang (the 2026-08-07 restart-pause diagnosis
chase). Now: a start line with the loaded watermark and segment count,
progress every 200 segments, and the live-entry gauge published as it
grows. No semantic change.
---
 src/internal/compact/steady.zig | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/src/internal/compact/steady.zig b/src/internal/compact/steady.zig
index 17358c1..3b68d48 100644
--- a/src/internal/compact/steady.zig
+++ b/src/internal/compact/steady.zig
@@ -100,6 +100,17 @@ pub const Compactor = struct {
         defer seg_dir.close(self.io);
         self.mu.lockUncancelable(self.io);
         defer self.mu.unlock(self.io);
+        // This scan runs before ingest dials (upstream ordering) and, with a
+        // low watermark on a large archive, takes hours. Announce the work up
+        // front and log progress so a long rebuild is a progress bar, never a
+        // silent hang (the 2026-08-07 "3.5h restart pause" diagnosis chase).
+        var total: u64 = 0;
+        var count_it = seg_dir.iterate();
+        while (try count_it.next(self.io)) |entry| {
+            if (archive_mod.parseSegmentIndex(entry.name) != null) total += 1;
+        }
+        log.info("tombstone rebuild starting above watermark {d}: {d} segments to fold (ingest dials after this completes)", .{ w, total });
+        var folded: u64 = 0;
         var it = seg_dir.iterate();
         while (try it.next(self.io)) |entry| {
             const idx = archive_mod.parseSegmentIndex(entry.name) orelse continue;
@@ -107,6 +118,11 @@ pub const Compactor = struct {
                 error.ActiveSegment => continue,
                 else => return err,
             };
+            folded += 1;
+            if (folded % 200 == 0) {
+                log.info("tombstone rebuild {d}/{d}: {d} live entries", .{ folded, total, self.live.len() });
+                if (self.stats) |s| s.compaction_tombstone_set_entries.store(self.live.len(), .monotonic);
+            }
         }
         if (self.stats) |s| s.compaction_watermark.store(w, .monotonic);
         self.publishTombstoneGauges();
-- 
2.51.2