From 22673af794ef63c4cff46f3e11c0689e04ca522b Mon Sep 17 00:00:00 2001
From: Radu Berinde <radu@cockroachlabs.com>
Date: Wed, 21 Feb 2024 20:39:40 -0800
Subject: [PATCH] db: add DebugString method

Add a `DB.DebugString()` method which can be used during debugging.
The meta test uses it to log the final state of the db (which after
reduction will be right after the problematic operation).
---
 db.go               |  7 +++++++
 metamorphic/meta.go | 11 +++++++++++
 2 files changed, 18 insertions(+)

diff --git a/db.go b/db.go
index 22ecc855b0..61538346ac 100644
--- a/db.go
+++ b/db.go
@@ -3082,3 +3082,10 @@ func (d *DB) checkVirtualBounds(m *fileMetadata) {
 		panic(err)
 	}
 }
+
+// DebugString returns a debugging string describing the LSM.
+func (d *DB) DebugString() string {
+	d.mu.Lock()
+	defer d.mu.Unlock()
+	return d.mu.versions.currentVersion().DebugString(base.DefaultFormatter)
+}
diff --git a/metamorphic/meta.go b/metamorphic/meta.go
index c2f2314324..cee666a5aa 100644
--- a/metamorphic/meta.go
+++ b/metamorphic/meta.go
@@ -527,6 +527,17 @@ func RunOnce(t TestingT, runDir string, seed uint64, historyPath string, rOpts .
 	if err := Execute(m); err != nil {
 		fmt.Fprintf(os.Stderr, "Seed: %d\n", seed)
 		fmt.Fprintln(os.Stderr, err)
+	}
+
+	// If we have unclosed databases, print LSM details. This will be the case
+	// when we use --try-to-reduce.
+	for i, db := range m.dbs {
+		if db != nil {
+			fmt.Fprintf(os.Stderr, "\ndb%d:\n%s", i+1, db.DebugString())
+		}
+	}
+
+	if err != nil {
 		m.saveInMemoryData()
 		os.Exit(1)
 	}