From d006b41eff60da036af2623c123ccd587f31d323 Mon Sep 17 00:00:00 2001
From: Aliaksandr Valialkin <valyala@gmail.com>
Date: Mon, 14 Dec 2020 19:25:23 +0200
Subject: [PATCH] lib/persistentqueue: verify that ReaderOffset doesnt exceed
 WriterOffset when opening the persistent queue

Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/964
---
 lib/persistentqueue/persistentqueue.go | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/lib/persistentqueue/persistentqueue.go b/lib/persistentqueue/persistentqueue.go
index 87e4b1a55..916276c3f 100644
--- a/lib/persistentqueue/persistentqueue.go
+++ b/lib/persistentqueue/persistentqueue.go
@@ -336,6 +336,10 @@ func tryOpeningQueue(path, name string, chunkFileSize, maxBlockSize, maxPendingB
 		cleanOnError()
 		return nil, fmt.Errorf("couldn't find chunk file for writing in %q", q.dir)
 	}
+	if q.readerOffset > q.writerOffset {
+		cleanOnError()
+		return nil, fmt.Errorf("readerOffset=%d cannot exceed writerOffset=%d", q.readerOffset, q.writerOffset)
+	}
 	mustCloseFlockF = false
 	return &q, nil
 }