From b7bc9cc0384209738066fa41d778228c3332510f Mon Sep 17 00:00:00 2001
From: Andrew Kryczka <andrewkr@fb.com>
Date: Mon, 30 Oct 2017 00:47:15 -0700
Subject: [PATCH] fix tracking oldest snapshot for bottom-level compaction

Summary:
The assertion was caught by `MySQLStyleTransactionTest/MySQLStyleTransactionTest.TransactionStressTest/5` when run in a loop. The caller doesn't track whether the released snapshot is oldest, so let this function handle that case.
Closes https://github.com/facebook/rocksdb/pull/3080

Differential Revision: D6185257

Pulled By: ajkr

fbshipit-source-id: 4b3015c11db5d31e46521a00af568546ef4558cd
---
 db/db_impl.cc | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/db/db_impl.cc b/db/db_impl.cc
index cbb1cd53b..84cc7b9cf 100644
--- a/db/db_impl.cc
+++ b/db/db_impl.cc
@@ -1618,7 +1618,9 @@ void DBImpl::ReleaseSnapshot(const Snapshot* s) {
     snapshots_.Delete(casted_s);
     uint64_t oldest_snapshot;
     if (snapshots_.empty()) {
-      oldest_snapshot = versions_->LastSequence();
+      oldest_snapshot = concurrent_prepare_ && seq_per_batch_
+                              ? versions_->LastToBeWrittenSequence()
+                              : versions_->LastSequence();
     } else {
       oldest_snapshot = snapshots_.oldest()->number_;
     }