From 5e0d6b4cc9f2f107853ddcff73330f3aa6d17559 Mon Sep 17 00:00:00 2001
From: Aaron Gao <gzh@fb.com>
Date: Tue, 18 Oct 2016 16:07:10 -0700
Subject: [PATCH] fix db_stress assertion failure

Summary: in rocksdb::DBIter::FindValueForCurrentKey(), last_not_merge_type could also be SingleDelete() which is omitted

Test Plan: db_iter_test

Reviewers: yhchiang, sdong

Reviewed By: sdong

Subscribers: andrewkr, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D65187
---
 db/db_iter.cc      |  3 ++-
 db/db_iter_test.cc | 20 ++++++++++++++++++++
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/db/db_iter.cc b/db/db_iter.cc
index 0c4f2b685..eb89d167f 100644
--- a/db/db_iter.cc
+++ b/db/db_iter.cc
@@ -658,7 +658,8 @@ bool DBIter::FindValueForCurrentKey() {
       return false;
     case kTypeMerge:
       current_entry_is_merged_ = true;
-      if (last_not_merge_type == kTypeDeletion) {
+      if (last_not_merge_type == kTypeDeletion ||
+          last_not_merge_type == kTypeSingleDeletion) {
         MergeHelper::TimedFullMerge(merge_operator_, saved_key_.GetKey(),
                                     nullptr, merge_context_.GetOperands(),
                                     &saved_value_, logger_, statistics_, env_,
diff --git a/db/db_iter_test.cc b/db/db_iter_test.cc
index c500ab5c5..35da751fd 100644
--- a/db/db_iter_test.cc
+++ b/db/db_iter_test.cc
@@ -1129,6 +1129,26 @@ TEST_F(DBIteratorTest, DBIterator5) {
     db_iter->Prev();
     ASSERT_TRUE(!db_iter->Valid());
   }
+
+  {
+    // put, singledelete, merge
+    TestIterator* internal_iter = new TestIterator(BytewiseComparator());
+    internal_iter->AddPut("a", "val_a");
+    internal_iter->AddSingleDeletion("a");
+    internal_iter->AddMerge("a", "merge_1");
+    internal_iter->AddMerge("a", "merge_2");
+    internal_iter->AddPut("b", "val_b");
+    internal_iter->Finish();
+    std::unique_ptr<Iterator> db_iter(NewDBIterator(
+        env_, ImmutableCFOptions(options), BytewiseComparator(), internal_iter,
+        10, options.max_sequential_skip_in_iterations, 0));
+    db_iter->Seek("b");
+    ASSERT_TRUE(db_iter->Valid());
+    ASSERT_EQ(db_iter->key().ToString(), "b");
+    db_iter->Prev();
+    ASSERT_TRUE(db_iter->Valid());
+    ASSERT_EQ(db_iter->key().ToString(), "a");
+  }
 }
 
 TEST_F(DBIteratorTest, DBIterator6) {