From cb885bccfe76df524cf40bc703efc479b0529956 Mon Sep 17 00:00:00 2001
From: Aaron Gao <gzh@fb.com>
Date: Thu, 20 Apr 2017 19:44:55 -0700
Subject: [PATCH] set compaction_iterator earliest_snapshot to max if no
 snapshot

Summary:
It is a potential bug that will be triggered if we ingest files before inserting the first key into an empty db.
0 is a special value reserved to indicate the concept of non-existence. But not good for seqno in this case because 0 is a valid seqno for ingestion(bulk loading)
Closes https://github.com/facebook/rocksdb/pull/2183

Differential Revision: D4919827

Pulled By: lightmark

fbshipit-source-id: 237eea40f88bd6487b66806109d90065dc02c362
---
 db/compaction_iterator.cc       | 4 ++--
 db/db_compaction_filter_test.cc | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/db/compaction_iterator.cc b/db/compaction_iterator.cc
index 2031331ca..a69c62578 100644
--- a/db/compaction_iterator.cc
+++ b/db/compaction_iterator.cc
@@ -82,7 +82,7 @@ CompactionIterator::CompactionIterator(
   if (snapshots_->size() == 0) {
     // optimize for fast path if there are no snapshots
     visible_at_tip_ = true;
-    earliest_snapshot_ = last_sequence;
+    earliest_snapshot_ = kMaxSequenceNumber;
     latest_snapshot_ = 0;
   } else {
     visible_at_tip_ = false;
@@ -543,7 +543,7 @@ void CompactionIterator::PrepareOutput() {
 
   // This is safe for TransactionDB write-conflict checking since transactions
   // only care about sequence number larger than any active snapshots.
-  if (bottommost_level_ && valid_ && ikey_.sequence < earliest_snapshot_ &&
+  if (bottommost_level_ && valid_ && ikey_.sequence <= earliest_snapshot_ &&
       ikey_.type != kTypeMerge &&
       !cmp_->Equal(compaction_->GetLargestUserKey(), ikey_.user_key)) {
     assert(ikey_.type != kTypeDeletion && ikey_.type != kTypeSingleDeletion);
diff --git a/db/db_compaction_filter_test.cc b/db/db_compaction_filter_test.cc
index db1bd3fb8..4e68c1dbe 100644
--- a/db/db_compaction_filter_test.cc
+++ b/db/db_compaction_filter_test.cc
@@ -626,7 +626,7 @@ TEST_F(DBTestCompactionFilter, CompactionFilterContextManual) {
       iter->Next();
     }
     ASSERT_EQ(total, 700);
-    ASSERT_EQ(count, 2);
+    ASSERT_EQ(count, 1);
   }
 }
 #endif  // ROCKSDB_LITE