From 9c2cf9479b1b59b22562a4ee673caf9826199ef3 Mon Sep 17 00:00:00 2001
From: Nathan Bronson <ngbronson@fb.com>
Date: Sun, 31 Jan 2016 10:48:43 -0800
Subject: [PATCH] Fix for --allow_concurrent_memtable_write with batching

Summary:
Concurrent memtable adds were incorrectly computing
the last sequence number for a write batch group when the
write batches were not solitary.  This is the cause of
https://github.com/facebook/mysql-5.6/issues/155

Test Plan:
1. unit tests
2. new unit test
3. parallel db_bench stress tests with batch size of 10 and asserts enabled

Reviewers: igor, sdong

Reviewed By: sdong

Subscribers: IslamAbdelRahman, MarkCallaghan, dhruba

Differential Revision: https://reviews.facebook.net/D53595
---
 db/db_impl.cc      | 8 ++++++--
 db/db_test_util.cc | 8 +++++++-
 db/db_test_util.h  | 7 ++++---
 3 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/db/db_impl.cc b/db/db_impl.cc
index 51ed9a3a03..f625c775e0 100644
--- a/db/db_impl.cc
+++ b/db/db_impl.cc
@@ -4137,7 +4137,9 @@ Status DBImpl::WriteImpl(const WriteOptions& write_options,
 
     if (write_thread_.CompleteParallelWorker(&w)) {
       // we're responsible for early exit
-      auto last_sequence = w.parallel_group->last_writer->sequence;
+      auto last_sequence =
+          w.parallel_group->last_writer->sequence +
+          WriteBatchInternal::Count(w.parallel_group->last_writer->batch) - 1;
       SetTickerCount(stats_, SEQUENCE_NUMBER, last_sequence);
       versions_->SetLastSequence(last_sequence);
       write_thread_.EarlyExitParallelGroup(&w);
@@ -4437,7 +4439,9 @@ Status DBImpl::WriteImpl(const WriteOptions& write_options,
             this, true /*dont_filter_deletes*/,
             true /*concurrent_memtable_writes*/);
 
-        assert(last_writer->sequence == last_sequence);
+        assert(last_writer->sequence +
+                   WriteBatchInternal::Count(last_writer->batch) - 1 ==
+               last_sequence);
         // CompleteParallelWorker returns true if this thread should
         // handle exit, false means somebody else did
         exit_completed_early = !write_thread_.CompleteParallelWorker(&w);
diff --git a/db/db_test_util.cc b/db/db_test_util.cc
index e6ee304a5d..f2906c7ca9 100644
--- a/db/db_test_util.cc
+++ b/db/db_test_util.cc
@@ -85,7 +85,8 @@ bool DBTestBase::ShouldSkipOptions(int option_config, int skip_mask) {
       option_config == kHashCuckoo || option_config == kUniversalCompaction ||
       option_config == kUniversalCompactionMultiLevel ||
       option_config == kUniversalSubcompactions ||
-      option_config == kFIFOCompaction) {
+      option_config == kFIFOCompaction ||
+      option_config == kConcurrentSkipList) {
     return true;
     }
 #endif
@@ -361,6 +362,11 @@ Options DBTestBase::CurrentOptions(
       options.max_subcompactions = 4;
       break;
     }
+    case kConcurrentSkipList: {
+      options.allow_concurrent_memtable_write = true;
+      options.enable_write_thread_adaptive_yield = true;
+      break;
+    }
 
     default:
       break;
diff --git a/db/db_test_util.h b/db/db_test_util.h
index 031057bbbc..b993af8cb5 100644
--- a/db/db_test_util.h
+++ b/db/db_test_util.h
@@ -525,9 +525,10 @@ class DBTestBase : public testing::Test {
     kOptimizeFiltersForHits = 27,
     kRowCache = 28,
     kRecycleLogFiles = 29,
-    kLevelSubcompactions = 30,
-    kUniversalSubcompactions = 31,
-    kEnd = 30
+    kConcurrentSkipList = 30,
+    kEnd = 31,
+    kLevelSubcompactions = 31,
+    kUniversalSubcompactions = 32,
   };
   int option_config_;