forbid merge during recovery

Summary:
Mitigate regression bug of options.max_successive_merges hit during DB Recovery
For https://reviews.facebook.net/D62625

Test Plan: make all check

Reviewers: horuff, sdong

Reviewed By: sdong

Subscribers: andrewkr, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D62655

db/db_impl.cc

@@ -1597,16 +1597,10 @@ Status DBImpl::RecoverLogFiles(const std::vector<uint64_t>& log_numbers,
       // we just ignore the update.
       // That's why we set ignore missing column families to true
       bool has_valid_writes = false;
-      // If we pass DB through and options.max_successive_merges is hit
-      // during recovery, Get() will be issued which will try to acquire
-      // DB mutex and cause deadlock, as DB mutex is already held.
-      // The DB pointer is not needed unless 2PC is used.
-      // TODO(sdong) fix the allow_2pc case too.
       status = WriteBatchInternal::InsertInto(
           &batch, column_family_memtables_.get(), &flush_scheduler_, true,
-          log_number, db_options_.allow_2pc ? this : nullptr,
-          false /* concurrent_memtable_writes */, next_sequence,
-          &has_valid_writes);
+          log_number, this, false /* concurrent_memtable_writes */,
+          next_sequence, &has_valid_writes);
       // If it is the first log file and there is no column family updated
       // after replaying the file, this file may be a stale file. We ignore
       // sequence IDs from the file. Otherwise, if a newer stale log file that

db/db_test2.cc

@@ -145,6 +145,22 @@ TEST_F(DBTest2, CacheIndexAndFilterWithDBRestart) {
   value = Get(1, "a");
 }
 
+TEST_F(DBTest2, MaxSuccessiveMergesChangeWithDBRecovery) {
+  Options options = CurrentOptions();
+  options.create_if_missing = true;
+  options.statistics = rocksdb::CreateDBStatistics();
+  options.max_successive_merges = 3;
+  options.merge_operator = MergeOperators::CreatePutOperator();
+  options.disable_auto_compactions = true;
+  DestroyAndReopen(options);
+  Put("poi", "Finch");
+  db_->Merge(WriteOptions(), "poi", "Reese");
+  db_->Merge(WriteOptions(), "poi", "Shaw");
+  db_->Merge(WriteOptions(), "poi", "Root");
+  options.max_successive_merges = 2;
+  Reopen(options);
+}
+
 #ifndef ROCKSDB_LITE
 class DBTestSharedWriteBufferAcrossCFs
     : public DBTestBase,
@@ -1889,23 +1905,6 @@ TEST_P(MergeOperatorPinningTest, TailingIterator) {
 }
 #endif  // ROCKSDB_LITE
 
-TEST_F(DBTest2, MaxSuccessiveMergesInRecovery) {
-  Options options;
-  options = CurrentOptions(options);
-  options.merge_operator = MergeOperators::CreatePutOperator();
-  DestroyAndReopen(options);
-
-  db_->Put(WriteOptions(), "foo", "bar");
-  ASSERT_OK(db_->Merge(WriteOptions(), "foo", "bar"));
-  ASSERT_OK(db_->Merge(WriteOptions(), "foo", "bar"));
-  ASSERT_OK(db_->Merge(WriteOptions(), "foo", "bar"));
-  ASSERT_OK(db_->Merge(WriteOptions(), "foo", "bar"));
-  ASSERT_OK(db_->Merge(WriteOptions(), "foo", "bar"));
-
-  options.max_successive_merges = 3;
-  Reopen(options);
-}
-
 size_t GetEncodedEntrySize(size_t key_size, size_t value_size) {
   std::string buffer;
 

db/write_batch.cc

@@ -882,10 +882,13 @@ class MemTableInserter : public WriteBatch::Handler {
         std::string merged_value;
 
         auto cf_handle = cf_mems_->GetColumnFamilyHandle();
+        Status s = Status::NotSupported();
+        if (db_ != nullptr && recovering_log_number_ != 0) {
           if (cf_handle == nullptr) {
             cf_handle = db_->DefaultColumnFamily();
           }
-        Status s = db_->Get(ropts, cf_handle, key, &prev_value);
+          s = db_->Get(ropts, cf_handle, key, &prev_value);
+        }
 
         char* prev_buffer = const_cast<char*>(prev_value.c_str());
         uint32_t prev_size = static_cast<uint32_t>(prev_value.size());
@@ -989,7 +992,12 @@ class MemTableInserter : public WriteBatch::Handler {
     auto* moptions = mem->GetMemTableOptions();
     bool perform_merge = false;
 
-    if (moptions->max_successive_merges > 0 && db_ != nullptr) {
+    // If we pass DB through and options.max_successive_merges is hit
+    // during recovery, Get() will be issued which will try to acquire
+    // DB mutex and cause deadlock, as DB mutex is already held.
+    // So we disable merge in recovery
+    if (moptions->max_successive_merges > 0 && db_ != nullptr &&
+        recovering_log_number_ == 0) {
       LookupKey lkey(key, sequence_);
 
       // Count the number of successive merges at the head