Add support for Merge with base value during Compaction in IntegratedBlobDB (#8445)

Summary:
Provide support for Merge operation with base values during
Compaction in IntegratedBlobDB.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8445

Test Plan: Add new unit test

Reviewed By: ltamasi

Differential Revision: D29343949

Pulled By: akankshamahajan15

fbshipit-source-id: 844f6f02f93388a11e6e08bda7bb3a2a28e47c70

db/blob/db_blob_compaction_test.cc

@@ -565,6 +565,32 @@ TEST_F(DBBlobCompactionTest, TrackGarbage) {
   }
 }
 
+TEST_F(DBBlobCompactionTest, MergeBlobWithBase) {
+  Options options = GetDefaultOptions();
+  options.enable_blob_files = true;
+  options.min_blob_size = 0;
+  options.merge_operator = MergeOperators::CreateStringAppendOperator();
+  options.disable_auto_compactions = true;
+
+  Reopen(options);
+  ASSERT_OK(Put("Key1", "v1_1"));
+  ASSERT_OK(Put("Key2", "v2_1"));
+  ASSERT_OK(Flush());
+
+  ASSERT_OK(Merge("Key1", "v1_2"));
+  ASSERT_OK(Merge("Key2", "v2_2"));
+  ASSERT_OK(Flush());
+
+  ASSERT_OK(Merge("Key1", "v1_3"));
+  ASSERT_OK(Flush());
+
+  ASSERT_OK(db_->CompactRange(CompactRangeOptions(), /*begin=*/nullptr,
+                              /*end=*/nullptr));
+  ASSERT_EQ(Get("Key1"), "v1_1,v1_2,v1_3");
+  ASSERT_EQ(Get("Key2"), "v2_1,v2_2");
+  Close();
+}
+
 }  // namespace ROCKSDB_NAMESPACE
 
 int main(int argc, char** argv) {

db/compaction/compaction_iterator.cc

@@ -754,13 +754,15 @@ void CompactionIterator::NextFromInput() {
       }
 
       pinned_iters_mgr_.StartPinning();
+      Version* version = compaction_ ? compaction_->input_version() : nullptr;
+
       // We know the merge type entry is not hidden, otherwise we would
       // have hit (A)
       // We encapsulate the merge related state machine in a different
       // object to minimize change to the existing flow.
-      Status s =
-          merge_helper_->MergeUntil(&input_, range_del_agg_, prev_snapshot,
-                                    bottommost_level_, allow_data_in_errors_);
+      Status s = merge_helper_->MergeUntil(&input_, range_del_agg_,
+                                           prev_snapshot, bottommost_level_,
+                                           allow_data_in_errors_, version);
       merge_out_iter_.SeekToFirst();
 
       if (!s.ok() && !s.IsMergeInProgress()) {

db/merge_helper.cc

@@ -7,6 +7,7 @@
 
 #include <string>
 
+#include "db/blob/blob_fetcher.h"
 #include "db/dbformat.h"
 #include "monitoring/perf_context_imp.h"
 #include "monitoring/statistics.h"
@@ -119,7 +120,8 @@ Status MergeHelper::MergeUntil(InternalIterator* iter,
                                CompactionRangeDelAggregator* range_del_agg,
                                const SequenceNumber stop_before,
                                const bool at_bottom,
-                               const bool allow_data_in_errors) {
+                               const bool allow_data_in_errors,
+                               Version* version) {
   // Get a copy of the internal key, before it's invalidated by iter->Next()
   // Also maintain the list of merge operands seen.
   assert(HasOperator());
@@ -203,12 +205,23 @@ Status MergeHelper::MergeUntil(InternalIterator* iter,
       // want. Also if we're in compaction and it's a put, it would be nice to
       // run compaction filter on it.
       const Slice val = iter->value();
+      PinnableSlice blob_value;
       const Slice* val_ptr;
-      if (kTypeValue == ikey.type &&
+      if ((kTypeValue == ikey.type || kTypeBlobIndex == ikey.type) &&
           (range_del_agg == nullptr ||
            !range_del_agg->ShouldDelete(
                ikey, RangeDelPositioningMode::kForwardTraversal))) {
+        if (ikey.type == kTypeBlobIndex) {
+          assert(version);
+          BlobFetcher blob_fetcher(version, ReadOptions());
+          s = blob_fetcher.FetchBlob(ikey.user_key, val, &blob_value);
+          if (!s.ok()) {
+            return s;
+          }
+          val_ptr = &blob_value;
+        } else {
           val_ptr = &val;
+        }
       } else {
         val_ptr = nullptr;
       }

db/merge_helper.h

@@ -84,7 +84,8 @@ class MergeHelper {
                     CompactionRangeDelAggregator* range_del_agg = nullptr,
                     const SequenceNumber stop_before = 0,
                     const bool at_bottom = false,
-                    const bool allow_data_in_errors = false);
+                    const bool allow_data_in_errors = false,
+                    Version* version = nullptr);
 
   // Filters a merge operand using the compaction filter specified
   // in the constructor. Returns the decision that the filter made.