From 719af44045dff21f3577ae7063b07edf7c4ee0ef Mon Sep 17 00:00:00 2001
From: leipeng <peng@topling.cn>
Date: Tue, 30 Aug 2022 13:24:49 +0800
Subject: [PATCH] DBImpl::GetApproximateSizes(): optimize by reusing
 InternalKey

---
 db/db_impl/db_impl.cc |  5 +++--
 db/dbformat.h         | 10 ++++++++++
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/db/db_impl/db_impl.cc b/db/db_impl/db_impl.cc
index 4c7c2f172..494d0e264 100644
--- a/db/db_impl/db_impl.cc
+++ b/db/db_impl/db_impl.cc
@@ -4140,6 +4140,7 @@ Status DBImpl::GetApproximateSizes(const SizeApproximationOptions& options,
   SuperVersion* sv = GetAndRefSuperVersion(cfd);
   v = sv->current;
 
+  InternalKey k1, k2;
   for (int i = 0; i < n; i++) {
     Slice start = range[i].start;
     Slice limit = range[i].limit;
@@ -4158,8 +4159,8 @@ Status DBImpl::GetApproximateSizes(const SizeApproximationOptions& options,
     }
   #endif
     // Convert user_key into a corresponding internal key.
-    InternalKey k1(start, kMaxSequenceNumber, kValueTypeForSeek);
-    InternalKey k2(limit, kMaxSequenceNumber, kValueTypeForSeek);
+    SetInternalKey(k1.rep(), start, kMaxSequenceNumber, kValueTypeForSeek);
+    SetInternalKey(k2.rep(), limit, kMaxSequenceNumber, kValueTypeForSeek);
     sizes[i] = 0;
     if (options.include_files) {
       sizes[i] += versions_->ApproximateSize(
diff --git a/db/dbformat.h b/db/dbformat.h
index ce251d0c3..4b33e9ec4 100644
--- a/db/dbformat.h
+++ b/db/dbformat.h
@@ -160,6 +160,16 @@ inline void UnPackSequenceAndType(uint64_t packed, uint64_t* seq,
 
 EntryType GetEntryType(ValueType value_type);
 
+inline void SetInternalKey(std::string* result, Slice ukey, uint64_t seqvt) {
+  result->assign(ukey.data(), ukey.size());
+  PutFixed64(result, seqvt);
+}
+inline void SetInternalKey(std::string* result, Slice ukey,
+                           SequenceNumber seq, ValueType vt) {
+  result->assign(ukey.data(), ukey.size());
+  PutFixed64(result, PackSequenceAndType(seq, vt));
+}
+
 // Append the serialization of "key" to *result.
 extern void AppendInternalKey(std::string* result,
                               const ParsedInternalKey& key);