From 37aaded8ba81fc0f4ac56f5340c9b40b98d0c688 Mon Sep 17 00:00:00 2001
From: zncleon <zncleon@gmail.com>
Date: Sun, 17 Sep 2023 11:23:21 +0800
Subject: [PATCH] Refactor BlockSplitBloomFilter

---
 src/types/bloom_filter.cc      |  6 ++++++
 src/types/bloom_filter.h       | 10 ++++++++++
 src/types/redis_bloom_chain.cc |  6 +++---
 3 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/src/types/bloom_filter.cc b/src/types/bloom_filter.cc
index e7c0debf352..bcbc06a4d10 100644
--- a/src/types/bloom_filter.cc
+++ b/src/types/bloom_filter.cc
@@ -64,6 +64,10 @@ bool BlockSplitBloomFilter::Init(std::string bitset) {
   return true;
 }
 
+std::unique_ptr<const BlockSplitBloomFilter> BlockSplitBloomFilter::CreateNonOwned(const std::string& bitset) {
+  return std::unique_ptr<const BlockSplitBloomFilter>(new BlockSplitBloomFilter(bitset));
+}
+
 static constexpr uint32_t kBloomFilterHeaderSizeGuess = 256;
 
 bool BlockSplitBloomFilter::FindHash(uint64_t hash) const {
@@ -94,3 +98,5 @@ void BlockSplitBloomFilter::InsertHash(uint64_t hash) {
 }
 
 uint64_t BlockSplitBloomFilter::Hash(const char* data, size_t length) { return XXH64(data, length, /*seed=*/0); }
+
+BlockSplitBloomFilter::BlockSplitBloomFilter(const std::string& bitset) : data_(bitset), num_bytes_(bitset.size()) {}
diff --git a/src/types/bloom_filter.h b/src/types/bloom_filter.h
index effe68e4b48..a6d7c0a5d89 100644
--- a/src/types/bloom_filter.h
+++ b/src/types/bloom_filter.h
@@ -84,6 +84,13 @@ class BlockSplitBloomFilter {
   /// @return false if the number of bytes of Bloom filter bitset is not a power of 2, and true means successfully init
   bool Init(std::string bitset);
 
+  /// Create the non-owned BlockSplitBloomFilter. It use the bitset as underlying bitset. It is the caller's
+  /// responsibility to ensure the bitset would not to change.
+  ///
+  /// @param bitset The given bitset for the Bloom filter underlying bitset.
+  /// @return the unique_ptr of the const non-owned BlockSplitBloomFilter
+  static std::unique_ptr<const BlockSplitBloomFilter> CreateNonOwned(const std::string& bitset);
+
   /// Minimum Bloom filter size, it sets to 32 bytes to fit a tiny Bloom filter.
   static constexpr uint32_t kMinimumBloomFilterBytes = 32;
 
@@ -166,6 +173,9 @@ class BlockSplitBloomFilter {
   static uint64_t Hash(const char* data, size_t length);
 
  private:
+  // The private constructor of BlockSplitBloomFilter. It's only used for CreateNonOwned
+  explicit BlockSplitBloomFilter(const std::string& bitset);
+
   // Bytes in a tiny Bloom filter block.
   static constexpr int kBytesPerFilterBlock = 32;
 
diff --git a/src/types/redis_bloom_chain.cc b/src/types/redis_bloom_chain.cc
index 8aa06e14e12..f36524d1653 100644
--- a/src/types/redis_bloom_chain.cc
+++ b/src/types/redis_bloom_chain.cc
@@ -112,11 +112,11 @@ void BloomChain::bloomAdd(const Slice &item, std::string *bf_data) {
 }
 
 bool BloomChain::bloomCheck(const Slice &item, std::string &bf_data) {
-  BlockSplitBloomFilter block_split_bloom_filter;
-  block_split_bloom_filter.Init(bf_data);
+  std::unique_ptr<const BlockSplitBloomFilter> block_split_bloom_filter_non_owned =
+      BlockSplitBloomFilter::CreateNonOwned(bf_data);
 
   uint64_t h = BlockSplitBloomFilter::Hash(item.data(), item.size());
-  return block_split_bloom_filter.FindHash(h);
+  return block_split_bloom_filter_non_owned->FindHash(h);
 }
 
 rocksdb::Status BloomChain::Reserve(const Slice &user_key, uint32_t capacity, double error_rate, uint16_t expansion) {