refactor: Use BlockFilterBase within BlockFilter

This commit allows for `BlockFilter` to hold any type that implements
the properties of a block filter, rather than concretely holding a GCS
filter.

Author: rustaceanrob

src/blockfilter.cpp

@@ -216,7 +216,7 @@ BlockFilter::BlockFilter(BlockFilterType filter_type, const uint256& block_hash,
     if (!BuildParams(params)) {
         throw std::invalid_argument("unknown filter_type");
     }
-    m_filter = GCSFilter(params, std::move(filter), skip_decode_check);
+    m_filter = std::make_unique<GCSFilter>(params, std::move(filter), skip_decode_check);
 }
 
 BlockFilter::BlockFilter(BlockFilterType filter_type, const CBlock& block, const CBlockUndo& block_undo)
@@ -226,7 +226,7 @@ BlockFilter::BlockFilter(BlockFilterType filter_type, const CBlock& block, const
     if (!BuildParams(params)) {
         throw std::invalid_argument("unknown filter_type");
     }
-    m_filter = GCSFilter(params, BasicFilterElements(block, block_undo));
+    m_filter = std::make_unique<GCSFilter>(params, BasicFilterElements(block, block_undo));
 }
 
 bool BlockFilter::BuildParams(GCSFilter::Params& params) const

src/blockfilter.h

@@ -8,6 +8,7 @@
 #include <cstddef>
 #include <cstdint>
 #include <ios>
+#include <memory>
 #include <set>
 #include <string>
 #include <string_view>
@@ -135,13 +136,13 @@ class BlockFilter
 private:
     BlockFilterType m_filter_type = BlockFilterType::INVALID;
     uint256 m_block_hash;
-    GCSFilter m_filter;
+    std::unique_ptr<BlockFilterBase> m_filter;
 
     bool BuildParams(GCSFilter::Params& params) const;
 
 public:
 
-    BlockFilter() = default;
+    BlockFilter() : m_filter(std::make_unique<GCSFilter>()) {}
 
     //! Reconstruct a BlockFilter from parts.
     BlockFilter(BlockFilterType filter_type, const uint256& block_hash,
@@ -152,11 +153,11 @@ class BlockFilter
 
     BlockFilterType GetFilterType() const { return m_filter_type; }
     const uint256& GetBlockHash() const LIFETIMEBOUND { return m_block_hash; }
-    const GCSFilter& GetFilter() const LIFETIMEBOUND { return m_filter; }
+    const BlockFilterBase& GetFilter() const LIFETIMEBOUND { return *m_filter; }
 
     const std::vector<unsigned char>& GetEncodedFilter() const LIFETIMEBOUND
     {
-        return m_filter.GetEncoded();
+        return m_filter->GetEncoded();
     }
 
     //! Compute the filter hash.
@@ -169,7 +170,7 @@ class BlockFilter
     void Serialize(Stream& s) const {
         s << static_cast<uint8_t>(m_filter_type)
           << m_block_hash
-          << m_filter.GetEncoded();
+          << m_filter->GetEncoded();
     }
 
     template <typename Stream>
@@ -187,7 +188,7 @@ class BlockFilter
         if (!BuildParams(params)) {
             throw std::ios_base::failure("unknown filter_type");
         }
-        m_filter = GCSFilter(params, std::move(encoded_filter), /*skip_decode_check=*/false);
+        m_filter = std::make_unique<GCSFilter>(params, std::move(encoded_filter), /*skip_decode_check=*/false);
     }
 };
 

src/test/blockfilter_tests.cpp

@@ -100,7 +100,7 @@ BOOST_AUTO_TEST_CASE(blockfilter_basic_test)
     block_undo.vtxundo.back().vprevout.emplace_back(CTxOut(700, excluded_scripts[3]), 100000, false);
 
     BlockFilter block_filter(BlockFilterType::BASIC, block, block_undo);
-    const GCSFilter& filter = block_filter.GetFilter();
+    const BlockFilterBase& filter = block_filter.GetFilter();
 
     for (const CScript& script : included_scripts) {
         BOOST_CHECK(filter.Match(GCSFilter::Element(script.begin(), script.end())));

src/test/fuzz/blockfilter.cpp

@@ -32,7 +32,7 @@ FUZZ_TARGET(blockfilter)
         (void)BlockFilterTypeName(block_filter_type);
     }
     {
-        const GCSFilter gcs_filter = block_filter->GetFilter();
+        const GCSFilter& gcs_filter = dynamic_cast<const GCSFilter&>(block_filter->GetFilter());
         (void)gcs_filter.GetN();
         (void)gcs_filter.GetParams();
         (void)gcs_filter.GetEncoded();