4 files changed, 104 insertions, 1 deletions

diff --git a/src/common/data_cache.h b/src/common/data_cache.h
new file mode 100644
index 000000000..5e70da115
--- /dev/null
+++ b/src/common/data_cache.h
@@ -0,0 +1,65 @@
+// Copyright (c) 2014-2022, The Monero Project
+// 
+// All rights reserved.
+// 
+// Redistribution and use in source and binary forms, with or without modification, are
+// permitted provided that the following conditions are met:
+// 
+// 1. Redistributions of source code must retain the above copyright notice, this list of
+//    conditions and the following disclaimer.
+// 
+// 2. Redistributions in binary form must reproduce the above copyright notice, this list
+//    of conditions and the following disclaimer in the documentation and/or other
+//    materials provided with the distribution.
+// 
+// 3. Neither the name of the copyright holder nor the names of its contributors may be
+//    used to endorse or promote products derived from this software without specific
+//    prior written permission.
+// 
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+// 
+// Parts of this file are originally copyright (c) 2012-2013 The Cryptonote developers
+
+#pragma once 
+
+#include <unordered_set>
+#include <mutex>
+
+namespace tools
+{
+  template<typename T, size_t MAX_SIZE>
+  class data_cache
+  {
+  public:
+    void add(const T& value)
+    {
+      std::lock_guard<std::mutex> lock(m);
+      if (data.insert(value).second)
+      {
+        T& old_value = buf[counter++ % MAX_SIZE];
+        data.erase(old_value);
+        old_value = value;
+      }
+    }
+
+    bool has(const T& value) const
+    {
+      std::lock_guard<std::mutex> lock(m);
+      return (data.find(value) != data.end());
+    }
+
+  private:
+    mutable std::mutex m;
+    std::unordered_set<T> data;
+    T buf[MAX_SIZE] = {};
+    size_t counter = 0;
+  };
+}
diff --git a/src/cryptonote_core/blockchain.cpp b/src/cryptonote_core/blockchain.cpp
index b1903cf6c..1baa6bff9 100644
--- a/src/cryptonote_core/blockchain.cpp
+++ b/src/cryptonote_core/blockchain.cpp
@@ -3631,7 +3631,7 @@ bool Blockchain::check_tx_inputs(transaction& tx, tx_verification_context &tvc,
         }
       }
 
-      if (!rct::verRctNonSemanticsSimple(rv))
+      if (!rct::verRctNonSemanticsSimpleCached(rv))
       {
         MERROR_VER("Failed to check ringct signatures!");
         return false;
diff --git a/src/ringct/rctSigs.cpp b/src/ringct/rctSigs.cpp
index 477a7907d..7b16f017b 100644
--- a/src/ringct/rctSigs.cpp
+++ b/src/ringct/rctSigs.cpp
@@ -30,6 +30,7 @@
 
 #include "misc_log_ex.h"
 #include "misc_language.h"
+#include "common/data_cache.h"
 #include "common/perf_timer.h"
 #include "common/threadpool.h"
 #include "common/util.h"
@@ -1578,6 +1579,42 @@ namespace rct {
       }
     }
 
+    bool verRctNonSemanticsSimpleCached(const rctSig & rv)
+    {
+      // Hello future Monero dev! If you got this assert, read the following carefully:
+      //
+      // RCT cache assumes that this function will serialize and hash all rv's fields used for RingCT verification
+      // If you're about to add a new RCTType here, first you must check that binary_archive serialization writes all rv's fields to the binary blob
+      // If it's not the case, rewrite this function to serialize everything, even some "temporary" fields which are not serialized normally
+      CHECK_AND_ASSERT_MES_L1(rv.type <= RCTTypeBulletproofPlus, false, "Unknown RCT type. Make sure RCT cache works correctly with this type and then enable it in the code here.");
+
+      // Don't cache older (or newer) rctSig types
+      // This cache only makes sense when it caches data from mempool first,
+      // so only "current fork version-enabled" RCT types need to be cached
+      if (rv.type != RCTTypeBulletproofPlus)
+        return verRctNonSemanticsSimple(rv);
+
+      // Get the hash of rv
+      std::stringstream ss;
+      binary_archive<true> ar(ss);
+
+      ::do_serialize(ar, const_cast<rctSig&>(rv));
+
+      crypto::hash h;
+      cryptonote::get_blob_hash(ss.str(), h);
+
+      static tools::data_cache<crypto::hash, 8192> cache;
+
+      if (cache.has(h))
+        return true;
+
+      const bool res = verRctNonSemanticsSimple(rv);
+      if (res)
+        cache.add(h);
+
+      return res;
+    }
+
     //RingCT protocol
     //genRct: 
     //   creates an rctSig with all data necessary to verify the rangeProofs and that the signer owns one of the
diff --git a/src/ringct/rctSigs.h b/src/ringct/rctSigs.h
index 17cfd77b9..18c7e5fe6 100644
--- a/src/ringct/rctSigs.h
+++ b/src/ringct/rctSigs.h
@@ -132,6 +132,7 @@ namespace rct {
     bool verRctSemanticsSimple(const rctSig & rv);
     bool verRctSemanticsSimple(const std::vector<const rctSig*> & rv);
     bool verRctNonSemanticsSimple(const rctSig & rv);
+    bool verRctNonSemanticsSimpleCached(const rctSig & rv);
     static inline bool verRctSimple(const rctSig & rv) { return verRctSemanticsSimple(rv) && verRctNonSemanticsSimple(rv); }
     xmr_amount decodeRct(const rctSig & rv, const key & sk, unsigned int i, key & mask, hw::device &hwdev);
     xmr_amount decodeRct(const rctSig & rv, const key & sk, unsigned int i, hw::device &hwdev);