common: remove unused data_cache.h

Dead since 40eb82873 (2025-10) moved verRct caching into the mempool;
only a stale #include remained in blockchain.cpp.

src/common/data_cache.h

@@ -1,65 +0,0 @@
-// Copyright (c) 2014-2024, 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;
-  };
-}

src/cryptonote_core/blockchain.cpp

@@ -57,7 +57,6 @@
 #include "common/notify.h"
 #include "common/varint.h"
 #include "common/pruning.h"
-#include "common/data_cache.h"
 #include "time_helper.h"
 
 #undef MONERO_DEFAULT_LOG_CATEGORY