index: Add Coinstats index

The index holds the values previously calculated in coinstats.cpp
for each block, representing the state of the UTXO set at each
height.

1 files changed, 52 insertions, 0 deletions

diff --git a/src/index/coinstatsindex.h b/src/index/coinstatsindex.h
new file mode 100644
index 0000000000..4d57e80770
--- /dev/null
+++ b/src/index/coinstatsindex.h
@@ -0,0 +1,52 @@
+// Copyright (c) 2020-2021 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_INDEX_COINSTATSINDEX_H
+#define BITCOIN_INDEX_COINSTATSINDEX_H
+
+#include <chain.h>
+#include <crypto/muhash.h>
+#include <flatfile.h>
+#include <index/base.h>
+#include <node/coinstats.h>
+
+/**
+ * CoinStatsIndex maintains statistics on the UTXO set.
+ */
+class CoinStatsIndex final : public BaseIndex
+{
+private:
+    std::string m_name;
+    std::unique_ptr<BaseIndex::DB> m_db;
+
+    MuHash3072 m_muhash;
+    uint64_t m_transaction_output_count{0};
+    uint64_t m_bogo_size{0};
+    CAmount m_total_amount{0};
+
+    bool ReverseBlock(const CBlock& block, const CBlockIndex* pindex);
+
+protected:
+    bool Init() override;
+
+    bool WriteBlock(const CBlock& block, const CBlockIndex* pindex) override;
+
+    bool Rewind(const CBlockIndex* current_tip, const CBlockIndex* new_tip) override;
+
+    BaseIndex::DB& GetDB() const override { return *m_db; }
+
+    const char* GetName() const override { return "coinstatsindex"; }
+
+public:
+    // Constructs the index, which becomes available to be queried.
+    explicit CoinStatsIndex(size_t n_cache_size, bool f_memory = false, bool f_wipe = false);
+
+    // Look up stats for a specific block using CBlockIndex
+    bool LookUpStats(const CBlockIndex* block_index, CCoinsStats& coins_stats) const;
+};
+
+/// The global UTXO set hash object.
+extern std::unique_ptr<CoinStatsIndex> g_coin_stats_index;
+
+#endif // BITCOIN_INDEX_COINSTATSINDEX_H