1 files changed, 203 insertions, 0 deletions
diff --git a/src/kernel/coinstats.cpp b/src/kernel/coinstats.cpp
new file mode 100644
index 0000000000..06a4b8c974
--- /dev/null
+++ b/src/kernel/coinstats.cpp
@@ -0,0 +1,203 @@
+// Copyright (c) 2022 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <kernel/coinstats.h>
+
+#include <chain.h>
+#include <coins.h>
+#include <crypto/muhash.h>
+#include <hash.h>
+#include <node/blockstorage.h>
+#include <primitives/transaction.h>
+#include <script/script.h>
+#include <serialize.h>
+#include <span.h>
+#include <streams.h>
+#include <sync.h>
+#include <tinyformat.h>
+#include <uint256.h>
+#include <util/check.h>
+#include <util/overflow.h>
+#include <util/system.h>
+#include <validation.h>
+#include <version.h>
+
+#include <cassert>
+#include <iosfwd>
+#include <iterator>
+#include <map>
+#include <memory>
+#include <string>
+#include <utility>
+
+namespace kernel {
+
+CCoinsStats::CCoinsStats(int block_height, const uint256& block_hash)
+    : nHeight(block_height),
+      hashBlock(block_hash) {}
+
+// Database-independent metric indicating the UTXO set size
+uint64_t GetBogoSize(const CScript& script_pub_key)
+{
+    return 32 /* txid */ +
+           4 /* vout index */ +
+           4 /* height + coinbase */ +
+           8 /* amount */ +
+           2 /* scriptPubKey len */ +
+           script_pub_key.size() /* scriptPubKey */;
+}
+
+CDataStream TxOutSer(const COutPoint& outpoint, const Coin& coin) {
+    CDataStream ss(SER_DISK, PROTOCOL_VERSION);
+    ss << outpoint;
+    ss << static_cast<uint32_t>(coin.nHeight * 2 + coin.fCoinBase);
+    ss << coin.out;
+    return ss;
+}
+
+//! Warning: be very careful when changing this! assumeutxo and UTXO snapshot
+//! validation commitments are reliant on the hash constructed by this
+//! function.
+//!
+//! If the construction of this hash is changed, it will invalidate
+//! existing UTXO snapshots. This will not result in any kind of consensus
+//! failure, but it will force clients that were expecting to make use of
+//! assumeutxo to do traditional IBD instead.
+//!
+//! It is also possible, though very unlikely, that a change in this
+//! construction could cause a previously invalid (and potentially malicious)
+//! UTXO snapshot to be considered valid.
+static void ApplyHash(HashWriter& ss, const uint256& hash, const std::map<uint32_t, Coin>& outputs)
+{
+    for (auto it = outputs.begin(); it != outputs.end(); ++it) {
+        if (it == outputs.begin()) {
+            ss << hash;
+            ss << VARINT(it->second.nHeight * 2 + it->second.fCoinBase ? 1u : 0u);
+        }
+
+        ss << VARINT(it->first + 1);
+        ss << it->second.out.scriptPubKey;
+        ss << VARINT_MODE(it->second.out.nValue, VarIntMode::NONNEGATIVE_SIGNED);
+
+        if (it == std::prev(outputs.end())) {
+            ss << VARINT(0u);
+        }
+    }
+}
+
+static void ApplyHash(std::nullptr_t, const uint256& hash, const std::map<uint32_t, Coin>& outputs) {}
+
+static void ApplyHash(MuHash3072& muhash, const uint256& hash, const std::map<uint32_t, Coin>& outputs)
+{
+    for (auto it = outputs.begin(); it != outputs.end(); ++it) {
+        COutPoint outpoint = COutPoint(hash, it->first);
+        Coin coin = it->second;
+        muhash.Insert(MakeUCharSpan(TxOutSer(outpoint, coin)));
+    }
+}
+
+static void ApplyStats(CCoinsStats& stats, const uint256& hash, const std::map<uint32_t, Coin>& outputs)
+{
+    assert(!outputs.empty());
+    stats.nTransactions++;
+    for (auto it = outputs.begin(); it != outputs.end(); ++it) {
+        stats.nTransactionOutputs++;
+        if (stats.total_amount.has_value()) {
+            stats.total_amount = CheckedAdd(*stats.total_amount, it->second.out.nValue);
+        }
+        stats.nBogoSize += GetBogoSize(it->second.out.scriptPubKey);
+    }
+}
+
+//! Calculate statistics about the unspent transaction output set
+template <typename T>
+static bool ComputeUTXOStats(CCoinsView* view, CCoinsStats& stats, T hash_obj, const std::function<void()>& interruption_point)
+{
+    std::unique_ptr<CCoinsViewCursor> pcursor(view->Cursor());
+    assert(pcursor);
+
+    PrepareHash(hash_obj, stats);
+
+    uint256 prevkey;
+    std::map<uint32_t, Coin> outputs;
+    while (pcursor->Valid()) {
+        interruption_point();
+        COutPoint key;
+        Coin coin;
+        if (pcursor->GetKey(key) && pcursor->GetValue(coin)) {
+            if (!outputs.empty() && key.hash != prevkey) {
+                ApplyStats(stats, prevkey, outputs);
+                ApplyHash(hash_obj, prevkey, outputs);
+                outputs.clear();
+            }
+            prevkey = key.hash;
+            outputs[key.n] = std::move(coin);
+            stats.coins_count++;
+        } else {
+            return error("%s: unable to read value", __func__);
+        }
+        pcursor->Next();
+    }
+    if (!outputs.empty()) {
+        ApplyStats(stats, prevkey, outputs);
+        ApplyHash(hash_obj, prevkey, outputs);
+    }
+
+    FinalizeHash(hash_obj, stats);
+
+    stats.nDiskSize = view->EstimateSize();
+
+    return true;
+}
+
+std::optional<CCoinsStats> ComputeUTXOStats(CoinStatsHashType hash_type, CCoinsView* view, node::BlockManager& blockman, const std::function<void()>& interruption_point)
+{
+    CBlockIndex* pindex = WITH_LOCK(::cs_main, return blockman.LookupBlockIndex(view->GetBestBlock()));
+    CCoinsStats stats{Assert(pindex)->nHeight, pindex->GetBlockHash()};
+
+    bool success = [&]() -> bool {
+        switch (hash_type) {
+        case(CoinStatsHashType::HASH_SERIALIZED): {
+            HashWriter ss{};
+            return ComputeUTXOStats(view, stats, ss, interruption_point);
+        }
+        case(CoinStatsHashType::MUHASH): {
+            MuHash3072 muhash;
+            return ComputeUTXOStats(view, stats, muhash, interruption_point);
+        }
+        case(CoinStatsHashType::NONE): {
+            return ComputeUTXOStats(view, stats, nullptr, interruption_point);
+        }
+        } // no default case, so the compiler can warn about missing cases
+        assert(false);
+    }();
+
+    if (!success) {
+        return std::nullopt;
+    }
+    return stats;
+}
+
+// The legacy hash serializes the hashBlock
+static void PrepareHash(HashWriter& ss, const CCoinsStats& stats)
+{
+    ss << stats.hashBlock;
+}
+// MuHash does not need the prepare step
+static void PrepareHash(MuHash3072& muhash, CCoinsStats& stats) {}
+static void PrepareHash(std::nullptr_t, CCoinsStats& stats) {}
+
+static void FinalizeHash(HashWriter& ss, CCoinsStats& stats)
+{
+    stats.hashSerialized = ss.GetHash();
+}
+static void FinalizeHash(MuHash3072& muhash, CCoinsStats& stats)
+{
+    uint256 out;
+    muhash.Finalize(out);
+    stats.hashSerialized = out;
+}
+static void FinalizeHash(std::nullptr_t, CCoinsStats& stats) {}
+
+} // namespace kernel