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# 1 : : // Copyright (c) 2009-2010 Satoshi Nakamoto
# 2 : : // Copyright (c) 2009-2020 The Bitcoin Core developers
# 3 : : // Distributed under the MIT software license, see the accompanying
# 4 : : // file COPYING or http://www.opensource.org/licenses/mit-license.php.
# 5 : :
# 6 : : #ifndef BITCOIN_COINS_H
# 7 : : #define BITCOIN_COINS_H
# 8 : :
# 9 : : #include <compressor.h>
# 10 : : #include <core_memusage.h>
# 11 : : #include <memusage.h>
# 12 : : #include <primitives/transaction.h>
# 13 : : #include <serialize.h>
# 14 : : #include <uint256.h>
# 15 : : #include <util/hasher.h>
# 16 : :
# 17 : : #include <assert.h>
# 18 : : #include <stdint.h>
# 19 : :
# 20 : : #include <functional>
# 21 : : #include <unordered_map>
# 22 : :
# 23 : : /**
# 24 : : * A UTXO entry.
# 25 : : *
# 26 : : * Serialized format:
# 27 : : * - VARINT((coinbase ? 1 : 0) | (height << 1))
# 28 : : * - the non-spent CTxOut (via TxOutCompression)
# 29 : : */
# 30 : : class Coin
# 31 : : {
# 32 : : public:
# 33 : : //! unspent transaction output
# 34 : : CTxOut out;
# 35 : :
# 36 : : //! whether containing transaction was a coinbase
# 37 : : unsigned int fCoinBase : 1;
# 38 : :
# 39 : : //! at which height this containing transaction was included in the active block chain
# 40 : : uint32_t nHeight : 31;
# 41 : :
# 42 : : //! construct a Coin from a CTxOut and height/coinbase information.
# 43 : 114 : Coin(CTxOut&& outIn, int nHeightIn, bool fCoinBaseIn) : out(std::move(outIn)), fCoinBase(fCoinBaseIn), nHeight(nHeightIn) {}
# 44 : 11235629 : Coin(const CTxOut& outIn, int nHeightIn, bool fCoinBaseIn) : out(outIn), fCoinBase(fCoinBaseIn),nHeight(nHeightIn) {}
# 45 : :
# 46 : 7865119 : void Clear() {
# 47 : 7865119 : out.SetNull();
# 48 : 7865119 : fCoinBase = false;
# 49 : 7865119 : nHeight = 0;
# 50 : 7865119 : }
# 51 : :
# 52 : : //! empty constructor
# 53 : 78525125 : Coin() : fCoinBase(false), nHeight(0) { }
# 54 : :
# 55 : 7779257 : bool IsCoinBase() const {
# 56 : 7779257 : return fCoinBase;
# 57 : 7779257 : }
# 58 : :
# 59 : : template<typename Stream>
# 60 : 248948 : void Serialize(Stream &s) const {
# 61 : 248948 : assert(!IsSpent());
# 62 : 248948 : uint32_t code = nHeight * uint32_t{2} + fCoinBase;
# 63 : 248948 : ::Serialize(s, VARINT(code));
# 64 : 248948 : ::Serialize(s, Using<TxOutCompression>(out));
# 65 : 248948 : }
# 66 : :
# 67 : : template<typename Stream>
# 68 : 160733 : void Unserialize(Stream &s) {
# 69 : 160733 : uint32_t code = 0;
# 70 : 160733 : ::Unserialize(s, VARINT(code));
# 71 : 160733 : nHeight = code >> 1;
# 72 : 160733 : fCoinBase = code & 1;
# 73 : 160733 : ::Unserialize(s, Using<TxOutCompression>(out));
# 74 : 160733 : }
# 75 : :
# 76 : : /** Either this coin never existed (see e.g. coinEmpty in coins.cpp), or it
# 77 : : * did exist and has been spent.
# 78 : : */
# 79 : 90295536 : bool IsSpent() const {
# 80 : 90295536 : return out.IsNull();
# 81 : 90295536 : }
# 82 : :
# 83 : 29786374 : size_t DynamicMemoryUsage() const {
# 84 : 29786374 : return memusage::DynamicUsage(out.scriptPubKey);
# 85 : 29786374 : }
# 86 : : };
# 87 : :
# 88 : : /**
# 89 : : * A Coin in one level of the coins database caching hierarchy.
# 90 : : *
# 91 : : * A coin can either be:
# 92 : : * - unspent or spent (in which case the Coin object will be nulled out - see Coin.Clear())
# 93 : : * - DIRTY or not DIRTY
# 94 : : * - FRESH or not FRESH
# 95 : : *
# 96 : : * Out of these 2^3 = 8 states, only some combinations are valid:
# 97 : : * - unspent, FRESH, DIRTY (e.g. a new coin created in the cache)
# 98 : : * - unspent, not FRESH, DIRTY (e.g. a coin changed in the cache during a reorg)
# 99 : : * - unspent, not FRESH, not DIRTY (e.g. an unspent coin fetched from the parent cache)
# 100 : : * - spent, FRESH, not DIRTY (e.g. a spent coin fetched from the parent cache)
# 101 : : * - spent, not FRESH, DIRTY (e.g. a coin is spent and spentness needs to be flushed to the parent)
# 102 : : */
# 103 : : struct CCoinsCacheEntry
# 104 : : {
# 105 : : Coin coin; // The actual cached data.
# 106 : : unsigned char flags;
# 107 : :
# 108 : : enum Flags {
# 109 : : /**
# 110 : : * DIRTY means the CCoinsCacheEntry is potentially different from the
# 111 : : * version in the parent cache. Failure to mark a coin as DIRTY when
# 112 : : * it is potentially different from the parent cache will cause a
# 113 : : * consensus failure, since the coin's state won't get written to the
# 114 : : * parent when the cache is flushed.
# 115 : : */
# 116 : : DIRTY = (1 << 0),
# 117 : : /**
# 118 : : * FRESH means the parent cache does not have this coin or that it is a
# 119 : : * spent coin in the parent cache. If a FRESH coin in the cache is
# 120 : : * later spent, it can be deleted entirely and doesn't ever need to be
# 121 : : * flushed to the parent. This is a performance optimization. Marking a
# 122 : : * coin as FRESH when it exists unspent in the parent cache will cause a
# 123 : : * consensus failure, since it might not be deleted from the parent
# 124 : : * when this cache is flushed.
# 125 : : */
# 126 : : FRESH = (1 << 1),
# 127 : : };
# 128 : :
# 129 : 11599829 : CCoinsCacheEntry() : flags(0) {}
# 130 : 9091077 : explicit CCoinsCacheEntry(Coin&& coin_) : coin(std::move(coin_)), flags(0) {}
# 131 : 438 : CCoinsCacheEntry(Coin&& coin_, unsigned char flag) : coin(std::move(coin_)), flags(flag) {}
# 132 : : };
# 133 : :
# 134 : : typedef std::unordered_map<COutPoint, CCoinsCacheEntry, SaltedOutpointHasher> CCoinsMap;
# 135 : :
# 136 : : /** Cursor for iterating over CoinsView state */
# 137 : : class CCoinsViewCursor
# 138 : : {
# 139 : : public:
# 140 : 344 : CCoinsViewCursor(const uint256 &hashBlockIn): hashBlock(hashBlockIn) {}
# 141 : 344 : virtual ~CCoinsViewCursor() {}
# 142 : :
# 143 : : virtual bool GetKey(COutPoint &key) const = 0;
# 144 : : virtual bool GetValue(Coin &coin) const = 0;
# 145 : : virtual unsigned int GetValueSize() const = 0;
# 146 : :
# 147 : : virtual bool Valid() const = 0;
# 148 : : virtual void Next() = 0;
# 149 : :
# 150 : : //! Get best block at the time this cursor was created
# 151 : 0 : const uint256 &GetBestBlock() const { return hashBlock; }
# 152 : : private:
# 153 : : uint256 hashBlock;
# 154 : : };
# 155 : :
# 156 : : /** Abstract view on the open txout dataset. */
# 157 : : class CCoinsView
# 158 : : {
# 159 : : public:
# 160 : : /** Retrieve the Coin (unspent transaction output) for a given outpoint.
# 161 : : * Returns true only when an unspent coin was found, which is returned in coin.
# 162 : : * When false is returned, coin's value is unspecified.
# 163 : : */
# 164 : : virtual bool GetCoin(const COutPoint &outpoint, Coin &coin) const;
# 165 : :
# 166 : : //! Just check whether a given outpoint is unspent.
# 167 : : virtual bool HaveCoin(const COutPoint &outpoint) const;
# 168 : :
# 169 : : //! Retrieve the block hash whose state this CCoinsView currently represents
# 170 : : virtual uint256 GetBestBlock() const;
# 171 : :
# 172 : : //! Retrieve the range of blocks that may have been only partially written.
# 173 : : //! If the database is in a consistent state, the result is the empty vector.
# 174 : : //! Otherwise, a two-element vector is returned consisting of the new and
# 175 : : //! the old block hash, in that order.
# 176 : : virtual std::vector<uint256> GetHeadBlocks() const;
# 177 : :
# 178 : : //! Do a bulk modification (multiple Coin changes + BestBlock change).
# 179 : : //! The passed mapCoins can be modified.
# 180 : : virtual bool BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock);
# 181 : :
# 182 : : //! Get a cursor to iterate over the whole state
# 183 : : virtual CCoinsViewCursor *Cursor() const;
# 184 : :
# 185 : : //! As we use CCoinsViews polymorphically, have a virtual destructor
# 186 : 816456 : virtual ~CCoinsView() {}
# 187 : :
# 188 : : //! Estimate database size (0 if not implemented)
# 189 : 0 : virtual size_t EstimateSize() const { return 0; }
# 190 : : };
# 191 : :
# 192 : :
# 193 : : /** CCoinsView backed by another CCoinsView */
# 194 : : class CCoinsViewBacked : public CCoinsView
# 195 : : {
# 196 : : protected:
# 197 : : CCoinsView *base;
# 198 : :
# 199 : : public:
# 200 : : CCoinsViewBacked(CCoinsView *viewIn);
# 201 : : bool GetCoin(const COutPoint &outpoint, Coin &coin) const override;
# 202 : : bool HaveCoin(const COutPoint &outpoint) const override;
# 203 : : uint256 GetBestBlock() const override;
# 204 : : std::vector<uint256> GetHeadBlocks() const override;
# 205 : : void SetBackend(CCoinsView &viewIn);
# 206 : : bool BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock) override;
# 207 : : CCoinsViewCursor *Cursor() const override;
# 208 : : size_t EstimateSize() const override;
# 209 : : };
# 210 : :
# 211 : :
# 212 : : /** CCoinsView that adds a memory cache for transactions to another CCoinsView */
# 213 : : class CCoinsViewCache : public CCoinsViewBacked
# 214 : : {
# 215 : : protected:
# 216 : : /**
# 217 : : * Make mutable so that we can "fill the cache" even from Get-methods
# 218 : : * declared as "const".
# 219 : : */
# 220 : : mutable uint256 hashBlock;
# 221 : : mutable CCoinsMap cacheCoins;
# 222 : :
# 223 : : /* Cached dynamic memory usage for the inner Coin objects. */
# 224 : : mutable size_t cachedCoinsUsage;
# 225 : :
# 226 : : public:
# 227 : : CCoinsViewCache(CCoinsView *baseIn);
# 228 : :
# 229 : : /**
# 230 : : * By deleting the copy constructor, we prevent accidentally using it when one intends to create a cache on top of a base cache.
# 231 : : */
# 232 : : CCoinsViewCache(const CCoinsViewCache &) = delete;
# 233 : :
# 234 : : // Standard CCoinsView methods
# 235 : : bool GetCoin(const COutPoint &outpoint, Coin &coin) const override;
# 236 : : bool HaveCoin(const COutPoint &outpoint) const override;
# 237 : : uint256 GetBestBlock() const override;
# 238 : : void SetBestBlock(const uint256 &hashBlock);
# 239 : : bool BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock) override;
# 240 : 0 : CCoinsViewCursor* Cursor() const override {
# 241 : 0 : throw std::logic_error("CCoinsViewCache cursor iteration not supported.");
# 242 : 0 : }
# 243 : :
# 244 : : /**
# 245 : : * Check if we have the given utxo already loaded in this cache.
# 246 : : * The semantics are the same as HaveCoin(), but no calls to
# 247 : : * the backing CCoinsView are made.
# 248 : : */
# 249 : : bool HaveCoinInCache(const COutPoint &outpoint) const;
# 250 : :
# 251 : : /**
# 252 : : * Return a reference to Coin in the cache, or coinEmpty if not found. This is
# 253 : : * more efficient than GetCoin.
# 254 : : *
# 255 : : * Generally, do not hold the reference returned for more than a short scope.
# 256 : : * While the current implementation allows for modifications to the contents
# 257 : : * of the cache while holding the reference, this behavior should not be relied
# 258 : : * on! To be safe, best to not hold the returned reference through any other
# 259 : : * calls to this cache.
# 260 : : */
# 261 : : const Coin& AccessCoin(const COutPoint &output) const;
# 262 : :
# 263 : : /**
# 264 : : * Add a coin. Set possible_overwrite to true if an unspent version may
# 265 : : * already exist in the cache.
# 266 : : */
# 267 : : void AddCoin(const COutPoint& outpoint, Coin&& coin, bool possible_overwrite);
# 268 : :
# 269 : : /**
# 270 : : * Emplace a coin into cacheCoins without performing any checks, marking
# 271 : : * the emplaced coin as dirty.
# 272 : : *
# 273 : : * NOT FOR GENERAL USE. Used only when loading coins from a UTXO snapshot.
# 274 : : * @sa ChainstateManager::PopulateAndValidateSnapshot()
# 275 : : */
# 276 : : void EmplaceCoinInternalDANGER(COutPoint&& outpoint, Coin&& coin);
# 277 : :
# 278 : : /**
# 279 : : * Spend a coin. Pass moveto in order to get the deleted data.
# 280 : : * If no unspent output exists for the passed outpoint, this call
# 281 : : * has no effect.
# 282 : : */
# 283 : : bool SpendCoin(const COutPoint &outpoint, Coin* moveto = nullptr);
# 284 : :
# 285 : : /**
# 286 : : * Push the modifications applied to this cache to its base.
# 287 : : * Failure to call this method before destruction will cause the changes to be forgotten.
# 288 : : * If false is returned, the state of this cache (and its backing view) will be undefined.
# 289 : : */
# 290 : : bool Flush();
# 291 : :
# 292 : : /**
# 293 : : * Removes the UTXO with the given outpoint from the cache, if it is
# 294 : : * not modified.
# 295 : : */
# 296 : : void Uncache(const COutPoint &outpoint);
# 297 : :
# 298 : : //! Calculate the size of the cache (in number of transaction outputs)
# 299 : : unsigned int GetCacheSize() const;
# 300 : :
# 301 : : //! Calculate the size of the cache (in bytes)
# 302 : : size_t DynamicMemoryUsage() const;
# 303 : :
# 304 : : //! Check whether all prevouts of the transaction are present in the UTXO set represented by this view
# 305 : : bool HaveInputs(const CTransaction& tx) const;
# 306 : :
# 307 : : //! Force a reallocation of the cache map. This is required when downsizing
# 308 : : //! the cache because the map's allocator may be hanging onto a lot of
# 309 : : //! memory despite having called .clear().
# 310 : : //!
# 311 : : //! See: https://stackoverflow.com/questions/42114044/how-to-release-unordered-map-memory
# 312 : : void ReallocateCache();
# 313 : :
# 314 : : private:
# 315 : : /**
# 316 : : * @note this is marked const, but may actually append to `cacheCoins`, increasing
# 317 : : * memory usage.
# 318 : : */
# 319 : : CCoinsMap::iterator FetchCoin(const COutPoint &outpoint) const;
# 320 : : };
# 321 : :
# 322 : : //! Utility function to add all of a transaction's outputs to a cache.
# 323 : : //! When check is false, this assumes that overwrites are only possible for coinbase transactions.
# 324 : : //! When check is true, the underlying view may be queried to determine whether an addition is
# 325 : : //! an overwrite.
# 326 : : // TODO: pass in a boolean to limit these possible overwrites to known
# 327 : : // (pre-BIP34) cases.
# 328 : : void AddCoins(CCoinsViewCache& cache, const CTransaction& tx, int nHeight, bool check = false);
# 329 : :
# 330 : : //! Utility function to find any unspent output with a given txid.
# 331 : : //! This function can be quite expensive because in the event of a transaction
# 332 : : //! which is not found in the cache, it can cause up to MAX_OUTPUTS_PER_BLOCK
# 333 : : //! lookups to database, so it should be used with care.
# 334 : : const Coin& AccessByTxid(const CCoinsViewCache& cache, const uint256& txid);
# 335 : :
# 336 : : /**
# 337 : : * This is a minimally invasive approach to shutdown on LevelDB read errors from the
# 338 : : * chainstate, while keeping user interface out of the common library, which is shared
# 339 : : * between bitcoind, and bitcoin-qt and non-server tools.
# 340 : : *
# 341 : : * Writes do not need similar protection, as failure to write is handled by the caller.
# 342 : : */
# 343 : : class CCoinsViewErrorCatcher final : public CCoinsViewBacked
# 344 : : {
# 345 : : public:
# 346 : 794 : explicit CCoinsViewErrorCatcher(CCoinsView* view) : CCoinsViewBacked(view) {}
# 347 : :
# 348 : 626 : void AddReadErrCallback(std::function<void()> f) {
# 349 : 626 : m_err_callbacks.emplace_back(std::move(f));
# 350 : 626 : }
# 351 : :
# 352 : : bool GetCoin(const COutPoint &outpoint, Coin &coin) const override;
# 353 : :
# 354 : : private:
# 355 : : /** A list of callbacks to execute upon leveldb read error. */
# 356 : : std::vector<std::function<void()>> m_err_callbacks;
# 357 : :
# 358 : : };
# 359 : :
# 360 : : #endif // BITCOIN_COINS_H
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