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1 : : // Copyright (c) 2009-2010 Satoshi Nakamoto
2 : : // Copyright (c) 2009-2022 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 <support/allocators/pool.h>
15 : : #include <uint256.h>
16 : : #include <util/check.h>
17 : : #include <util/hasher.h>
18 : :
19 : : #include <assert.h>
20 : : #include <stdint.h>
21 : :
22 : : #include <functional>
23 : : #include <unordered_map>
24 : :
25 : : /**
26 : : * A UTXO entry.
27 : : *
28 : : * Serialized format:
29 : : * - VARINT((coinbase ? 1 : 0) | (height << 1))
30 : : * - the non-spent CTxOut (via TxOutCompression)
31 : : */
32 [ # # # # ]: 0 : class Coin
[ # # # # ]
[ # # # #
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33 : : {
34 : : public:
35 : : //! unspent transaction output
36 : : CTxOut out;
37 : :
38 : : //! whether containing transaction was a coinbase
39 : : unsigned int fCoinBase : 1;
40 : :
41 : : //! at which height this containing transaction was included in the active block chain
42 : : uint32_t nHeight : 31;
43 : :
44 : : //! construct a Coin from a CTxOut and height/coinbase information.
45 : : Coin(CTxOut&& outIn, int nHeightIn, bool fCoinBaseIn) : out(std::move(outIn)), fCoinBase(fCoinBaseIn), nHeight(nHeightIn) {}
46 [ # # ][ # # : 0 : Coin(const CTxOut& outIn, int nHeightIn, bool fCoinBaseIn) : out(outIn), fCoinBase(fCoinBaseIn),nHeight(nHeightIn) {}
# # # # ]
[ # # # # ]
47 : :
48 : 0 : void Clear() {
49 : 0 : out.SetNull();
50 : 0 : fCoinBase = false;
51 : 0 : nHeight = 0;
52 : 0 : }
53 : :
54 : : //! empty constructor
55 : 4 : Coin() : fCoinBase(false), nHeight(0) { }
56 : :
57 : 0 : bool IsCoinBase() const {
58 [ # # ]: 0 : return fCoinBase;
[ # # # # ]
59 : : }
60 : :
61 : : template<typename Stream>
62 : 0 : void Serialize(Stream &s) const {
63 [ # # ]: 0 : assert(!IsSpent());
64 : 0 : uint32_t code = nHeight * uint32_t{2} + fCoinBase;
65 : 0 : ::Serialize(s, VARINT(code));
66 : 0 : ::Serialize(s, Using<TxOutCompression>(out));
67 : 0 : }
68 : :
69 : : template<typename Stream>
70 : 0 : void Unserialize(Stream &s) {
71 : 0 : uint32_t code = 0;
72 : 0 : ::Unserialize(s, VARINT(code));
73 : 0 : nHeight = code >> 1;
74 : 0 : fCoinBase = code & 1;
75 : 0 : ::Unserialize(s, Using<TxOutCompression>(out));
76 : 0 : }
77 : :
78 : : /** Either this coin never existed (see e.g. coinEmpty in coins.cpp), or it
79 : : * did exist and has been spent.
80 : : */
81 : 0 : bool IsSpent() const {
82 [ # # ][ # # : 0 : return out.IsNull();
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83 : : }
84 : :
85 : 0 : size_t DynamicMemoryUsage() const {
86 [ # # ][ # # : 0 : return memusage::DynamicUsage(out.scriptPubKey);
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87 : : }
88 : : };
89 : :
90 : : struct CCoinsCacheEntry;
91 : : using CoinsCachePair = std::pair<const COutPoint, CCoinsCacheEntry>;
92 : :
93 : : /**
94 : : * A Coin in one level of the coins database caching hierarchy.
95 : : *
96 : : * A coin can either be:
97 : : * - unspent or spent (in which case the Coin object will be nulled out - see Coin.Clear())
98 : : * - DIRTY or not DIRTY
99 : : * - FRESH or not FRESH
100 : : *
101 : : * Out of these 2^3 = 8 states, only some combinations are valid:
102 : : * - unspent, FRESH, DIRTY (e.g. a new coin created in the cache)
103 : : * - unspent, not FRESH, DIRTY (e.g. a coin changed in the cache during a reorg)
104 : : * - unspent, not FRESH, not DIRTY (e.g. an unspent coin fetched from the parent cache)
105 : : * - spent, FRESH, not DIRTY (e.g. a spent coin fetched from the parent cache)
106 : : * - spent, not FRESH, DIRTY (e.g. a coin is spent and spentness needs to be flushed to the parent)
107 : : */
108 : : struct CCoinsCacheEntry
109 : : {
110 : : private:
111 : : /**
112 : : * These are used to create a doubly linked list of flagged entries.
113 : : * They are set in AddFlags and unset in ClearFlags.
114 : : * A flagged entry is any entry that is either DIRTY, FRESH, or both.
115 : : *
116 : : * DIRTY entries are tracked so that only modified entries can be passed to
117 : : * the parent cache for batch writing. This is a performance optimization
118 : : * compared to giving all entries in the cache to the parent and having the
119 : : * parent scan for only modified entries.
120 : : *
121 : : * FRESH-but-not-DIRTY coins can not occur in practice, since that would
122 : : * mean a spent coin exists in the parent CCoinsView and not in the child
123 : : * CCoinsViewCache. Nevertheless, if a spent coin is retrieved from the
124 : : * parent cache, the FRESH-but-not-DIRTY coin will be tracked by the linked
125 : : * list and deleted when Sync or Flush is called on the CCoinsViewCache.
126 : : */
127 : : CoinsCachePair* m_prev{nullptr};
128 : : CoinsCachePair* m_next{nullptr};
129 : : uint8_t m_flags{0};
130 : :
131 : : public:
132 : : Coin coin; // The actual cached data.
133 : :
134 : : enum Flags {
135 : : /**
136 : : * DIRTY means the CCoinsCacheEntry is potentially different from the
137 : : * version in the parent cache. Failure to mark a coin as DIRTY when
138 : : * it is potentially different from the parent cache will cause a
139 : : * consensus failure, since the coin's state won't get written to the
140 : : * parent when the cache is flushed.
141 : : */
142 : : DIRTY = (1 << 0),
143 : : /**
144 : : * FRESH means the parent cache does not have this coin or that it is a
145 : : * spent coin in the parent cache. If a FRESH coin in the cache is
146 : : * later spent, it can be deleted entirely and doesn't ever need to be
147 : : * flushed to the parent. This is a performance optimization. Marking a
148 : : * coin as FRESH when it exists unspent in the parent cache will cause a
149 : : * consensus failure, since it might not be deleted from the parent
150 : : * when this cache is flushed.
151 : : */
152 : : FRESH = (1 << 1),
153 : : };
154 : :
155 : 0 : CCoinsCacheEntry() noexcept = default;
156 : 0 : explicit CCoinsCacheEntry(Coin&& coin_) noexcept : coin(std::move(coin_)) {}
157 : 0 : ~CCoinsCacheEntry()
158 : : {
159 : 0 : ClearFlags();
160 : 0 : }
161 : :
162 : : //! Adding a flag also requires a self reference to the pair that contains
163 : : //! this entry in the CCoinsCache map and a reference to the sentinel of the
164 : : //! flagged pair linked list.
165 : 0 : inline void AddFlags(uint8_t flags, CoinsCachePair& self, CoinsCachePair& sentinel) noexcept
166 : : {
167 : 0 : Assume(&self.second == this);
168 [ # # # # ]: 0 : if (!m_flags && flags) {
169 : 0 : m_prev = sentinel.second.m_prev;
170 : 0 : m_next = &sentinel;
171 : 0 : sentinel.second.m_prev = &self;
172 : 0 : m_prev->second.m_next = &self;
173 : : }
174 : 0 : m_flags |= flags;
175 : 0 : }
176 : 0 : inline void ClearFlags() noexcept
177 : : {
178 [ # # ]: 0 : if (!m_flags) return;
179 : 0 : m_next->second.m_prev = m_prev;
180 : 0 : m_prev->second.m_next = m_next;
181 : 0 : m_flags = 0;
182 : : }
183 : : inline uint8_t GetFlags() const noexcept { return m_flags; }
184 [ # # ][ # # : 0 : inline bool IsDirty() const noexcept { return m_flags & DIRTY; }
# # # # #
# ]
185 [ # # # # : 0 : inline bool IsFresh() const noexcept { return m_flags & FRESH; }
# # # # #
# ]
186 : :
187 : : //! Only call Next when this entry is DIRTY, FRESH, or both
188 : 0 : inline CoinsCachePair* Next() const noexcept {
189 : 0 : Assume(m_flags);
190 : 0 : return m_next;
191 : : }
192 : :
193 : : //! Only call Prev when this entry is DIRTY, FRESH, or both
194 : 0 : inline CoinsCachePair* Prev() const noexcept {
195 : 0 : Assume(m_flags);
196 : 0 : return m_prev;
197 : : }
198 : :
199 : : //! Only use this for initializing the linked list sentinel
200 : 0 : inline void SelfRef(CoinsCachePair& self) noexcept
201 : : {
202 : 0 : Assume(&self.second == this);
203 : 0 : m_prev = &self;
204 : 0 : m_next = &self;
205 : : // Set sentinel to DIRTY so we can call Next on it
206 : 0 : m_flags = DIRTY;
207 : 0 : }
208 : : };
209 : :
210 : : /**
211 : : * PoolAllocator's MAX_BLOCK_SIZE_BYTES parameter here uses sizeof the data, and adds the size
212 : : * of 4 pointers. We do not know the exact node size used in the std::unordered_node implementation
213 : : * because it is implementation defined. Most implementations have an overhead of 1 or 2 pointers,
214 : : * so nodes can be connected in a linked list, and in some cases the hash value is stored as well.
215 : : * Using an additional sizeof(void*)*4 for MAX_BLOCK_SIZE_BYTES should thus be sufficient so that
216 : : * all implementations can allocate the nodes from the PoolAllocator.
217 : : */
218 : : using CCoinsMap = std::unordered_map<COutPoint,
219 : : CCoinsCacheEntry,
220 : : SaltedOutpointHasher,
221 : : std::equal_to<COutPoint>,
222 : : PoolAllocator<CoinsCachePair,
223 : : sizeof(CoinsCachePair) + sizeof(void*) * 4>>;
224 : :
225 : : using CCoinsMapMemoryResource = CCoinsMap::allocator_type::ResourceType;
226 : :
227 : : /** Cursor for iterating over CoinsView state */
228 : : class CCoinsViewCursor
229 : : {
230 : : public:
231 : 0 : CCoinsViewCursor(const uint256 &hashBlockIn): hashBlock(hashBlockIn) {}
232 : 0 : virtual ~CCoinsViewCursor() = default;
233 : :
234 : : virtual bool GetKey(COutPoint &key) const = 0;
235 : : virtual bool GetValue(Coin &coin) const = 0;
236 : :
237 : : virtual bool Valid() const = 0;
238 : : virtual void Next() = 0;
239 : :
240 : : //! Get best block at the time this cursor was created
241 : : const uint256 &GetBestBlock() const { return hashBlock; }
242 : : private:
243 : : uint256 hashBlock;
244 : : };
245 : :
246 : : /**
247 : : * Cursor for iterating over the linked list of flagged entries in CCoinsViewCache.
248 : : *
249 : : * This is a helper struct to encapsulate the diverging logic between a non-erasing
250 : : * CCoinsViewCache::Sync and an erasing CCoinsViewCache::Flush. This allows the receiver
251 : : * of CCoinsView::BatchWrite to iterate through the flagged entries without knowing
252 : : * the caller's intent.
253 : : *
254 : : * However, the receiver can still call CoinsViewCacheCursor::WillErase to see if the
255 : : * caller will erase the entry after BatchWrite returns. If so, the receiver can
256 : : * perform optimizations such as moving the coin out of the CCoinsCachEntry instead
257 : : * of copying it.
258 : : */
259 : : struct CoinsViewCacheCursor
260 : : {
261 : : //! If will_erase is not set, iterating through the cursor will erase spent coins from the map,
262 : : //! and other coins will be unflagged (removing them from the linked list).
263 : : //! If will_erase is set, the underlying map and linked list will not be modified,
264 : : //! as the caller is expected to wipe the entire map anyway.
265 : : //! This is an optimization compared to erasing all entries as the cursor iterates them when will_erase is set.
266 : : //! Calling CCoinsMap::clear() afterwards is faster because a CoinsCachePair cannot be coerced back into a
267 : : //! CCoinsMap::iterator to be erased, and must therefore be looked up again by key in the CCoinsMap before being erased.
268 : 0 : CoinsViewCacheCursor(size_t& usage LIFETIMEBOUND,
269 : : CoinsCachePair& sentinel LIFETIMEBOUND,
270 : : CCoinsMap& map LIFETIMEBOUND,
271 : : bool will_erase) noexcept
272 : 0 : : m_usage(usage), m_sentinel(sentinel), m_map(map), m_will_erase(will_erase) {}
273 : :
274 : 0 : inline CoinsCachePair* Begin() const noexcept { return m_sentinel.second.Next(); }
275 [ # # ]: 0 : inline CoinsCachePair* End() const noexcept { return &m_sentinel; }
276 : :
277 : : //! Return the next entry after current, possibly erasing current
278 : 0 : inline CoinsCachePair* NextAndMaybeErase(CoinsCachePair& current) noexcept
279 : : {
280 : 0 : const auto next_entry{current.second.Next()};
281 : : // If we are not going to erase the cache, we must still erase spent entries.
282 : : // Otherwise clear the flags on the entry.
283 [ # # ]: 0 : if (!m_will_erase) {
284 [ # # ]: 0 : if (current.second.coin.IsSpent()) {
285 [ # # ]: 0 : m_usage -= current.second.coin.DynamicMemoryUsage();
286 : 0 : m_map.erase(current.first);
287 : : } else {
288 [ # # ]: 0 : current.second.ClearFlags();
289 : : }
290 : : }
291 : 0 : return next_entry;
292 : : }
293 : :
294 [ # # # # ]: 0 : inline bool WillErase(CoinsCachePair& current) const noexcept { return m_will_erase || current.second.coin.IsSpent(); }
[ # # # #
# # # # ]
295 : : private:
296 : : size_t& m_usage;
297 : : CoinsCachePair& m_sentinel;
298 : : CCoinsMap& m_map;
299 : : bool m_will_erase;
300 : : };
301 : :
302 : : /** Abstract view on the open txout dataset. */
303 : 0 : class CCoinsView
304 : : {
305 : : public:
306 : : //! Retrieve the Coin (unspent transaction output) for a given outpoint.
307 : : virtual std::optional<Coin> GetCoin(const COutPoint& outpoint) const;
308 : :
309 : : //! Just check whether a given outpoint is unspent.
310 : : virtual bool HaveCoin(const COutPoint &outpoint) const;
311 : :
312 : : //! Retrieve the block hash whose state this CCoinsView currently represents
313 : : virtual uint256 GetBestBlock() const;
314 : :
315 : : //! Retrieve the range of blocks that may have been only partially written.
316 : : //! If the database is in a consistent state, the result is the empty vector.
317 : : //! Otherwise, a two-element vector is returned consisting of the new and
318 : : //! the old block hash, in that order.
319 : : virtual std::vector<uint256> GetHeadBlocks() const;
320 : :
321 : : //! Do a bulk modification (multiple Coin changes + BestBlock change).
322 : : //! The passed cursor is used to iterate through the coins.
323 : : virtual bool BatchWrite(CoinsViewCacheCursor& cursor, const uint256& hashBlock);
324 : :
325 : : //! Get a cursor to iterate over the whole state
326 : : virtual std::unique_ptr<CCoinsViewCursor> Cursor() const;
327 : :
328 : : //! As we use CCoinsViews polymorphically, have a virtual destructor
329 : 0 : virtual ~CCoinsView() = default;
330 : :
331 : : //! Estimate database size (0 if not implemented)
332 : 0 : virtual size_t EstimateSize() const { return 0; }
333 : : };
334 : :
335 : :
336 : : /** CCoinsView backed by another CCoinsView */
337 : 0 : class CCoinsViewBacked : public CCoinsView
338 : : {
339 : : protected:
340 : : CCoinsView *base;
341 : :
342 : : public:
343 : : CCoinsViewBacked(CCoinsView *viewIn);
344 : : std::optional<Coin> GetCoin(const COutPoint& outpoint) const override;
345 : : bool HaveCoin(const COutPoint &outpoint) const override;
346 : : uint256 GetBestBlock() const override;
347 : : std::vector<uint256> GetHeadBlocks() const override;
348 : : void SetBackend(CCoinsView &viewIn);
349 : : bool BatchWrite(CoinsViewCacheCursor& cursor, const uint256 &hashBlock) override;
350 : : std::unique_ptr<CCoinsViewCursor> Cursor() const override;
351 : : size_t EstimateSize() const override;
352 : : };
353 : :
354 : :
355 : : /** CCoinsView that adds a memory cache for transactions to another CCoinsView */
356 : : class CCoinsViewCache : public CCoinsViewBacked
357 : : {
358 : : private:
359 : : const bool m_deterministic;
360 : :
361 : : protected:
362 : : /**
363 : : * Make mutable so that we can "fill the cache" even from Get-methods
364 : : * declared as "const".
365 : : */
366 : : mutable uint256 hashBlock;
367 : : mutable CCoinsMapMemoryResource m_cache_coins_memory_resource{};
368 : : /* The starting sentinel of the flagged entry circular doubly linked list. */
369 : : mutable CoinsCachePair m_sentinel;
370 : : mutable CCoinsMap cacheCoins;
371 : :
372 : : /* Cached dynamic memory usage for the inner Coin objects. */
373 : : mutable size_t cachedCoinsUsage{0};
374 : :
375 : : public:
376 : : CCoinsViewCache(CCoinsView *baseIn, bool deterministic = false);
377 : :
378 : : /**
379 : : * By deleting the copy constructor, we prevent accidentally using it when one intends to create a cache on top of a base cache.
380 : : */
381 : : CCoinsViewCache(const CCoinsViewCache &) = delete;
382 : :
383 : : // Standard CCoinsView methods
384 : : std::optional<Coin> GetCoin(const COutPoint& outpoint) const override;
385 : : bool HaveCoin(const COutPoint &outpoint) const override;
386 : : uint256 GetBestBlock() const override;
387 : : void SetBestBlock(const uint256 &hashBlock);
388 : : bool BatchWrite(CoinsViewCacheCursor& cursor, const uint256 &hashBlock) override;
389 : 0 : std::unique_ptr<CCoinsViewCursor> Cursor() const override {
390 [ # # ]: 0 : throw std::logic_error("CCoinsViewCache cursor iteration not supported.");
391 : : }
392 : :
393 : : /**
394 : : * Check if we have the given utxo already loaded in this cache.
395 : : * The semantics are the same as HaveCoin(), but no calls to
396 : : * the backing CCoinsView are made.
397 : : */
398 : : bool HaveCoinInCache(const COutPoint &outpoint) const;
399 : :
400 : : /**
401 : : * Return a reference to Coin in the cache, or coinEmpty if not found. This is
402 : : * more efficient than GetCoin.
403 : : *
404 : : * Generally, do not hold the reference returned for more than a short scope.
405 : : * While the current implementation allows for modifications to the contents
406 : : * of the cache while holding the reference, this behavior should not be relied
407 : : * on! To be safe, best to not hold the returned reference through any other
408 : : * calls to this cache.
409 : : */
410 : : const Coin& AccessCoin(const COutPoint &output) const;
411 : :
412 : : /**
413 : : * Add a coin. Set possible_overwrite to true if an unspent version may
414 : : * already exist in the cache.
415 : : */
416 : : void AddCoin(const COutPoint& outpoint, Coin&& coin, bool possible_overwrite);
417 : :
418 : : /**
419 : : * Emplace a coin into cacheCoins without performing any checks, marking
420 : : * the emplaced coin as dirty.
421 : : *
422 : : * NOT FOR GENERAL USE. Used only when loading coins from a UTXO snapshot.
423 : : * @sa ChainstateManager::PopulateAndValidateSnapshot()
424 : : */
425 : : void EmplaceCoinInternalDANGER(COutPoint&& outpoint, Coin&& coin);
426 : :
427 : : /**
428 : : * Spend a coin. Pass moveto in order to get the deleted data.
429 : : * If no unspent output exists for the passed outpoint, this call
430 : : * has no effect.
431 : : */
432 : : bool SpendCoin(const COutPoint &outpoint, Coin* moveto = nullptr);
433 : :
434 : : /**
435 : : * Push the modifications applied to this cache to its base and wipe local state.
436 : : * Failure to call this method or Sync() before destruction will cause the changes
437 : : * to be forgotten.
438 : : * If false is returned, the state of this cache (and its backing view) will be undefined.
439 : : */
440 : : bool Flush();
441 : :
442 : : /**
443 : : * Push the modifications applied to this cache to its base while retaining
444 : : * the contents of this cache (except for spent coins, which we erase).
445 : : * Failure to call this method or Flush() before destruction will cause the changes
446 : : * to be forgotten.
447 : : * If false is returned, the state of this cache (and its backing view) will be undefined.
448 : : */
449 : : bool Sync();
450 : :
451 : : /**
452 : : * Removes the UTXO with the given outpoint from the cache, if it is
453 : : * not modified.
454 : : */
455 : : void Uncache(const COutPoint &outpoint);
456 : :
457 : : //! Calculate the size of the cache (in number of transaction outputs)
458 : : unsigned int GetCacheSize() const;
459 : :
460 : : //! Calculate the size of the cache (in bytes)
461 : : size_t DynamicMemoryUsage() const;
462 : :
463 : : //! Check whether all prevouts of the transaction are present in the UTXO set represented by this view
464 : : bool HaveInputs(const CTransaction& tx) const;
465 : :
466 : : //! Force a reallocation of the cache map. This is required when downsizing
467 : : //! the cache because the map's allocator may be hanging onto a lot of
468 : : //! memory despite having called .clear().
469 : : //!
470 : : //! See: https://stackoverflow.com/questions/42114044/how-to-release-unordered-map-memory
471 : : void ReallocateCache();
472 : :
473 : : //! Run an internal sanity check on the cache data structure. */
474 : : void SanityCheck() const;
475 : :
476 : : private:
477 : : /**
478 : : * @note this is marked const, but may actually append to `cacheCoins`, increasing
479 : : * memory usage.
480 : : */
481 : : CCoinsMap::iterator FetchCoin(const COutPoint &outpoint) const;
482 : : };
483 : :
484 : : //! Utility function to add all of a transaction's outputs to a cache.
485 : : //! When check is false, this assumes that overwrites are only possible for coinbase transactions.
486 : : //! When check is true, the underlying view may be queried to determine whether an addition is
487 : : //! an overwrite.
488 : : // TODO: pass in a boolean to limit these possible overwrites to known
489 : : // (pre-BIP34) cases.
490 : : void AddCoins(CCoinsViewCache& cache, const CTransaction& tx, int nHeight, bool check = false);
491 : :
492 : : //! Utility function to find any unspent output with a given txid.
493 : : //! This function can be quite expensive because in the event of a transaction
494 : : //! which is not found in the cache, it can cause up to MAX_OUTPUTS_PER_BLOCK
495 : : //! lookups to database, so it should be used with care.
496 : : const Coin& AccessByTxid(const CCoinsViewCache& cache, const Txid& txid);
497 : :
498 : : /**
499 : : * This is a minimally invasive approach to shutdown on LevelDB read errors from the
500 : : * chainstate, while keeping user interface out of the common library, which is shared
501 : : * between bitcoind, and bitcoin-qt and non-server tools.
502 : : *
503 : : * Writes do not need similar protection, as failure to write is handled by the caller.
504 : : */
505 : : class CCoinsViewErrorCatcher final : public CCoinsViewBacked
506 : : {
507 : : public:
508 [ # # ]: 0 : explicit CCoinsViewErrorCatcher(CCoinsView* view) : CCoinsViewBacked(view) {}
509 : :
510 : 0 : void AddReadErrCallback(std::function<void()> f) {
511 [ # # ]: 0 : m_err_callbacks.emplace_back(std::move(f));
512 : 0 : }
513 : :
514 : : std::optional<Coin> GetCoin(const COutPoint& outpoint) const override;
515 : : bool HaveCoin(const COutPoint &outpoint) const override;
516 : :
517 : : private:
518 : : /** A list of callbacks to execute upon leveldb read error. */
519 : : std::vector<std::function<void()>> m_err_callbacks;
520 : :
521 : : };
522 : :
523 : : #endif // BITCOIN_COINS_H
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