Branch data Line data Source code
1 : : // Copyright (c) 2009-2010 Satoshi Nakamoto
2 : : // Copyright (c) 2009-present 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 <attributes.h>
10 : : #include <compressor.h>
11 : : #include <core_memusage.h>
12 : : #include <memusage.h>
13 : : #include <primitives/transaction.h>
14 : : #include <serialize.h>
15 : : #include <support/allocators/pool.h>
16 : : #include <uint256.h>
17 : : #include <util/check.h>
18 : : #include <util/overflow.h>
19 : : #include <util/hasher.h>
20 : :
21 : : #include <cassert>
22 : : #include <cstdint>
23 : :
24 : : #include <functional>
25 : : #include <unordered_map>
26 : :
27 : : /**
28 : : * A UTXO entry.
29 : : *
30 : : * Serialized format:
31 : : * - VARINT((coinbase ? 1 : 0) | (height << 1))
32 : : * - the non-spent CTxOut (via TxOutCompression)
33 : : */
34 [ + - + - : 74031971 : class Coin
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35 : : {
36 : : public:
37 : : //! unspent transaction output
38 : : CTxOut out;
39 : :
40 : : //! whether containing transaction was a coinbase
41 : : unsigned int fCoinBase : 1;
42 : :
43 : : //! at which height this containing transaction was included in the active block chain
44 : : uint32_t nHeight : 31;
45 : :
46 : : //! construct a Coin from a CTxOut and height/coinbase information.
47 [ + + ]: 66 : Coin(CTxOut&& outIn, int nHeightIn, bool fCoinBaseIn) : out(std::move(outIn)), fCoinBase(fCoinBaseIn), nHeight(nHeightIn) {}
48 [ + + + + ]: 16773666 : Coin(const CTxOut& outIn, int nHeightIn, bool fCoinBaseIn) : out(outIn), fCoinBase(fCoinBaseIn),nHeight(nHeightIn) {}
[ + - ]
49 : :
50 : 10445039 : void Clear() {
51 : 10445039 : out.SetNull();
52 : 10445039 : fCoinBase = false;
53 [ - + + + : 10445039 : nHeight = 0;
+ - ]
54 : 10376996 : }
55 : :
56 : : //! empty constructor
57 [ + - + - ]: 64057789 : Coin() : fCoinBase(false), nHeight(0) { }
[ + + ][ + -
+ - + - ]
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58 : :
59 : 10752743 : bool IsCoinBase() const {
60 [ + + + + ]: 10752743 : return fCoinBase;
[ + + ]
61 : : }
62 : :
63 : : template<typename Stream>
64 : 299441 : void Serialize(Stream &s) const {
65 [ - + ]: 299441 : assert(!IsSpent());
66 : 299441 : uint32_t code = nHeight * uint32_t{2} + fCoinBase;
67 : 299441 : ::Serialize(s, VARINT(code));
68 : 299441 : ::Serialize(s, Using<TxOutCompression>(out));
69 : 299441 : }
70 : :
71 : : template<typename Stream>
72 : 313392 : void Unserialize(Stream &s) {
73 : 313392 : uint32_t code = 0;
74 : 313392 : ::Unserialize(s, VARINT(code));
75 : 313392 : nHeight = code >> 1;
76 : 313392 : fCoinBase = code & 1;
77 : 313392 : ::Unserialize(s, Using<TxOutCompression>(out));
78 : 313389 : }
79 : :
80 : : /** Either this coin never existed (see e.g. coinEmpty in coins.cpp), or it
81 : : * did exist and has been spent.
82 : : */
83 [ + - ]: 100842608 : bool IsSpent() const {
84 [ - - - + : 100172608 : return out.IsNull();
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85 : : }
86 : :
87 : 39990661 : size_t DynamicMemoryUsage() const {
88 [ + + + + : 40775612 : return memusage::DynamicUsage(out.scriptPubKey);
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89 : : }
90 : : };
91 : :
92 : : struct CCoinsCacheEntry;
93 : : using CoinsCachePair = std::pair<const COutPoint, CCoinsCacheEntry>;
94 : :
95 : : /**
96 : : * A Coin in one level of the coins database caching hierarchy.
97 : : *
98 : : * A coin can either be:
99 : : * - unspent or spent (in which case the Coin object will be nulled out - see Coin.Clear())
100 : : * - DIRTY or not DIRTY
101 : : * - FRESH or not FRESH
102 : : *
103 : : * Out of these 2^3 = 8 states, only some combinations are valid:
104 : : * - unspent, FRESH, DIRTY (e.g. a new coin created in the cache)
105 : : * - unspent, not FRESH, DIRTY (e.g. a coin changed in the cache during a reorg)
106 : : * - unspent, not FRESH, not DIRTY (e.g. an unspent coin fetched from the parent cache)
107 : : * - spent, not FRESH, DIRTY (e.g. a coin is spent and spentness needs to be flushed to the parent)
108 : : */
109 : : struct CCoinsCacheEntry
110 : : {
111 : : private:
112 : : /**
113 : : * These are used to create a doubly linked list of flagged entries.
114 : : * They are set in SetDirty, SetFresh, and unset in SetClean.
115 : : * A flagged entry is any entry that is either DIRTY, FRESH, or both.
116 : : *
117 : : * DIRTY entries are tracked so that only modified entries can be passed to
118 : : * the parent cache for batch writing. This is a performance optimization
119 : : * compared to giving all entries in the cache to the parent and having the
120 : : * parent scan for only modified entries.
121 : : */
122 : : CoinsCachePair* m_prev{nullptr};
123 : : CoinsCachePair* m_next{nullptr};
124 : : uint8_t m_flags{0};
125 : :
126 : : //! Adding a flag requires a reference to the sentinel of the flagged pair linked list.
127 : 43774965 : static void AddFlags(uint8_t flags, CoinsCachePair& pair, CoinsCachePair& sentinel) noexcept
128 : : {
129 [ + + ]: 43774965 : Assume(flags & (DIRTY | FRESH));
130 [ + + ]: 43774965 : if (!pair.second.m_flags) {
131 : 27326444 : Assume(!pair.second.m_prev && !pair.second.m_next);
132 : 27326444 : pair.second.m_prev = sentinel.second.m_prev;
133 : 27326444 : pair.second.m_next = &sentinel;
134 : 27326444 : sentinel.second.m_prev = &pair;
135 : 27326444 : pair.second.m_prev->second.m_next = &pair;
136 : : }
137 : 43774965 : Assume(pair.second.m_prev && pair.second.m_next);
138 : 43774965 : pair.second.m_flags |= flags;
139 : 43774965 : }
140 : :
141 : : public:
142 : : Coin coin; // The actual cached data.
143 : :
144 : : enum Flags {
145 : : /**
146 : : * DIRTY means the CCoinsCacheEntry is potentially different from the
147 : : * version in the parent cache. Failure to mark a coin as DIRTY when
148 : : * it is potentially different from the parent cache will cause a
149 : : * consensus failure, since the coin's state won't get written to the
150 : : * parent when the cache is flushed.
151 : : */
152 : : DIRTY = (1 << 0),
153 : : /**
154 : : * FRESH means the parent cache does not have this coin or that it is a
155 : : * spent coin in the parent cache. If a FRESH coin in the cache is
156 : : * later spent, it can be deleted entirely and doesn't ever need to be
157 : : * flushed to the parent. This is a performance optimization. Marking a
158 : : * coin as FRESH when it exists unspent in the parent cache will cause a
159 : : * consensus failure, since it might not be deleted from the parent
160 : : * when this cache is flushed.
161 : : */
162 : : FRESH = (1 << 1),
163 : : };
164 : :
165 : 51261640 : CCoinsCacheEntry() noexcept = default;
166 : 24808 : explicit CCoinsCacheEntry(Coin&& coin_) noexcept : coin(std::move(coin_)) {}
167 : 51286768 : ~CCoinsCacheEntry()
168 : : {
169 : 102573536 : SetClean();
170 : 51286768 : }
171 : :
172 : 27333842 : static void SetDirty(CoinsCachePair& pair, CoinsCachePair& sentinel) noexcept { AddFlags(DIRTY, pair, sentinel); }
173 : 16441123 : static void SetFresh(CoinsCachePair& pair, CoinsCachePair& sentinel) noexcept { AddFlags(FRESH, pair, sentinel); }
174 : :
175 : 51347332 : void SetClean() noexcept
176 : : {
177 [ + + ][ + - : 51286774 : if (!m_flags) return;
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178 : 27728726 : m_next->second.m_prev = m_prev;
179 : 27728726 : m_prev->second.m_next = m_next;
180 : 27728726 : m_flags = 0;
181 : 27728726 : m_prev = m_next = nullptr;
182 : : }
183 [ + - ][ + - : 28875238 : bool IsDirty() const noexcept { return m_flags & DIRTY; }
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184 [ + + + + : 11544142 : bool IsFresh() const noexcept { return m_flags & FRESH; }
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185 : :
186 : : //! Only call Next when this entry is DIRTY, FRESH, or both
187 : 1201356 : CoinsCachePair* Next() const noexcept
188 : : {
189 [ - + ][ + - : 1010072 : Assume(m_flags);
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190 [ - + ][ + - : 194502 : return m_next;
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191 : : }
192 : :
193 : : //! Only call Prev when this entry is DIRTY, FRESH, or both
194 : 83463 : CoinsCachePair* Prev() const noexcept
195 : : {
196 [ - + ][ + - : 41751 : Assume(m_flags);
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197 [ - + - + ]: 41751 : return m_prev;
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198 : : }
199 : :
200 : : //! Only use this for initializing the linked list sentinel
201 : 402282 : void SelfRef(CoinsCachePair& pair) noexcept
202 : : {
203 [ + - + - : 402282 : Assume(&pair.second == this);
+ - ][ + - ]
204 : 402282 : m_prev = &pair;
205 : 402282 : m_next = &pair;
206 : : // Set sentinel to DIRTY so we can call Next on it
207 [ + - + - : 402282 : m_flags = DIRTY;
+ - ][ + - ]
208 : : }
209 : : };
210 : :
211 : : /**
212 : : * PoolAllocator's MAX_BLOCK_SIZE_BYTES parameter here uses sizeof the data, and adds the size
213 : : * of 4 pointers. We do not know the exact node size used in the std::unordered_node implementation
214 : : * because it is implementation defined. Most implementations have an overhead of 1 or 2 pointers,
215 : : * so nodes can be connected in a linked list, and in some cases the hash value is stored as well.
216 : : * Using an additional sizeof(void*)*4 for MAX_BLOCK_SIZE_BYTES should thus be sufficient so that
217 : : * all implementations can allocate the nodes from the PoolAllocator.
218 : : */
219 : : using CCoinsMap = std::unordered_map<COutPoint,
220 : : CCoinsCacheEntry,
221 : : SaltedOutpointHasher,
222 : : std::equal_to<COutPoint>,
223 : : PoolAllocator<CoinsCachePair,
224 : : sizeof(CoinsCachePair) + sizeof(void*) * 4>>;
225 : :
226 : : using CCoinsMapMemoryResource = CCoinsMap::allocator_type::ResourceType;
227 : :
228 : : /** Cursor for iterating over CoinsView state */
229 : : class CCoinsViewCursor
230 : : {
231 : : public:
232 : 1221 : CCoinsViewCursor(const uint256& in_block_hash) : block_hash(in_block_hash) {}
233 : 1221 : virtual ~CCoinsViewCursor() = default;
234 : :
235 : : virtual bool GetKey(COutPoint &key) const = 0;
236 : : virtual bool GetValue(Coin &coin) const = 0;
237 : :
238 : : virtual bool Valid() const = 0;
239 : : virtual void Next() = 0;
240 : :
241 : : //! Get best block at the time this cursor was created
242 [ + - ]: 108 : const uint256& GetBestBlock() const { return block_hash; }
243 : : private:
244 : : uint256 block_hash;
245 : : };
246 : :
247 : : /**
248 : : * Cursor for iterating over the linked list of flagged entries in CCoinsViewCache.
249 : : *
250 : : * This is a helper struct to encapsulate the diverging logic between a non-erasing
251 : : * CCoinsViewCache::Sync and an erasing CCoinsViewCache::Flush. This allows the receiver
252 : : * of CCoinsView::BatchWrite to iterate through the flagged entries without knowing
253 : : * the caller's intent.
254 : : *
255 : : * However, the receiver can still call CoinsViewCacheCursor::WillErase to see if the
256 : : * caller will erase the entry after BatchWrite returns. If so, the receiver can
257 : : * perform optimizations such as moving the coin out of the CCoinsCachEntry instead
258 : : * of copying it.
259 : : */
260 : : struct CoinsViewCacheCursor
261 : : {
262 : : //! If will_erase is not set, iterating through the cursor will erase spent coins from the map,
263 : : //! and other coins will be unflagged (removing them from the linked list).
264 : : //! If will_erase is set, the underlying map and linked list will not be modified,
265 : : //! as the caller is expected to wipe the entire map anyway.
266 : : //! This is an optimization compared to erasing all entries as the cursor iterates them when will_erase is set.
267 : : //! Calling CCoinsMap::clear() afterwards is faster because a CoinsCachePair cannot be coerced back into a
268 : : //! CCoinsMap::iterator to be erased, and must therefore be looked up again by key in the CCoinsMap before being erased.
269 : 150983 : CoinsViewCacheCursor(size_t& dirty_count LIFETIMEBOUND,
270 : : CoinsCachePair& sentinel LIFETIMEBOUND,
271 : : CCoinsMap& map LIFETIMEBOUND,
272 : : bool will_erase) noexcept
273 [ + + ]: 150983 : : m_dirty_count(dirty_count), m_sentinel(sentinel), m_map(map), m_will_erase(will_erase) {}
274 : :
275 : 150983 : inline CoinsCachePair* Begin() const noexcept { return m_sentinel.second.Next(); }
276 [ + + ]: 1074413 : inline CoinsCachePair* End() const noexcept { return &m_sentinel; }
277 : :
278 : : //! Return the next entry after current, possibly erasing current
279 : 923430 : inline CoinsCachePair* NextAndMaybeErase(CoinsCachePair& current) noexcept
280 : : {
281 [ + - ]: 923430 : const auto next_entry{current.second.Next()};
282 [ + - + + ]: 1846860 : Assume(TrySub(m_dirty_count, current.second.IsDirty()));
283 : : // If we are not going to erase the cache, we must still erase spent entries.
284 : : // Otherwise, clear the state of the entry.
285 [ + + ]: 923430 : if (!m_will_erase) {
286 [ + + ]: 78201 : if (current.second.coin.IsSpent()) {
287 [ - + - - ]: 17643 : assert(current.second.coin.DynamicMemoryUsage() == 0); // scriptPubKey was already cleared in SpendCoin
288 : 17643 : m_map.erase(current.first);
289 : : } else {
290 [ + - ]: 60558 : current.second.SetClean();
291 : : }
292 : : }
293 : 923430 : return next_entry;
294 : : }
295 : :
296 [ + + + + : 478773 : inline bool WillErase(CoinsCachePair& current) const noexcept { return m_will_erase || current.second.coin.IsSpent(); }
+ + + + ]
297 : 3706 : size_t GetDirtyCount() const noexcept { return m_dirty_count; }
298 [ + - ]: 3706 : size_t GetTotalCount() const noexcept { return m_map.size(); }
299 : : private:
300 : : size_t& m_dirty_count;
301 : : CoinsCachePair& m_sentinel;
302 : : CCoinsMap& m_map;
303 : : bool m_will_erase;
304 : : };
305 : :
306 : : /** Pure abstract view on the open txout dataset. */
307 : 444824 : class CCoinsView
308 : : {
309 : : public:
310 : : //! As we use CCoinsViews polymorphically, have a virtual destructor
311 : 6 : virtual ~CCoinsView() = default;
312 : :
313 : : //! Retrieve the Coin (unspent transaction output) for a given outpoint.
314 : : //! May populate the cache. Use PeekCoin() to perform a non-caching lookup.
315 : : virtual std::optional<Coin> GetCoin(const COutPoint& outpoint) const = 0;
316 : :
317 : : //! Retrieve the Coin (unspent transaction output) for a given outpoint, without caching results.
318 : : //! Does not populate the cache. Use GetCoin() to cache the result.
319 : : virtual std::optional<Coin> PeekCoin(const COutPoint& outpoint) const = 0;
320 : :
321 : : //! Just check whether a given outpoint is unspent.
322 : : //! May populate the cache. Use PeekCoin() to perform a non-caching lookup.
323 : : virtual bool HaveCoin(const COutPoint& outpoint) const = 0;
324 : :
325 : : //! Retrieve the block hash whose state this CCoinsView currently represents
326 : : virtual uint256 GetBestBlock() const = 0;
327 : :
328 : : //! Retrieve the range of blocks that may have been only partially written.
329 : : //! If the database is in a consistent state, the result is the empty vector.
330 : : //! Otherwise, a two-element vector is returned consisting of the new and
331 : : //! the old block hash, in that order.
332 : : virtual std::vector<uint256> GetHeadBlocks() const = 0;
333 : :
334 : : //! Do a bulk modification (multiple Coin changes + BestBlock change).
335 : : //! The passed cursor is used to iterate through the coins.
336 : : virtual void BatchWrite(CoinsViewCacheCursor& cursor, const uint256& block_hash) = 0;
337 : :
338 : : //! Get a cursor to iterate over the whole state. Implementations may return nullptr.
339 : : virtual std::unique_ptr<CCoinsViewCursor> Cursor() const = 0;
340 : :
341 : : //! Estimate database size
342 : : virtual size_t EstimateSize() const = 0;
343 : : };
344 : :
345 : : /** Noop coins view. */
346 : 4 : class CoinsViewEmpty : public CCoinsView
347 : : {
348 : : protected:
349 [ + - + - : 4 : CoinsViewEmpty() = default;
+ - ]
350 : :
351 : : public:
352 : : static CoinsViewEmpty& Get();
353 : :
354 : : CoinsViewEmpty(const CoinsViewEmpty&) = delete;
355 : : CoinsViewEmpty& operator=(const CoinsViewEmpty&) = delete;
356 : :
357 : 28 : std::optional<Coin> GetCoin(const COutPoint&) const override { return {}; }
358 : 1 : std::optional<Coin> PeekCoin(const COutPoint& outpoint) const override { return GetCoin(outpoint); }
359 : 0 : bool HaveCoin(const COutPoint& outpoint) const override { return !!GetCoin(outpoint); }
360 : 0 : uint256 GetBestBlock() const override { return {}; }
361 : 0 : std::vector<uint256> GetHeadBlocks() const override { return {}; }
362 : 0 : void BatchWrite(CoinsViewCacheCursor& cursor, const uint256&) override
363 : : {
364 [ # # ]: 0 : for (auto it{cursor.Begin()}; it != cursor.End(); it = cursor.NextAndMaybeErase(*it)) { }
365 : 0 : }
366 : 0 : std::unique_ptr<CCoinsViewCursor> Cursor() const override { return {}; }
367 : 0 : size_t EstimateSize() const override { return 0; }
368 : : };
369 : :
370 : : /** CCoinsView backed by another CCoinsView */
371 : 0 : class CCoinsViewBacked : public CCoinsView
372 : : {
373 : : protected:
374 : : CCoinsView* base;
375 : :
376 : : public:
377 [ - + ]: 443532 : explicit CCoinsViewBacked(CCoinsView* in_view) : base{Assert(in_view)} {}
378 : :
379 [ + - + - ]: 67231 : void SetBackend(CCoinsView& in_view) { base = &in_view; }
380 : :
381 : 895592 : std::optional<Coin> GetCoin(const COutPoint& outpoint) const override { return base->GetCoin(outpoint); }
382 : 424186 : std::optional<Coin> PeekCoin(const COutPoint& outpoint) const override { return base->PeekCoin(outpoint); }
383 : 0 : bool HaveCoin(const COutPoint& outpoint) const override { return base->HaveCoin(outpoint); }
384 : 34359 : uint256 GetBestBlock() const override { return base->GetBestBlock(); }
385 : 0 : std::vector<uint256> GetHeadBlocks() const override { return base->GetHeadBlocks(); }
386 : 3526 : void BatchWrite(CoinsViewCacheCursor& cursor, const uint256& block_hash) override { base->BatchWrite(cursor, block_hash); }
387 : 0 : std::unique_ptr<CCoinsViewCursor> Cursor() const override { return base->Cursor(); }
388 : 0 : size_t EstimateSize() const override { return base->EstimateSize(); }
389 : : };
390 : :
391 : :
392 : : /** CCoinsView that adds a memory cache for transactions to another CCoinsView */
393 : : class CCoinsViewCache : public CCoinsViewBacked
394 : : {
395 : : private:
396 : : const bool m_deterministic;
397 : :
398 : : protected:
399 : : /**
400 : : * Make mutable so that we can "fill the cache" even from Get-methods
401 : : * declared as "const".
402 : : */
403 : : mutable uint256 m_block_hash;
404 : : mutable CCoinsMapMemoryResource m_cache_coins_memory_resource{};
405 : : /* The starting sentinel of the flagged entry circular doubly linked list. */
406 : : mutable CoinsCachePair m_sentinel;
407 : : mutable CCoinsMap cacheCoins;
408 : :
409 : : /* Cached dynamic memory usage for the inner Coin objects. */
410 : : mutable size_t cachedCoinsUsage{0};
411 : : /* Running count of dirty Coin cache entries. */
412 : : mutable size_t m_dirty_count{0};
413 : :
414 : : /**
415 : : * Discard all modifications made to this cache without flushing to the base view.
416 : : * This can be used to efficiently reuse a cache instance across multiple operations.
417 : : */
418 : : void Reset() noexcept;
419 : :
420 : : /* Fetch the coin from base. Used for cache misses in FetchCoin. */
421 : : virtual std::optional<Coin> FetchCoinFromBase(const COutPoint& outpoint) const;
422 : :
423 : : public:
424 : : CCoinsViewCache(CCoinsView* in_base, bool deterministic = false);
425 : :
426 : : /**
427 : : * By deleting the copy constructor, we prevent accidentally using it when one intends to create a cache on top of a base cache.
428 : : */
429 : : CCoinsViewCache(const CCoinsViewCache &) = delete;
430 : :
431 : : // Standard CCoinsView methods
432 : : std::optional<Coin> GetCoin(const COutPoint& outpoint) const override;
433 : : std::optional<Coin> PeekCoin(const COutPoint& outpoint) const override;
434 : : bool HaveCoin(const COutPoint& outpoint) const override;
435 : : uint256 GetBestBlock() const override;
436 : : void SetBestBlock(const uint256& block_hash);
437 : : void BatchWrite(CoinsViewCacheCursor& cursor, const uint256& block_hash) override;
438 : 0 : std::unique_ptr<CCoinsViewCursor> Cursor() const override {
439 [ # # ]: 0 : throw std::logic_error("CCoinsViewCache cursor iteration not supported.");
440 : : }
441 : :
442 : : /**
443 : : * Check if we have the given utxo already loaded in this cache.
444 : : * The semantics are the same as HaveCoin(), but no calls to
445 : : * the backing CCoinsView are made.
446 : : */
447 : : bool HaveCoinInCache(const COutPoint &outpoint) const;
448 : :
449 : : /**
450 : : * Return a reference to Coin in the cache, or coinEmpty if not found. This is
451 : : * more efficient than GetCoin.
452 : : *
453 : : * Generally, do not hold the reference returned for more than a short scope.
454 : : * While the current implementation allows for modifications to the contents
455 : : * of the cache while holding the reference, this behavior should not be relied
456 : : * on! To be safe, best to not hold the returned reference through any other
457 : : * calls to this cache.
458 : : */
459 : : const Coin& AccessCoin(const COutPoint &output) const;
460 : :
461 : : /**
462 : : * Add a coin. Set possible_overwrite to true if an unspent version may
463 : : * already exist in the cache.
464 : : */
465 : : void AddCoin(const COutPoint& outpoint, Coin&& coin, bool possible_overwrite);
466 : :
467 : : /**
468 : : * Emplace a coin into cacheCoins without performing any checks, marking
469 : : * the emplaced coin as dirty.
470 : : *
471 : : * NOT FOR GENERAL USE. Used only when loading coins from a UTXO snapshot.
472 : : * @sa ChainstateManager::PopulateAndValidateSnapshot()
473 : : */
474 : : void EmplaceCoinInternalDANGER(COutPoint&& outpoint, Coin&& coin);
475 : :
476 : : /**
477 : : * Spend a coin. Pass moveto in order to get the deleted data.
478 : : * If no unspent output exists for the passed outpoint, this call
479 : : * has no effect.
480 : : */
481 : : bool SpendCoin(const COutPoint &outpoint, Coin* moveto = nullptr);
482 : :
483 : : /**
484 : : * Push the modifications applied to this cache to its base and wipe local state.
485 : : * Failure to call this method or Sync() before destruction will cause the changes
486 : : * to be forgotten.
487 : : * If reallocate_cache is false, the cache will retain the same memory footprint
488 : : * after flushing and should be destroyed to deallocate.
489 : : */
490 : : void Flush(bool reallocate_cache = true);
491 : :
492 : : /**
493 : : * Push the modifications applied to this cache to its base while retaining
494 : : * the contents of this cache (except for spent coins, which we erase).
495 : : * Failure to call this method or Flush() before destruction will cause the changes
496 : : * to be forgotten.
497 : : */
498 : : void Sync();
499 : :
500 : : /**
501 : : * Removes the UTXO with the given outpoint from the cache, if it is
502 : : * not modified.
503 : : */
504 : : void Uncache(const COutPoint &outpoint);
505 : :
506 : : //! Size of the cache (in number of transaction outputs)
507 : : unsigned int GetCacheSize() const;
508 : :
509 : : //! Number of dirty cache entries (transaction outputs)
510 [ + - ][ + - : 3506 : size_t GetDirtyCount() const noexcept { return m_dirty_count; }
+ - + - +
- + - ]
511 : :
512 : : //! Calculate the size of the cache (in bytes)
513 : : size_t DynamicMemoryUsage() const;
514 : :
515 : : //! Check whether all prevouts of the transaction are present in the UTXO set represented by this view
516 : : bool HaveInputs(const CTransaction& tx) const;
517 : :
518 : : //! Force a reallocation of the cache map. This is required when downsizing
519 : : //! the cache because the map's allocator may be hanging onto a lot of
520 : : //! memory despite having called .clear().
521 : : //!
522 : : //! See: https://stackoverflow.com/questions/42114044/how-to-release-unordered-map-memory
523 : : void ReallocateCache();
524 : :
525 : : //! Run an internal sanity check on the cache data structure. */
526 : : void SanityCheck() const;
527 : :
528 : : class ResetGuard
529 : : {
530 : : private:
531 : : friend CCoinsViewCache;
532 : : CCoinsViewCache& m_cache;
533 : 134910 : explicit ResetGuard(CCoinsViewCache& cache LIFETIMEBOUND) noexcept : m_cache{cache} {}
534 : :
535 : : public:
536 : : ResetGuard(const ResetGuard&) = delete;
537 : : ResetGuard& operator=(const ResetGuard&) = delete;
538 : : ResetGuard(ResetGuard&&) = delete;
539 : : ResetGuard& operator=(ResetGuard&&) = delete;
540 : :
541 [ + - + - ]: 134910 : ~ResetGuard() { m_cache.Reset(); }
542 : : };
543 : :
544 : : //! Create a scoped guard that will call `Reset()` on this cache when it goes out of scope.
545 [ + - ]: 134910 : [[nodiscard]] ResetGuard CreateResetGuard() noexcept { return ResetGuard{*this}; }
546 : :
547 : : private:
548 : : /**
549 : : * @note this is marked const, but may actually append to `cacheCoins`, increasing
550 : : * memory usage.
551 : : */
552 : : CCoinsMap::iterator FetchCoin(const COutPoint &outpoint) const;
553 : : };
554 : :
555 : : /**
556 : : * CCoinsViewCache overlay that avoids populating/mutating parent cache layers on cache misses.
557 : : *
558 : : * This is achieved by fetching coins from the base view using PeekCoin() instead of GetCoin(),
559 : : * so intermediate CCoinsViewCache layers are not filled.
560 : : *
561 : : * Used during ConnectBlock() as an ephemeral, resettable top-level view that is flushed only
562 : : * on success, so invalid blocks don't pollute the underlying cache.
563 : : */
564 : 4 : class CoinsViewOverlay : public CCoinsViewCache
565 : : {
566 : : private:
567 : 479531 : std::optional<Coin> FetchCoinFromBase(const COutPoint& outpoint) const override
568 : : {
569 : 479531 : return base->PeekCoin(outpoint);
570 : : }
571 : :
572 : : public:
573 [ + - ][ + - : 1284 : using CCoinsViewCache::CCoinsViewCache;
+ - + - +
- + - +
- ]
574 : : };
575 : :
576 : : //! Utility function to add all of a transaction's outputs to a cache.
577 : : //! When check is false, this assumes that overwrites are only possible for coinbase transactions.
578 : : //! When check is true, the underlying view may be queried to determine whether an addition is
579 : : //! an overwrite.
580 : : // TODO: pass in a boolean to limit these possible overwrites to known
581 : : // (pre-BIP34) cases.
582 : : void AddCoins(CCoinsViewCache& cache, const CTransaction& tx, int nHeight, bool check = false);
583 : :
584 : : //! Utility function to find any unspent output with a given txid.
585 : : //! This function can be quite expensive because in the event of a transaction
586 : : //! which is not found in the cache, it can cause up to MAX_OUTPUTS_PER_BLOCK
587 : : //! lookups to database, so it should be used with care.
588 : : const Coin& AccessByTxid(const CCoinsViewCache& cache, const Txid& txid);
589 : :
590 : : /**
591 : : * This is a minimally invasive approach to shutdown on LevelDB read errors from the
592 : : * chainstate, while keeping user interface out of the common library, which is shared
593 : : * between bitcoind, and bitcoin-qt and non-server tools.
594 : : *
595 : : * Writes do not need similar protection, as failure to write is handled by the caller.
596 : : */
597 : : class CCoinsViewErrorCatcher final : public CCoinsViewBacked
598 : : {
599 : : public:
600 [ + - ]: 1280 : explicit CCoinsViewErrorCatcher(CCoinsView* view) : CCoinsViewBacked(view) {}
601 : :
602 : 1063 : void AddReadErrCallback(std::function<void()> f) {
603 [ + - ]: 1063 : m_err_callbacks.emplace_back(std::move(f));
604 : 1063 : }
605 : :
606 : : std::optional<Coin> GetCoin(const COutPoint& outpoint) const override;
607 : : bool HaveCoin(const COutPoint& outpoint) const override;
608 : : std::optional<Coin> PeekCoin(const COutPoint& outpoint) const override;
609 : :
610 : : private:
611 : : /** A list of callbacks to execute upon leveldb read error. */
612 : : std::vector<std::function<void()>> m_err_callbacks;
613 : :
614 : : };
615 : :
616 : : #endif // BITCOIN_COINS_H
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