coins_tests.cpp raw

   1  // Copyright (c) 2014-present The Bitcoin Core developers
   2  // Distributed under the MIT software license, see the accompanying
   3  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
   4  
   5  #include <addresstype.h>
   6  #include <clientversion.h>
   7  #include <coins.h>
   8  #include <streams.h>
   9  #include <test/util/common.h>
  10  #include <test/util/poolresourcetester.h>
  11  #include <test/util/random.h>
  12  #include <test/util/setup_common.h>
  13  #include <txdb.h>
  14  #include <uint256.h>
  15  #include <undo.h>
  16  #include <util/byte_units.h>
  17  #include <util/check.h>
  18  #include <util/strencodings.h>
  19  
  20  #include <map>
  21  #include <string>
  22  #include <variant>
  23  #include <vector>
  24  
  25  #include <boost/test/unit_test.hpp>
  26  
  27  using namespace util::hex_literals;
  28  
  29  int ApplyTxInUndo(Coin&& undo, CCoinsViewCache& view, const COutPoint& out);
  30  void UpdateCoins(const CTransaction& tx, CCoinsViewCache& inputs, CTxUndo &txundo, int nHeight);
  31  
  32  namespace
  33  {
  34  //! equality test
  35  bool operator==(const Coin &a, const Coin &b) {
  36      // Empty Coin objects are always equal.
  37      if (a.IsSpent() && b.IsSpent()) return true;
  38      return a.fCoinBase == b.fCoinBase &&
  39             a.nHeight == b.nHeight &&
  40             a.out == b.out;
  41  }
  42  
  43  class CCoinsViewTest : public CoinsViewEmpty
  44  {
  45      FastRandomContext& m_rng;
  46      uint256 hashBestBlock_;
  47      std::map<COutPoint, Coin> map_;
  48  
  49  public:
  50      explicit CCoinsViewTest(FastRandomContext& rng) : m_rng{rng} {}
  51  
  52      std::optional<Coin> GetCoin(const COutPoint& outpoint) const override
  53      {
  54          if (auto it{map_.find(outpoint)}; it != map_.end() && !it->second.IsSpent()) return it->second;
  55          return std::nullopt;
  56      }
  57  
  58      uint256 GetBestBlock() const override { return hashBestBlock_; }
  59  
  60      void BatchWrite(CoinsViewCacheCursor& cursor, const uint256& block_hash) override
  61      {
  62          for (auto it{cursor.Begin()}; it != cursor.End(); it = cursor.NextAndMaybeErase(*it)){
  63              if (it->second.IsDirty()) {
  64                  // Same optimization used in CCoinsViewDB is to only write dirty entries.
  65                  map_[it->first] = it->second.coin;
  66                  if (it->second.coin.IsSpent() && m_rng.randrange(3) == 0) {
  67                      // Randomly delete empty entries on write.
  68                      map_.erase(it->first);
  69                  }
  70              }
  71          }
  72          if (!block_hash.IsNull())
  73              hashBestBlock_ = block_hash;
  74      }
  75  };
  76  
  77  class CCoinsViewCacheTest : public CCoinsViewCache
  78  {
  79  public:
  80      explicit CCoinsViewCacheTest(CCoinsView* _base) : CCoinsViewCache(_base) {}
  81  
  82      void SelfTest(bool sanity_check = true) const
  83      {
  84          // Manually recompute the dynamic usage of the whole data, and compare it.
  85          size_t ret = memusage::DynamicUsage(cacheCoins);
  86          size_t count = 0;
  87          for (const auto& entry : cacheCoins) {
  88              ret += entry.second.coin.DynamicMemoryUsage();
  89              ++count;
  90          }
  91          BOOST_CHECK_EQUAL(GetCacheSize(), count);
  92          BOOST_CHECK_EQUAL(DynamicMemoryUsage(), ret);
  93          if (sanity_check) {
  94              SanityCheck();
  95          }
  96      }
  97  
  98      CCoinsMap& map() const { return cacheCoins; }
  99      CoinsCachePair& sentinel() const { return m_sentinel; }
 100      size_t& usage() const { return cachedCoinsUsage; }
 101      size_t& dirty() const { return m_dirty_count; }
 102  };
 103  
 104  } // namespace
 105  
 106  static const unsigned int NUM_SIMULATION_ITERATIONS = 40000;
 107  
 108  struct CacheTest : BasicTestingSetup {
 109  // This is a large randomized insert/remove simulation test on a variable-size
 110  // stack of caches on top of CCoinsViewTest.
 111  //
 112  // It will randomly create/update/delete Coin entries to a tip of caches, with
 113  // txids picked from a limited list of random 256-bit hashes. Occasionally, a
 114  // new tip is added to the stack of caches, or the tip is flushed and removed.
 115  //
 116  // During the process, booleans are kept to make sure that the randomized
 117  // operation hits all branches.
 118  //
 119  // If fake_best_block is true, assign a random uint256 to mock the recording
 120  // of best block on flush. This is necessary when using CCoinsViewDB as the base,
 121  // otherwise we'll hit an assertion in BatchWrite.
 122  //
 123  void SimulationTest(CCoinsView* base, bool fake_best_block)
 124  {
 125      // Various coverage trackers.
 126      bool removed_all_caches = false;
 127      bool reached_4_caches = false;
 128      bool added_an_entry = false;
 129      bool added_an_unspendable_entry = false;
 130      bool removed_an_entry = false;
 131      bool updated_an_entry = false;
 132      bool found_an_entry = false;
 133      bool missed_an_entry = false;
 134      bool uncached_an_entry = false;
 135      bool flushed_without_erase = false;
 136  
 137      // A simple map to track what we expect the cache stack to represent.
 138      std::map<COutPoint, Coin> result;
 139  
 140      // The cache stack.
 141      std::vector<std::unique_ptr<CCoinsViewCacheTest>> stack; // A stack of CCoinsViewCaches on top.
 142      stack.push_back(std::make_unique<CCoinsViewCacheTest>(base)); // Start with one cache.
 143  
 144      // Use a limited set of random transaction ids, so we do test overwriting entries.
 145      std::vector<Txid> txids;
 146      txids.resize(NUM_SIMULATION_ITERATIONS / 8);
 147      for (unsigned int i = 0; i < txids.size(); i++) {
 148          txids[i] = Txid::FromUint256(m_rng.rand256());
 149      }
 150  
 151      for (unsigned int i = 0; i < NUM_SIMULATION_ITERATIONS; i++) {
 152          // Do a random modification.
 153          {
 154              auto txid = txids[m_rng.randrange(txids.size())]; // txid we're going to modify in this iteration.
 155              Coin& coin = result[COutPoint(txid, 0)];
 156  
 157              // Determine whether to test HaveCoin before or after Access* (or both). As these functions
 158              // can influence each other's behaviour by pulling things into the cache, all combinations
 159              // are tested.
 160              bool test_havecoin_before = m_rng.randbits(2) == 0;
 161              bool test_havecoin_after = m_rng.randbits(2) == 0;
 162  
 163              bool result_havecoin = test_havecoin_before ? stack.back()->HaveCoin(COutPoint(txid, 0)) : false;
 164  
 165              // Infrequently, test usage of AccessByTxid instead of AccessCoin - the
 166              // former just delegates to the latter and returns the first unspent in a txn.
 167              const Coin& entry = (m_rng.randrange(500) == 0) ?
 168                  AccessByTxid(*stack.back(), txid) : stack.back()->AccessCoin(COutPoint(txid, 0));
 169              BOOST_CHECK(coin == entry);
 170  
 171              if (test_havecoin_before) {
 172                  BOOST_CHECK(result_havecoin == !entry.IsSpent());
 173              }
 174  
 175              if (test_havecoin_after) {
 176                  bool ret = stack.back()->HaveCoin(COutPoint(txid, 0));
 177                  BOOST_CHECK(ret == !entry.IsSpent());
 178              }
 179  
 180              if (m_rng.randrange(5) == 0 || coin.IsSpent()) {
 181                  Coin newcoin;
 182                  newcoin.out.nValue = RandMoney(m_rng);
 183                  newcoin.nHeight = 1;
 184  
 185                  // Infrequently test adding unspendable coins.
 186                  if (m_rng.randrange(16) == 0 && coin.IsSpent()) {
 187                      newcoin.out.scriptPubKey.assign(1 + m_rng.randbits(6), OP_RETURN);
 188                      BOOST_CHECK(newcoin.out.scriptPubKey.IsUnspendable());
 189                      added_an_unspendable_entry = true;
 190                  } else {
 191                      // Random sizes so we can test memory usage accounting
 192                      newcoin.out.scriptPubKey.assign(m_rng.randbits(6), 0);
 193                      (coin.IsSpent() ? added_an_entry : updated_an_entry) = true;
 194                      coin = newcoin;
 195                  }
 196                  if (COutPoint op(txid, 0); !stack.back()->map().contains(op) && !newcoin.out.scriptPubKey.IsUnspendable() && m_rng.randbool()) {
 197                      stack.back()->EmplaceCoinInternalDANGER(std::move(op), std::move(newcoin));
 198                  } else {
 199                      stack.back()->AddCoin(op, std::move(newcoin), /*possible_overwrite=*/!coin.IsSpent() || m_rng.randbool());
 200                  }
 201              } else {
 202                  // Spend the coin.
 203                  removed_an_entry = true;
 204                  coin.Clear();
 205                  BOOST_CHECK(stack.back()->SpendCoin(COutPoint(txid, 0)));
 206              }
 207          }
 208  
 209          // Once every 10 iterations, remove a random entry from the cache
 210          if (m_rng.randrange(10) == 0) {
 211              COutPoint out(txids[m_rng.rand32() % txids.size()], 0);
 212              int cacheid = m_rng.rand32() % stack.size();
 213              stack[cacheid]->Uncache(out);
 214              uncached_an_entry |= !stack[cacheid]->HaveCoinInCache(out);
 215          }
 216  
 217          // Once every 1000 iterations and at the end, verify the full cache.
 218          if (m_rng.randrange(1000) == 1 || i == NUM_SIMULATION_ITERATIONS - 1) {
 219              for (const auto& entry : result) {
 220                  bool have = stack.back()->HaveCoin(entry.first);
 221                  const Coin& coin = stack.back()->AccessCoin(entry.first);
 222                  BOOST_CHECK(have == !coin.IsSpent());
 223                  BOOST_CHECK(coin == entry.second);
 224                  if (coin.IsSpent()) {
 225                      missed_an_entry = true;
 226                  } else {
 227                      BOOST_CHECK(stack.back()->HaveCoinInCache(entry.first));
 228                      found_an_entry = true;
 229                  }
 230              }
 231              for (const auto& test : stack) {
 232                  test->SelfTest();
 233              }
 234          }
 235  
 236          if (m_rng.randrange(100) == 0) {
 237              // Every 100 iterations, flush an intermediate cache
 238              if (stack.size() > 1 && m_rng.randbool() == 0) {
 239                  unsigned int flushIndex = m_rng.randrange(stack.size() - 1);
 240                  if (fake_best_block) stack[flushIndex]->SetBestBlock(m_rng.rand256());
 241                  bool should_erase = m_rng.randrange(4) < 3;
 242                  should_erase ? stack[flushIndex]->Flush() : stack[flushIndex]->Sync();
 243                  flushed_without_erase |= !should_erase;
 244              }
 245          }
 246          if (m_rng.randrange(100) == 0) {
 247              // Every 100 iterations, change the cache stack.
 248              if (stack.size() > 0 && m_rng.randbool() == 0) {
 249                  //Remove the top cache
 250                  if (fake_best_block) stack.back()->SetBestBlock(m_rng.rand256());
 251                  bool should_erase = m_rng.randrange(4) < 3;
 252                  should_erase ? stack.back()->Flush() : stack.back()->Sync();
 253                  flushed_without_erase |= !should_erase;
 254                  stack.pop_back();
 255              }
 256              if (stack.size() == 0 || (stack.size() < 4 && m_rng.randbool())) {
 257                  //Add a new cache
 258                  CCoinsView* tip = base;
 259                  if (stack.size() > 0) {
 260                      tip = stack.back().get();
 261                  } else {
 262                      removed_all_caches = true;
 263                  }
 264                  stack.push_back(std::make_unique<CCoinsViewCacheTest>(tip));
 265                  if (stack.size() == 4) {
 266                      reached_4_caches = true;
 267                  }
 268              }
 269          }
 270      }
 271  
 272      // Verify coverage.
 273      BOOST_CHECK(removed_all_caches);
 274      BOOST_CHECK(reached_4_caches);
 275      BOOST_CHECK(added_an_entry);
 276      BOOST_CHECK(added_an_unspendable_entry);
 277      BOOST_CHECK(removed_an_entry);
 278      BOOST_CHECK(updated_an_entry);
 279      BOOST_CHECK(found_an_entry);
 280      BOOST_CHECK(missed_an_entry);
 281      BOOST_CHECK(uncached_an_entry);
 282      BOOST_CHECK(flushed_without_erase);
 283  }
 284  }; // struct CacheTest
 285  
 286  BOOST_FIXTURE_TEST_SUITE(coins_tests_base, BasicTestingSetup)
 287  
 288  // Run the above simulation for multiple base types.
 289  BOOST_FIXTURE_TEST_CASE(coins_cache_base_simulation_test, CacheTest)
 290  {
 291      CCoinsViewTest base{m_rng};
 292      SimulationTest(&base, false);
 293  }
 294  
 295  BOOST_AUTO_TEST_SUITE_END()
 296  
 297  BOOST_FIXTURE_TEST_SUITE(coins_tests_dbbase, BasicTestingSetup)
 298  
 299  BOOST_FIXTURE_TEST_CASE(coins_cache_dbbase_simulation_test, CacheTest)
 300  {
 301      CCoinsViewDB db_base{{.path = "test", .cache_bytes = 8_MiB, .memory_only = true}, {}};
 302      SimulationTest(&db_base, true);
 303  }
 304  
 305  BOOST_AUTO_TEST_SUITE_END()
 306  
 307  BOOST_FIXTURE_TEST_SUITE(coins_tests, BasicTestingSetup)
 308  
 309  struct UpdateTest : BasicTestingSetup {
 310  // Store of all necessary tx and undo data for next test
 311  typedef std::map<COutPoint, std::tuple<CTransaction,CTxUndo,Coin>> UtxoData;
 312  UtxoData utxoData;
 313  
 314  UtxoData::iterator FindRandomFrom(const std::set<COutPoint> &utxoSet) {
 315      assert(utxoSet.size());
 316      auto utxoSetIt = utxoSet.lower_bound(COutPoint(Txid::FromUint256(m_rng.rand256()), 0));
 317      if (utxoSetIt == utxoSet.end()) {
 318          utxoSetIt = utxoSet.begin();
 319      }
 320      auto utxoDataIt = utxoData.find(*utxoSetIt);
 321      assert(utxoDataIt != utxoData.end());
 322      return utxoDataIt;
 323  }
 324  }; // struct UpdateTest
 325  
 326  
 327  // This test is similar to the previous test
 328  // except the emphasis is on testing the functionality of UpdateCoins
 329  // random txs are created and UpdateCoins is used to update the cache stack
 330  // In particular it is tested that spending a duplicate coinbase tx
 331  // has the expected effect (the other duplicate is overwritten at all cache levels)
 332  BOOST_FIXTURE_TEST_CASE(updatecoins_simulation_test, UpdateTest)
 333  {
 334      SeedRandomForTest(SeedRand::ZEROS);
 335  
 336      bool spent_a_duplicate_coinbase = false;
 337      // A simple map to track what we expect the cache stack to represent.
 338      std::map<COutPoint, Coin> result;
 339  
 340      // The cache stack.
 341      CCoinsViewTest base{m_rng}; // A CCoinsViewTest at the bottom.
 342      std::vector<std::unique_ptr<CCoinsViewCacheTest>> stack; // A stack of CCoinsViewCaches on top.
 343      stack.push_back(std::make_unique<CCoinsViewCacheTest>(&base)); // Start with one cache.
 344  
 345      // Track the txids we've used in various sets
 346      std::set<COutPoint> coinbase_coins;
 347      std::set<COutPoint> disconnected_coins;
 348      std::set<COutPoint> duplicate_coins;
 349      std::set<COutPoint> utxoset;
 350  
 351      for (unsigned int i = 0; i < NUM_SIMULATION_ITERATIONS; i++) {
 352          uint32_t randiter = m_rng.rand32();
 353  
 354          // 19/20 txs add a new transaction
 355          if (randiter % 20 < 19) {
 356              CMutableTransaction tx;
 357              tx.vin.resize(1);
 358              tx.vout.resize(1);
 359              tx.vout[0].nValue = i; //Keep txs unique unless intended to duplicate
 360              tx.vout[0].scriptPubKey.assign(m_rng.rand32() & 0x3F, 0); // Random sizes so we can test memory usage accounting
 361              const int height{int(m_rng.rand32() >> 1)};
 362              Coin old_coin;
 363  
 364              // 2/20 times create a new coinbase
 365              if (randiter % 20 < 2 || coinbase_coins.size() < 10) {
 366                  // 1/10 of those times create a duplicate coinbase
 367                  if (m_rng.randrange(10) == 0 && coinbase_coins.size()) {
 368                      auto utxod = FindRandomFrom(coinbase_coins);
 369                      // Reuse the exact same coinbase
 370                      tx = CMutableTransaction{std::get<0>(utxod->second)};
 371                      // shouldn't be available for reconnection if it's been duplicated
 372                      disconnected_coins.erase(utxod->first);
 373  
 374                      duplicate_coins.insert(utxod->first);
 375                  }
 376                  else {
 377                      coinbase_coins.insert(COutPoint(tx.GetHash(), 0));
 378                  }
 379                  assert(CTransaction(tx).IsCoinBase());
 380              }
 381  
 382              // 17/20 times reconnect previous or add a regular tx
 383              else {
 384  
 385                  COutPoint prevout;
 386                  // 1/20 times reconnect a previously disconnected tx
 387                  if (randiter % 20 == 2 && disconnected_coins.size()) {
 388                      auto utxod = FindRandomFrom(disconnected_coins);
 389                      tx = CMutableTransaction{std::get<0>(utxod->second)};
 390                      prevout = tx.vin[0].prevout;
 391                      if (!CTransaction(tx).IsCoinBase() && !utxoset.contains(prevout)) {
 392                          disconnected_coins.erase(utxod->first);
 393                          continue;
 394                      }
 395  
 396                      // If this tx is already IN the UTXO, then it must be a coinbase, and it must be a duplicate
 397                      if (utxoset.contains(utxod->first)) {
 398                          assert(CTransaction(tx).IsCoinBase());
 399                          assert(duplicate_coins.contains(utxod->first));
 400                      }
 401                      disconnected_coins.erase(utxod->first);
 402                  }
 403  
 404                  // 16/20 times create a regular tx
 405                  else {
 406                      auto utxod = FindRandomFrom(utxoset);
 407                      prevout = utxod->first;
 408  
 409                      // Construct the tx to spend the coins of prevouthash
 410                      tx.vin[0].prevout = prevout;
 411                      assert(!CTransaction(tx).IsCoinBase());
 412                  }
 413                  // In this simple test coins only have two states, spent or unspent, save the unspent state to restore
 414                  old_coin = result[prevout];
 415                  // Update the expected result of prevouthash to know these coins are spent
 416                  result[prevout].Clear();
 417  
 418                  utxoset.erase(prevout);
 419  
 420                  // The test is designed to ensure spending a duplicate coinbase will work properly
 421                  // if that ever happens and not resurrect the previously overwritten coinbase
 422                  if (duplicate_coins.contains(prevout)) {
 423                      spent_a_duplicate_coinbase = true;
 424                  }
 425  
 426              }
 427              // Update the expected result to know about the new output coins
 428              assert(tx.vout.size() == 1);
 429              const COutPoint outpoint(tx.GetHash(), 0);
 430              result[outpoint] = Coin{tx.vout[0], height, CTransaction{tx}.IsCoinBase()};
 431  
 432              // Call UpdateCoins on the top cache
 433              CTxUndo undo;
 434              UpdateCoins(CTransaction{tx}, *(stack.back()), undo, height);
 435  
 436              // Update the utxo set for future spends
 437              utxoset.insert(outpoint);
 438  
 439              // Track this tx and undo info to use later
 440              utxoData.emplace(outpoint, std::make_tuple(tx,undo,old_coin));
 441          } else if (utxoset.size()) {
 442              //1/20 times undo a previous transaction
 443              auto utxod = FindRandomFrom(utxoset);
 444  
 445              CTransaction &tx = std::get<0>(utxod->second);
 446              CTxUndo &undo = std::get<1>(utxod->second);
 447              Coin &orig_coin = std::get<2>(utxod->second);
 448  
 449              // Update the expected result
 450              // Remove new outputs
 451              result[utxod->first].Clear();
 452              // If not coinbase restore prevout
 453              if (!tx.IsCoinBase()) {
 454                  result[tx.vin[0].prevout] = orig_coin;
 455              }
 456  
 457              // Disconnect the tx from the current UTXO
 458              // See code in DisconnectBlock
 459              // remove outputs
 460              BOOST_CHECK(stack.back()->SpendCoin(utxod->first));
 461              // restore inputs
 462              if (!tx.IsCoinBase()) {
 463                  const COutPoint &out = tx.vin[0].prevout;
 464                  Coin coin = undo.vprevout[0];
 465                  ApplyTxInUndo(std::move(coin), *(stack.back()), out);
 466              }
 467              // Store as a candidate for reconnection
 468              disconnected_coins.insert(utxod->first);
 469  
 470              // Update the utxoset
 471              utxoset.erase(utxod->first);
 472              if (!tx.IsCoinBase())
 473                  utxoset.insert(tx.vin[0].prevout);
 474          }
 475  
 476          // Once every 1000 iterations and at the end, verify the full cache.
 477          if (m_rng.randrange(1000) == 1 || i == NUM_SIMULATION_ITERATIONS - 1) {
 478              for (const auto& entry : result) {
 479                  bool have = stack.back()->HaveCoin(entry.first);
 480                  const Coin& coin = stack.back()->AccessCoin(entry.first);
 481                  BOOST_CHECK(have == !coin.IsSpent());
 482                  BOOST_CHECK(coin == entry.second);
 483              }
 484          }
 485  
 486          // One every 10 iterations, remove a random entry from the cache
 487          if (utxoset.size() > 1 && m_rng.randrange(30) == 0) {
 488              stack[m_rng.rand32() % stack.size()]->Uncache(FindRandomFrom(utxoset)->first);
 489          }
 490          if (disconnected_coins.size() > 1 && m_rng.randrange(30) == 0) {
 491              stack[m_rng.rand32() % stack.size()]->Uncache(FindRandomFrom(disconnected_coins)->first);
 492          }
 493          if (duplicate_coins.size() > 1 && m_rng.randrange(30) == 0) {
 494              stack[m_rng.rand32() % stack.size()]->Uncache(FindRandomFrom(duplicate_coins)->first);
 495          }
 496  
 497          if (m_rng.randrange(100) == 0) {
 498              // Every 100 iterations, flush an intermediate cache
 499              if (stack.size() > 1 && m_rng.randbool() == 0) {
 500                  unsigned int flushIndex = m_rng.randrange(stack.size() - 1);
 501                  stack[flushIndex]->Flush();
 502              }
 503          }
 504          if (m_rng.randrange(100) == 0) {
 505              // Every 100 iterations, change the cache stack.
 506              if (stack.size() > 0 && m_rng.randbool() == 0) {
 507                  stack.back()->Flush();
 508                  stack.pop_back();
 509              }
 510              if (stack.size() == 0 || (stack.size() < 4 && m_rng.randbool())) {
 511                  CCoinsView* tip = &base;
 512                  if (stack.size() > 0) {
 513                      tip = stack.back().get();
 514                  }
 515                  stack.push_back(std::make_unique<CCoinsViewCacheTest>(tip));
 516              }
 517          }
 518      }
 519  
 520      // Verify coverage.
 521      BOOST_CHECK(spent_a_duplicate_coinbase);
 522  }
 523  
 524  BOOST_AUTO_TEST_CASE(ccoins_serialization)
 525  {
 526      // Good example
 527      Coin cc1;
 528      SpanReader{"97f23c835800816115944e077fe7c803cfa57f29b36bf87c1d35"_hex} >> cc1;
 529      BOOST_CHECK_EQUAL(cc1.IsCoinBase(), false);
 530      BOOST_CHECK_EQUAL(cc1.nHeight, 203998U);
 531      BOOST_CHECK_EQUAL(cc1.out.nValue, CAmount{60000000000});
 532      BOOST_CHECK_EQUAL(HexStr(cc1.out.scriptPubKey), HexStr(GetScriptForDestination(PKHash(uint160("816115944e077fe7c803cfa57f29b36bf87c1d35"_hex_u8)))));
 533  
 534      // Good example
 535      Coin cc2;
 536      SpanReader{"8ddf77bbd123008c988f1a4a4de2161e0f50aac7f17e7f9555caa4"_hex} >> cc2;
 537      BOOST_CHECK_EQUAL(cc2.IsCoinBase(), true);
 538      BOOST_CHECK_EQUAL(cc2.nHeight, 120891U);
 539      BOOST_CHECK_EQUAL(cc2.out.nValue, 110397);
 540      BOOST_CHECK_EQUAL(HexStr(cc2.out.scriptPubKey), HexStr(GetScriptForDestination(PKHash(uint160("8c988f1a4a4de2161e0f50aac7f17e7f9555caa4"_hex_u8)))));
 541  
 542      // Smallest possible example
 543      Coin cc3;
 544      SpanReader{"000006"_hex} >> cc3;
 545      BOOST_CHECK_EQUAL(cc3.IsCoinBase(), false);
 546      BOOST_CHECK_EQUAL(cc3.nHeight, 0U);
 547      BOOST_CHECK_EQUAL(cc3.out.nValue, 0);
 548      BOOST_CHECK_EQUAL(cc3.out.scriptPubKey.size(), 0U);
 549  
 550      // scriptPubKey that ends beyond the end of the stream
 551      try {
 552          Coin cc4;
 553          SpanReader{"000007"_hex} >> cc4;
 554          BOOST_CHECK_MESSAGE(false, "We should have thrown");
 555      } catch (const std::ios_base::failure&) {
 556      }
 557  
 558      // Very large scriptPubKey (3*10^9 bytes) past the end of the stream
 559      DataStream tmp{};
 560      uint64_t x = 3000000000ULL;
 561      tmp << VARINT(x);
 562      BOOST_CHECK_EQUAL(HexStr(tmp), "8a95c0bb00");
 563      try {
 564          Coin cc5;
 565          SpanReader{"00008a95c0bb00"_hex} >> cc5;
 566          BOOST_CHECK_MESSAGE(false, "We should have thrown");
 567      } catch (const std::ios_base::failure&) {
 568      }
 569  }
 570  
 571  const static COutPoint OUTPOINT;
 572  constexpr CAmount SPENT {-1};
 573  constexpr CAmount ABSENT{-2};
 574  constexpr CAmount VALUE1{100};
 575  constexpr CAmount VALUE2{200};
 576  constexpr CAmount VALUE3{300};
 577  
 578  struct CoinEntry {
 579      enum class State { CLEAN, DIRTY, FRESH, DIRTY_FRESH };
 580  
 581      const CAmount value;
 582      const State state;
 583  
 584      constexpr CoinEntry(const CAmount v, const State s) : value{v}, state{s} {}
 585  
 586      bool operator==(const CoinEntry& o) const = default;
 587      friend std::ostream& operator<<(std::ostream& os, const CoinEntry& e) { return os << e.value << ", " << e.state; }
 588  
 589      constexpr bool IsDirtyFresh() const { return state == State::DIRTY_FRESH; }
 590      constexpr bool IsDirty() const { return state == State::DIRTY || IsDirtyFresh(); }
 591      constexpr bool IsFresh() const { return state == State::FRESH || IsDirtyFresh(); }
 592  
 593      static constexpr State ToState(const bool is_dirty, const bool is_fresh) {
 594          if (is_dirty && is_fresh) return State::DIRTY_FRESH;
 595          if (is_dirty) return State::DIRTY;
 596          if (is_fresh) return State::FRESH;
 597          return State::CLEAN;
 598      }
 599  };
 600  
 601  using MaybeCoin   = std::optional<CoinEntry>;
 602  using CoinOrError = std::variant<MaybeCoin, std::string>;
 603  
 604  constexpr MaybeCoin MISSING           {std::nullopt};
 605  constexpr MaybeCoin SPENT_DIRTY       {{SPENT,  CoinEntry::State::DIRTY}};
 606  constexpr MaybeCoin SPENT_DIRTY_FRESH {{SPENT,  CoinEntry::State::DIRTY_FRESH}};
 607  constexpr MaybeCoin SPENT_FRESH       {{SPENT,  CoinEntry::State::FRESH}};
 608  constexpr MaybeCoin SPENT_CLEAN       {{SPENT,  CoinEntry::State::CLEAN}};
 609  constexpr MaybeCoin VALUE1_DIRTY      {{VALUE1, CoinEntry::State::DIRTY}};
 610  constexpr MaybeCoin VALUE1_DIRTY_FRESH{{VALUE1, CoinEntry::State::DIRTY_FRESH}};
 611  constexpr MaybeCoin VALUE1_FRESH      {{VALUE1, CoinEntry::State::FRESH}};
 612  constexpr MaybeCoin VALUE1_CLEAN      {{VALUE1, CoinEntry::State::CLEAN}};
 613  constexpr MaybeCoin VALUE2_DIRTY      {{VALUE2, CoinEntry::State::DIRTY}};
 614  constexpr MaybeCoin VALUE2_DIRTY_FRESH{{VALUE2, CoinEntry::State::DIRTY_FRESH}};
 615  constexpr MaybeCoin VALUE2_FRESH      {{VALUE2, CoinEntry::State::FRESH}};
 616  constexpr MaybeCoin VALUE2_CLEAN      {{VALUE2, CoinEntry::State::CLEAN}};
 617  constexpr MaybeCoin VALUE3_DIRTY      {{VALUE3, CoinEntry::State::DIRTY}};
 618  constexpr MaybeCoin VALUE3_DIRTY_FRESH{{VALUE3, CoinEntry::State::DIRTY_FRESH}};
 619  
 620  constexpr auto EX_OVERWRITE_UNSPENT{"Attempted to overwrite an unspent coin (when possible_overwrite is false)"};
 621  constexpr auto EX_FRESH_MISAPPLIED {"FRESH flag misapplied to coin that exists in parent cache"};
 622  
 623  static void SetCoinsValue(const CAmount value, Coin& coin)
 624  {
 625      assert(value != ABSENT);
 626      coin.Clear();
 627      assert(coin.IsSpent());
 628      if (value != SPENT) {
 629          coin.out.nValue = value;
 630          coin.nHeight = 1;
 631          assert(!coin.IsSpent());
 632      }
 633  }
 634  
 635  static size_t InsertCoinsMapEntry(CCoinsMap& map, CoinsCachePair& sentinel, const CoinEntry& cache_coin)
 636  {
 637      CCoinsCacheEntry entry;
 638      SetCoinsValue(cache_coin.value, entry.coin);
 639      auto [iter, inserted] = map.emplace(OUTPOINT, std::move(entry));
 640      assert(inserted);
 641      if (cache_coin.IsDirty()) CCoinsCacheEntry::SetDirty(*iter, sentinel);
 642      if (cache_coin.IsFresh()) CCoinsCacheEntry::SetFresh(*iter, sentinel);
 643      return iter->second.coin.DynamicMemoryUsage();
 644  }
 645  
 646  static MaybeCoin GetCoinsMapEntry(const CCoinsMap& map, const COutPoint& outp = OUTPOINT)
 647  {
 648      if (auto it{map.find(outp)}; it != map.end()) {
 649          return CoinEntry{
 650              it->second.coin.IsSpent() ? SPENT : it->second.coin.out.nValue,
 651              CoinEntry::ToState(it->second.IsDirty(), it->second.IsFresh())};
 652      }
 653      return MISSING;
 654  }
 655  
 656  static void WriteCoinsViewEntry(CCoinsView& view, const MaybeCoin& cache_coin)
 657  {
 658      CoinsCachePair sentinel{};
 659      sentinel.second.SelfRef(sentinel);
 660      CCoinsMapMemoryResource resource;
 661      CCoinsMap map{0, CCoinsMap::hasher{}, CCoinsMap::key_equal{}, &resource};
 662      if (cache_coin) InsertCoinsMapEntry(map, sentinel, *cache_coin);
 663      size_t dirty_count{cache_coin && cache_coin->IsDirty()};
 664      auto cursor{CoinsViewCacheCursor(dirty_count, sentinel, map, /*will_erase=*/true)};
 665      view.BatchWrite(cursor, {});
 666      BOOST_CHECK_EQUAL(dirty_count, 0U);
 667  }
 668  
 669  class SingleEntryCacheTest
 670  {
 671  public:
 672      SingleEntryCacheTest(const CAmount base_value, const MaybeCoin& cache_coin)
 673      {
 674          auto base_cache_coin{base_value == ABSENT ? MISSING : CoinEntry{base_value, CoinEntry::State::DIRTY}};
 675          WriteCoinsViewEntry(base, base_cache_coin);
 676          if (cache_coin) {
 677              cache.usage() += InsertCoinsMapEntry(cache.map(), cache.sentinel(), *cache_coin);
 678              cache.dirty() += cache_coin->IsDirty();
 679          }
 680      }
 681  
 682      CCoinsViewCacheTest base{&CoinsViewEmpty::Get()};
 683      CCoinsViewCacheTest cache{&base};
 684  };
 685  
 686  static void CheckAccessCoin(const CAmount base_value, const MaybeCoin& cache_coin, const MaybeCoin& expected)
 687  {
 688      SingleEntryCacheTest test{base_value, cache_coin};
 689      auto& coin = test.cache.AccessCoin(OUTPOINT);
 690      BOOST_CHECK_EQUAL(coin.IsSpent(), !test.cache.GetCoin(OUTPOINT));
 691      test.cache.SelfTest(/*sanity_check=*/false);
 692      BOOST_CHECK_EQUAL(GetCoinsMapEntry(test.cache.map()), expected);
 693  }
 694  
 695  BOOST_AUTO_TEST_CASE(ccoins_access)
 696  {
 697      /* Check AccessCoin behavior, requesting a coin from a cache view layered on
 698       * top of a base view, and checking the resulting entry in the cache after
 699       * the access.
 700       *                  Base        Cache               Expected
 701       */
 702      for (auto base_value : {ABSENT, SPENT, VALUE1}) {
 703          CheckAccessCoin(base_value, MISSING,            base_value == VALUE1 ? VALUE1_CLEAN : MISSING);
 704  
 705          CheckAccessCoin(base_value, SPENT_CLEAN,        SPENT_CLEAN       );
 706          CheckAccessCoin(base_value, SPENT_FRESH,        SPENT_FRESH       );
 707          CheckAccessCoin(base_value, SPENT_DIRTY,        SPENT_DIRTY       );
 708          CheckAccessCoin(base_value, SPENT_DIRTY_FRESH,  SPENT_DIRTY_FRESH );
 709  
 710          CheckAccessCoin(base_value, VALUE2_CLEAN,       VALUE2_CLEAN      );
 711          CheckAccessCoin(base_value, VALUE2_FRESH,       VALUE2_FRESH      );
 712          CheckAccessCoin(base_value, VALUE2_DIRTY,       VALUE2_DIRTY      );
 713          CheckAccessCoin(base_value, VALUE2_DIRTY_FRESH, VALUE2_DIRTY_FRESH);
 714      }
 715  }
 716  
 717  static void CheckSpendCoins(const CAmount base_value, const MaybeCoin& cache_coin, const MaybeCoin& expected)
 718  {
 719      SingleEntryCacheTest test{base_value, cache_coin};
 720      test.cache.SpendCoin(OUTPOINT);
 721      test.cache.SelfTest();
 722      BOOST_CHECK_EQUAL(GetCoinsMapEntry(test.cache.map()), expected);
 723  }
 724  
 725  BOOST_AUTO_TEST_CASE(ccoins_spend)
 726  {
 727      /* Check SpendCoin behavior, requesting a coin from a cache view layered on
 728       * top of a base view, spending, and then checking
 729       * the resulting entry in the cache after the modification.
 730       *                  Base        Cache               Expected
 731       */
 732      for (auto base_value : {ABSENT, SPENT, VALUE1}) {
 733          CheckSpendCoins(base_value, MISSING,            base_value == VALUE1 ? SPENT_DIRTY : MISSING);
 734  
 735          CheckSpendCoins(base_value, SPENT_CLEAN,        SPENT_DIRTY);
 736          CheckSpendCoins(base_value, SPENT_FRESH,        MISSING    );
 737          CheckSpendCoins(base_value, SPENT_DIRTY,        SPENT_DIRTY);
 738          CheckSpendCoins(base_value, SPENT_DIRTY_FRESH,  MISSING    );
 739  
 740          CheckSpendCoins(base_value, VALUE2_CLEAN,       SPENT_DIRTY);
 741          CheckSpendCoins(base_value, VALUE2_FRESH,       MISSING    );
 742          CheckSpendCoins(base_value, VALUE2_DIRTY,       SPENT_DIRTY);
 743          CheckSpendCoins(base_value, VALUE2_DIRTY_FRESH, MISSING    );
 744      }
 745  }
 746  
 747  static void CheckAddCoin(const CAmount base_value, const MaybeCoin& cache_coin, const CAmount modify_value, const CoinOrError& expected, const bool coinbase)
 748  {
 749      SingleEntryCacheTest test{base_value, cache_coin};
 750      bool possible_overwrite{coinbase};
 751      auto add_coin{[&] { test.cache.AddCoin(OUTPOINT, Coin{CTxOut{modify_value, CScript{}}, 1, coinbase}, possible_overwrite); }};
 752      if (auto* expected_coin{std::get_if<MaybeCoin>(&expected)}) {
 753          add_coin();
 754          test.cache.SelfTest();
 755          BOOST_CHECK_EQUAL(GetCoinsMapEntry(test.cache.map()), *expected_coin);
 756      } else {
 757          BOOST_CHECK_EXCEPTION(add_coin(), std::logic_error, HasReason(std::get<std::string>(expected)));
 758      }
 759  }
 760  
 761  BOOST_AUTO_TEST_CASE(ccoins_add)
 762  {
 763      /* Check AddCoin behavior, requesting a new coin from a cache view,
 764       * writing a modification to the coin, and then checking the resulting
 765       * entry in the cache after the modification. Verify behavior with the
 766       * AddCoin coinbase argument set to false, and to true.
 767       *               Base        Cache               Write   Expected              Coinbase
 768       */
 769      for (auto base_value : {ABSENT, SPENT, VALUE1}) {
 770          CheckAddCoin(base_value, MISSING,            VALUE3, VALUE3_DIRTY_FRESH,   false);
 771          CheckAddCoin(base_value, MISSING,            VALUE3, VALUE3_DIRTY,         true );
 772  
 773          CheckAddCoin(base_value, SPENT_CLEAN,        VALUE3, VALUE3_DIRTY_FRESH,   false);
 774          CheckAddCoin(base_value, SPENT_CLEAN,        VALUE3, VALUE3_DIRTY,         true );
 775          CheckAddCoin(base_value, SPENT_FRESH,        VALUE3, VALUE3_DIRTY_FRESH,   false);
 776          CheckAddCoin(base_value, SPENT_FRESH,        VALUE3, VALUE3_DIRTY_FRESH,   true );
 777          CheckAddCoin(base_value, SPENT_DIRTY,        VALUE3, VALUE3_DIRTY,         false);
 778          CheckAddCoin(base_value, SPENT_DIRTY,        VALUE3, VALUE3_DIRTY,         true );
 779          CheckAddCoin(base_value, SPENT_DIRTY_FRESH,  VALUE3, VALUE3_DIRTY_FRESH,   false);
 780          CheckAddCoin(base_value, SPENT_DIRTY_FRESH,  VALUE3, VALUE3_DIRTY_FRESH,   true );
 781  
 782          CheckAddCoin(base_value, VALUE2_CLEAN,       VALUE3, EX_OVERWRITE_UNSPENT, false);
 783          CheckAddCoin(base_value, VALUE2_CLEAN,       VALUE3, VALUE3_DIRTY,         true );
 784          CheckAddCoin(base_value, VALUE2_FRESH,       VALUE3, EX_OVERWRITE_UNSPENT, false);
 785          CheckAddCoin(base_value, VALUE2_FRESH,       VALUE3, VALUE3_DIRTY_FRESH,   true );
 786          CheckAddCoin(base_value, VALUE2_DIRTY,       VALUE3, EX_OVERWRITE_UNSPENT, false);
 787          CheckAddCoin(base_value, VALUE2_DIRTY,       VALUE3, VALUE3_DIRTY,         true );
 788          CheckAddCoin(base_value, VALUE2_DIRTY_FRESH, VALUE3, EX_OVERWRITE_UNSPENT, false);
 789          CheckAddCoin(base_value, VALUE2_DIRTY_FRESH, VALUE3, VALUE3_DIRTY_FRESH,   true );
 790      }
 791  }
 792  
 793  static void CheckWriteCoins(const MaybeCoin& parent, const MaybeCoin& child, const CoinOrError& expected)
 794  {
 795      SingleEntryCacheTest test{ABSENT, parent};
 796      auto write_coins{[&] { WriteCoinsViewEntry(test.cache, child); }};
 797      if (auto* expected_coin{std::get_if<MaybeCoin>(&expected)}) {
 798          write_coins();
 799          test.cache.SelfTest(/*sanity_check=*/false);
 800          BOOST_CHECK_EQUAL(GetCoinsMapEntry(test.cache.map()), *expected_coin);
 801      } else {
 802          BOOST_CHECK_EXCEPTION(write_coins(), std::logic_error, HasReason(std::get<std::string>(expected)));
 803      }
 804  }
 805  
 806  BOOST_AUTO_TEST_CASE(ccoins_write)
 807  {
 808      /* Check BatchWrite behavior, flushing one entry from a child cache to a
 809       * parent cache, and checking the resulting entry in the parent cache
 810       * after the write.
 811       *              Parent              Child               Expected
 812       */
 813      CheckWriteCoins(MISSING,            MISSING,            MISSING            );
 814      CheckWriteCoins(MISSING,            SPENT_DIRTY,        SPENT_DIRTY        );
 815      CheckWriteCoins(MISSING,            SPENT_DIRTY_FRESH,  MISSING            );
 816      CheckWriteCoins(MISSING,            VALUE2_DIRTY,       VALUE2_DIRTY       );
 817      CheckWriteCoins(MISSING,            VALUE2_DIRTY_FRESH, VALUE2_DIRTY_FRESH );
 818      CheckWriteCoins(SPENT_CLEAN,        MISSING,            SPENT_CLEAN        );
 819      CheckWriteCoins(SPENT_FRESH,        MISSING,            SPENT_FRESH        );
 820      CheckWriteCoins(SPENT_DIRTY,        MISSING,            SPENT_DIRTY        );
 821      CheckWriteCoins(SPENT_DIRTY_FRESH,  MISSING,            SPENT_DIRTY_FRESH  );
 822  
 823      CheckWriteCoins(SPENT_CLEAN,        SPENT_DIRTY,        SPENT_DIRTY        );
 824      CheckWriteCoins(SPENT_CLEAN,        SPENT_DIRTY_FRESH,  SPENT_DIRTY        );
 825      CheckWriteCoins(SPENT_FRESH,        SPENT_DIRTY,        MISSING            );
 826      CheckWriteCoins(SPENT_FRESH,        SPENT_DIRTY_FRESH,  MISSING            );
 827      CheckWriteCoins(SPENT_DIRTY,        SPENT_DIRTY,        SPENT_DIRTY        );
 828      CheckWriteCoins(SPENT_DIRTY,        SPENT_DIRTY_FRESH,  SPENT_DIRTY        );
 829      CheckWriteCoins(SPENT_DIRTY_FRESH,  SPENT_DIRTY,        MISSING            );
 830      CheckWriteCoins(SPENT_DIRTY_FRESH,  SPENT_DIRTY_FRESH,  MISSING            );
 831  
 832      CheckWriteCoins(SPENT_CLEAN,        VALUE2_DIRTY,       VALUE2_DIRTY       );
 833      CheckWriteCoins(SPENT_CLEAN,        VALUE2_DIRTY_FRESH, VALUE2_DIRTY       );
 834      CheckWriteCoins(SPENT_FRESH,        VALUE2_DIRTY,       VALUE2_DIRTY_FRESH );
 835      CheckWriteCoins(SPENT_FRESH,        VALUE2_DIRTY_FRESH, VALUE2_DIRTY_FRESH );
 836      CheckWriteCoins(SPENT_DIRTY,        VALUE2_DIRTY,       VALUE2_DIRTY       );
 837      CheckWriteCoins(SPENT_DIRTY,        VALUE2_DIRTY_FRESH, VALUE2_DIRTY       );
 838      CheckWriteCoins(SPENT_DIRTY_FRESH,  VALUE2_DIRTY,       VALUE2_DIRTY_FRESH );
 839      CheckWriteCoins(SPENT_DIRTY_FRESH,  VALUE2_DIRTY_FRESH, VALUE2_DIRTY_FRESH );
 840  
 841      CheckWriteCoins(VALUE1_CLEAN,       MISSING,            VALUE1_CLEAN       );
 842      CheckWriteCoins(VALUE1_FRESH,       MISSING,            VALUE1_FRESH       );
 843      CheckWriteCoins(VALUE1_DIRTY,       MISSING,            VALUE1_DIRTY       );
 844      CheckWriteCoins(VALUE1_DIRTY_FRESH, MISSING,            VALUE1_DIRTY_FRESH );
 845      CheckWriteCoins(VALUE1_CLEAN,       SPENT_DIRTY,        SPENT_DIRTY        );
 846      CheckWriteCoins(VALUE1_CLEAN,       SPENT_DIRTY_FRESH,  EX_FRESH_MISAPPLIED);
 847      CheckWriteCoins(VALUE1_FRESH,       SPENT_DIRTY,        MISSING            );
 848      CheckWriteCoins(VALUE1_FRESH,       SPENT_DIRTY_FRESH,  EX_FRESH_MISAPPLIED);
 849      CheckWriteCoins(VALUE1_DIRTY,       SPENT_DIRTY,        SPENT_DIRTY        );
 850      CheckWriteCoins(VALUE1_DIRTY,       SPENT_DIRTY_FRESH,  EX_FRESH_MISAPPLIED);
 851      CheckWriteCoins(VALUE1_DIRTY_FRESH, SPENT_DIRTY,        MISSING            );
 852      CheckWriteCoins(VALUE1_DIRTY_FRESH, SPENT_DIRTY_FRESH,  EX_FRESH_MISAPPLIED);
 853  
 854      CheckWriteCoins(VALUE1_CLEAN,       VALUE2_DIRTY,       VALUE2_DIRTY       );
 855      CheckWriteCoins(VALUE1_CLEAN,       VALUE2_DIRTY_FRESH, EX_FRESH_MISAPPLIED);
 856      CheckWriteCoins(VALUE1_FRESH,       VALUE2_DIRTY,       VALUE2_DIRTY_FRESH );
 857      CheckWriteCoins(VALUE1_FRESH,       VALUE2_DIRTY_FRESH, EX_FRESH_MISAPPLIED);
 858      CheckWriteCoins(VALUE1_DIRTY,       VALUE2_DIRTY,       VALUE2_DIRTY       );
 859      CheckWriteCoins(VALUE1_DIRTY,       VALUE2_DIRTY_FRESH, EX_FRESH_MISAPPLIED);
 860      CheckWriteCoins(VALUE1_DIRTY_FRESH, VALUE2_DIRTY,       VALUE2_DIRTY_FRESH );
 861      CheckWriteCoins(VALUE1_DIRTY_FRESH, VALUE2_DIRTY_FRESH, EX_FRESH_MISAPPLIED);
 862  
 863      // The checks above omit cases where the child state is not DIRTY, since
 864      // they would be too repetitive (the parent cache is never updated in these
 865      // cases). The loop below covers these cases and makes sure the parent cache
 866      // is always left unchanged.
 867      for (const MaybeCoin& parent : {MISSING,
 868                                      SPENT_CLEAN, SPENT_DIRTY, SPENT_FRESH, SPENT_DIRTY_FRESH,
 869                                      VALUE1_CLEAN, VALUE1_DIRTY, VALUE1_FRESH, VALUE1_DIRTY_FRESH}) {
 870          for (const MaybeCoin& child : {MISSING,
 871                                         SPENT_CLEAN, SPENT_FRESH,
 872                                         VALUE2_CLEAN, VALUE2_FRESH}) {
 873              auto expected{CoinOrError{parent}}; // TODO test failure cases as well
 874              CheckWriteCoins(parent, child, expected);
 875          }
 876      }
 877  }
 878  
 879  struct FlushTest : BasicTestingSetup {
 880  Coin MakeCoin()
 881  {
 882      Coin coin;
 883      coin.out.nValue = m_rng.rand32();
 884      coin.nHeight = m_rng.randrange(4096);
 885      coin.fCoinBase = false;
 886      return coin;
 887  }
 888  
 889  
 890  //! For CCoinsViewCache instances backed by either another cache instance or
 891  //! leveldb, test cache behavior and flag state (DIRTY/FRESH) by
 892  //!
 893  //! 1. Adding a random coin to the child-most cache,
 894  //! 2. Flushing all caches (without erasing),
 895  //! 3. Ensure the entry still exists in the cache and has been written to parent,
 896  //! 4. (if `do_erasing_flush`) Flushing the caches again (with erasing),
 897  //! 5. (if `do_erasing_flush`) Ensure the entry has been written to the parent and is no longer in the cache,
 898  //! 6. Spend the coin, ensure it no longer exists in the parent.
 899  //!
 900  void TestFlushBehavior(
 901      CCoinsViewCacheTest* view,
 902      CCoinsViewDB& base,
 903      std::vector<std::unique_ptr<CCoinsViewCacheTest>>& all_caches,
 904      bool do_erasing_flush)
 905  {
 906      size_t cache_usage;
 907      size_t cache_size;
 908  
 909      auto flush_all = [this, &all_caches](bool erase) {
 910          // Flush in reverse order to ensure that flushes happen from children up.
 911          for (auto i = all_caches.rbegin(); i != all_caches.rend(); ++i) {
 912              auto& cache = *i;
 913              cache->SanityCheck();
 914              // block_hash must be filled before flushing to disk; value is
 915              // unimportant here. This is normally done during connect/disconnect block.
 916              cache->SetBestBlock(m_rng.rand256());
 917              erase ? cache->Flush() : cache->Sync();
 918          }
 919      };
 920  
 921      Txid txid = Txid::FromUint256(m_rng.rand256());
 922      COutPoint outp = COutPoint(txid, 0);
 923      Coin coin = MakeCoin();
 924      // Ensure the coins views haven't seen this coin before.
 925      BOOST_CHECK(!base.HaveCoin(outp));
 926      BOOST_CHECK(!view->HaveCoin(outp));
 927  
 928      // --- 1. Adding a random coin to the child cache
 929      //
 930      view->AddCoin(outp, Coin(coin), false);
 931  
 932      cache_usage = view->DynamicMemoryUsage();
 933      cache_size = view->map().size();
 934  
 935      // `base` shouldn't have coin (no flush yet) but `view` should have cached it.
 936      BOOST_CHECK(!base.HaveCoin(outp));
 937      BOOST_CHECK(view->HaveCoin(outp));
 938  
 939      BOOST_CHECK_EQUAL(GetCoinsMapEntry(view->map(), outp), CoinEntry(coin.out.nValue, CoinEntry::State::DIRTY_FRESH));
 940  
 941      // --- 2. Flushing all caches (without erasing)
 942      //
 943      flush_all(/*erase=*/ false);
 944  
 945      // CoinsMap usage should be unchanged since we didn't erase anything.
 946      BOOST_CHECK_EQUAL(cache_usage, view->DynamicMemoryUsage());
 947      BOOST_CHECK_EQUAL(cache_size, view->map().size());
 948  
 949      // --- 3. Ensuring the entry still exists in the cache and has been written to parent
 950      //
 951      BOOST_CHECK_EQUAL(GetCoinsMapEntry(view->map(), outp), CoinEntry(coin.out.nValue, CoinEntry::State::CLEAN)); // State should have been wiped.
 952  
 953      // Both views should now have the coin.
 954      BOOST_CHECK(base.HaveCoin(outp));
 955      BOOST_CHECK(view->HaveCoin(outp));
 956  
 957      if (do_erasing_flush) {
 958          // --- 4. Flushing the caches again (with erasing)
 959          //
 960          flush_all(/*erase=*/ true);
 961  
 962          // Memory does not necessarily go down due to the map using a memory pool
 963          BOOST_TEST(view->DynamicMemoryUsage() <= cache_usage);
 964          // Size of the cache must go down though
 965          BOOST_TEST(view->map().size() < cache_size);
 966  
 967          // --- 5. Ensuring the entry is no longer in the cache
 968          //
 969          BOOST_CHECK(!GetCoinsMapEntry(view->map(), outp));
 970          view->AccessCoin(outp);
 971          BOOST_CHECK_EQUAL(GetCoinsMapEntry(view->map(), outp), CoinEntry(coin.out.nValue, CoinEntry::State::CLEAN));
 972      }
 973  
 974      // Can't overwrite an entry without specifying that an overwrite is
 975      // expected.
 976      BOOST_CHECK_THROW(
 977          view->AddCoin(outp, Coin(coin), /*possible_overwrite=*/ false),
 978          std::logic_error);
 979  
 980      // --- 6. Spend the coin.
 981      //
 982      BOOST_CHECK(view->SpendCoin(outp));
 983  
 984      // The coin should be in the cache, but spent and marked dirty.
 985      BOOST_CHECK_EQUAL(GetCoinsMapEntry(view->map(), outp), SPENT_DIRTY);
 986      BOOST_CHECK(!view->HaveCoin(outp)); // Coin should be considered spent in `view`.
 987      BOOST_CHECK(base.HaveCoin(outp));  // But coin should still be unspent in `base`.
 988  
 989      flush_all(/*erase=*/ false);
 990  
 991      // Coin should be considered spent in both views.
 992      BOOST_CHECK(!view->HaveCoin(outp));
 993      BOOST_CHECK(!base.HaveCoin(outp));
 994  
 995      // Spent coin should not be spendable.
 996      BOOST_CHECK(!view->SpendCoin(outp));
 997  
 998      // --- Bonus check: ensure that a coin added to the base view via one cache
 999      //     can be spent by another cache which has never seen it.
1000      //
1001      txid = Txid::FromUint256(m_rng.rand256());
1002      outp = COutPoint(txid, 0);
1003      coin = MakeCoin();
1004      BOOST_CHECK(!base.HaveCoin(outp));
1005      BOOST_CHECK(!all_caches[0]->HaveCoin(outp));
1006      BOOST_CHECK(!all_caches[1]->HaveCoin(outp));
1007  
1008      all_caches[0]->AddCoin(outp, std::move(coin), false);
1009      all_caches[0]->Sync();
1010      BOOST_CHECK(base.HaveCoin(outp));
1011      BOOST_CHECK(all_caches[0]->HaveCoin(outp));
1012      BOOST_CHECK(!all_caches[1]->HaveCoinInCache(outp));
1013  
1014      BOOST_CHECK(all_caches[1]->SpendCoin(outp));
1015      flush_all(/*erase=*/ false);
1016      BOOST_CHECK(!base.HaveCoin(outp));
1017      BOOST_CHECK(!all_caches[0]->HaveCoin(outp));
1018      BOOST_CHECK(!all_caches[1]->HaveCoin(outp));
1019  
1020      flush_all(/*erase=*/ true); // Erase all cache content.
1021  
1022      // --- Bonus check 2: ensure that a FRESH, spent coin is deleted by Sync()
1023      //
1024      txid = Txid::FromUint256(m_rng.rand256());
1025      outp = COutPoint(txid, 0);
1026      coin = MakeCoin();
1027      CAmount coin_val = coin.out.nValue;
1028      BOOST_CHECK(!base.HaveCoin(outp));
1029      BOOST_CHECK(!all_caches[0]->HaveCoin(outp));
1030      BOOST_CHECK(!all_caches[1]->HaveCoin(outp));
1031  
1032      // Add and spend from same cache without flushing.
1033      all_caches[0]->AddCoin(outp, std::move(coin), false);
1034  
1035      // Coin should be FRESH in the cache.
1036      BOOST_CHECK_EQUAL(GetCoinsMapEntry(all_caches[0]->map(), outp), CoinEntry(coin_val, CoinEntry::State::DIRTY_FRESH));
1037      // Base shouldn't have seen coin.
1038      BOOST_CHECK(!base.HaveCoin(outp));
1039  
1040      BOOST_CHECK(all_caches[0]->SpendCoin(outp));
1041      all_caches[0]->Sync();
1042  
1043      // Ensure there is no sign of the coin after spend/flush.
1044      BOOST_CHECK(!GetCoinsMapEntry(all_caches[0]->map(), outp));
1045      BOOST_CHECK(!all_caches[0]->HaveCoinInCache(outp));
1046      BOOST_CHECK(!base.HaveCoin(outp));
1047  }
1048  }; // struct FlushTest
1049  
1050  BOOST_FIXTURE_TEST_CASE(ccoins_flush_behavior, FlushTest)
1051  {
1052      // Create two in-memory caches atop a leveldb view.
1053      CCoinsViewDB base{{.path = "test", .cache_bytes = 8_MiB, .memory_only = true}, {}};
1054      std::vector<std::unique_ptr<CCoinsViewCacheTest>> caches;
1055      caches.push_back(std::make_unique<CCoinsViewCacheTest>(&base));
1056      caches.push_back(std::make_unique<CCoinsViewCacheTest>(caches.back().get()));
1057  
1058      for (const auto& view : caches) {
1059          TestFlushBehavior(view.get(), base, caches, /*do_erasing_flush=*/false);
1060          TestFlushBehavior(view.get(), base, caches, /*do_erasing_flush=*/true);
1061      }
1062  }
1063  
1064  BOOST_FIXTURE_TEST_CASE(coins_db_leveldb_layout, FlushTest)
1065  {
1066      auto level2_files{[](CCoinsViewDB& base) {
1067          return *Assert(ToIntegral<int>(*Assert(base.GetDBProperty("leveldb.num-files-at-level2"))));
1068      }};
1069      const COutPoint outpoint{Txid::FromUint256(m_rng.rand256()), 0};
1070      const Coin coin{MakeCoin()};
1071      const uint256 block_hash{m_rng.rand256()};
1072  
1073      CCoinsViewDB base{{.path = m_args.GetDataDirBase() / "coins_db_leveldb_layout", .cache_bytes = 1_MiB, .wipe_data = true}, {}};
1074      CCoinsViewCache cache{&base};
1075  
1076      cache.EmplaceCoinInternalDANGER(COutPoint{outpoint}, Coin{coin});
1077      cache.SetBestBlock(block_hash);
1078      cache.Sync();
1079  
1080      BOOST_CHECK_EQUAL(level2_files(base), 0);
1081      WITH_LOCK(::cs_main, return base.CompactFullAsync()).wait();
1082      BOOST_CHECK_EQUAL(level2_files(base), 1);
1083  
1084      BOOST_CHECK(*Assert(base.GetCoin(outpoint)) == coin);
1085      BOOST_CHECK_EQUAL(base.GetBestBlock(), block_hash);
1086  }
1087  
1088  BOOST_AUTO_TEST_CASE(coins_resource_is_used)
1089  {
1090      CCoinsMapMemoryResource resource;
1091      PoolResourceTester::CheckAllDataAccountedFor(resource);
1092  
1093      {
1094          CCoinsMap map{0, CCoinsMap::hasher{}, CCoinsMap::key_equal{}, &resource};
1095          BOOST_TEST(memusage::DynamicUsage(map) >= resource.ChunkSizeBytes());
1096  
1097          map.reserve(1000);
1098  
1099          // The resource has preallocated a chunk, so we should have space for at several nodes without the need to allocate anything else.
1100          const auto usage_before = memusage::DynamicUsage(map);
1101  
1102          COutPoint out_point{};
1103          for (size_t i = 0; i < 1000; ++i) {
1104              out_point.n = i;
1105              map[out_point];
1106          }
1107          BOOST_TEST(usage_before == memusage::DynamicUsage(map));
1108      }
1109  
1110      PoolResourceTester::CheckAllDataAccountedFor(resource);
1111  }
1112  
1113  BOOST_AUTO_TEST_CASE(ccoins_addcoin_exception_keeps_usage_balanced)
1114  {
1115      CCoinsViewCacheTest cache{&CoinsViewEmpty::Get()};
1116  
1117      const COutPoint outpoint{Txid::FromUint256(m_rng.rand256()), m_rng.rand32()};
1118  
1119      const Coin coin1{CTxOut{m_rng.randrange(10), CScript{} << m_rng.randbytes(CScriptBase::STATIC_SIZE + 1)}, 1, false};
1120      cache.AddCoin(outpoint, Coin{coin1}, /*possible_overwrite=*/false);
1121      cache.SelfTest();
1122  
1123      const Coin coin2{CTxOut{m_rng.randrange(20), CScript{} << m_rng.randbytes(CScriptBase::STATIC_SIZE + 2)}, 2, false};
1124      BOOST_CHECK_THROW(cache.AddCoin(outpoint, Coin{coin2}, /*possible_overwrite=*/false), std::logic_error);
1125      cache.SelfTest();
1126  
1127      BOOST_CHECK(cache.AccessCoin(outpoint) == coin1);
1128  }
1129  
1130  BOOST_AUTO_TEST_CASE(ccoins_emplace_duplicate_keeps_usage_balanced)
1131  {
1132      CCoinsViewCacheTest cache{&CoinsViewEmpty::Get()};
1133  
1134      const COutPoint outpoint{Txid::FromUint256(m_rng.rand256()), m_rng.rand32()};
1135  
1136      const Coin coin1{CTxOut{m_rng.randrange(10), CScript{} << m_rng.randbytes(CScriptBase::STATIC_SIZE + 1)}, 1, false};
1137      cache.EmplaceCoinInternalDANGER(COutPoint{outpoint}, Coin{coin1});
1138      cache.SelfTest();
1139  
1140      const Coin coin2{CTxOut{m_rng.randrange(20), CScript{} << m_rng.randbytes(CScriptBase::STATIC_SIZE + 2)}, 2, false};
1141      cache.EmplaceCoinInternalDANGER(COutPoint{outpoint}, Coin{coin2});
1142      cache.SelfTest();
1143  
1144      BOOST_CHECK(cache.AccessCoin(outpoint) == coin1);
1145  }
1146  
1147  BOOST_AUTO_TEST_CASE(ccoins_reset_guard)
1148  {
1149      CCoinsViewTest root{m_rng};
1150      CCoinsViewCache root_cache{&root};
1151      uint256 base_best_block{m_rng.rand256()};
1152      root_cache.SetBestBlock(base_best_block);
1153      root_cache.Flush();
1154  
1155      CCoinsViewCache cache{&root};
1156  
1157      const COutPoint outpoint{Txid::FromUint256(m_rng.rand256()), m_rng.rand32()};
1158  
1159      const Coin coin{CTxOut{m_rng.randrange(10), CScript{} << m_rng.randbytes(CScriptBase::STATIC_SIZE + 1)}, 1, false};
1160      cache.EmplaceCoinInternalDANGER(COutPoint{outpoint}, Coin{coin});
1161      BOOST_CHECK_EQUAL(cache.GetDirtyCount(), 1U);
1162  
1163      uint256 cache_best_block{m_rng.rand256()};
1164      cache.SetBestBlock(cache_best_block);
1165  
1166      {
1167          const auto reset_guard{cache.CreateResetGuard()};
1168          BOOST_CHECK(cache.AccessCoin(outpoint) == coin);
1169          BOOST_CHECK(!cache.AccessCoin(outpoint).IsSpent());
1170          BOOST_CHECK_EQUAL(cache.GetCacheSize(), 1);
1171          BOOST_CHECK_EQUAL(cache.GetDirtyCount(), 1);
1172          BOOST_CHECK_EQUAL(cache.GetBestBlock(), cache_best_block);
1173          BOOST_CHECK(!root_cache.HaveCoinInCache(outpoint));
1174      }
1175  
1176      BOOST_CHECK(cache.AccessCoin(outpoint).IsSpent());
1177      BOOST_CHECK_EQUAL(cache.GetCacheSize(), 0);
1178      BOOST_CHECK_EQUAL(cache.GetDirtyCount(), 0);
1179      BOOST_CHECK_EQUAL(cache.GetBestBlock(), base_best_block);
1180      BOOST_CHECK(!root_cache.HaveCoinInCache(outpoint));
1181  
1182      // Using a reset guard again is idempotent
1183      {
1184          const auto reset_guard{cache.CreateResetGuard()};
1185      }
1186  
1187      BOOST_CHECK(cache.AccessCoin(outpoint).IsSpent());
1188      BOOST_CHECK_EQUAL(cache.GetCacheSize(), 0);
1189      BOOST_CHECK_EQUAL(cache.GetDirtyCount(), 0U);
1190      BOOST_CHECK_EQUAL(cache.GetBestBlock(), base_best_block);
1191      BOOST_CHECK(!root_cache.HaveCoinInCache(outpoint));
1192  
1193      // Flush should be a no-op after reset.
1194      cache.Flush();
1195      BOOST_CHECK_EQUAL(cache.GetDirtyCount(), 0U);
1196  }
1197  
1198  BOOST_AUTO_TEST_CASE(ccoins_peekcoin)
1199  {
1200      CCoinsViewTest base{m_rng};
1201  
1202      // Populate the base view with a coin.
1203      const COutPoint outpoint{Txid::FromUint256(m_rng.rand256()), m_rng.rand32()};
1204      const Coin coin{CTxOut{m_rng.randrange(10), CScript{}}, 1, false};
1205      {
1206          CCoinsViewCache cache{&base};
1207          cache.AddCoin(outpoint, Coin{coin}, /*possible_overwrite=*/false);
1208          cache.Flush();
1209      }
1210  
1211      // Verify PeekCoin can read through the cache stack without mutating the intermediate cache.
1212      CCoinsViewCacheTest main_cache{&base};
1213      const auto fetched{main_cache.PeekCoin(outpoint)};
1214      BOOST_CHECK(fetched.has_value());
1215      BOOST_CHECK(*fetched == coin);
1216      BOOST_CHECK(!main_cache.HaveCoinInCache(outpoint));
1217  }
1218  
1219  BOOST_AUTO_TEST_SUITE_END()
1220