miner: Make mempool optional for BlockAssembler

...also adjust callers

Changes:

- In BlockAssembler::CreateNewBlock, we now only lock m_mempool->cs and
  call addPackageTxs if m_mempool is not nullptr
- BlockAssembler::addPackageTxs now takes in a mempool reference, and is
  annotated to require that mempool's lock.
- In TestChain100Setup::CreateBlock and generateblock, don't construct
  an empty mempool, just pass in a nullptr for mempool

src/node/miner.cpp

@@ -62,7 +62,7 @@ BlockAssembler::Options::Options()
     nBlockMaxWeight = DEFAULT_BLOCK_MAX_WEIGHT;
 }
 
-BlockAssembler::BlockAssembler(CChainState& chainstate, const CTxMemPool& mempool, const Options& options)
+BlockAssembler::BlockAssembler(CChainState& chainstate, const CTxMemPool* mempool, const Options& options)
     : chainparams{chainstate.m_chainman.GetParams()},
       m_mempool(mempool),
       m_chainstate(chainstate)
@@ -87,7 +87,7 @@ static BlockAssembler::Options DefaultOptions()
     return options;
 }
 
-BlockAssembler::BlockAssembler(CChainState& chainstate, const CTxMemPool& mempool)
+BlockAssembler::BlockAssembler(CChainState& chainstate, const CTxMemPool* mempool)
     : BlockAssembler(chainstate, mempool, DefaultOptions()) {}
 
 void BlockAssembler::resetBlock()
@@ -121,7 +121,7 @@ std::unique_ptr<CBlockTemplate> BlockAssembler::CreateNewBlock(const CScript& sc
     pblocktemplate->vTxFees.push_back(-1); // updated at end
     pblocktemplate->vTxSigOpsCost.push_back(-1); // updated at end
 
-    LOCK2(cs_main, m_mempool.cs);
+    LOCK(::cs_main);
     CBlockIndex* pindexPrev = m_chainstate.m_chain.Tip();
     assert(pindexPrev != nullptr);
     nHeight = pindexPrev->nHeight + 1;
@@ -138,7 +138,10 @@ std::unique_ptr<CBlockTemplate> BlockAssembler::CreateNewBlock(const CScript& sc
 
     int nPackagesSelected = 0;
     int nDescendantsUpdated = 0;
-    addPackageTxs(nPackagesSelected, nDescendantsUpdated);
+    if (m_mempool) {
+        LOCK(m_mempool->cs);
+        addPackageTxs(*m_mempool, nPackagesSelected, nDescendantsUpdated);
+    }
 
     int64_t nTime1 = GetTimeMicros();
 
@@ -287,9 +290,9 @@ void BlockAssembler::SortForBlock(const CTxMemPool::setEntries& package, std::ve
 // Each time through the loop, we compare the best transaction in
 // mapModifiedTxs with the next transaction in the mempool to decide what
 // transaction package to work on next.
-void BlockAssembler::addPackageTxs(int& nPackagesSelected, int& nDescendantsUpdated)
+void BlockAssembler::addPackageTxs(const CTxMemPool& mempool, int& nPackagesSelected, int& nDescendantsUpdated)
 {
-    AssertLockHeld(m_mempool.cs);
+    AssertLockHeld(mempool.cs);
 
     // mapModifiedTx will store sorted packages after they are modified
     // because some of their txs are already in the block
@@ -297,7 +300,7 @@ void BlockAssembler::addPackageTxs(int& nPackagesSelected, int& nDescendantsUpda
     // Keep track of entries that failed inclusion, to avoid duplicate work
     CTxMemPool::setEntries failedTx;
 
-    CTxMemPool::indexed_transaction_set::index<ancestor_score>::type::iterator mi = m_mempool.mapTx.get<ancestor_score>().begin();
+    CTxMemPool::indexed_transaction_set::index<ancestor_score>::type::iterator mi = mempool.mapTx.get<ancestor_score>().begin();
     CTxMemPool::txiter iter;
 
     // Limit the number of attempts to add transactions to the block when it is
@@ -306,7 +309,7 @@ void BlockAssembler::addPackageTxs(int& nPackagesSelected, int& nDescendantsUpda
     const int64_t MAX_CONSECUTIVE_FAILURES = 1000;
     int64_t nConsecutiveFailed = 0;
 
-    while (mi != m_mempool.mapTx.get<ancestor_score>().end() || !mapModifiedTx.empty()) {
+    while (mi != mempool.mapTx.get<ancestor_score>().end() || !mapModifiedTx.empty()) {
         // First try to find a new transaction in mapTx to evaluate.
         //
         // Skip entries in mapTx that are already in a block or are present
@@ -320,9 +323,9 @@ void BlockAssembler::addPackageTxs(int& nPackagesSelected, int& nDescendantsUpda
         // cached size/sigops/fee values that are not actually correct.
         /** Return true if given transaction from mapTx has already been evaluated,
          * or if the transaction's cached data in mapTx is incorrect. */
-        if (mi != m_mempool.mapTx.get<ancestor_score>().end()) {
+        if (mi != mempool.mapTx.get<ancestor_score>().end()) {
-            auto it = m_mempool.mapTx.project<0>(mi);
+            auto it = mempool.mapTx.project<0>(mi);
-            assert(it != m_mempool.mapTx.end());
+            assert(it != mempool.mapTx.end());
             if (mapModifiedTx.count(it) || inBlock.count(it) || failedTx.count(it)) {
                 ++mi;
                 continue;
@@ -334,13 +337,13 @@ void BlockAssembler::addPackageTxs(int& nPackagesSelected, int& nDescendantsUpda
         bool fUsingModified = false;
 
         modtxscoreiter modit = mapModifiedTx.get<ancestor_score>().begin();
-        if (mi == m_mempool.mapTx.get<ancestor_score>().end()) {
+        if (mi == mempool.mapTx.get<ancestor_score>().end()) {
             // We're out of entries in mapTx; use the entry from mapModifiedTx
             iter = modit->iter;
             fUsingModified = true;
         } else {
             // Try to compare the mapTx entry to the mapModifiedTx entry
-            iter = m_mempool.mapTx.project<0>(mi);
+            iter = mempool.mapTx.project<0>(mi);
             if (modit != mapModifiedTx.get<ancestor_score>().end() &&
                     CompareTxMemPoolEntryByAncestorFee()(*modit, CTxMemPoolModifiedEntry(iter))) {
                 // The best entry in mapModifiedTx has higher score
@@ -395,7 +398,7 @@ void BlockAssembler::addPackageTxs(int& nPackagesSelected, int& nDescendantsUpda
         CTxMemPool::setEntries ancestors;
         uint64_t nNoLimit = std::numeric_limits<uint64_t>::max();
         std::string dummy;
-        m_mempool.CalculateMemPoolAncestors(*iter, ancestors, nNoLimit, nNoLimit, nNoLimit, nNoLimit, dummy, false);
+        mempool.CalculateMemPoolAncestors(*iter, ancestors, nNoLimit, nNoLimit, nNoLimit, nNoLimit, dummy, false);
 
         onlyUnconfirmed(ancestors);
         ancestors.insert(iter);
@@ -425,7 +428,7 @@ void BlockAssembler::addPackageTxs(int& nPackagesSelected, int& nDescendantsUpda
         ++nPackagesSelected;
 
         // Update transactions that depend on each of these
-        nDescendantsUpdated += UpdatePackagesForAdded(m_mempool, ancestors, mapModifiedTx);
+        nDescendantsUpdated += UpdatePackagesForAdded(mempool, ancestors, mapModifiedTx);
     }
 }
 } // namespace node

src/node/miner.h

@@ -147,7 +147,7 @@ private:
     int64_t m_lock_time_cutoff;
 
     const CChainParams& chainparams;
-    const CTxMemPool& m_mempool;
+    const CTxMemPool* const m_mempool;
     CChainState& m_chainstate;
 
 public:
@@ -157,8 +157,8 @@ public:
         CFeeRate blockMinFeeRate;
     };
 
-    explicit BlockAssembler(CChainState& chainstate, const CTxMemPool& mempool);
+    explicit BlockAssembler(CChainState& chainstate, const CTxMemPool* mempool);
-    explicit BlockAssembler(CChainState& chainstate, const CTxMemPool& mempool, const Options& options);
+    explicit BlockAssembler(CChainState& chainstate, const CTxMemPool* mempool, const Options& options);
 
     /** Construct a new block template with coinbase to scriptPubKeyIn */
     std::unique_ptr<CBlockTemplate> CreateNewBlock(const CScript& scriptPubKeyIn);
@@ -177,7 +177,7 @@ private:
     /** Add transactions based on feerate including unconfirmed ancestors
       * Increments nPackagesSelected / nDescendantsUpdated with corresponding
       * statistics from the package selection (for logging statistics). */
-    void addPackageTxs(int& nPackagesSelected, int& nDescendantsUpdated) EXCLUSIVE_LOCKS_REQUIRED(m_mempool.cs);
+    void addPackageTxs(const CTxMemPool& mempool, int& nPackagesSelected, int& nDescendantsUpdated) EXCLUSIVE_LOCKS_REQUIRED(mempool.cs);
 
     // helper functions for addPackageTxs()
     /** Remove confirmed (inBlock) entries from given set */

src/rpc/mining.cpp

@@ -144,7 +144,7 @@ static UniValue generateBlocks(ChainstateManager& chainman, const CTxMemPool& me
 {
     UniValue blockHashes(UniValue::VARR);
     while (nGenerate > 0 && !ShutdownRequested()) {
-        std::unique_ptr<CBlockTemplate> pblocktemplate(BlockAssembler{chainman.ActiveChainstate(), mempool}.CreateNewBlock(coinbase_script));
+        std::unique_ptr<CBlockTemplate> pblocktemplate(BlockAssembler{chainman.ActiveChainstate(), &mempool}.CreateNewBlock(coinbase_script));
         if (!pblocktemplate.get())
             throw JSONRPCError(RPC_INTERNAL_ERROR, "Couldn't create new block");
         CBlock *pblock = &pblocktemplate->block;
@@ -354,8 +354,7 @@ static RPCHelpMan generateblock()
     {
         LOCK(cs_main);
 
-        CTxMemPool empty_mempool;
+        std::unique_ptr<CBlockTemplate> blocktemplate(BlockAssembler{chainman.ActiveChainstate(), nullptr}.CreateNewBlock(coinbase_script));
-        std::unique_ptr<CBlockTemplate> blocktemplate(BlockAssembler{chainman.ActiveChainstate(), empty_mempool}.CreateNewBlock(coinbase_script));
         if (!blocktemplate) {
             throw JSONRPCError(RPC_INTERNAL_ERROR, "Couldn't create new block");
         }
@@ -753,7 +752,7 @@ static RPCHelpMan getblocktemplate()
 
         // Create new block
         CScript scriptDummy = CScript() << OP_TRUE;
-        pblocktemplate = BlockAssembler{active_chainstate, mempool}.CreateNewBlock(scriptDummy);
+        pblocktemplate = BlockAssembler{active_chainstate, &mempool}.CreateNewBlock(scriptDummy);
         if (!pblocktemplate)
             throw JSONRPCError(RPC_OUT_OF_MEMORY, "Out of memory");
 

src/test/blockfilter_index_tests.cpp

@@ -65,7 +65,7 @@ CBlock BuildChainTestingSetup::CreateBlock(const CBlockIndex* prev,
     const std::vector<CMutableTransaction>& txns,
     const CScript& scriptPubKey)
 {
-    std::unique_ptr<CBlockTemplate> pblocktemplate = BlockAssembler{m_node.chainman->ActiveChainstate(), *m_node.mempool}.CreateNewBlock(scriptPubKey);
+    std::unique_ptr<CBlockTemplate> pblocktemplate = BlockAssembler{m_node.chainman->ActiveChainstate(), m_node.mempool.get()}.CreateNewBlock(scriptPubKey);
     CBlock& block = pblocktemplate->block;
     block.hashPrevBlock = prev->GetBlockHash();
     block.nTime = prev->nTime + 1;

src/test/fuzz/tx_pool.cpp

@@ -97,7 +97,7 @@ void Finish(FuzzedDataProvider& fuzzed_data_provider, MockedTxPool& tx_pool, CCh
         BlockAssembler::Options options;
         options.nBlockMaxWeight = fuzzed_data_provider.ConsumeIntegralInRange(0U, MAX_BLOCK_WEIGHT);
         options.blockMinFeeRate = CFeeRate{ConsumeMoney(fuzzed_data_provider, /*max=*/COIN)};
-        auto assembler = BlockAssembler{chainstate, *static_cast<CTxMemPool*>(&tx_pool), options};
+        auto assembler = BlockAssembler{chainstate, &tx_pool, options};
         auto block_template = assembler.CreateNewBlock(CScript{} << OP_TRUE);
         Assert(block_template->block.vtx.size() >= 1);
     }

src/test/miner_tests.cpp

@@ -52,7 +52,7 @@ BlockAssembler MinerTestingSetup::AssemblerForTest(const CChainParams& params)
 
     options.nBlockMaxWeight = MAX_BLOCK_WEIGHT;
     options.blockMinFeeRate = blockMinFeeRate;
-    return BlockAssembler{m_node.chainman->ActiveChainstate(), *m_node.mempool, options};
+    return BlockAssembler{m_node.chainman->ActiveChainstate(), m_node.mempool.get(), options};
 }
 
 constexpr static struct {

src/test/util/mining.cpp

@@ -77,7 +77,7 @@ CTxIn MineBlock(const NodeContext& node, const CScript& coinbase_scriptPubKey)
 std::shared_ptr<CBlock> PrepareBlock(const NodeContext& node, const CScript& coinbase_scriptPubKey)
 {
     auto block = std::make_shared<CBlock>(
-        BlockAssembler{Assert(node.chainman)->ActiveChainstate(), *Assert(node.mempool)}
+        BlockAssembler{Assert(node.chainman)->ActiveChainstate(), Assert(node.mempool.get())}
             .CreateNewBlock(coinbase_scriptPubKey)
             ->block);
 

src/test/util/setup_common.cpp

@@ -277,8 +277,7 @@ CBlock TestChain100Setup::CreateBlock(
     const CScript& scriptPubKey,
     CChainState& chainstate)
 {
-    CTxMemPool empty_pool;
+    CBlock block = BlockAssembler{chainstate, nullptr}.CreateNewBlock(scriptPubKey)->block;
-    CBlock block = BlockAssembler{chainstate, empty_pool}.CreateNewBlock(scriptPubKey)->block;
 
     Assert(block.vtx.size() == 1);
     for (const CMutableTransaction& tx : txns) {

src/test/validation_block_tests.cpp

@@ -65,7 +65,7 @@ std::shared_ptr<CBlock> MinerTestingSetup::Block(const uint256& prev_hash)
     static int i = 0;
     static uint64_t time = Params().GenesisBlock().nTime;
 
-    auto ptemplate = BlockAssembler{m_node.chainman->ActiveChainstate(), *m_node.mempool}.CreateNewBlock(CScript{} << i++ << OP_TRUE);
+    auto ptemplate = BlockAssembler{m_node.chainman->ActiveChainstate(), m_node.mempool.get()}.CreateNewBlock(CScript{} << i++ << OP_TRUE);
     auto pblock = std::make_shared<CBlock>(ptemplate->block);
     pblock->hashPrevBlock = prev_hash;
     pblock->nTime = ++time;
@@ -327,7 +327,7 @@ BOOST_AUTO_TEST_CASE(witness_commitment_index)
 {
     CScript pubKey;
     pubKey << 1 << OP_TRUE;
-    auto ptemplate = BlockAssembler{m_node.chainman->ActiveChainstate(), *m_node.mempool}.CreateNewBlock(pubKey);
+    auto ptemplate = BlockAssembler{m_node.chainman->ActiveChainstate(), m_node.mempool.get()}.CreateNewBlock(pubKey);
     CBlock pblock = ptemplate->block;
 
     CTxOut witness;