Merge #19556: Remove mempool global

fafb381af8279b2d2ca768df0bf68d7eb036a2f9 Remove mempool global (MarcoFalke)
fa0359c5b30730744aa8a7cd9ffab79ded91041f Remove mempool global from p2p (MarcoFalke)
eeee1104d78eb59a582ee1709ff4ac2c33ee1190 Remove mempool global from init (MarcoFalke)

Pull request description:

  This refactor unlocks some nice potential features, such as, but not limited to:
  * Removing the fee estimates global (would avoid slightly fragile workarounds such as #18766)
  * Making the mempool optional for a "blocksonly" operation mode

  Even absent those features, the new code without the global should be easier to maintain, read and write tests for.

ACKs for top commit:
  jnewbery:
    utACK fafb381af8279b2d2ca768df0bf68d7eb036a2f9
  hebasto:
    ACK fafb381af8279b2d2ca768df0bf68d7eb036a2f9, I have reviewed the code and it looks OK, I agree it can be merged.
  darosior:
    ACK fafb381af8279b2d2ca768df0bf68d7eb036a2f9

Tree-SHA512: a2e696dc377e2e81eaf9c389e6d13dde4a48d81f3538df88f4da502d3012dd61078495140ab5a5854f360a06249fe0e1f6a094c4e006d8b5cc2552a946becf26

9 files changed, 38 insertions, 28 deletions

diff --git a/src/init.cpp b/src/init.cpp
index bb93f5c797..633dd8cefc 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -187,7 +187,7 @@ void Shutdown(NodeContext& node)
     /// Be sure that anything that writes files or flushes caches only does this if the respective
     /// module was initialized.
     util::ThreadRename("shutoff");
-    mempool.AddTransactionsUpdated(1);
+    if (node.mempool) node.mempool->AddTransactionsUpdated(1);
 
     StopHTTPRPC();
     StopREST();
@@ -231,8 +231,8 @@ void Shutdown(NodeContext& node)
     node.connman.reset();
     node.banman.reset();
 
-    if (::mempool.IsLoaded() && node.args->GetArg("-persistmempool", DEFAULT_PERSIST_MEMPOOL)) {
-        DumpMempool(::mempool);
+    if (node.mempool && node.mempool->IsLoaded() && node.args->GetArg("-persistmempool", DEFAULT_PERSIST_MEMPOOL)) {
+        DumpMempool(*node.mempool);
     }
 
     if (fFeeEstimatesInitialized)
@@ -302,7 +302,7 @@ void Shutdown(NodeContext& node)
     GetMainSignals().UnregisterBackgroundSignalScheduler();
     globalVerifyHandle.reset();
     ECC_Stop();
-    node.mempool = nullptr;
+    node.mempool.reset();
     node.chainman = nullptr;
     node.scheduler.reset();
 
@@ -738,10 +738,7 @@ static void ThreadImport(ChainstateManager& chainman, std::vector<fs::path> vImp
         return;
     }
     } // End scope of CImportingNow
-    if (args.GetArg("-persistmempool", DEFAULT_PERSIST_MEMPOOL)) {
-        LoadMempool(::mempool);
-    }
-    ::mempool.SetIsLoaded(!ShutdownRequested());
+    chainman.ActiveChainstate().LoadMempool(args);
 }
 
 /** Sanity checks
@@ -1054,11 +1051,6 @@ bool AppInitParameterInteraction(const ArgsManager& args)
         }
     }
 
-    // Checkmempool and checkblockindex default to true in regtest mode
-    int ratio = std::min<int>(std::max<int>(args.GetArg("-checkmempool", chainparams.DefaultConsistencyChecks() ? 1 : 0), 0), 1000000);
-    if (ratio != 0) {
-        mempool.setSanityCheck(1.0 / ratio);
-    }
     fCheckBlockIndex = args.GetBoolArg("-checkblockindex", chainparams.DefaultConsistencyChecks());
     fCheckpointsEnabled = args.GetBoolArg("-checkpoints", DEFAULT_CHECKPOINTS_ENABLED);
 
@@ -1368,10 +1360,18 @@ bool AppInitMain(const util::Ref& context, NodeContext& node, interfaces::BlockA
     node.banman = MakeUnique<BanMan>(GetDataDir() / "banlist.dat", &uiInterface, args.GetArg("-bantime", DEFAULT_MISBEHAVING_BANTIME));
     assert(!node.connman);
     node.connman = MakeUnique<CConnman>(GetRand(std::numeric_limits<uint64_t>::max()), GetRand(std::numeric_limits<uint64_t>::max()), args.GetBoolArg("-networkactive", true));
+
     // Make mempool generally available in the node context. For example the connection manager, wallet, or RPC threads,
     // which are all started after this, may use it from the node context.
     assert(!node.mempool);
-    node.mempool = &::mempool;
+    node.mempool = MakeUnique<CTxMemPool>(&::feeEstimator);
+    if (node.mempool) {
+        int ratio = std::min<int>(std::max<int>(args.GetArg("-checkmempool", chainparams.DefaultConsistencyChecks() ? 1 : 0), 0), 1000000);
+        if (ratio != 0) {
+            node.mempool->setSanityCheck(1.0 / ratio);
+        }
+    }
+
     assert(!node.chainman);
     node.chainman = &g_chainman;
     ChainstateManager& chainman = *Assert(node.chainman);
@@ -1559,7 +1559,7 @@ bool AppInitMain(const util::Ref& context, NodeContext& node, interfaces::BlockA
                 chainman.m_total_coinstip_cache = nCoinCacheUsage;
                 chainman.m_total_coinsdb_cache = nCoinDBCache;
 
-                UnloadBlockIndex(node.mempool);
+                UnloadBlockIndex(node.mempool.get());
 
                 // new CBlockTreeDB tries to delete the existing file, which
                 // fails if it's still open from the previous loop. Close it first:
diff --git a/src/net_processing.cpp b/src/net_processing.cpp
index 8d6ecf2779..15508683ce 100644
--- a/src/net_processing.cpp
+++ b/src/net_processing.cpp
@@ -1710,7 +1710,7 @@ void static ProcessGetBlockData(CNode& pfrom, const CChainParams& chainparams, c
 }
 
 //! Determine whether or not a peer can request a transaction, and return it (or nullptr if not found or not allowed).
-CTransactionRef static FindTxForGetData(const CNode& peer, const GenTxid& gtxid, const std::chrono::seconds mempool_req, const std::chrono::seconds now) LOCKS_EXCLUDED(cs_main)
+static CTransactionRef FindTxForGetData(const CTxMemPool& mempool, const CNode& peer, const GenTxid& gtxid, const std::chrono::seconds mempool_req, const std::chrono::seconds now) LOCKS_EXCLUDED(cs_main)
 {
     auto txinfo = mempool.info(gtxid);
     if (txinfo.tx) {
@@ -1766,7 +1766,7 @@ void static ProcessGetData(CNode& pfrom, const CChainParams& chainparams, CConnm
             continue;
         }
 
-        CTransactionRef tx = FindTxForGetData(pfrom, ToGenTxid(inv), mempool_req, now);
+        CTransactionRef tx = FindTxForGetData(mempool, pfrom, ToGenTxid(inv), mempool_req, now);
         if (tx) {
             // WTX and WITNESS_TX imply we serialize with witness
             int nSendFlags = (inv.IsMsgTx() ? SERIALIZE_TRANSACTION_NO_WITNESS : 0);
@@ -2732,7 +2732,7 @@ void PeerLogicValidation::ProcessMessage(CNode& pfrom, const std::string& msg_ty
                 }
             } else if (inv.IsGenTxMsg()) {
                 const GenTxid gtxid = ToGenTxid(inv);
-                const bool fAlreadyHave = AlreadyHaveTx(gtxid, mempool);
+                const bool fAlreadyHave = AlreadyHaveTx(gtxid, m_mempool);
                 LogPrint(BCLog::NET, "got inv: %s  %s peer=%d\n", inv.ToString(), fAlreadyHave ? "have" : "new", pfrom.GetId());
 
                 pfrom.AddKnownTx(inv.hash);
@@ -3003,7 +3003,7 @@ void PeerLogicValidation::ProcessMessage(CNode& pfrom, const std::string& msg_ty
 
         std::list<CTransactionRef> lRemovedTxn;
 
-        // We do the AlreadyHave() check using wtxid, rather than txid - in the
+        // We do the AlreadyHaveTx() check using wtxid, rather than txid - in the
         // absence of witness malleation, this is strictly better, because the
         // recent rejects filter may contain the wtxid but rarely contains
         // the txid of a segwit transaction that has been rejected.
diff --git a/src/node/context.cpp b/src/node/context.cpp
index 0238aab0d9..49d0c37235 100644
--- a/src/node/context.cpp
+++ b/src/node/context.cpp
@@ -9,6 +9,7 @@
 #include <net.h>
 #include <net_processing.h>
 #include <scheduler.h>
+#include <txmempool.h>
 
 NodeContext::NodeContext() {}
 NodeContext::~NodeContext() {}
diff --git a/src/node/context.h b/src/node/context.h
index 793c9dfc34..d9d0750951 100644
--- a/src/node/context.h
+++ b/src/node/context.h
@@ -35,7 +35,7 @@ class WalletClient;
 //! be used without pulling in unwanted dependencies or functionality.
 struct NodeContext {
     std::unique_ptr<CConnman> connman;
-    CTxMemPool* mempool{nullptr}; // Currently a raw pointer because the memory is not managed by this struct
+    std::unique_ptr<CTxMemPool> mempool;
     std::unique_ptr<PeerLogicValidation> peer_logic;
     ChainstateManager* chainman{nullptr}; // Currently a raw pointer because the memory is not managed by this struct
     std::unique_ptr<BanMan> banman;
diff --git a/src/rest.cpp b/src/rest.cpp
index 7130625d5c..f0bcbe55f9 100644
--- a/src/rest.cpp
+++ b/src/rest.cpp
@@ -102,7 +102,7 @@ static CTxMemPool* GetMemPool(const util::Ref& context, HTTPRequest* req)
         RESTERR(req, HTTP_NOT_FOUND, "Mempool disabled or instance not found");
         return nullptr;
     }
-    return node->mempool;
+    return node->mempool.get();
 }
 
 static RetFormat ParseDataFormat(std::string& param, const std::string& strReq)
@@ -393,7 +393,7 @@ static bool rest_tx(const util::Ref& context, HTTPRequest* req, const std::strin
     const NodeContext* const node = GetNodeContext(context, req);
     if (!node) return false;
     uint256 hashBlock = uint256();
-    const CTransactionRef tx = GetTransaction(/* block_index */ nullptr, node->mempool, hash, Params().GetConsensus(), hashBlock);
+    const CTransactionRef tx = GetTransaction(/* block_index */ nullptr, node->mempool.get(), hash, Params().GetConsensus(), hashBlock);
     if (!tx) {
         return RESTERR(req, HTTP_NOT_FOUND, hashStr + " not found");
     }
diff --git a/src/rpc/rawtransaction.cpp b/src/rpc/rawtransaction.cpp
index f46dee8258..93e8357e86 100644
--- a/src/rpc/rawtransaction.cpp
+++ b/src/rpc/rawtransaction.cpp
@@ -191,7 +191,7 @@ static UniValue getrawtransaction(const JSONRPCRequest& request)
     }
 
     uint256 hash_block;
-    const CTransactionRef tx = GetTransaction(blockindex, node.mempool, hash, Params().GetConsensus(), hash_block);
+    const CTransactionRef tx = GetTransaction(blockindex, node.mempool.get(), hash, Params().GetConsensus(), hash_block);
     if (!tx) {
         std::string errmsg;
         if (blockindex) {
diff --git a/src/test/util/setup_common.cpp b/src/test/util/setup_common.cpp
index 8a88e75892..536a131313 100644
--- a/src/test/util/setup_common.cpp
+++ b/src/test/util/setup_common.cpp
@@ -141,7 +141,7 @@ TestingSetup::TestingSetup(const std::string& chainName, const std::vector<const
 
     pblocktree.reset(new CBlockTreeDB(1 << 20, true));
 
-    m_node.mempool = &::mempool;
+    m_node.mempool = MakeUnique<CTxMemPool>(&::feeEstimator);
     m_node.mempool->setSanityCheck(1.0);
 
     m_node.chainman = &::g_chainman;
@@ -187,8 +187,8 @@ TestingSetup::~TestingSetup()
     m_node.connman.reset();
     m_node.banman.reset();
     m_node.args = nullptr;
-    UnloadBlockIndex(m_node.mempool);
-    m_node.mempool = nullptr;
+    UnloadBlockIndex(m_node.mempool.get());
+    m_node.mempool.reset();
     m_node.scheduler.reset();
     m_node.chainman->Reset();
     m_node.chainman = nullptr;
diff --git a/src/validation.cpp b/src/validation.cpp
index 58af8744d9..bdbae66511 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -148,7 +148,6 @@ arith_uint256 nMinimumChainWork;
 CFeeRate minRelayTxFee = CFeeRate(DEFAULT_MIN_RELAY_TX_FEE);
 
 CBlockPolicyEstimator feeEstimator;
-CTxMemPool mempool(&feeEstimator);
 
 // Internal stuff
 namespace {
@@ -4227,6 +4226,14 @@ bool static LoadBlockIndexDB(ChainstateManager& chainman, const CChainParams& ch
     return true;
 }
 
+void CChainState::LoadMempool(const ArgsManager& args)
+{
+    if (args.GetArg("-persistmempool", DEFAULT_PERSIST_MEMPOOL)) {
+        ::LoadMempool(m_mempool);
+    }
+    m_mempool.SetIsLoaded(!ShutdownRequested());
+}
+
 bool CChainState::LoadChainTip(const CChainParams& chainparams)
 {
     AssertLockHeld(cs_main);
diff --git a/src/validation.h b/src/validation.h
index cac9473c7a..53c2dd65e5 100644
--- a/src/validation.h
+++ b/src/validation.h
@@ -113,7 +113,6 @@ enum class SynchronizationState {
 
 extern RecursiveMutex cs_main;
 extern CBlockPolicyEstimator feeEstimator;
-extern CTxMemPool mempool;
 typedef std::unordered_map<uint256, CBlockIndex*, BlockHasher> BlockMap;
 extern Mutex g_best_block_mutex;
 extern std::condition_variable g_best_block_cv;
@@ -671,6 +670,9 @@ public:
      */
     void CheckBlockIndex(const Consensus::Params& consensusParams);
 
+    /** Load the persisted mempool from disk */
+    void LoadMempool(const ArgsManager& args);
+
     /** Update the chain tip based on database information, i.e. CoinsTip()'s best block. */
     bool LoadChainTip(const CChainParams& chainparams) EXCLUSIVE_LOCKS_REQUIRED(cs_main);