Add a CValidationInterface::TransactionRemovedFromMempool

This is currently unused, but will by used by wallet to cache when
transactions are in the mempool, obviating the need for calls to
mempool from CWalletTx::InMempool()

Author: TheBlueMatt

src/init.cpp

@@ -265,6 +265,7 @@ void Shutdown()
 #endif
     UnregisterAllValidationInterfaces();
     GetMainSignals().UnregisterBackgroundSignalScheduler();
+    GetMainSignals().UnregisterWithMempoolSignals(mempool);
 #ifdef ENABLE_WALLET
     CloseWallets();
 #endif
@@ -1240,6 +1241,7 @@ bool AppInitMain(boost::thread_group& threadGroup, CScheduler& scheduler)
     threadGroup.create_thread(boost::bind(&TraceThread<CScheduler::Function>, "scheduler", serviceLoop));
 
     GetMainSignals().RegisterBackgroundSignalScheduler(scheduler);
+    GetMainSignals().RegisterWithMempoolSignals(mempool);
 
     /* Start the RPC server already.  It will be started in "warmup" mode
      * and not really process calls already (but it will signify connections

src/txmempool.h

@@ -513,6 +513,9 @@ class CTxMemPool
     // to track size/count of descendant transactions.  First version of
     // addUnchecked can be used to have it call CalculateMemPoolAncestors(), and
     // then invoke the second version.
+    // Note that addUnchecked is ONLY called from ATMP outside of tests
+    // and any other callers may break wallet's in-mempool tracking (due to
+    // lack of CValidationInterface::TransactionAddedToMempool callbacks).
     bool addUnchecked(const uint256& hash, const CTxMemPoolEntry &entry, bool validFeeEstimate = true);
     bool addUnchecked(const uint256& hash, const CTxMemPoolEntry &entry, setEntries &setAncestors, bool validFeeEstimate = true);
 

src/validationinterface.cpp

@@ -9,6 +9,7 @@
 #include "primitives/block.h"
 #include "scheduler.h"
 #include "sync.h"
+#include "txmempool.h"
 #include "util.h"
 
 #include <list>
@@ -21,6 +22,7 @@ struct MainSignalsInstance {
     boost::signals2::signal<void (const CTransactionRef &)> TransactionAddedToMempool;
     boost::signals2::signal<void (const std::shared_ptr<const CBlock> &, const CBlockIndex *pindex, const std::vector<CTransactionRef>&)> BlockConnected;
     boost::signals2::signal<void (const std::shared_ptr<const CBlock> &)> BlockDisconnected;
+    boost::signals2::signal<void (const CTransactionRef &)> TransactionRemovedFromMempool;
     boost::signals2::signal<void (const CBlockLocator &)> SetBestChain;
     boost::signals2::signal<void (const uint256 &)> Inventory;
     boost::signals2::signal<void (int64_t nBestBlockTime, CConnman* connman)> Broadcast;
@@ -50,6 +52,14 @@ void CMainSignals::FlushBackgroundCallbacks() {
     m_internals->m_schedulerClient.EmptyQueue();
 }
 
+void CMainSignals::RegisterWithMempoolSignals(CTxMemPool& pool) {
+    pool.NotifyEntryRemoved.connect(boost::bind(&CMainSignals::MempoolEntryRemoved, this, _1, _2));
+}
+
+void CMainSignals::UnregisterWithMempoolSignals(CTxMemPool& pool) {
+    pool.NotifyEntryRemoved.disconnect(boost::bind(&CMainSignals::MempoolEntryRemoved, this, _1, _2));
+}
+
 CMainSignals& GetMainSignals()
 {
     return g_signals;
@@ -60,6 +70,7 @@ void RegisterValidationInterface(CValidationInterface* pwalletIn) {
     g_signals.m_internals->TransactionAddedToMempool.connect(boost::bind(&CValidationInterface::TransactionAddedToMempool, pwalletIn, _1));
     g_signals.m_internals->BlockConnected.connect(boost::bind(&CValidationInterface::BlockConnected, pwalletIn, _1, _2, _3));
     g_signals.m_internals->BlockDisconnected.connect(boost::bind(&CValidationInterface::BlockDisconnected, pwalletIn, _1));
+    g_signals.m_internals->TransactionRemovedFromMempool.connect(boost::bind(&CValidationInterface::TransactionRemovedFromMempool, pwalletIn, _1));
     g_signals.m_internals->SetBestChain.connect(boost::bind(&CValidationInterface::SetBestChain, pwalletIn, _1));
     g_signals.m_internals->Inventory.connect(boost::bind(&CValidationInterface::Inventory, pwalletIn, _1));
     g_signals.m_internals->Broadcast.connect(boost::bind(&CValidationInterface::ResendWalletTransactions, pwalletIn, _1, _2));
@@ -75,6 +86,7 @@ void UnregisterValidationInterface(CValidationInterface* pwalletIn) {
     g_signals.m_internals->TransactionAddedToMempool.disconnect(boost::bind(&CValidationInterface::TransactionAddedToMempool, pwalletIn, _1));
     g_signals.m_internals->BlockConnected.disconnect(boost::bind(&CValidationInterface::BlockConnected, pwalletIn, _1, _2, _3));
     g_signals.m_internals->BlockDisconnected.disconnect(boost::bind(&CValidationInterface::BlockDisconnected, pwalletIn, _1));
+    g_signals.m_internals->TransactionRemovedFromMempool.disconnect(boost::bind(&CValidationInterface::TransactionRemovedFromMempool, pwalletIn, _1));
     g_signals.m_internals->UpdatedBlockTip.disconnect(boost::bind(&CValidationInterface::UpdatedBlockTip, pwalletIn, _1, _2, _3));
     g_signals.m_internals->NewPoWValidBlock.disconnect(boost::bind(&CValidationInterface::NewPoWValidBlock, pwalletIn, _1, _2));
 }
@@ -87,10 +99,17 @@ void UnregisterAllValidationInterfaces() {
     g_signals.m_internals->TransactionAddedToMempool.disconnect_all_slots();
     g_signals.m_internals->BlockConnected.disconnect_all_slots();
     g_signals.m_internals->BlockDisconnected.disconnect_all_slots();
+    g_signals.m_internals->TransactionRemovedFromMempool.disconnect_all_slots();
     g_signals.m_internals->UpdatedBlockTip.disconnect_all_slots();
     g_signals.m_internals->NewPoWValidBlock.disconnect_all_slots();
 }
 
+void CMainSignals::MempoolEntryRemoved(CTransactionRef ptx, MemPoolRemovalReason reason) {
+    if (reason != MemPoolRemovalReason::BLOCK && reason != MemPoolRemovalReason::CONFLICT) {
+        m_internals->TransactionRemovedFromMempool(ptx);
+    }
+}
+
 void CMainSignals::UpdatedBlockTip(const CBlockIndex *pindexNew, const CBlockIndex *pindexFork, bool fInitialDownload) {
     m_internals->UpdatedBlockTip(pindexNew, pindexFork, fInitialDownload);
 }

src/validationinterface.h

@@ -20,6 +20,8 @@ class CValidationInterface;
 class CValidationState;
 class uint256;
 class CScheduler;
+class CTxMemPool;
+enum class MemPoolRemovalReason;
 
 // These functions dispatch to one or all registered wallets
 
@@ -36,6 +38,15 @@ class CValidationInterface {
     virtual void UpdatedBlockTip(const CBlockIndex *pindexNew, const CBlockIndex *pindexFork, bool fInitialDownload) {}
     /** Notifies listeners of a transaction having been added to mempool. */
     virtual void TransactionAddedToMempool(const CTransactionRef &ptxn) {}
+    /**
+     * Notifies listeners of a transaction leaving mempool.
+     *
+     * This only fires for transactions which leave mempool because of expiry,
+     * size limiting, reorg (changes in lock times/coinbase maturity), or
+     * replacement. This does not include any transactions which are included
+     * in BlockConnectedDisconnected either in block->vtx or in txnConflicted.
+     */
+    virtual void TransactionRemovedFromMempool(const CTransactionRef &ptx) {}
     /**
      * Notifies listeners of a block being connected.
      * Provides a vector of transactions evicted from the mempool as a result.
@@ -74,6 +85,8 @@ class CMainSignals {
     friend void ::UnregisterValidationInterface(CValidationInterface*);
     friend void ::UnregisterAllValidationInterfaces();
 
+    void MempoolEntryRemoved(CTransactionRef tx, MemPoolRemovalReason reason);
+
 public:
     /** Register a CScheduler to give callbacks which should run in the background (may only be called once) */
     void RegisterBackgroundSignalScheduler(CScheduler& scheduler);
@@ -82,6 +95,11 @@ class CMainSignals {
     /** Call any remaining callbacks on the calling thread */
     void FlushBackgroundCallbacks();
 
+    /** Register with mempool to call TransactionRemovedFromMempool callbacks */
+    void RegisterWithMempoolSignals(CTxMemPool& pool);
+    /** Unregister with mempool */
+    void UnregisterWithMempoolSignals(CTxMemPool& pool);
+
     void UpdatedBlockTip(const CBlockIndex *, const CBlockIndex *, bool fInitialDownload);
     void TransactionAddedToMempool(const CTransactionRef &);
     void BlockConnected(const std::shared_ptr<const CBlock> &, const CBlockIndex *pindex, const std::vector<CTransactionRef> &);