Merge bitcoin/bitcoin#27307: wallet: track mempool conflicts with wallet transactions

5952292133d6cc889f51ae771f2e0557311e1efe wallet, rpc: show mempool conflicts in `gettransaction` result (ishaanam)
54e07ee22ff16fc68583ade0d2b8ffffc81d444a wallet: track mempool conflicts (ishaanam)
d64922b5903e5ffc8d2ce0e6761f99f173b60800 wallet refactor: use CWalletTx member functions to determine tx state (ishaanam)
ffe5ff1fb622a8da11b66289e1b778e45e449811 scripted-diff: wallet: s/TxStateConflicted/TxStateBlockConflicted (ishaanam)
180973a94180f9849bf7cb0dab7c9177a942efb8 test: Add tests for wallet mempool conflicts (ishaanam)

Pull request description:

  The `mempool_conflicts` variable is added to `CWalletTx`, it is a set of txids of txs in the mempool conflicting with the wallet tx or a wallet tx's parent. This PR only changes how mempool-conflicted txs are dealt with in memory.

  `IsSpent` now returns false for an output being spent by a mempool conflicted transaction where it previously returned true.

  A txid is added to `mempool_conflicts` during  `transactionAddedToMempool`. A txid is removed from `mempool_conflicts` during  `transactionRemovedFromMempool`.

  This PR also adds a `mempoolconflicts` field to the `gettransaction` wallet RPC result.

  Builds on #27145
  Second attempt at #18600

ACKs for top commit:
  achow101:
    ACK 5952292133d6cc889f51ae771f2e0557311e1efe
  ryanofsky:
    Code review ACK 5952292133d6cc889f51ae771f2e0557311e1efe. Just small suggested changes since last review
  furszy:
    ACK 59522921

Tree-SHA512: 615779606723dbb6c2e302681d8e58ae2052ffee52d721ee0389746ddbbcf4b4c4afacf01ddf42b6405bc6f883520524186a955bf6b628fe9b3ae54cffc56a29

1 files changed, 43 insertions, 11 deletions

diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index 9c15c2a827..591c5eca6e 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -752,8 +752,8 @@ bool CWallet::IsSpent(const COutPoint& outpoint) const
         const uint256& wtxid = it->second;
         const auto mit = mapWallet.find(wtxid);
         if (mit != mapWallet.end()) {
-            int depth = GetTxDepthInMainChain(mit->second);
-            if (depth > 0  || (depth == 0 && !mit->second.isAbandoned()))
+            const auto& wtx = mit->second;
+            if (!wtx.isAbandoned() && !wtx.isBlockConflicted() && !wtx.isMempoolConflicted())
                 return true; // Spent
         }
     }
@@ -1197,7 +1197,7 @@ bool CWallet::LoadToWallet(const uint256& hash, const UpdateWalletTxFn& fill_wtx
         auto it = mapWallet.find(txin.prevout.hash);
         if (it != mapWallet.end()) {
             CWalletTx& prevtx = it->second;
-            if (auto* prev = prevtx.state<TxStateConflicted>()) {
+            if (auto* prev = prevtx.state<TxStateBlockConflicted>()) {
                 MarkConflicted(prev->conflicting_block_hash, prev->conflicting_block_height, wtx.GetHash());
             }
         }
@@ -1309,7 +1309,7 @@ bool CWallet::AbandonTransaction(const uint256& hashTx)
         assert(!wtx.isConfirmed());
         assert(!wtx.InMempool());
         // If already conflicted or abandoned, no need to set abandoned
-        if (!wtx.isConflicted() && !wtx.isAbandoned()) {
+        if (!wtx.isBlockConflicted() && !wtx.isAbandoned()) {
             wtx.m_state = TxStateInactive{/*abandoned=*/true};
             return TxUpdate::NOTIFY_CHANGED;
         }
@@ -1346,7 +1346,7 @@ void CWallet::MarkConflicted(const uint256& hashBlock, int conflicting_height, c
         if (conflictconfirms < GetTxDepthInMainChain(wtx)) {
             // Block is 'more conflicted' than current confirm; update.
             // Mark transaction as conflicted with this block.
-            wtx.m_state = TxStateConflicted{hashBlock, conflicting_height};
+            wtx.m_state = TxStateBlockConflicted{hashBlock, conflicting_height};
             return TxUpdate::CHANGED;
         }
         return TxUpdate::UNCHANGED;
@@ -1360,7 +1360,10 @@ void CWallet::MarkConflicted(const uint256& hashBlock, int conflicting_height, c
 void CWallet::RecursiveUpdateTxState(const uint256& tx_hash, const TryUpdatingStateFn& try_updating_state) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet) {
     // Do not flush the wallet here for performance reasons
     WalletBatch batch(GetDatabase(), false);
+    RecursiveUpdateTxState(&batch, tx_hash, try_updating_state);
+}
 
+void CWallet::RecursiveUpdateTxState(WalletBatch* batch, const uint256& tx_hash, const TryUpdatingStateFn& try_updating_state) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet) {
     std::set<uint256> todo;
     std::set<uint256> done;
 
@@ -1377,7 +1380,7 @@ void CWallet::RecursiveUpdateTxState(const uint256& tx_hash, const TryUpdatingSt
         TxUpdate update_state = try_updating_state(wtx);
         if (update_state != TxUpdate::UNCHANGED) {
             wtx.MarkDirty();
-            batch.WriteTx(wtx);
+            if (batch) batch->WriteTx(wtx);
             // Iterate over all its outputs, and update those tx states as well (if applicable)
             for (unsigned int i = 0; i < wtx.tx->vout.size(); ++i) {
                 std::pair<TxSpends::const_iterator, TxSpends::const_iterator> range = mapTxSpends.equal_range(COutPoint(Txid::FromUint256(now), i));
@@ -1418,6 +1421,20 @@ void CWallet::transactionAddedToMempool(const CTransactionRef& tx) {
     if (it != mapWallet.end()) {
         RefreshMempoolStatus(it->second, chain());
     }
+
+    const Txid& txid = tx->GetHash();
+
+    for (const CTxIn& tx_in : tx->vin) {
+        // For each wallet transaction spending this prevout..
+        for (auto range = mapTxSpends.equal_range(tx_in.prevout); range.first != range.second; range.first++) {
+            const uint256& spent_id = range.first->second;
+            // Skip the recently added tx
+            if (spent_id == txid) continue;
+            RecursiveUpdateTxState(/*batch=*/nullptr, spent_id, [&txid](CWalletTx& wtx) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet) {
+                return wtx.mempool_conflicts.insert(txid).second ? TxUpdate::CHANGED : TxUpdate::UNCHANGED;
+            });
+        }
+    }
 }
 
 void CWallet::transactionRemovedFromMempool(const CTransactionRef& tx, MemPoolRemovalReason reason) {
@@ -1455,6 +1472,21 @@ void CWallet::transactionRemovedFromMempool(const CTransactionRef& tx, MemPoolRe
         // https://github.com/bitcoin-core/bitcoin-devwiki/wiki/Wallet-Transaction-Conflict-Tracking
         SyncTransaction(tx, TxStateInactive{});
     }
+
+    const Txid& txid = tx->GetHash();
+
+    for (const CTxIn& tx_in : tx->vin) {
+        // Iterate over all wallet transactions spending txin.prev
+        // and recursively mark them as no longer conflicting with
+        // txid
+        for (auto range = mapTxSpends.equal_range(tx_in.prevout); range.first != range.second; range.first++) {
+            const uint256& spent_id = range.first->second;
+
+            RecursiveUpdateTxState(/*batch=*/nullptr, spent_id, [&txid](CWalletTx& wtx) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet) {
+                return wtx.mempool_conflicts.erase(txid) ? TxUpdate::CHANGED : TxUpdate::UNCHANGED;
+            });
+        }
+    }
 }
 
 void CWallet::blockConnected(ChainstateRole role, const interfaces::BlockInfo& block)
@@ -1506,11 +1538,11 @@ void CWallet::blockDisconnected(const interfaces::BlockInfo& block)
             for (TxSpends::const_iterator _it = range.first; _it != range.second; ++_it) {
                 CWalletTx& wtx = mapWallet.find(_it->second)->second;
 
-                if (!wtx.isConflicted()) continue;
+                if (!wtx.isBlockConflicted()) continue;
 
                 auto try_updating_state = [&](CWalletTx& tx) {
-                    if (!tx.isConflicted()) return TxUpdate::UNCHANGED;
-                    if (tx.state<TxStateConflicted>()->conflicting_block_height >= disconnect_height) {
+                    if (!tx.isBlockConflicted()) return TxUpdate::UNCHANGED;
+                    if (tx.state<TxStateBlockConflicted>()->conflicting_block_height >= disconnect_height) {
                         tx.m_state = TxStateInactive{};
                         return TxUpdate::CHANGED;
                     }
@@ -2787,7 +2819,7 @@ unsigned int CWallet::ComputeTimeSmart(const CWalletTx& wtx, bool rescanning_old
     std::optional<uint256> block_hash;
     if (auto* conf = wtx.state<TxStateConfirmed>()) {
         block_hash = conf->confirmed_block_hash;
-    } else if (auto* conf = wtx.state<TxStateConflicted>()) {
+    } else if (auto* conf = wtx.state<TxStateBlockConflicted>()) {
         block_hash = conf->conflicting_block_hash;
     }
 
@@ -3377,7 +3409,7 @@ int CWallet::GetTxDepthInMainChain(const CWalletTx& wtx) const
     if (auto* conf = wtx.state<TxStateConfirmed>()) {
         assert(conf->confirmed_block_height >= 0);
         return GetLastBlockHeight() - conf->confirmed_block_height + 1;
-    } else if (auto* conf = wtx.state<TxStateConflicted>()) {
+    } else if (auto* conf = wtx.state<TxStateBlockConflicted>()) {
         assert(conf->conflicting_block_height >= 0);
         return -1 * (GetLastBlockHeight() - conf->conflicting_block_height + 1);
     } else {