Remove CWalletTx merging logic from AddToWallet

Instead of AddToWallet taking a temporary CWalletTx object and then potentially
merging it with a pre-existing CWalletTx, have it take a callback so callers
can update the pre-existing CWalletTx directly.

This makes AddToWallet simpler because now it is only has to be concerned with
saving CWalletTx objects and not merging them.

This makes AddToWallet calls clearer because they can now make direct updates to
CWalletTx entries without having to make temporary objects and then worry about
how they will be merged.

This is a pure refactoring, no behavior is changing.

5 files changed, 53 insertions, 64 deletions

diff --git a/src/wallet/rpcdump.cpp b/src/wallet/rpcdump.cpp
index c863d22530..7bf3d169c3 100644
--- a/src/wallet/rpcdump.cpp
+++ b/src/wallet/rpcdump.cpp
@@ -345,7 +345,6 @@ UniValue importprunedfunds(const JSONRPCRequest& request)
     if (!DecodeHexTx(tx, request.params[0].get_str()))
         throw JSONRPCError(RPC_DESERIALIZATION_ERROR, "TX decode failed");
     uint256 hashTx = tx.GetHash();
-    CWalletTx wtx(pwallet, MakeTransactionRef(std::move(tx)));
 
     CDataStream ssMB(ParseHexV(request.params[1], "proof"), SER_NETWORK, PROTOCOL_VERSION);
     CMerkleBlock merkleBlock;
@@ -372,10 +371,10 @@ UniValue importprunedfunds(const JSONRPCRequest& request)
     unsigned int txnIndex = vIndex[it - vMatch.begin()];
 
     CWalletTx::Confirmation confirm(CWalletTx::Status::CONFIRMED, height, merkleBlock.header.GetHash(), txnIndex);
-    wtx.m_confirm = confirm;
 
-    if (pwallet->IsMine(*wtx.tx)) {
-        pwallet->AddToWallet(wtx, false);
+    CTransactionRef tx_ref = MakeTransactionRef(tx);
+    if (pwallet->IsMine(*tx_ref)) {
+        pwallet->AddToWallet(std::move(tx_ref), confirm);
         return NullUniValue;
     }
 
diff --git a/src/wallet/test/coinselector_tests.cpp b/src/wallet/test/coinselector_tests.cpp
index 66f4542cf9..657d0828f2 100644
--- a/src/wallet/test/coinselector_tests.cpp
+++ b/src/wallet/test/coinselector_tests.cpp
@@ -24,8 +24,6 @@ BOOST_FIXTURE_TEST_SUITE(coinselector_tests, WalletTestingSetup)
 // we repeat those tests this many times and only complain if all iterations of the test fail
 #define RANDOM_REPEATS 5
 
-std::vector<std::unique_ptr<CWalletTx>> wtxn;
-
 typedef std::set<CInputCoin> CoinSet;
 
 static std::vector<COutput> vCoins;
@@ -74,16 +72,14 @@ static void add_coin(CWallet& wallet, const CAmount& nValue, int nAge = 6*24, bo
         // so stop vin being empty, and cache a non-zero Debit to fake out IsFromMe()
         tx.vin.resize(1);
     }
-    std::unique_ptr<CWalletTx> wtx = MakeUnique<CWalletTx>(&wallet, MakeTransactionRef(std::move(tx)));
+    CWalletTx* wtx = wallet.AddToWallet(MakeTransactionRef(std::move(tx)), /* confirm= */ {});
     if (fIsFromMe)
     {
         wtx->m_amounts[CWalletTx::DEBIT].Set(ISMINE_SPENDABLE, 1);
         wtx->m_is_cache_empty = false;
     }
-    COutput output(wtx.get(), nInput, nAge, true /* spendable */, true /* solvable */, true /* safe */);
+    COutput output(wtx, nInput, nAge, true /* spendable */, true /* solvable */, true /* safe */);
     vCoins.push_back(output);
-    wallet.AddToWallet(*wtx.get());
-    wtxn.emplace_back(std::move(wtx));
 }
 static void add_coin(const CAmount& nValue, int nAge = 6*24, bool fIsFromMe = false, int nInput=0, bool spendable = false)
 {
@@ -93,7 +89,6 @@ static void add_coin(const CAmount& nValue, int nAge = 6*24, bool fIsFromMe = fa
 static void empty_wallet(void)
 {
     vCoins.clear();
-    wtxn.clear();
     balance = 0;
 }
 
diff --git a/src/wallet/test/wallet_tests.cpp b/src/wallet/test/wallet_tests.cpp
index c049f2f15f..f6273bcecd 100644
--- a/src/wallet/test/wallet_tests.cpp
+++ b/src/wallet/test/wallet_tests.cpp
@@ -331,6 +331,7 @@ BOOST_FIXTURE_TEST_CASE(coin_mark_dirty_immature_credit, TestChain100Setup)
 static int64_t AddTx(CWallet& wallet, uint32_t lockTime, int64_t mockTime, int64_t blockTime)
 {
     CMutableTransaction tx;
+    CWalletTx::Confirmation confirm;
     tx.nLockTime = lockTime;
     SetMockTime(mockTime);
     CBlockIndex* block = nullptr;
@@ -341,23 +342,15 @@ static int64_t AddTx(CWallet& wallet, uint32_t lockTime, int64_t mockTime, int64
         block = inserted.first->second;
         block->nTime = blockTime;
         block->phashBlock = &hash;
+        confirm = {CWalletTx::Status::CONFIRMED, block->nHeight, hash, 0};
     }
 
-    CWalletTx wtx(&wallet, MakeTransactionRef(tx));
-    LOCK(wallet.cs_wallet);
     // If transaction is already in map, to avoid inconsistencies, unconfirmation
     // is needed before confirm again with different block.
-    std::map<uint256, CWalletTx>::iterator it = wallet.mapWallet.find(wtx.GetHash());
-    if (it != wallet.mapWallet.end()) {
+    return wallet.AddToWallet(MakeTransactionRef(tx), confirm, [&](CWalletTx& wtx, bool /* new_tx */) {
         wtx.setUnconfirmed();
-        wallet.AddToWallet(wtx);
-    }
-    if (block) {
-        CWalletTx::Confirmation confirm(CWalletTx::Status::CONFIRMED, block->nHeight, block->GetBlockHash(), 0);
-        wtx.m_confirm = confirm;
-    }
-    wallet.AddToWallet(wtx);
-    return wallet.mapWallet.at(wtx.GetHash()).nTimeSmart;
+        return true;
+    })->nTimeSmart;
 }
 
 // Simple test to verify assignment of CWalletTx::nSmartTime value. Could be
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index a20ede59fd..9c60b62a16 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -783,19 +783,19 @@ bool CWallet::IsSpentKey(const uint256& hash, unsigned int n) const
     return false;
 }
 
-bool CWallet::AddToWallet(const CWalletTx& wtxIn, bool fFlushOnClose)
+CWalletTx* CWallet::AddToWallet(CTransactionRef tx, const CWalletTx::Confirmation& confirm, const UpdateWalletTxFn& update_wtx, bool fFlushOnClose)
 {
     LOCK(cs_wallet);
 
     WalletBatch batch(*database, "r+", fFlushOnClose);
 
-    uint256 hash = wtxIn.GetHash();
+    uint256 hash = tx->GetHash();
 
     if (IsWalletFlagSet(WALLET_FLAG_AVOID_REUSE)) {
         // Mark used destinations
         std::set<CTxDestination> tx_destinations;
 
-        for (const CTxIn& txin : wtxIn.tx->vin) {
+        for (const CTxIn& txin : tx->vin) {
             const COutPoint& op = txin.prevout;
             SetSpentKeyState(batch, op.hash, op.n, true, tx_destinations);
         }
@@ -804,11 +804,13 @@ bool CWallet::AddToWallet(const CWalletTx& wtxIn, bool fFlushOnClose)
     }
 
     // Inserts only if not already there, returns tx inserted or tx found
-    std::pair<std::map<uint256, CWalletTx>::iterator, bool> ret = mapWallet.insert(std::make_pair(hash, wtxIn));
+    auto ret = mapWallet.emplace(std::piecewise_construct, std::forward_as_tuple(hash), std::forward_as_tuple(this, tx));
     CWalletTx& wtx = (*ret.first).second;
     wtx.BindWallet(this);
     bool fInsertedNew = ret.second;
+    bool fUpdated = update_wtx && update_wtx(wtx, fInsertedNew);
     if (fInsertedNew) {
+        wtx.m_confirm = confirm;
         wtx.nTimeReceived = chain().getAdjustedTime();
         wtx.nOrderPos = IncOrderPosNext(&batch);
         wtx.m_it_wtxOrdered = wtxOrdered.insert(std::make_pair(wtx.nOrderPos, &wtx));
@@ -816,43 +818,37 @@ bool CWallet::AddToWallet(const CWalletTx& wtxIn, bool fFlushOnClose)
         AddToSpends(hash);
     }
 
-    bool fUpdated = false;
     if (!fInsertedNew)
     {
-        if (wtxIn.m_confirm.status != wtx.m_confirm.status) {
-            wtx.m_confirm.status = wtxIn.m_confirm.status;
-            wtx.m_confirm.nIndex = wtxIn.m_confirm.nIndex;
-            wtx.m_confirm.hashBlock = wtxIn.m_confirm.hashBlock;
-            wtx.m_confirm.block_height = wtxIn.m_confirm.block_height;
+        if (confirm.status != wtx.m_confirm.status) {
+            wtx.m_confirm.status = confirm.status;
+            wtx.m_confirm.nIndex = confirm.nIndex;
+            wtx.m_confirm.hashBlock = confirm.hashBlock;
+            wtx.m_confirm.block_height = confirm.block_height;
             fUpdated = true;
         } else {
-            assert(wtx.m_confirm.nIndex == wtxIn.m_confirm.nIndex);
-            assert(wtx.m_confirm.hashBlock == wtxIn.m_confirm.hashBlock);
-            assert(wtx.m_confirm.block_height == wtxIn.m_confirm.block_height);
-        }
-        if (wtxIn.fFromMe && wtxIn.fFromMe != wtx.fFromMe)
-        {
-            wtx.fFromMe = wtxIn.fFromMe;
-            fUpdated = true;
+            assert(wtx.m_confirm.nIndex == confirm.nIndex);
+            assert(wtx.m_confirm.hashBlock == confirm.hashBlock);
+            assert(wtx.m_confirm.block_height == confirm.block_height);
         }
         // If we have a witness-stripped version of this transaction, and we
         // see a new version with a witness, then we must be upgrading a pre-segwit
         // wallet.  Store the new version of the transaction with the witness,
         // as the stripped-version must be invalid.
         // TODO: Store all versions of the transaction, instead of just one.
-        if (wtxIn.tx->HasWitness() && !wtx.tx->HasWitness()) {
-            wtx.SetTx(wtxIn.tx);
+        if (tx->HasWitness() && !wtx.tx->HasWitness()) {
+            wtx.SetTx(tx);
             fUpdated = true;
         }
     }
 
     //// debug print
-    WalletLogPrintf("AddToWallet %s  %s%s\n", wtxIn.GetHash().ToString(), (fInsertedNew ? "new" : ""), (fUpdated ? "update" : ""));
+    WalletLogPrintf("AddToWallet %s  %s%s\n", hash.ToString(), (fInsertedNew ? "new" : ""), (fUpdated ? "update" : ""));
 
     // Write to disk
     if (fInsertedNew || fUpdated)
         if (!batch.WriteTx(wtx))
-            return false;
+            return nullptr;
 
     // Break debit/credit balance caches:
     wtx.MarkDirty();
@@ -866,7 +862,7 @@ bool CWallet::AddToWallet(const CWalletTx& wtxIn, bool fFlushOnClose)
 
     if (!strCmd.empty())
     {
-        boost::replace_all(strCmd, "%s", wtxIn.GetHash().GetHex());
+        boost::replace_all(strCmd, "%s", hash.GetHex());
 #ifndef WIN32
         // Substituting the wallet name isn't currently supported on windows
         // because windows shell escaping has not been implemented yet:
@@ -880,7 +876,7 @@ bool CWallet::AddToWallet(const CWalletTx& wtxIn, bool fFlushOnClose)
     }
 #endif
 
-    return true;
+    return &wtx;
 }
 
 void CWallet::LoadToWallet(CWalletTx& wtxIn)
@@ -960,13 +956,9 @@ bool CWallet::AddToWalletIfInvolvingMe(const CTransactionRef& ptx, CWalletTx::Co
                 }
             }
 
-            CWalletTx wtx(this, ptx);
-
             // Block disconnection override an abandoned tx as unconfirmed
             // which means user may have to call abandontransaction again
-            wtx.m_confirm = confirm;
-
-            return AddToWallet(wtx, false);
+            return AddToWallet(MakeTransactionRef(tx), confirm, /* update_wtx= */ nullptr, /* fFlushOnClose= */ false);
         }
     }
     return false;
@@ -3007,21 +2999,22 @@ bool CWallet::CreateTransaction(const std::vector<CRecipient>& vecSend, CTransac
 void CWallet::CommitTransaction(CTransactionRef tx, mapValue_t mapValue, std::vector<std::pair<std::string, std::string>> orderForm)
 {
     LOCK(cs_wallet);
-
-    CWalletTx wtxNew(this, std::move(tx));
-    wtxNew.mapValue = std::move(mapValue);
-    wtxNew.vOrderForm = std::move(orderForm);
-    wtxNew.fTimeReceivedIsTxTime = true;
-    wtxNew.fFromMe = true;
-
-    WalletLogPrintf("CommitTransaction:\n%s", wtxNew.tx->ToString()); /* Continued */
+    WalletLogPrintf("CommitTransaction:\n%s", tx->ToString()); /* Continued */
 
     // Add tx to wallet, because if it has change it's also ours,
     // otherwise just for transaction history.
-    AddToWallet(wtxNew);
+    AddToWallet(tx, {}, [&](CWalletTx& wtx, bool new_tx) {
+        CHECK_NONFATAL(wtx.mapValue.empty());
+        CHECK_NONFATAL(wtx.vOrderForm.empty());
+        wtx.mapValue = std::move(mapValue);
+        wtx.vOrderForm = std::move(orderForm);
+        wtx.fTimeReceivedIsTxTime = true;
+        wtx.fFromMe = true;
+        return true;
+    });
 
     // Notify that old coins are spent
-    for (const CTxIn& txin : wtxNew.tx->vin) {
+    for (const CTxIn& txin : tx->vin) {
         CWalletTx &coin = mapWallet.at(txin.prevout.hash);
         coin.BindWallet(this);
         NotifyTransactionChanged(this, coin.GetHash(), CT_UPDATED);
@@ -3029,7 +3022,7 @@ void CWallet::CommitTransaction(CTransactionRef tx, mapValue_t mapValue, std::ve
 
     // Get the inserted-CWalletTx from mapWallet so that the
     // fInMempool flag is cached properly
-    CWalletTx& wtx = mapWallet.at(wtxNew.GetHash());
+    CWalletTx& wtx = mapWallet.at(tx->GetHash());
 
     if (!fBroadcastTransactions) {
         // Don't submit tx to the mempool
diff --git a/src/wallet/wallet.h b/src/wallet/wallet.h
index 72b3cf1fb8..b1ae975bd8 100644
--- a/src/wallet/wallet.h
+++ b/src/wallet/wallet.h
@@ -886,7 +886,16 @@ public:
     DBErrors ReorderTransactions();
 
     void MarkDirty();
-    bool AddToWallet(const CWalletTx& wtxIn, bool fFlushOnClose=true);
+
+    //! Callback for updating transaction metadata in mapWallet.
+    //!
+    //! @param wtx - reference to mapWallet transaction to update
+    //! @param new_tx - true if wtx is newly inserted, false if it previously existed
+    //!
+    //! @return true if wtx is changed and needs to be saved to disk, otherwise false
+    using UpdateWalletTxFn = std::function<bool(CWalletTx& wtx, bool new_tx)>;
+
+    CWalletTx* AddToWallet(CTransactionRef tx, const CWalletTx::Confirmation& confirm, const UpdateWalletTxFn& update_wtx=nullptr, bool fFlushOnClose=true);
     void LoadToWallet(CWalletTx& wtxIn) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     void transactionAddedToMempool(const CTransactionRef& tx) override;
     void blockConnected(const CBlock& block, int height) override;