Remove use of CCoinsViewMemPool::GetCoin in wallet code

This commit does not change behavior.

src/Makefile.am

@@ -154,6 +154,7 @@ BITCOIN_CORE_H = \
   netaddress.h \
   netbase.h \
   netmessagemaker.h \
+  node/coin.h \
   node/transaction.h \
   noui.h \
   optional.h \
@@ -262,6 +263,7 @@ libbitcoin_server_a_SOURCES = \
   miner.cpp \
   net.cpp \
   net_processing.cpp \
+  node/coin.cpp \
   node/transaction.cpp \
   noui.cpp \
   outputtype.cpp \

src/interfaces/chain.cpp

@@ -9,6 +9,7 @@
 #include <interfaces/handler.h>
 #include <interfaces/wallet.h>
 #include <net.h>
+#include <node/coin.h>
 #include <policy/fees.h>
 #include <policy/policy.h>
 #include <policy/rbf.h>
@@ -287,6 +288,7 @@ public:
         }
         return true;
     }
+    void findCoins(std::map<COutPoint, Coin>& coins) override { return FindCoins(coins); }
     double guessVerificationProgress(const uint256& block_hash) override
     {
         LOCK(cs_main);

src/interfaces/chain.h

@@ -19,6 +19,7 @@ class CFeeRate;
 class CRPCCommand;
 class CScheduler;
 class CValidationState;
+class Coin;
 class uint256;
 enum class RBFTransactionState;
 struct CBlockLocator;
@@ -168,6 +169,11 @@ public:
         int64_t* time = nullptr,
         int64_t* max_time = nullptr) = 0;
 
+    //! Look up unspent output information. Returns coins in the mempool and in
+    //! the current chain UTXO set. Iterates through all the keys in the map and
+    //! populates the values.
+    virtual void findCoins(std::map<COutPoint, Coin>& coins) = 0;
+
     //! Estimate fraction of total transactions verified if blocks up to
     //! the specified block hash are verified.
     virtual double guessVerificationProgress(const uint256& block_hash) = 0;

src/node/coin.cpp

@@ -0,0 +1,22 @@
+// Copyright (c) 2019 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <node/coin.h>
+
+#include <txmempool.h>
+#include <validation.h>
+
+void FindCoins(std::map<COutPoint, Coin>& coins)
+{
+    LOCK2(cs_main, ::mempool.cs);
+    assert(pcoinsTip);
+    CCoinsViewCache& chain_view = *::pcoinsTip;
+    CCoinsViewMemPool mempool_view(&chain_view, ::mempool);
+    for (auto& coin : coins) {
+        if (!mempool_view.GetCoin(coin.first, coin.second)) {
+            // Either the coin is not in the CCoinsViewCache or is spent. Clear it.
+            coin.second.Clear();
+        }
+    }
+}

src/node/coin.h

@@ -0,0 +1,22 @@
+// Copyright (c) 2019 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_NODE_COIN_H
+#define BITCOIN_NODE_COIN_H
+
+#include <map>
+
+class COutPoint;
+class Coin;
+
+/**
+ * Look up unspent output information. Returns coins in the mempool and in the
+ * current chain UTXO set. Iterates through all the keys in the map and
+ * populates the values.
+ *
+ * @param[in,out] coins map to fill
+ */
+void FindCoins(std::map<COutPoint, Coin>& coins);
+
+#endif // BITCOIN_NODE_COIN_H

src/rpc/rawtransaction.cpp

@@ -11,6 +11,7 @@
 #include <core_io.h>
 #include <index/txindex.h>
 #include <init.h>
+#include <interfaces/chain.h>
 #include <key_io.h>
 #include <keystore.h>
 #include <merkleblock.h>
@@ -790,23 +791,20 @@ static UniValue combinerawtransaction(const JSONRPCRequest& request)
     return EncodeHexTx(CTransaction(mergedTx));
 }
 
+// TODO(https://github.com/bitcoin/bitcoin/pull/10973#discussion_r267084237):
+// This function is called from both wallet and node rpcs
+// (signrawtransactionwithwallet and signrawtransactionwithkey). It should be
+// moved to a util file so wallet code doesn't need to link against node code.
+// Also the dependency on interfaces::Chain should be removed, so
+// signrawtransactionwithkey doesn't need access to a Chain instance.
 UniValue SignTransaction(interfaces::Chain& chain, CMutableTransaction& mtx, const UniValue& prevTxsUnival, CBasicKeyStore *keystore, bool is_temp_keystore, const UniValue& hashType)
 {
     // Fetch previous transactions (inputs):
-    CCoinsView viewDummy;
-    CCoinsViewCache view(&viewDummy);
-    {
-        LOCK2(cs_main, mempool.cs);
-        CCoinsViewCache &viewChain = *pcoinsTip;
-        CCoinsViewMemPool viewMempool(&viewChain, mempool);
-        view.SetBackend(viewMempool); // temporarily switch cache backend to db+mempool view
-
-        for (const CTxIn& txin : mtx.vin) {
-            view.AccessCoin(txin.prevout); // Load entries from viewChain into view; can fail.
-        }
-
-        view.SetBackend(viewDummy); // switch back to avoid locking mempool for too long
+    std::map<COutPoint, Coin> coins;
+    for (const CTxIn& txin : mtx.vin) {
+        coins[txin.prevout]; // Create empty map entry keyed by prevout.
     }
+    chain.findCoins(coins);
 
     // Add previous txouts given in the RPC call:
     if (!prevTxsUnival.isNull()) {
@@ -838,10 +836,10 @@ UniValue SignTransaction(interfaces::Chain& chain, CMutableTransaction& mtx, con
             CScript scriptPubKey(pkData.begin(), pkData.end());
 
             {
-                const Coin& coin = view.AccessCoin(out);
-                if (!coin.IsSpent() && coin.out.scriptPubKey != scriptPubKey) {
+                auto coin = coins.find(out);
+                if (coin != coins.end() && !coin->second.IsSpent() && coin->second.out.scriptPubKey != scriptPubKey) {
                     std::string err("Previous output scriptPubKey mismatch:\n");
-                    err = err + ScriptToAsmStr(coin.out.scriptPubKey) + "\nvs:\n"+
+                    err = err + ScriptToAsmStr(coin->second.out.scriptPubKey) + "\nvs:\n"+
                         ScriptToAsmStr(scriptPubKey);
                     throw JSONRPCError(RPC_DESERIALIZATION_ERROR, err);
                 }
@@ -852,7 +850,7 @@ UniValue SignTransaction(interfaces::Chain& chain, CMutableTransaction& mtx, con
                     newcoin.out.nValue = AmountFromValue(find_value(prevOut, "amount"));
                 }
                 newcoin.nHeight = 1;
-                view.AddCoin(out, std::move(newcoin), true);
+                coins[out] = std::move(newcoin);
             }
 
             // if redeemScript and private keys were given, add redeemScript to the keystore so it can be signed
@@ -896,15 +894,15 @@ UniValue SignTransaction(interfaces::Chain& chain, CMutableTransaction& mtx, con
     // Sign what we can:
     for (unsigned int i = 0; i < mtx.vin.size(); i++) {
         CTxIn& txin = mtx.vin[i];
-        const Coin& coin = view.AccessCoin(txin.prevout);
-        if (coin.IsSpent()) {
+        auto coin = coins.find(txin.prevout);
+        if (coin == coins.end() || coin->second.IsSpent()) {
             TxInErrorToJSON(txin, vErrors, "Input not found or already spent");
             continue;
         }
-        const CScript& prevPubKey = coin.out.scriptPubKey;
-        const CAmount& amount = coin.out.nValue;
+        const CScript& prevPubKey = coin->second.out.scriptPubKey;
+        const CAmount& amount = coin->second.out.nValue;
 
-        SignatureData sigdata = DataFromTransaction(mtx, i, coin.out);
+        SignatureData sigdata = DataFromTransaction(mtx, i, coin->second.out);
         // Only sign SIGHASH_SINGLE if there's a corresponding output:
         if (!fHashSingle || (i < mtx.vout.size())) {
             ProduceSignature(*keystore, MutableTransactionSignatureCreator(&mtx, i, amount, nHashType), prevPubKey, sigdata);
@@ -914,7 +912,7 @@ UniValue SignTransaction(interfaces::Chain& chain, CMutableTransaction& mtx, con
 
         // amount must be specified for valid segwit signature
         if (amount == MAX_MONEY && !txin.scriptWitness.IsNull()) {
-            throw JSONRPCError(RPC_TYPE_ERROR, strprintf("Missing amount for %s", coin.out.ToString()));
+            throw JSONRPCError(RPC_TYPE_ERROR, strprintf("Missing amount for %s", coin->second.out.ToString()));
         }
 
         ScriptError serror = SCRIPT_ERR_OK;