Define CTxMemPool::lookupOutpoint.

The memory pool mainly tracks transactions by txid; however, in some
places, we actually need to look up the transaction by the output hash
it creates (which will be different from the txid after segwit light).

This introduces a new method CTxMemPool::lookupOutpoint, which is meant
to be used for these situations (even though for now it does the same
as lookup).  It also updates the code to use the new method where
this is appropriate.

Author: domob1812

divi/src/BlockMemoryPoolTransactionCollector.cpp

@@ -206,7 +206,7 @@ std::vector<TxPriority> BlockMemoryPoolTransactionCollector::PrioritizeMempoolTr
             // Read prev transaction
             if (!view.HaveCoins(txin.prevout.hash)) {
                 CTransaction prevTx;
-                if(!mempool_.lookup(txin.prevout.hash, prevTx)) {
+                if(!mempool_.lookupOutpoint(txin.prevout.hash, prevTx)) {
                     // This should never happen; all transactions in the memory
                     // pool should connect to either transactions in the chain
                     // or other transactions in the memory pool.

divi/src/rpcblockchain.cpp

@@ -218,8 +218,9 @@ Value getrawmempool(const Array& params, bool fHelp)
             info.push_back(Pair("currentpriority", e.GetPriority(chainActive.Height())));
             const CTransaction& tx = e.GetTx();
             set<string> setDepends;
-            BOOST_FOREACH (const CTxIn& txin, tx.vin) {
-                if (mempool.exists(txin.prevout.hash))
+            for (const CTxIn& txin : tx.vin) {
+                CTransaction dummyResult;
+                if (mempool.lookupOutpoint(txin.prevout.hash, dummyResult))
                     setDepends.insert(txin.prevout.hash.ToString());
             }
             Array depends(setDepends.begin(), setDepends.end());

divi/src/txmempool.cpp

@@ -638,7 +638,7 @@ void CTxMemPool::removeCoinbaseSpends(const CCoinsViewCache* pcoins, unsigned in
         const CTransaction& tx = entry.second.GetTx();
         for (const auto& txin : tx.vin) {
             CTransaction tx2;
-            if (lookup(txin.prevout.hash, tx2))
+            if (lookupOutpoint(txin.prevout.hash, tx2))
                 continue;
             const CCoins* coins = pcoins->AccessCoins(txin.prevout.hash);
             if (fSanityCheck) assert(coins);
@@ -723,7 +723,7 @@ void CTxMemPool::check(const CCoinsViewCache* pcoins, const BlockMap& blockIndex
         for (const auto& txin : tx.vin) {
             // Check that every mempool transaction's inputs refer to available coins, or other mempool tx's.
             CTransaction tx2;
-            if (lookup(txin.prevout.hash, tx2)) {
+            if (lookupOutpoint(txin.prevout.hash, tx2)) {
                 assert(tx2.vout.size() > txin.prevout.n && !tx2.vout[txin.prevout.n].IsNull());
                 fDependsWait = true;
             } else {
@@ -803,6 +803,13 @@ bool CTxMemPool::lookupBareTxid(const uint256& btxid, CTransaction& result) cons
     return true;
 }
 
+bool CTxMemPool::lookupOutpoint(const uint256& hash, CTransaction& result) const
+{
+    /* For now (until we add the UTXO hasher and segwit light), the outpoint
+       is just the transaction ID.  */
+    return lookup(hash, result);
+}
+
 CFeeRate CTxMemPool::estimateFee(int nBlocks) const
 {
     LOCK(cs);
@@ -882,7 +889,7 @@ bool CCoinsViewMemPool::GetCoins(const uint256& txid, CCoins& coins) const
     // conflict with the underlying cache, and it cannot have pruned entries (as it contains full)
     // transactions. First checking the underlying cache risks returning a pruned entry instead.
     CTransaction tx;
-    if (mempool.lookup(txid, tx)) {
+    if (mempool.lookupOutpoint(txid, tx)) {
         coins = CCoins(tx, MEMPOOL_HEIGHT);
         return true;
     }
@@ -891,5 +898,9 @@ bool CCoinsViewMemPool::GetCoins(const uint256& txid, CCoins& coins) const
 
 bool CCoinsViewMemPool::HaveCoins(const uint256& txid) const
 {
-    return mempool.exists(txid) || base->HaveCoins(txid);
+    CTransaction dummy;
+    if (mempool.lookupOutpoint(txid, dummy))
+        return true;
+
+    return base->HaveCoins(txid);
 }

divi/src/txmempool.h

@@ -201,6 +201,10 @@ class CTxMemPool
     bool lookup(const uint256& hash, CTransaction& result) const;
     bool lookupBareTxid(const uint256& btxid, CTransaction& result) const;
 
+    /** Looks up a transaction by its outpoint for spending, taking potential changes
+     *  from the raw txid (e.g. segwit light) into account.  */
+    bool lookupOutpoint(const uint256& hash, CTransaction& result) const;
+
     /** Estimate fee rate needed to get into the next nBlocks */
     CFeeRate estimateFee(int nBlocks) const;