Replace CCoins-based CTxMemPool::pruneSpent with isSpent

Author: sipa

src/rest.cpp

@@ -513,8 +513,7 @@ static bool rest_getutxos(HTTPRequest* req, const std::string& strURIPart)
             uint256 hash = vOutPoints[i].hash;
             bool hit = false;
             if (view.GetCoins(hash, coins)) {
-                mempool.pruneSpent(hash, coins);
-                if (coins.IsAvailable(vOutPoints[i].n)) {
+                if (coins.IsAvailable(vOutPoints[i].n) && !mempool.isSpent(vOutPoints[i])) {
                     hit = true;
                     // Safe to index into vout here because IsAvailable checked if it's off the end of the array, or if
                     // n is valid but points to an already spent output (IsNull).

src/rpc/blockchain.cpp

@@ -973,9 +973,8 @@ UniValue gettxout(const JSONRPCRequest& request)
     if (fMempool) {
         LOCK(mempool.cs);
         CCoinsViewMemPool view(pcoinsTip, mempool);
-        if (!view.GetCoins(hash, coins))
+        if (!view.GetCoins(hash, coins) || mempool.isSpent(COutPoint(hash, n))) // TODO: this should be done by the CCoinsViewMemPool
             return NullUniValue;
-        mempool.pruneSpent(hash, coins); // TODO: this should be done by the CCoinsViewMemPool
     } else {
         if (!pcoinsTip->GetCoins(hash, coins))
             return NullUniValue;

src/txmempool.cpp

@@ -343,17 +343,10 @@ CTxMemPool::CTxMemPool(CBlockPolicyEstimator* estimator) :
     nCheckFrequency = 0;
 }
 
-void CTxMemPool::pruneSpent(const uint256 &hashTx, CCoins &coins)
+bool CTxMemPool::isSpent(const COutPoint& outpoint)
 {
     LOCK(cs);
-
-    auto it = mapNextTx.lower_bound(COutPoint(hashTx, 0));
-
-    // iterate over all COutPoints in mapNextTx whose hash equals the provided hashTx
-    while (it != mapNextTx.end() && it->first->hash == hashTx) {
-        coins.Spend(it->first->n); // and remove those outputs from coins
-        it++;
-    }
+    return mapNextTx.count(outpoint);
 }
 
 unsigned int CTxMemPool::GetTransactionsUpdated() const

src/txmempool.h

@@ -509,7 +509,7 @@ class CTxMemPool
     void _clear(); //lock free
     bool CompareDepthAndScore(const uint256& hasha, const uint256& hashb);
     void queryHashes(std::vector<uint256>& vtxid);
-    void pruneSpent(const uint256& hash, CCoins &coins);
+    bool isSpent(const COutPoint& outpoint);
     unsigned int GetTransactionsUpdated() const;
     void AddTransactionsUpdated(unsigned int n);
     /**