[c++11] Use std::unique_ptr for block creation.

CreateNewBlock returns a pointer for which the caller takes ownership.
Use std::unique_ptr to make this explicit and simplify handling of these
objects in getblocktemplate.

src/miner.cpp

@@ -29,6 +29,7 @@
 #include <boost/thread.hpp>
 #include <boost/tuple/tuple.hpp>
 #include <queue>
+#include <utility>
 
 using namespace std;
 
@@ -102,14 +103,14 @@ void BlockAssembler::resetBlock()
     blockFinished = false;
 }
 
-CBlockTemplate* BlockAssembler::CreateNewBlock(const CScript& scriptPubKeyIn)
+std::unique_ptr<CBlockTemplate> BlockAssembler::CreateNewBlock(const CScript& scriptPubKeyIn)
 {
     resetBlock();
 
     pblocktemplate.reset(new CBlockTemplate());
 
     if(!pblocktemplate.get())
-        return NULL;
+        return nullptr;
     pblock = &pblocktemplate->block; // pointer for convenience
 
     // Add dummy coinbase tx as first transaction
@@ -164,7 +165,7 @@ CBlockTemplate* BlockAssembler::CreateNewBlock(const CScript& scriptPubKeyIn)
         throw std::runtime_error(strprintf("%s: TestBlockValidity failed: %s", __func__, FormatStateMessage(state)));
     }
 
-    return pblocktemplate.release();
+    return std::move(pblocktemplate);
 }
 
 bool BlockAssembler::isStillDependent(CTxMemPool::txiter iter)

src/miner.h

@@ -160,7 +160,7 @@ private:
 public:
     BlockAssembler(const CChainParams& chainparams);
     /** Construct a new block template with coinbase to scriptPubKeyIn */
-    CBlockTemplate* CreateNewBlock(const CScript& scriptPubKeyIn);
+    std::unique_ptr<CBlockTemplate> CreateNewBlock(const CScript& scriptPubKeyIn);
 
 private:
     // utility functions

src/rpc/mining.cpp

@@ -22,6 +22,7 @@
 #include "utilstrencodings.h"
 #include "validationinterface.h"
 
+#include <memory>
 #include <stdint.h>
 
 #include <boost/assign/list_of.hpp>
@@ -508,12 +509,12 @@ UniValue getblocktemplate(const UniValue& params, bool fHelp)
     // Update block
     static CBlockIndex* pindexPrev;
     static int64_t nStart;
-    static CBlockTemplate* pblocktemplate;
+    static std::unique_ptr<CBlockTemplate> pblocktemplate;
     if (pindexPrev != chainActive.Tip() ||
         (mempool.GetTransactionsUpdated() != nTransactionsUpdatedLast && GetTime() - nStart > 5))
     {
         // Clear pindexPrev so future calls make a new block, despite any failures from here on
-        pindexPrev = NULL;
+        pindexPrev = nullptr;
 
         // Store the pindexBest used before CreateNewBlock, to avoid races
         nTransactionsUpdatedLast = mempool.GetTransactionsUpdated();
@@ -521,11 +522,6 @@ UniValue getblocktemplate(const UniValue& params, bool fHelp)
         nStart = GetTime();
 
         // Create new block
-        if(pblocktemplate)
-        {
-            delete pblocktemplate;
-            pblocktemplate = NULL;
-        }
         CScript scriptDummy = CScript() << OP_TRUE;
         pblocktemplate = BlockAssembler(Params()).CreateNewBlock(scriptDummy);
         if (!pblocktemplate)

src/test/miner_tests.cpp

@@ -18,6 +18,8 @@
 
 #include "test/test_bitcoin.h"
 
+#include <memory>
+
 #include <boost/test/unit_test.hpp>
 
 BOOST_FIXTURE_TEST_SUITE(miner_tests, TestingSetup)
@@ -105,7 +107,7 @@ void TestPackageSelection(const CChainParams& chainparams, CScript scriptPubKey,
     uint256 hashHighFeeTx = tx.GetHash();
     mempool.addUnchecked(hashHighFeeTx, entry.Fee(50000).Time(GetTime()).SpendsCoinbase(false).FromTx(tx));
 
-    CBlockTemplate *pblocktemplate = BlockAssembler(chainparams).CreateNewBlock(scriptPubKey);
+    std::unique_ptr<CBlockTemplate> pblocktemplate = BlockAssembler(chainparams).CreateNewBlock(scriptPubKey);
     BOOST_CHECK(pblocktemplate->block.vtx[1].GetHash() == hashParentTx);
     BOOST_CHECK(pblocktemplate->block.vtx[2].GetHash() == hashHighFeeTx);
     BOOST_CHECK(pblocktemplate->block.vtx[3].GetHash() == hashMediumFeeTx);
@@ -183,7 +185,7 @@ BOOST_AUTO_TEST_CASE(CreateNewBlock_validity)
 {
     const CChainParams& chainparams = Params(CBaseChainParams::MAIN);
     CScript scriptPubKey = CScript() << ParseHex("04678afdb0fe5548271967f1a67130b7105cd6a828e03909a67962e0ea1f61deb649f6bc3f4cef38c4f35504e51ec112de5c384df7ba0b8d578a4c702b6bf11d5f") << OP_CHECKSIG;
-    CBlockTemplate *pblocktemplate;
+    std::unique_ptr<CBlockTemplate> pblocktemplate;
     CMutableTransaction tx,tx2;
     CScript script;
     uint256 hash;
@@ -225,11 +227,9 @@ BOOST_AUTO_TEST_CASE(CreateNewBlock_validity)
         BOOST_CHECK(state.IsValid());
         pblock->hashPrevBlock = pblock->GetHash();
     }
-    delete pblocktemplate;
 
     // Just to make sure we can still make simple blocks
     BOOST_CHECK(pblocktemplate = BlockAssembler(chainparams).CreateNewBlock(scriptPubKey));
-    delete pblocktemplate;
 
     const CAmount BLOCKSUBSIDY = 50*COIN;
     const CAmount LOWFEE = CENT;
@@ -268,7 +268,6 @@ BOOST_AUTO_TEST_CASE(CreateNewBlock_validity)
         tx.vin[0].prevout.hash = hash;
     }
     BOOST_CHECK(pblocktemplate = BlockAssembler(chainparams).CreateNewBlock(scriptPubKey));
-    delete pblocktemplate;
     mempool.clear();
 
     // block size > limit
@@ -289,7 +288,6 @@ BOOST_AUTO_TEST_CASE(CreateNewBlock_validity)
         tx.vin[0].prevout.hash = hash;
     }
     BOOST_CHECK(pblocktemplate = BlockAssembler(chainparams).CreateNewBlock(scriptPubKey));
-    delete pblocktemplate;
     mempool.clear();
 
     // orphan in mempool, template creation fails
@@ -313,7 +311,6 @@ BOOST_AUTO_TEST_CASE(CreateNewBlock_validity)
     hash = tx.GetHash();
     mempool.addUnchecked(hash, entry.Fee(HIGHERFEE).Time(GetTime()).SpendsCoinbase(true).FromTx(tx));
     BOOST_CHECK(pblocktemplate = BlockAssembler(chainparams).CreateNewBlock(scriptPubKey));
-    delete pblocktemplate;
     mempool.clear();
 
     // coinbase in mempool, template creation fails
@@ -371,7 +368,6 @@ BOOST_AUTO_TEST_CASE(CreateNewBlock_validity)
         chainActive.SetTip(next);
     }
     BOOST_CHECK(pblocktemplate = BlockAssembler(chainparams).CreateNewBlock(scriptPubKey));
-    delete pblocktemplate;
     // Extend to a 210000-long block chain.
     while (chainActive.Tip()->nHeight < 210000) {
         CBlockIndex* prev = chainActive.Tip();
@@ -384,7 +380,6 @@ BOOST_AUTO_TEST_CASE(CreateNewBlock_validity)
         chainActive.SetTip(next);
     }
     BOOST_CHECK(pblocktemplate = BlockAssembler(chainparams).CreateNewBlock(scriptPubKey));
-    delete pblocktemplate;
     // Delete the dummy blocks again.
     while (chainActive.Tip()->nHeight > nHeight) {
         CBlockIndex* del = chainActive.Tip();
@@ -477,7 +472,6 @@ BOOST_AUTO_TEST_CASE(CreateNewBlock_validity)
     // but relative locked txs will if inconsistently added to mempool.
     // For now these will still generate a valid template until BIP68 soft fork
     BOOST_CHECK_EQUAL(pblocktemplate->block.vtx.size(), 3);
-    delete pblocktemplate;
     // However if we advance height by 1 and time by 512, all of them should be mined
     for (int i = 0; i < CBlockIndex::nMedianTimeSpan; i++)
         chainActive.Tip()->GetAncestor(chainActive.Tip()->nHeight - i)->nTime += 512; //Trick the MedianTimePast
@@ -486,7 +480,6 @@ BOOST_AUTO_TEST_CASE(CreateNewBlock_validity)
 
     BOOST_CHECK(pblocktemplate = BlockAssembler(chainparams).CreateNewBlock(scriptPubKey));
     BOOST_CHECK_EQUAL(pblocktemplate->block.vtx.size(), 5);
-    delete pblocktemplate;
 
     chainActive.Tip()->nHeight--;
     SetMockTime(0);

src/test/test_bitcoin.cpp

@@ -22,6 +22,8 @@
 
 #include "test/testutil.h"
 
+#include <memory>
+
 #include <boost/filesystem.hpp>
 #include <boost/test/unit_test.hpp>
 #include <boost/thread.hpp>
@@ -98,7 +100,7 @@ CBlock
 TestChain100Setup::CreateAndProcessBlock(const std::vector<CMutableTransaction>& txns, const CScript& scriptPubKey)
 {
     const CChainParams& chainparams = Params();
-    CBlockTemplate *pblocktemplate = BlockAssembler(chainparams).CreateNewBlock(scriptPubKey);
+    std::unique_ptr<CBlockTemplate> pblocktemplate = BlockAssembler(chainparams).CreateNewBlock(scriptPubKey);
     CBlock& block = pblocktemplate->block;
 
     // Replace mempool-selected txns with just coinbase plus passed-in txns:
@@ -115,7 +117,6 @@ TestChain100Setup::CreateAndProcessBlock(const std::vector<CMutableTransaction>&
     ProcessNewBlock(state, chainparams, NULL, &block, true, NULL);
 
     CBlock result = block;
-    delete pblocktemplate;
     return result;
 }