Chainparams: Refactor: Decouple main::GetBlockValue() from Params() [renamed GetBlockSubsidy]

Remove redundant getter CChainParams::SubsidyHalvingInterval()

src/chainparams.h

@@ -49,7 +49,6 @@ public:
     const CMessageHeader::MessageStartChars& MessageStart() const { return pchMessageStart; }
     const std::vector<unsigned char>& AlertKey() const { return vAlertPubKey; }
     int GetDefaultPort() const { return nDefaultPort; }
-    int SubsidyHalvingInterval() const { return consensus.nSubsidyHalvingInterval; }
 
     /** Used if GenerateBitcoins is called with a negative number of threads */
     int DefaultMinerThreads() const { return nMinerThreads; }

src/main.cpp

@@ -1188,19 +1188,17 @@ bool ReadBlockFromDisk(CBlock& block, const CBlockIndex* pindex)
     return true;
 }
 
-CAmount GetBlockValue(int nHeight, const CAmount& nFees)
+CAmount GetBlockSubsidy(int nHeight, const Consensus::Params& consensusParams)
 {
-    CAmount nSubsidy = 50 * COIN;
-    int halvings = nHeight / Params().SubsidyHalvingInterval();
-
+    int halvings = nHeight / consensusParams.nSubsidyHalvingInterval;
     // Force block reward to zero when right shift is undefined.
     if (halvings >= 64)
-        return nFees;
+        return 0;
 
+    CAmount nSubsidy = 50 * COIN;
     // Subsidy is cut in half every 210,000 blocks which will occur approximately every 4 years.
     nSubsidy >>= halvings;
-
-    return nSubsidy + nFees;
+    return nSubsidy;
 }
 
 bool IsInitialBlockDownload()
@@ -1809,10 +1807,11 @@ bool ConnectBlock(const CBlock& block, CValidationState& state, CBlockIndex* pin
     int64_t nTime1 = GetTimeMicros(); nTimeConnect += nTime1 - nTimeStart;
     LogPrint("bench", "      - Connect %u transactions: %.2fms (%.3fms/tx, %.3fms/txin) [%.2fs]\n", (unsigned)block.vtx.size(), 0.001 * (nTime1 - nTimeStart), 0.001 * (nTime1 - nTimeStart) / block.vtx.size(), nInputs <= 1 ? 0 : 0.001 * (nTime1 - nTimeStart) / (nInputs-1), nTimeConnect * 0.000001);
 
-    if (block.vtx[0].GetValueOut() > GetBlockValue(pindex->nHeight, nFees))
+    CAmount blockReward = nFees + GetBlockSubsidy(pindex->nHeight, chainparams.GetConsensus());
+    if (block.vtx[0].GetValueOut() > blockReward)
         return state.DoS(100,
                          error("ConnectBlock(): coinbase pays too much (actual=%d vs limit=%d)",
-                               block.vtx[0].GetValueOut(), GetBlockValue(pindex->nHeight, nFees)),
+                               block.vtx[0].GetValueOut(), blockReward),
                                REJECT_INVALID, "bad-cb-amount");
 
     if (!control.Wait())

src/main.h

@@ -202,7 +202,7 @@ std::string GetWarnings(std::string strFor);
 bool GetTransaction(const uint256 &hash, CTransaction &tx, uint256 &hashBlock, bool fAllowSlow = false);
 /** Find the best known block, and make it the tip of the block chain */
 bool ActivateBestChain(CValidationState &state, CBlock *pblock = NULL);
-CAmount GetBlockValue(int nHeight, const CAmount& nFees);
+CAmount GetBlockSubsidy(int nHeight, const Consensus::Params& consensusParams);
 
 /**
  * Prune block and undo files (blk???.dat and undo???.dat) so that the disk space used is less than a user-defined target.

src/miner.cpp

@@ -91,6 +91,7 @@ void UpdateTime(CBlockHeader* pblock, const Consensus::Params& consensusParams,
 
 CBlockTemplate* CreateNewBlock(const CScript& scriptPubKeyIn)
 {
+    const CChainParams& chainparams = Params();
     // Create new block
     auto_ptr<CBlockTemplate> pblocktemplate(new CBlockTemplate());
     if(!pblocktemplate.get())
@@ -320,7 +321,7 @@ CBlockTemplate* CreateNewBlock(const CScript& scriptPubKeyIn)
         LogPrintf("CreateNewBlock(): total size %u\n", nBlockSize);
 
         // Compute final coinbase transaction.
-        txNew.vout[0].nValue = GetBlockValue(nHeight, nFees);
+        txNew.vout[0].nValue = nFees + GetBlockSubsidy(nHeight, chainparams.GetConsensus());
         txNew.vin[0].scriptSig = CScript() << nHeight << OP_0;
         pblock->vtx[0] = txNew;
         pblocktemplate->vTxFees[0] = -nFees;

src/test/main_tests.cpp

@@ -2,25 +2,58 @@
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
-#include "primitives/transaction.h"
+#include "chainparams.h"
 #include "main.h"
 
 #include "test/test_bitcoin.h"
 
+#include <boost/signals2/signal.hpp>
 #include <boost/test/unit_test.hpp>
 
 BOOST_FIXTURE_TEST_SUITE(main_tests, TestingSetup)
 
+static void TestBlockSubsidyHalvings(const Consensus::Params& consensusParams)
+{
+    int maxHalvings = 64;
+    CAmount nInitialSubsidy = 50 * COIN;
+
+    CAmount nPreviousSubsidy = nInitialSubsidy * 2; // for height == 0
+    BOOST_CHECK_EQUAL(nPreviousSubsidy, nInitialSubsidy * 2);
+    for (int nHalvings = 0; nHalvings < maxHalvings; nHalvings++) {
+        int nHeight = nHalvings * consensusParams.nSubsidyHalvingInterval;
+        CAmount nSubsidy = GetBlockSubsidy(nHeight, consensusParams);
+        BOOST_CHECK(nSubsidy <= nInitialSubsidy);
+        BOOST_CHECK_EQUAL(nSubsidy, nPreviousSubsidy / 2);
+        nPreviousSubsidy = nSubsidy;
+    }
+    BOOST_CHECK_EQUAL(GetBlockSubsidy(maxHalvings * consensusParams.nSubsidyHalvingInterval, consensusParams), 0);
+}
+
+static void TestBlockSubsidyHalvings(int nSubsidyHalvingInterval)
+{
+    Consensus::Params consensusParams;
+    consensusParams.nSubsidyHalvingInterval = nSubsidyHalvingInterval;
+    TestBlockSubsidyHalvings(consensusParams);
+}
+
+BOOST_AUTO_TEST_CASE(block_subsidy_test)
+{
+    TestBlockSubsidyHalvings(Params(CBaseChainParams::MAIN).GetConsensus()); // As in main
+    TestBlockSubsidyHalvings(150); // As in regtest
+    TestBlockSubsidyHalvings(1000); // Just another interval
+}
+
 BOOST_AUTO_TEST_CASE(subsidy_limit_test)
 {
+    const Consensus::Params& consensusParams = Params(CBaseChainParams::MAIN).GetConsensus();
     CAmount nSum = 0;
     for (int nHeight = 0; nHeight < 14000000; nHeight += 1000) {
-        CAmount nSubsidy = GetBlockValue(nHeight, 0);
+        CAmount nSubsidy = GetBlockSubsidy(nHeight, consensusParams);
         BOOST_CHECK(nSubsidy <= 50 * COIN);
         nSum += nSubsidy * 1000;
         BOOST_CHECK(MoneyRange(nSum));
     }
-    BOOST_CHECK(nSum == 2099999997690000ULL);
+    BOOST_CHECK_EQUAL(nSum, 2099999997690000ULL);
 }
 
 bool ReturnFalse() { return false; }