Add DefaultMinerThreads chain parameter

src/chainparams.cpp

@@ -112,6 +112,7 @@ class CMainParams : public CChainParams {
         nRPCPort = 8332;
         bnProofOfWorkLimit = ~uint256(0) >> 32;
         nSubsidyHalvingInterval = 210000;
+        nMinerThreads = 0;
 
         // Build the genesis block. Note that the output of the genesis coinbase cannot
         // be spent as it did not originally exist in the database.
@@ -233,6 +234,7 @@ class CRegTestParams : public CTestNetParams {
         pchMessageStart[2] = 0xb5;
         pchMessageStart[3] = 0xda;
         nSubsidyHalvingInterval = 150;
+        nMinerThreads = 1;
         bnProofOfWorkLimit = ~uint256(0) >> 1;
         genesis.nTime = 1296688602;
         genesis.nBits = 0x207fffff;

src/chainparams.h

@@ -57,6 +57,8 @@ class CChainParams
     int GetDefaultPort() const { return nDefaultPort; }
     const uint256& ProofOfWorkLimit() const { return bnProofOfWorkLimit; }
     int SubsidyHalvingInterval() const { return nSubsidyHalvingInterval; }
+    /* Used if GenerateBitcoins is called with a negative number of threads */
+    int DefaultMinerThreads() const { return nMinerThreads; }
     virtual const CBlock& GenesisBlock() const = 0;
     virtual bool RequireRPCPassword() const { return true; }
     /* Make miner wait to have peers to avoid wasting work */
@@ -82,6 +84,7 @@ class CChainParams
     uint256 bnProofOfWorkLimit;
     int nSubsidyHalvingInterval;
     string strDataDir;
+    int nMinerThreads;
     vector<CDNSSeedData> vSeeds;
     std::vector<unsigned char> base58Prefixes[MAX_BASE58_TYPES];
 };

src/miner.cpp

@@ -652,8 +652,9 @@ void GenerateBitcoins(bool fGenerate, CWallet* pwallet, int nThreads)
     static boost::thread_group* minerThreads = NULL;
 
     if (nThreads < 0) {
-        if (Params().NetworkID() == CChainParams::REGTEST)
-            nThreads = 1;
+        // In regtest threads defaults to 1
+        if (Params().DefaultMinerThreads())
+            nThreads = Params().DefaultMinerThreads();
         else
             nThreads = boost::thread::hardware_concurrency();
     }