Merge bitcoin#617: [Wallet] Adjust staking properties to lower orphan…

… rates.

4c862f2 Lower stake hashdrift to 30 seconds. (presstab)
355e2d3 Update zPIV stake set more frequently. (presstab)

Tree-SHA512: fcbfeb23bdf5e84c38d64780b97cd0a3f6d7ecb630b2b2e7ba13daf2538d691409be70d889b418b3165c79c0ec0bcc8080dd1aec072d559bf77b1e9093af75e7

src/kernel.cpp

@@ -315,7 +315,7 @@ bool Stake(CStakeInput* stakeInput, unsigned int nBits, unsigned int nTimeBlockF
     bool fSuccess = false;
     unsigned int nTryTime = 0;
     int nHeightStart = chainActive.Height();
-    int nHashDrift = 45;
+    int nHashDrift = 30;
     CDataStream ssUniqueID = stakeInput->GetUniqueness();
     CAmount nValueIn = stakeInput->GetValue();
     for (int i = 0; i < nHashDrift; i++) //iterate the hashing

src/wallet.cpp

@@ -2115,9 +2115,15 @@ bool CWallet::SelectStakeCoins(std::list<std::unique_ptr<CStakeInput> >& listInp
 
     //zPIV
     if (GetBoolArg("-zpivstake", true) && chainActive.Height() > Params().Zerocoin_Block_V2_Start() && !IsSporkActive(SPORK_16_ZEROCOIN_MAINTENANCE_MODE)) {
-        //Add zPIV
-        set<CMintMeta> setMints = zpivTracker->ListMints(true, true, true);
+        //Only update zPIV set once per update interval
+        bool fUpdate = false;
+        static int64_t nTimeLastUpdate = 0;
+        if (GetAdjustedTime() - nTimeLastUpdate > nStakeSetUpdateTime) {
+            fUpdate = true;
+            nTimeLastUpdate = GetAdjustedTime();
+        }
 
+        set<CMintMeta> setMints = zpivTracker->ListMints(true, true, fUpdate);
         for (auto meta : setMints) {
             if (meta.hashStake == 0) {
                 CZerocoinMint mint;
@@ -2944,16 +2950,10 @@ bool CWallet::CreateCoinStake(const CKeyStore& keystore, unsigned int nBits, int
     if (nBalance > 0 && nBalance <= nReserveBalance)
         return false;
 
-    // Initialize as static and don't update the set on every run of CreateCoinStake() in order to lighten resource use
-    static int nLastStakeSetUpdate = 0;
-    static list<std::unique_ptr<CStakeInput> > listInputs;
-    if (GetTime() - nLastStakeSetUpdate > nStakeSetUpdateTime) {
-        listInputs.clear();
-        if (!SelectStakeCoins(listInputs, nBalance - nReserveBalance))
-            return false;
-
-        nLastStakeSetUpdate = GetTime();
-    }
+    // Get the list of stakable inputs
+    std::list<std::unique_ptr<CStakeInput> > listInputs;
+    if (!SelectStakeCoins(listInputs, nBalance - nReserveBalance))
+        return false;
 
     if (listInputs.empty())
         return false;
@@ -3084,7 +3084,6 @@ bool CWallet::CreateCoinStake(const CKeyStore& keystore, unsigned int nBits, int
     }
 
     // Successfully generated coinstake
-    nLastStakeSetUpdate = 0; //this will trigger stake set to repopulate next round
     return true;
 }