CBR 3

src/gridcoin/staking/reward.cpp

@@ -38,6 +38,15 @@ CAmount GRC::GetConstantBlockReward(const CBlockIndex* index)
     CAmount MIN_CBR = 0;
     CAmount MAX_CBR = 0;
 
+    // GetConstantBlockReward is called with a CBlockIndex pointer as an argument, which means it is expected to
+    // return the correct value at that position in the chain. The TryActive call in the protocol registry returns
+    // the CURRENT active value if that exists. This is not what we need if index is not actually pIndexBest.
+    // Here we find the last protocol entry in the historical linked list of protocol entries for the key "blockreward1"
+    // that has a timestamp that is less than or equal to the block time. This will filter for the correct historical
+    // value of blockreward1 that was valid at the index given. One could argue there is some fuzziness here in using
+    // the block time versus the transaction context time implied by the protocol registry entry; however the actual
+    // change of CBR must occur on a block boundary anyway, and as long as there is consistent application for consensus
+    // for V13+ we are safe.
     ProtocolEntryOption reward_entry = GetProtocolRegistry().TryLastBeforeTimestamp("blockreward1",
                                                                                     index->GetBlockTime());