Chain trust score computation.
[NovacoinLibrary.git] / Novacoin / CBlockStore.cs
index 6753bfe..94fc2b6 100644 (file)
@@ -16,7 +16,7 @@ namespace Novacoin
     /// Block headers table
     /// </summary>
     [Table("BlockStorage")]
-    class CBlockStoreItem
+    public class CBlockStoreItem
     {
         /// <summary>
         /// Item ID in the database
@@ -61,6 +61,11 @@ namespace Novacoin
         public uint nNonce { get; set; }
 
         /// <summary>
+        /// Next block hash.
+        /// </summary>
+        public byte[] nextHash { get; set; }
+
+        /// <summary>
         /// Block type flags
         /// </summary>
         public BlockType BlockTypeFlag { get; set; }
@@ -71,14 +76,14 @@ namespace Novacoin
         public long nStakeModifier { get; set; }
 
         /// <summary>
-        /// Stake entropy bit
+        /// Chain trust score
         /// </summary>
-        public byte nEntropyBit { get; set; }
+        public byte[] ChainTrust { get; set; }
 
         /// <summary>
-        /// Next block hash
+        /// Proof-of-Stake hash
         /// </summary>
-        public byte[] NextHash { get; set; }
+        public byte[] hashProofOfStake { get; set; }
 
         /// <summary>
         /// Block height
@@ -212,6 +217,222 @@ namespace Novacoin
                 return false;
             }
         }
+
+        /// <summary>
+        /// Previous block cursor
+        /// </summary>
+        [Ignore]
+        public CBlockStoreItem prev {
+            get { return CBlockStore.Instance.GetCursor(prevHash); }
+        }
+
+        /// <summary>
+        /// Next block cursor
+        /// </summary>
+        [Ignore]
+        public CBlockStoreItem next
+        {
+            get { return CBlockStore.Instance.GetCursor(nextHash); }
+        }
+
+        [Ignore]
+        bool IsInMainChain
+        {
+            get { return (next != null); }
+        }
+
+        /// <summary>
+        /// STake modifier generation flag
+        /// </summary>
+        [Ignore]
+        public bool GeneratedStakeModifier
+        {
+            get { return (BlockTypeFlag & BlockType.BLOCK_STAKE_MODIFIER) != 0; }
+        }
+
+        /// <summary>
+        /// Stake entropy bit
+        /// </summary>
+        [Ignore]
+        public uint StakeEntropyBit
+        {
+            get { return ((uint)(BlockTypeFlag & BlockType.BLOCK_STAKE_ENTROPY) >> 1); }
+        }
+
+        /// <summary>
+        /// Sets stake modifier and flag.
+        /// </summary>
+        /// <param name="nModifier">New stake modifier.</param>
+        /// <param name="fGeneratedStakeModifier">Set generation flag?</param>
+        public void SetStakeModifier(long nModifier, bool fGeneratedStakeModifier)
+        {
+            nStakeModifier = nModifier;
+            if (fGeneratedStakeModifier)
+                BlockTypeFlag |= BlockType.BLOCK_STAKE_MODIFIER;
+        }
+
+        /// <summary>
+        /// Set entropy bit.
+        /// </summary>
+        /// <param name="nEntropyBit">Entropy bit value (0 or 1).</param>
+        /// <returns>False if value is our of range.</returns>
+        public bool SetStakeEntropyBit(byte nEntropyBit)
+        {
+            if (nEntropyBit > 1)
+                return false;
+            BlockTypeFlag |= (nEntropyBit != 0 ? BlockType.BLOCK_STAKE_ENTROPY : 0);
+            return true;
+        }
+
+        /// <summary>
+        /// Set proof-of-stake flag.
+        /// </summary>
+        public void SetProofOfStake()
+        {
+            BlockTypeFlag |= BlockType.BLOCK_PROOF_OF_STAKE;
+        }
+
+        /// <summary>
+        /// Block has no proof-of-stake flag.
+        /// </summary>
+        [Ignore]
+        public bool IsProofOfWork
+        {
+            get { return (BlockTypeFlag & BlockType.BLOCK_PROOF_OF_STAKE) == 0; }
+        }
+
+        /// <summary>
+        /// Block has proof-of-stake flag set.
+        /// </summary>
+        [Ignore]
+        public bool IsProofOfStake 
+        {
+            get { return (BlockTypeFlag & BlockType.BLOCK_PROOF_OF_STAKE) != 0; }
+        }
+
+        /// <summary>
+        /// Chain trust score.
+        /// </summary>
+        [Ignore]
+        public uint256 nChainTrust {
+            get
+            {
+                if (ChainTrust.Length != 32)
+                {
+                    byte[] tmp = ChainTrust;
+                    Array.Resize(ref tmp, 32);
+                    ChainTrust = tmp;
+                }
+
+                return ChainTrust;
+            }
+            set { ChainTrust = Interop.TrimArray(value); }
+        }
+
+        /// <summary>
+        /// Block trust score.
+        /// </summary>
+        [Ignore]
+        public uint256 nBlockTrust
+        {
+            get
+            {
+                uint256 nTarget = 0;
+                nTarget.Compact = nBits;
+
+                /* Old protocol */
+                if (nTime < NetUtils.nChainChecksSwitchTime)
+                {
+                    return IsProofOfStake ? (new uint256(1) << 256) / (nTarget + 1) : 1;
+                }
+
+                /* New protocol */
+
+                // Calculate work amount for block
+                var nPoWTrust = NetUtils.nPoWBase / (nTarget + 1);
+
+                // Set nPowTrust to 1 if we are checking PoS block or PoW difficulty is too low
+                nPoWTrust = (IsProofOfStake || !nPoWTrust) ? 1 : nPoWTrust;
+
+                // Return nPoWTrust for the first 12 blocks
+                if (prev == null || prev.nHeight < 12)
+                    return nPoWTrust;
+
+                CBlockStoreItem currentIndex = prev;
+
+                if (IsProofOfStake)
+                {
+                    var nNewTrust = (new uint256(1) << 256) / (nTarget + 1);
+
+                    // Return 1/3 of score if parent block is not the PoW block
+                    if (!prev.IsProofOfWork)
+                    {
+                        return nNewTrust / 3;
+                    }
+
+                    int nPoWCount = 0;
+
+                    // Check last 12 blocks type
+                    while (prev.nHeight - currentIndex.nHeight < 12)
+                    {
+                        if (currentIndex.IsProofOfWork)
+                        {
+                            nPoWCount++;
+                        }
+                        currentIndex = currentIndex.prev;
+                    }
+
+                    // Return 1/3 of score if less than 3 PoW blocks found
+                    if (nPoWCount < 3)
+                    {
+                        return nNewTrust / 3;
+                    }
+
+                    return nNewTrust;
+                }
+                else
+                {
+                    var nLastBlockTrust = prev.nChainTrust - prev.prev.nChainTrust;
+
+                    // Return nPoWTrust + 2/3 of previous block score if two parent blocks are not PoS blocks
+                    if (!prev.IsProofOfStake || !prev.prev.IsProofOfStake)
+                    {
+                        return nPoWTrust + (2 * nLastBlockTrust / 3);
+                    }
+
+                    int nPoSCount = 0;
+
+                    // Check last 12 blocks type
+                    while (prev.nHeight - currentIndex.nHeight < 12)
+                    {
+                        if (currentIndex.IsProofOfStake)
+                        {
+                            nPoSCount++;
+                        }
+                        currentIndex = currentIndex.prev;
+                    }
+
+                    // Return nPoWTrust + 2/3 of previous block score if less than 7 PoS blocks found
+                    if (nPoSCount < 7)
+                    {
+                        return nPoWTrust + (2 * nLastBlockTrust / 3);
+                    }
+
+                    nTarget.Compact = prev.nBits;
+
+                    if (!nTarget)
+                    {
+                        return 0;
+                    }
+
+                    var nNewTrust = (new uint256(1) << 256) / (nTarget + 1);
+
+                    // Return nPoWTrust + full trust score for previous block nBits
+                    return nPoWTrust + nNewTrust;
+                }
+            }
+        }
+
     }
 
     /// <summary>
@@ -219,10 +440,9 @@ namespace Novacoin
     /// </summary>
     public enum BlockType
     {
-        PROOF_OF_WORK,
-        PROOF_OF_WORK_MODIFIER,
-        PROOF_OF_STAKE,
-        PROOF_OF_STAKE_MODIFIER
+        BLOCK_PROOF_OF_STAKE = (1 << 0), // is proof-of-stake block
+        BLOCK_STAKE_ENTROPY = (1 << 1), // entropy bit for stake modifier
+        BLOCK_STAKE_MODIFIER = (1 << 2), // regenerated stake modifier
     };
 
     /// <summary>
@@ -362,6 +582,8 @@ namespace Novacoin
 
             fStreamReadWrite = File.Open(strBlockFile, FileMode.OpenOrCreate, FileAccess.ReadWrite);
 
+            Instance = this;
+
             if (firstInit)
             {
                 lock (LockObj)
@@ -418,8 +640,6 @@ namespace Novacoin
                     blockMap.TryAdd(item.Hash, item);
                 }
             }
-
-            Instance = this;
         }
 
         public bool GetTransaction(uint256 TxID, ref CTransaction tx)
@@ -448,12 +668,23 @@ namespace Novacoin
                 return false;
             }
 
-            // TODO: compute chain trust, set stake entropy bit, record proof-of-stake hash value
+            // Compute chain trust score
+            itemTemplate.nChainTrust = (itemTemplate.prev != null ? itemTemplate.prev.nChainTrust : 0) + itemTemplate.nBlockTrust;
+
+            if (!itemTemplate.SetStakeEntropyBit(Entropy.GetStakeEntropyBit(itemTemplate.nHeight, blockHash)))
+            {
+                return false; // SetStakeEntropyBit() failed
+            }
+
+            // TODO: set stake entropy bit, record proof-of-stake hash value
 
             // TODO: compute stake modifier
 
             // Add to index
-            itemTemplate.BlockTypeFlag = block.IsProofOfStake ? BlockType.PROOF_OF_STAKE : BlockType.PROOF_OF_WORK;
+            if (block.IsProofOfStake)
+            {
+                itemTemplate.SetProofOfStake();
+            }
 
             if (!itemTemplate.WriteToFile(ref writer, ref block))
             {
@@ -501,9 +732,9 @@ namespace Novacoin
 
         public bool AcceptBlock(ref CBlock block)
         {
-            uint256 hash = block.header.Hash;
+            uint256 nHash = block.header.Hash;
 
-            if (blockMap.ContainsKey(hash))
+            if (blockMap.ContainsKey(nHash))
             {
                 // Already have this block.
                 return false;
@@ -542,7 +773,7 @@ namespace Novacoin
             // Write block to file.
             var itemTemplate = new CBlockStoreItem()
             {
-                nHeight = nHeight
+                nHeight = nHeight,
             };
 
             itemTemplate.FillHeader(block.header);
@@ -571,6 +802,38 @@ namespace Novacoin
             return false;
         }
 
+        /// <summary>
+        /// Get block cursor from map.
+        /// </summary>
+        /// <param name="blockHash">block hash</param>
+        /// <returns>Cursor or null</returns>
+        public CBlockStoreItem GetCursor(uint256 blockHash)
+        {
+            if (blockHash == 0)
+            {
+                // Genesis block has zero prevHash and no parent.
+                return null;
+            }
+
+            // First, check our block map.
+            CBlockStoreItem item = null;
+            if (blockMap.TryGetValue(blockHash, out item))
+            {
+                return item;
+            }
+
+            // Trying to get cursor from the database.
+            var QueryBlockCursor = dbConn.Query<CBlockStoreItem>("select * from [BlockStorage] where [Hash] = ?", (byte[])blockHash);
+
+            if (QueryBlockCursor.Count == 1)
+            {
+                return QueryBlockCursor[0];
+            }
+
+            // Nothing found.
+            return null;
+        }
+
         public bool ProcessBlock(ref CBlock block)
         {
             var blockHash = block.header.Hash;