BlockIngestor.java

package snowblossom;

import com.google.protobuf.ByteString;

import snowblossom.proto.Block;
import snowblossom.proto.BlockSummary;
import snowblossom.proto.BlockHeader;

import snowblossom.trie.HashUtils;

import snowblossom.db.DB;
import org.junit.Assert;


import java.util.logging.Logger;
import java.util.logging.Level;

import java.math.BigInteger;

/**
 * This class takes in new blocks, validates them and stores them in the db.
 * In appropritate, updates the tip of the chain.
 */
public class BlockIngestor
{

  private static final Logger logger = Logger.getLogger("snowblossom.blockchain");
  private SnowBlossomNode node;
  private DB db;
  private NetworkParams params;
  
  private volatile BlockSummary chainhead;

  private static final ByteString HEAD = ByteString.copyFrom(new String("head").getBytes());

  private LRUCache<ChainHash, Long> block_pull_map = new LRUCache<>(1000);


  public BlockIngestor(SnowBlossomNode node)
  {
    this.node = node;
    this.db = node.getDB();
    this.params = node.getParams();

    chainhead = db.getBlockSummaryMap().get(HEAD);
    if (chainhead != null)
    {
      logger.info(String.format("Loaded chain tip: %d %s", 
        chainhead.getHeader().getBlockHeight(), 
        new ChainHash(chainhead.getHeader().getSnowHash())));
    }
  }

  public boolean ingestBlock(Block blk)
    throws ValidationException
  {
    Validation.checkBlockBasics(node.getParams(), blk, true);

    ChainHash blockhash = new ChainHash(blk.getHeader().getSnowHash());

    if (db.getBlockSummaryMap().containsKey(blockhash.getBytes() ))
    {
      return false;
    }

    ChainHash prevblock = new ChainHash(blk.getHeader().getPrevBlockHash());

    BlockSummary prev_summary;
    if (prevblock.equals(ChainHash.ZERO_HASH))
    {
      prev_summary = BlockSummary.newBuilder()
          .setHeader(BlockHeader.newBuilder().setUtxoRootHash( HashUtils.hashOfEmpty() ).build())
        .build();
    }
    else
    {
      prev_summary = db.getBlockSummaryMap().get( prevblock.getBytes() );
    }

    if (prev_summary == null)
    {
      return false;
    }

    // TODO - deeper validation here
    BlockSummary summary = getNewSummary(blk.getHeader(), prev_summary, node.getParams());

    Validation.deepBlockValidation(node, blk, prev_summary);

    db.getBlockMap().put( blockhash.getBytes(), blk);
    db.getBlockSummaryMap().put( blockhash.getBytes(), summary);

    BigInteger summary_work_sum = BlockchainUtil.readInteger(summary.getWorkSum());
    BigInteger chainhead_work_sum = BigInteger.ZERO;
    if (chainhead != null)
    {
      chainhead_work_sum = BlockchainUtil.readInteger(chainhead.getWorkSum());
    }

    if (summary_work_sum.compareTo(chainhead_work_sum) > 0)
    {
      chainhead = summary;
      db.getBlockSummaryMap().put(HEAD, summary);
      //System.out.println("UTXO at new root: " + HexUtil.getHexString(summary.getHeader().getUtxoRootHash()));
      //node.getUtxoHashedTrie().printTree(summary.getHeader().getUtxoRootHash());

      updateHeights(summary);

      logger.info(String.format("New chain tip: Height %d %s (tx:%d sz:%d)", blk.getHeader().getBlockHeight(), blockhash, blk.getTransactionsCount(), blk.toByteString().size()));

      SnowUserService u = node.getUserService();
      if (u != null)
      {
        u.tickleBlocks();
      }
    }


    node.getPeerage().sendAllTips();
    return true;

  }

  private void updateHeights(BlockSummary summary)
  {
    while(true)
    {
      int height = summary.getHeader().getBlockHeight();
      ChainHash found = db.getBlockHashAtHeight(height);
      ChainHash hash = new ChainHash(summary.getHeader().getSnowHash());
      if ((found == null) || (!found.equals(hash)))
      {
        db.setBlockHashAtHeight(height, hash);
        if (height == 0) return;
        summary = db.getBlockSummaryMap().get(summary.getHeader().getPrevBlockHash());
      }
      else
      {
        return;
      }
    }
    
  }

  public BlockSummary getHead()
  {
    return chainhead;
  }

  public static BlockSummary getNewSummary(BlockHeader header, BlockSummary prev_summary, NetworkParams params)
  {
    BlockSummary.Builder bs = BlockSummary.newBuilder();

    BigInteger target = BlockchainUtil.targetBytesToBigInteger(header.getTarget());

    BigInteger slice = BigInteger.valueOf(1024L);

    // So a block at max target is 'slice' number of work units
    // A block at half the target (harder) is twice the number of slices.
    BigInteger work_in_block = params.getMaxTarget().multiply(slice).divide(target);
    BigInteger prev_work_sum = BlockchainUtil.readInteger(prev_summary.getWorkSum());


    BigInteger worksum = prev_work_sum.add(work_in_block);

    bs.setWorkSum(worksum.toString());

    long weight = params.getAvgWeight();
    long decay = 1000L - weight;
    BigInteger decay_bi = BigInteger.valueOf(decay);
    BigInteger weight_bi = BigInteger.valueOf(weight);

    long block_time;
    long prev_block_time;
    BigInteger prev_target_avg;

    if (prev_summary.getHeader().getTimestamp() == 0)
    { // first block, just pick a time
      block_time = params.getBlockTimeTarget();
      prev_block_time = params.getBlockTimeTarget();
      prev_target_avg = params.getMaxTarget();
    }
    else
    {
      block_time = header.getTimestamp() - prev_summary.getHeader().getTimestamp();
      prev_block_time = prev_summary.getBlocktimeAverageMs();
      prev_target_avg = BlockchainUtil.readInteger(prev_summary.getTargetAverage());
    }
    int field = prev_summary.getActivatedField();
    bs.setActivatedField( field );

    SnowFieldInfo next_field = params.getSnowFieldInfo(field + 1);
    if (next_field != null)
    {

      
      /*System.out.println(String.format("Field %d Target %f, activation %f", field+1,
        PowUtil.getDiffForTarget(prev_target_avg), 
        PowUtil.getDiffForTarget(next_field.getActivationTarget())));*/
      if (prev_target_avg.compareTo(next_field.getActivationTarget()) <= 0)
      {
        bs.setActivatedField( field + 1 );
      }
    }

    bs.setBlocktimeAverageMs(  (prev_block_time * decay + block_time * weight) / 1000L );

    bs.setTargetAverage( 
      prev_target_avg.multiply(decay_bi)
        .add(target.multiply(weight_bi))
        .divide(BigInteger.valueOf(1000L))
        .toString());

    bs.setHeader(header);
    
    return bs.build();

  }

  public boolean reserveBlock(ChainHash hash)
  {
    synchronized(block_pull_map)
    {
      long tm = System.currentTimeMillis();
      if (block_pull_map.containsKey(hash) && (block_pull_map.get(hash) + 15000L > tm))
      {
        return false;
      }
      block_pull_map.put(hash, tm);
      return true;
    }
  }

}