GenerateBlock generates a valid, but unsigned, candidate block from the current pending transaction pool. It returns the new block and a snapshot of what the state snapshot is if the block is applied. After generating the block, the pending transaction pool will be empty.
(ctx context.Context, prev *legacy.Block, snapshot *state.Snapshot, now time.Time, txs []*legacy.Tx)
| 49 | // After generating the block, the pending transaction pool will be |
| 50 | // empty. |
| 51 | func (c *Chain) GenerateBlock(ctx context.Context, prev *legacy.Block, snapshot *state.Snapshot, now time.Time, txs []*legacy.Tx) (*legacy.Block, *state.Snapshot, error) { |
| 52 | // TODO(kr): move this into a lower-level package (e.g. chain/protocol/bc) |
| 53 | // so that other packages (e.g. chain/protocol/validation) unit tests can |
| 54 | // call this function. |
| 55 | |
| 56 | timestampMS := bc.Millis(now) |
| 57 | if timestampMS < prev.TimestampMS { |
| 58 | return nil, nil, fmt.Errorf("timestamp %d is earlier than prevblock timestamp %d", timestampMS, prev.TimestampMS) |
| 59 | } |
| 60 | |
| 61 | // Make a copy of the snapshot that we can apply our changes to. |
| 62 | newSnapshot := state.Copy(c.state.snapshot) |
| 63 | newSnapshot.PruneNonces(timestampMS) |
| 64 | |
| 65 | b := &legacy.Block{ |
| 66 | BlockHeader: legacy.BlockHeader{ |
| 67 | Version: 1, |
| 68 | Height: prev.Height + 1, |
| 69 | PreviousBlockHash: prev.Hash(), |
| 70 | TimestampMS: timestampMS, |
| 71 | BlockCommitment: legacy.BlockCommitment{ |
| 72 | ConsensusProgram: prev.ConsensusProgram, |
| 73 | }, |
| 74 | }, |
| 75 | } |
| 76 | |
| 77 | var txEntries []*bc.Tx |
| 78 | |
| 79 | for _, tx := range txs { |
| 80 | if len(b.Transactions) >= maxBlockTxs { |
| 81 | break |
| 82 | } |
| 83 | |
| 84 | // Filter out transactions that are not well-formed. |
| 85 | err := c.ValidateTx(tx.Tx) |
| 86 | if err != nil { |
| 87 | // TODO(bobg): log this? |
| 88 | continue |
| 89 | } |
| 90 | |
| 91 | // Filter out transactions that are not yet valid, or no longer |
| 92 | // valid, per the block's timestamp. |
| 93 | if tx.Tx.MinTimeMs > 0 && tx.Tx.MinTimeMs > b.TimestampMS { |
| 94 | continue |
| 95 | } |
| 96 | if tx.Tx.MaxTimeMs > 0 && tx.Tx.MaxTimeMs < b.TimestampMS { |
| 97 | continue |
| 98 | } |
| 99 | |
| 100 | // Filter out double-spends etc. |
| 101 | err = newSnapshot.ApplyTx(tx.Tx) |
| 102 | if err != nil { |
| 103 | // TODO(bobg): log this? |
| 104 | continue |
| 105 | } |
| 106 | |
| 107 | b.Transactions = append(b.Transactions, tx) |
| 108 | txEntries = append(txEntries, tx.Tx) |