Alternative crosslink data construction, take 1 #1278
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Properties: * Optimal data packing * Fixed depth * All data is encoded; makes fraud proofs not-too-difficult Weaknesses: * Uses SSZ serialization. * Positions of blocks dynamic, so accesses require an extra Merkle branch
| ) | ||
| MAXLEN = ( | ||
| BYTES_PER_SHARD_BLOCK_HEADER + BYTES_PER_SHARD_BLOCK_BODY | ||
| ) * SHARD_SLOTS_PER_EPOCH * MAX_EPOCHS_PER_CROSSLINK |
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SHARD_SLOTS_PER_EPOCH is undefined. Should it be SHARD_SLOTS_PER_BEACON_SLOT(#1276) * SLOTS_PER_EPOCH?
| @@ -76,7 +79,7 @@ The following types are defined, mapping into `DomainType` (little endian): | |||
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| | Name | Value | | |||
| | - | - | | |||
| | `PLACEHOLDER` | `2**32` | | |||
| | `PLACEHOLDER` | `2**3` | | |||
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I changed it to 2**3 for testing.
| @@ -107,7 +110,7 @@ class ShardBlock(Container): | |||
| shard: Shard | |||
| beacon_chain_root: Bytes32 | |||
| parent_root: Bytes32 | |||
| data: ShardBlockBody | |||
| body: ShardBlockBody | |||
| def compute_crosslink_data(blocks: Sequence[ShardBlock]) -> Bytes32: | ||
| """ | ||
| Flattens a series of blocks. Designed to be equivalent to SSZ serializing a list of | ||
| flattened blocks with one empty block at the end as a termination marker. |
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Could you elaborate what do you mean by "one empty block at the end" here?
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Could you elaborate what's the main advantage of this one over just using SSZ serialize like:
class CrosslinkingBlocks:
data: List[ShardBlock, SHARD_SLOTS_PER_EPOCH * MAX_EPOCHS_PER_CROSSLINK]
assert len(blocks) <= SHARD_SLOTS_PER_EPOCH * MAX_EPOCHS_PER_CROSSLINK
crosslinking_blocks = CrosslinkingBlocks(data=blocks)
return serialize(crosslinking_blocks)?
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| ```python | ||
| def flatten_block(block: ShardBlock) -> Bytes: | ||
| return zpad(serialize(get_shard_header(block)), BYTES_PER_SHARD_BLOCK_HEADER) + serialize(block.body) |
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I added serialize() here, correct?
Co-Authored-By: Hsiao-Wei Wang <[email protected]>
| positions = [4 * len(blocks)] | ||
| bodies = [] | ||
| for block in blocks: | ||
| bodies.append(flatten_block(block)) |
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Doesn't flattening the block here reduce our ability to construct proofs about components of a block through the crosslink root? Still possible but not as clean due to flattening to bytes
I wouldn't see that as a weakness, if it is the right tool for the job, I think we should be able to bring it into consensus. |
agreed. |
Co-Authored-By: Hsiao-Wei Wang <[email protected]>
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Closing -- superseded by #1294 |
Properties:
Weaknesses: