Remove the DataAvailabilityHeader from Block

[evan-forbes]

Summary

We don't strictly need the DataAvailabilityHeader to be in Block, so we can remove it.

Problem Definition

Since the DataAvailabilityHeader does not have to be in Block, and validators already have to regenerate the DataAvailabilityHeader to verify the block, then we could optimize the size of the Block struct by removing the DataAvailabilityHeader field.

Proposal

Instead of passing the DataAvailabilityHeader with the Block, we can remove the DataAvailabilityHeader field and instead generate it after receiving the Block. The DataAvailabilityHeader would then be passed to any function that needs it, or regenerated.

Note: this is purely an optimization, and should therefore not be prioritized until later. This could also be accomplished in conjunction with #505, as that will be required to fully remove the DAH from the block

Implementation

• Remove the DataAvailabilityHeader from block
• Regenerate the DAH when verifying the block
• Save the DAH in BlockMeta by passing it the SaveBlock method
• Pass the DAH to PutBlock (assuming we keep PutBlock at all)

blocked by:
#518
#505

[adlerjohn]

Makes sense

[evan-forbes]

We also have to the option to only remove the DAH from the proto type of tmrpoto.Block and not from the tendermint type types.Block, which would give us the optimization while also allowing us to pass the DAH around with the Block for convenience purposes.

[evan-forbes]

closed by the merging of #534