EIP-4444 Prototyping

This repo contains some early dev work around EIP-4444. Right now, the two main pieces are:

1. A SSZ-based specification for block archive files. These files contain block headers, bodies, and receipts. The specification is tracked in #1.
2. A command line tool bart (block archive tool) to encode/decode these files to/from RLP.

bart: CLI tool

$ bart -h
Usage of bart:
  -f string
    	write data to given output file (default stdout)
  -hash
    	compute ssz hash of block list (read only mode, no output is written)
  -i string
    	format of input data [rlp,rlprc,ssz] (default "ssz")
  -info
    	print block number info (read only mode, no output is written)
  -o string
    	format for output data [rlp,rlprc,ssz], where rlp is the standard RLP block encoding and rlprc is rlp with interleaved receipts (default "ssz")
  -targetsize int
    	target output size (approximate) when encoding from rlp to ssz. Results in multiple sequential ssz files. Set '0' to slurp all data into one output file.

A note on the above formats: rlp is the existing rlp block format exported by geth. rlprc is like rlp, but with the addition of receipts (currently not in geth but in this fork: https://github.com/henridf/go-ethereum/commit/f50b363f78acd5ed0962f57164e60235db37cfe3).

An example that takes an input rlprc-format file, encodes it to ssz, then computes the hash tree root.

$ bart -i rlprc -f out.ssz blocks-receipts-2000000-2100000.rlp

$ bart -info out.ssz 
Format version 0
First block: 2000000, last block: 2100001

$ bart -hash out.ssz 
hash_tree_root: 7eace3fd41367784d233117ef16f1c5828428b8502af8b7d3de317138777787b

Reading/writing multiple files

bart's driving use case is to encode an entire chain history from rlp to ssz. Given that history (on most chains) is too large to fit in a single file, bart supports reading multiple input rlp/rlprc files, and outputting multiple ssz files. The input files are to be listed on the command line and should be contiguous and in order of increasing blocks. Presenting out-of-order and/or non-contiguous input files will result in an error. The -targetsize flag can be used to indicate the (approximate) desired size of output ssz files. When present, bart will write numbered output files with a naming scheme name-0.ssz, name-1.ssz, ..., where name.ssz is the parameter passed to the -o flag.

For example,

bart -i rlprc -o archive.ssz -targesize 100000000 blocks-receipts-0-999999.rlp blocks-receipts-1000000-1999999.rlp blocks-receipts-2000000-2999999.rlp blocks-receipts-3000000-3999999.rlp

will result in the four contiguous rlp block files being read, and written to files archive-0.ssz, archive-1.ssz, ... archive-n.ssz of size approximately 10MB. If the -targetsize parameter is absent, all input is read in and written to a single output file.

This size-based splitting is only supported when converting rlp to ssz. When converting ssz to rlp, if multiple input ssz files are provided, they are all read in and written to a single rlp output.