feat: bb faster init

[charlielye]

Faster init. At least in most cases. It builds the circuit first, to determine number of gates, then only loads the amount of CRS actually needed. This speeds up startup time a lot.

The tradeoff however is that for larger circuits you may spend a lot of time building the circuit, at which point you'd have been faster just ripping in the whole CRS. Still, for most of our cases right now this is the better option.

[AztecBot]

Benchmark results

All benchmarks are run on txs on the Benchmarking contract on the repository. Each tx consists of a batch call to create_note and increment_balance, which guarantees that each tx has a private call, a nested private call, a public call, and a nested public call, as well as an emitted private note, an unencrypted log, and public storage read and write.

L2 block published to L1

Each column represents the number of txs on an L2 block published to L1.

Metric	8 txs	32 txs	128 txs
l1_rollup_calldata_size_in_bytes	45444	179588	716132
l1_rollup_calldata_gas	222984	867896	3449444
l1_rollup_execution_gas	842071	3595004	22204813
l2_block_processing_time_in_ms	1030	3938	15483
note_successful_decrypting_time_in_ms	329	1008	3737
note_trial_decrypting_time_in_ms	32	107	138
l2_block_building_time_in_ms	8976	36065	149394
l2_block_rollup_simulation_time_in_ms	6651	26725	105602
l2_block_public_tx_process_time_in_ms	2286	9213	42980

L2 chain processing

Each column represents the number of blocks on the L2 chain where each block has 16 txs.

Metric	10 blocks	20 blocks	30 blocks
node_history_sync_time_in_ms	32088	77913	139870
note_history_successful_decrypting_time_in_ms	4877	13573	20706
note_history_trial_decrypting_time_in_ms	146	264	283
node_database_size_in_bytes	1192773	1899443	2755113
pxe_database_size_in_bytes	54187	108338	162578

Circuits stats

Stats on running time and I/O sizes collected for every circuit run across all benchmarks.

Circuit	circuit_simulation_time_in_ms	circuit_input_size_in_bytes	circuit_output_size_in_bytes
private-kernel-init	56.10889570552147	56577	14745
private-kernel-ordering	30.312116564417177	20137	8089
base-rollup	870	631604	810
root-rollup	38.1219512195122	4072	1097
private-kernel-inner	52.18132716049383	72288	14745
public-kernel-private-input	51.93441358024691	37359	14745
public-kernel-non-first-iteration	31.192901234567902	37401	14745
merge-rollup	0.9651162790697675	2592	873