feat: Validium mode

[ilitteri]

NOTE: This PR is the Validium base working branch.

Changes

The commits are self-explanatory, so I'll list them and briefly describe what has been made on them.

• Add Validium mode example. This is a binary that implements an example that will be used for testing things out in both modes.
• Use Ethereum's L1 gas price. To have more precise results, we're altering the gas costs for mainnet ones, Ethereum's L1 gas cost is between ~35-47 Gwei, and in zkSync mainnet the L2 fair gas price si 0.1 Gwei (the latter is untouched as it is already set).
• Add --validium-mode flag to zk init command. This changes allow the system to run in Validium mode, spreading out the flag thought the codebase where it is necessary, and also setting the environmental variable for later era-contracts and zksync_server use.
• Do not construct the pubdata in Validium mode. In Validium mode we do not want to send the pubdata to L1, our workaround on this for the PoC is to not construct it. For that, we read the VALIDIUM_MODE env set by the init.ts step.
• Do not charge for pubdata in Validium mode. In Validium mode we also do not want to charge the user for pubdata, for that, thanks to the new fee model (V2) most of the changes can be done in the chain.toml file but one, this is l1_pubdata_price, which when set to 0 gives a huge gas use improvement in addition to the said config (yes, said config impacts the gas used by its own, setting l1_pubdata_price to 0 lowers more the gas usage).

Testing scenario

For comparing results between Rollup and Validium mode we are running the validium_mode_example binary with the system initialized both with zk init and zk init --validium-mode and running the server with zk server.

The validium_mode_example binary deposits some ETH to an account which will be used to deploy an ERC20 contract that is going to be called twice, for minting and transferring. For every mentioned action, some useful data like the transaction hash gas used will be printed to the stdout for later analysis.

In parallel, we are also using a debugging tool developed by Marcin that displays batch info. It is very useful to see data like L2 -> L1 messages, Large L2 -> L1 messages, Published bytecodes, and writes to the storage. As a TLDR, it is a server from which you can query batches by number and analyze said data. It's easy to know in which batch a transaction has been added with the eth_getTransactionByHash method.

In the section below you'll find a step-by-step guide to run said test scenario and see the results by yourself

Step-by-step

For running the example in Rollup mode

• Run zk && zk clean --all && zk init to initialize the system in Rollup mode in a clear environment.
• Run zk server to run the server in one console.
• Run cargo run --release --bin validium_mode_example to run the Validium mode example in another console.
• To run the Batch Status app
  • Clone https://github.com/mm-zk/zksync_tools and cd into it.
  • Run python3 operator/app.py.
  • Go to http://127.0.0.1:5000 in your browser.
  • Query by /batch/<batch_number>

For running the example in Validium mode

• Run zk && zk clean --all && zk init --validium-mode to initialize the system in Validium mode in a clear environment.
• Run zk server to run the server in one console.
• Run cargo run --release --bin validium_mode_example to run the Validium mode example in another console.
• To run the Batch Status app
  • Clone https://github.com/mm-zk/zksync_tools and cd into it.
  • Run python3 operator/app.py.
  • Go to http://127.0.0.1:5000 in your browser.
  • Query by /batch/<batch_number>

Results

Config:

	Rollup	Validium
max_pubdata_per_batch	120.000	1.000.000.000.000
pubdata_overhead_part	0.7	0
compute_overhead_part	0.5	1
batch_overhead_l1_gas	1.000.000	1.000.000
internal_enforced_l1_gas_price	45.000.000.000	45.000.000.000

Fee Model		Gas Used		Ratio	Gas used Improvement
V1	Transaction	Rollup Mode	Validium Mode	Validium gasUsed / Rollup gasUsed	Gas Difference / Rollup gasUsed
	ERC20 Transfer	581.716	130.366
	ERC20 Mint	810.134	129.284
	ERC20 Second Deploy	1.884.480	163.230
	ERC20 First Deploy	71.551.780	490.930
V2
	ERC20 Transfer	794.116	140.431
	ERC20 Mint	1.130.534	139.349
	ERC20 Second Deploy	2.705.730	173.295
	ERC20 First Deploy	TODO	500.995