Optimistic Rollups: Sequencer & Batch Submitter

OVM Transaction Queue

Source: https://docs.optimism.io/

This is where the sequencer is allowed to post transactions which they recieved off chain to be applied to the rollup chain. Transactions can only be moved from the OVM Transaction Queue to the Canonical Transaction Chain if the transactions in the L1->L2 transaction queue are not older than some number of L1 blocks.

Sequencer (Geth L2 node)

It looks like the Sequencer is a Geth L2 node while ROLLUP_VERIFIER_ENABLE is not set.

Log from sequencer Ingesting transactions from L1

Handle the enqueue'd transactions. This codepath is only useful for the sequencer, as the verifier should only handle transactions from sequencer batch append and queue batch append. The transactions need to be played in order and there is no guarantee of order when it comes to the txcache iteration, so collect an array of pointers and then sort them by index.

INFO [11-16|07:41:49.097] Ingesting transactions from L1           count=0
INFO [11-16|07:41:49.098] Sequencer Ingest Queue Status            syncing=false tip-height=42
DEBUG[11-16|07:41:59.661] Served rollup_getInfo                    conn=172.21.0.5:48970 reqid=75 t=89.136µs
DEBUG[11-16|07:41:59.698] Served eth_blockNumber                   conn=172.21.0.5:48976 reqid=76 t=37.69µs
DEBUG[11-16|07:41:59.699] Served eth_chainId                       conn=172.21.0.5:48978 reqid=77 t=25.656µs
DEBUG[11-16|07:42:01.466] Current full block not old enough        number=0 hash=f07849…7c07aa delay=90000

Batch Submitter (node.js service)

Repo: https://github.com/ethereum-optimism/optimism-monorepo

File path: optimism-monorepo/packages/batch-submitter/exec/run-batch-submitter.js

Contains an executable batch submitter service which watches L1 and a local L2 node and submits batches to the CanonicalTransactionChain & StateCommitmentChain based on its local information.

const requiredEnvVars = {
    SEQUENCER_PRIVATE_KEY: 'SEQUENCER_PRIVATE_KEY',
    L1_NODE_WEB3_URL: 'L1_NODE_WEB3_URL',
    L2_NODE_WEB3_URL: 'L2_NODE_WEB3_URL',
    MIN_TX_SIZE: 'MIN_TX_SIZE',
    MAX_TX_SIZE: 'MAX_TX_SIZE',
    MAX_BATCH_SIZE: 'MAX_BATCH_SIZE',
    POLL_INTERVAL: 'POLL_INTERVAL',
    NUM_CONFIRMATIONS: 'NUM_CONFIRMATIONS',
    FINALITY_CONFIRMATIONS: 'FINALITY_CONFIRMATIONS',
    RUN_TX_BATCH_SUBMITTER: 'RUN_TX_BATCH_SUBMITTER',
    RUN_STATE_BATCH_SUBMITTER: 'RUN_STATE_BATCH_SUBMITTER',
};

After ROLLUP_VERIFIER_ENABLE=true:

batch_submitter_1  | 2020-11-30T13:21:05.853Z error:oe:batch-submitter:tx-chain Verifier mode enabled! Batch submitter only compatible with sequencer mode
optimism-integration_batch_submitter_1 exited with code 1

Geth L2 console output:

batch_submitter_1  | 2020-11-30T13:50:43.187Z info:oe:batch-submitter:tx-chain No txs to submit. Skipping batch submission...
geth_l2_1          | DEBUG[11-30|13:50:51.878] Current full block not old enough        number=0 hash=cfd33d…8e5e6d delay=90000
geth_l2_1          | DEBUG[11-30|13:50:52.774] get common ancestor                      index=6846271 count=2
geth_l2_1          | DEBUG[11-30|13:50:52.774] Processing block                         height=6846272 hash=0xc803cb335076c33a7a12a1c03bde81ac41dc39b844fcbef21956b6accd420235
geth_l2_1          | INFO [11-30|13:50:52.783] Ingesting transactions from L1           count=0
geth_l2_1          | DEBUG[11-30|13:50:52.783] Processing block                         height=6846273 hash=0x0c3c1e64611183c3511ed8cf3123efd8c4efa89e5fdaaca9e47c6d5cd3e11ee3
geth_l2_1          | INFO [11-30|13:50:52.792] Ingesting transactions from L1           count=0
geth_l2_1          | DEBUG[11-30|13:50:58.205] Served rollup_getInfo                    conn=34.107.106.8:48194 reqid=102 t=125.018µs
geth_l2_1          | DEBUG[11-30|13:50:58.319] Served eth_blockNumber                   conn=34.107.106.8:48208 reqid=103 t=52.541µs
geth_l2_1          | DEBUG[11-30|13:50:58.320] Served eth_chainId                       conn=34.107.106.8:48210 reqid=104 t=22.823µs
batch_submitter_1  | 2020-11-30T13:50:58.322Z info:oe:batch-submitter:tx-chain No txs to submit. Skipping batch submission...

No txs to submit. Skipping batch submission... output comes from this code fragment:

async _getBatchStartAndEnd() {
        const startBlock = parseInt(await this.chainContract.getTotalElements(), 16) + 1;
        const endBlock = Math.min(startBlock + this.maxBatchSize, await this.l2Provider.getBlockNumber()) + 1;
        if (startBlock >= endBlock) {
            if (startBlock > endBlock) {
                this.log
                    .error(`More chain elements in L1 (${startBlock}) than in the L2 node (${endBlock}).
                   This shouldn't happen because we don't submit batches if the sequencer is syncing.`);
            }
            this.log.info(`No txs to submit. Skipping batch submission...`);
            return;
        }
        return {
            start: startBlock,
            end: endBlock,
        };
    }