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Introduction

Forwarder is the service responsible for:

  • sending L1 and L2 interactions from the database to Redis
  • assigning last_sort_key to L1 interactions

Run​

# Start from the latest saved block
./syncer forward

Architecture​

Processing L1 interactions​

Forwarder receives changes of Syncer's finished block height through Postgres notifications. This change informs that all L1 interactions from this block are saved in the database and are ready for processing. Forwarder downloads all interactions (in batches) from the database, computes last_sort_key for each interaction, and saves results in the database.

FORWARDER_FINISHED_HEIGHT is updated with the last batch.

Sending L1 and L2 interactions​

L2 interactions are received asynchronously with a Postgres notification from the database and sent to Redis. If a new L1 block is detected then sending L2 interactions is paused to prevent mixing L1 and L2 in the stream. It's resumed after the last L1 interaction is sent.

Dependency on Syncer​

Forwarder works closely with Syncer in a two-stage process. Syncer downloads interactions and Forwarder processes them.

Internals​

Here are some details about how Forwarder works internally. Each box in the diagram is a separate Task, everything is set up in controller.go.