BC-Parser

Eth indexer and parser challenge

Build

Make sure you have go1.22 installed.

And just run

make build

Run

Run this

./parser-api

Usage

The service creates a REST API to interact with the provided parser interface

Get current block

Returns the last block (in decimal) the indexer processed

curl http://localhost:8081/api/v1/last_block

Response

{"last_block":19590123}

Subscribe address

Add an address to the watch list for to/from transactions. If the address is already on the list endpoint returns succesfully ok. If is the address is invalid for eth an error is returned.

curl -X POST http://localhost:8081/api/v1/subscribe/0x1c9fce6dd765a22040d500019ada91acce65b5d2

response:

{"status": "ok"}

in case of error:

http code: 400

{"error":"invalid address"}

Get transactions

Get a list of transactions for and address. Returns error if the privided address is not subscribed. Returns error if the provided address is invalid.

curl http://localhost:8081/api/v1/transactions/0x1c9fce6dd765a22040d500019ada91acce65b5d2

response:

{
  "transactions": [
    {
      "blockHash": "0x602128504604c7369abb788836fbe7a1c3ab16a8b0d884b60c596db6711460aa",
      "blockNumber": "0x12aebe8",
      "from": "0x6907894f656b95d67e380349a5edc1f75bc45b8c",
      "gas": "0x5208",
      "gasPrice": "0x7c94f11fe",
      "maxFeePerGas": "0xa1d35fe21",
      "maxPriorityFeePerGas": "0x24bbc6a",
      "hash": "0x5363e5b048a841874afe8ce1389e9db4a4a662882ef9345270fd43b368198103",
      "input": "0x",
      "nonce": "0x4c",
      "to": "0x1c9fce6dd765a22040d500019ada91acce65b5d2",
      "transactionIndex": "0xaf",
      "value": "0x354a6ba7a18000",
      "type": "0x2",
      "chainId": "0x1",
      "v": "0x0",
      "r": "0xd089a65636f574fe4023f5c0da550d59f59a9ccce1b8a40935295846006eb6a4",
      "s": "0x14268bebbbde9c715b547b02aa09ef7e55759be2a2ee61e02504fe44ccdc168f"
    },
    {
      "blockHash": "0x9332e6354ba81948c46ecd17496c58b2f6895460be780be21528b2ff4a9abe1f",
      "blockNumber": "0x12aec0a",
      "from": "0x1c9fce6dd765a22040d500019ada91acce65b5d2",
      "gas": "0x5208",
      "gasPrice": "0x84ad299a8",
      "maxFeePerGas": "0xa3e9ab800",
      "maxPriorityFeePerGas": "0x3938700",
      "hash": "0xa7ea5928d5a65f89f70585b28dc0c70626b80c8265ddd7c6f9760113a83faed2",
      "input": "0x",
      "nonce": "0x32",
      "to": "0xf52605c7b778563a5a9144ef4dc53b57463ca2c7",
      "transactionIndex": "0x56",
      "value": "0x32d143c2fe6a00",
      "type": "0x2",
      "chainId": "0x1",
      "v": "0x1",
      "r": "0x45d1b6c46937b0d0b08c67dd78b25fb272b7a19f6971907c97aef843cff0c2b6",
      "s": "0x1a6bd8d046b38b72ecb0cde1036b8b261087ee25e5a7d237263cbc0650de0ebf",
      "yParity": "0x1"
    }
  ]
}

in case of error:

http code: 400

{"error":"invalid address"}

or

{"error":"address not subscribed"}

Future improvements and ideas

• read config from env (inital block, rpc endpoint, etc)
• add more tests
• improve error handling / implement retries on the indexer when rpc calls fail
• json rpc client could be improved (didnt want to wast time there)
• the indexer could be modified to process more than one block at the same time

Packages

Client

Is the implementation of JSONRPC methods used for the indexer

Indexer

Is the process to index blocks form the blockchain Its a single thread process that sequencially read blocks untile its up-to-date to the last block. The output is sent to a channel to be used by other services. It could by improved to concurrently read many blocks to speed up the process.

Storage

Is the in-memory storage, its modeled so i can also use it to hold the subscription addresses

Observer

Is the code that implements the proposed interface (Parser) for the challenge

App

Contains the handlers for the rest api