Fuel

Fuel support is in beta stage. Here is a simple example built for spark.fi.

Two important files:

• abis/fuel/orderbook-abi.json project's ABI file in json format, used to do codegen
• processor.ts entry point for processing logic

You can also create an example project by

npx @sentio/cli@latest create -n <project name> --chain-type fuel

OnLog Handler

In your sway code, if you define statement as follow

log(TradeEvent(...))

There will be related entries in the ABI file,

{
  ...
  "types": [
   ...
    "typeId": 20,
    "type": "struct TradeEvent",
    "components": [
      ...
    ]
  ],
  "loggedTypes": [
    ...
    {
      "logId": 27,
      "loggedType": {
        "name": "",
        "type": 20,
        "typeArguments": []
      }
    }
  ]
}

Then Sentio SDK will use this definition to generate an Processor you could add your custom logic after the log is collected

import { OrderbookProcessor } from "./types/fuel/OrderbookProcessor.js";

OrderbookProcessor.bind({
  chainId: FuelNetwork.TEST_NET,
  address: '0x0f0c1065a7b82d026069c5cf070b21ee65713fd1ac92ec1d25eacc3100187f78'
})
    .onLogTradeEvent(async (trade: FuelLog<TradeEventOutput>, ctx: FuelContext) => {
        const vol = trade.data.trade_price.mul(trade.data.trade_size).scaleDown(2 * 10)
        ctx.eventLogger.emit('trade', {
          distinctId: ctx.transaction?.sender,
          ...trade,
          vol: vol
        })
    })
    ... other handlers

The handler takes two parameters

• FuelLog<type>: include the log type, it include log data, e.g data: TradeEventOutput, which is the type generated by the official codegen, along with other utility fields like logId and receiptIndex. Notice one type could have different logId if you log it in multiple places.
• FuelContext:
  • hold the tools for doing data submission, like eventLogger and meter, which records logs-in-processor and metrics-in-processors.
  • hold the FuelTransaction, which is extends from official SDK's TransactionSummary and also decoded logs an

OnTransfer Handler

You can also track assets changes by using FuelAssetProcessor, you can filter it by from, to, or assetsId, all or them could be single element or a list. Then the handler will be taking FuelTransfer which represent all assets transfers (not limited by the filter) in the transactions that satisfied the filter.

import { BaseAssetId } from '@fuel-ts/address/configs'
import { FuelAssetProcessor, FuelNetwork } from "@sentio/sdk/fuel";

FuelAssetProcessor.bind({
  chainId: FuelNetwork.TEST_NET
}).onTransfer(
    {
      from: "0xd3fe20c8ff68a4054d8587ac170c40db7d1e200208a575780542bd9a7e3eec08",
      assetId: BaseAssetId
    },
    async (transfer: FuelTransfer, ctx) => {
      ...
    }
)

Handle Big Numbers

Fuel SDK use BN type to represent big numbers, but doing recording we might want use more readable number format. Use .asBigDecimal and convert to BigDecimal or use scaleDown with decimal number. Read more in general handle-big-numbers.