Block Functions

What are block functions?

A Block Function in Project Zero is a customizable data operation executed on Project Zero's infrastructure for every new block. It allows users to filter, transform, and manipulate blockchain data directly at the source without managing their own infrastructure. This enables rapid and scalable data operations in real-time.

How to use Block Functions

1. On the Dataset & Filter page, click on the "Block Functions" toggle on the right-hand side.
2. Enter the code for your Block Function.
3. Optionally, test your Block Function for a specific block or use the default setting to test on the latest block.
4. You can also preview the data that will be passed into your Block Function by clicking the "Preview Block" button.

How does it work?

Block Functions run server-side for each new block that is processed on the blockchain.

Users can write custom logic in JavaScript to process blockchain data, allowing precise and tailored data extraction or manipulation for various use cases.

Each Block Function is triggered as blocks are generated and can interact with specific blockchain events, transactions, or contract data, transforming the data before it’s delivered to your preferred destination.

Available Libraries and Tools

• Lodash Library

  You can use Lodash, a utility library for working with arrays, objects, and other data structures. It is accessible via the global object _.

• Web3-eth-abi Library

  You can interact with the Ethereum ABI (Application Binary Interface) using the Web3-eth-abi library, available via the ABI global object.

Features

• Real-Time Data Transformation

  Perform operations on each block’s data as it streams through, such as filtering or transforming specific contract events or transactions.

• Server-Side Execution

  Offload computational tasks to Project Zero's infrastructure, allowing you to focus on business logic rather than backend management.

• Flexible Integration

  Custom code written in JavaScript can be easily deployed and modified without downtime.

Limitations

• Memory

  Each Block Function execution is limited to 128 Mb RAM to ensure optimal performance and resource allocation.

• Execution Time

  Block Functions can run for a maximum of 30 seconds per block. This ensures that the system remains performant as new blocks are generated.

Code Sample: Extracting and Transforming Swap Events with Lodash

const swapEventABI = {
  "anonymous": false,
  "inputs": [
    {"indexed": true, "internalType": "address", "name": "sender", "type": "address"},
    {"indexed": true, "internalType": "address", "name": "recipient", "type": "address"},
    {"indexed": false, "internalType": "int256", "name": "amount0", "type": "int256"},
    {"indexed": false, "internalType": "int256", "name": "amount1", "type": "int256"},
    {"indexed": false, "internalType": "uint160", "name": "sqrtPriceX96", "type": "uint160"},
    {"indexed": false, "internalType": "uint128", "name": "liquidity", "type": "uint128"},
    {"indexed": false, "internalType": "int24", "name": "tick", "type": "int24"}
  ],
  "name": "Swap",
  "type": "event"
};
const swapTopic = ABI.encodeEventSignature(swapEventABI); // Event signature for filtering
 
/** @param {Input} block **/
function main(block) {
   const swapTxs = [];
   for (let tx of block.transactions) { 
      if (_.get(tx, 'topics[0]') === swapTopic) {  // Lodash usage for safe access
         const swapData = ABI.decodeParameters(swapEventABI.inputs, tx.data);
         swapTxs.push({
           sender: swapData.sender,
           recipient: swapData.recipient,
           amount0: swapData.amount0,
           amount1: swapData.amount1
         });
      }
   }
 
   // Use Lodash to sort transactions by amount0
   const sortedSwaps = _.orderBy(swapTxs, ['amount0'], ['desc']);
   return sortedSwaps;
}

The function will return an array of swap transaction objects with sorted data. Each object will include:

• sender: Address of the sender.
• recipient: Address of the recipient.
• amount0: The first token amount swapped.
• amount1: The second token amount swapped.