Automate Your On-Chain Game Loops

1// SPDX-License-Identifier: MIT
2pragma solidity ^0.8.13;
3
4// Import the base contract that makes any
5// contract compatible with AutoLoop workers
6import {AutoLoopCompatible} from
7    "autoloop/AutoLoopCompatible.sol";
8
9// A simple demo: number goes up every interval
10contract NumberGoUp is AutoLoopCompatible {
11    uint256 public number;
12    uint256 public interval;
13    uint256 public lastTimeStamp;
14    uint256 private _loopID;
15
16    constructor(uint256 _interval) {
17        interval = _interval;
18        lastTimeStamp = block.timestamp;
19    }
20
21    // Workers call this every block to check
22    // if the contract is ready for an update
23    function shouldProgressLoop()
24        external view override
25        returns (
26            bool loopIsReady,
27            bytes memory progressWithData
28        )
29    {
30        // Ready when enough time has passed
31        loopIsReady =
32            (block.timestamp - lastTimeStamp) > interval;
33        // Pass loop ID to prevent duplicate runs
34        progressWithData = abi.encode(_loopID);
35    }
36
37    // Called by AutoLoop when shouldProgressLoop
38    // returns true — this is your update logic
39    function progressLoop(
40        bytes calldata progressWithData
41    ) external override {
42        uint256 loopID =
43            abi.decode(progressWithData, (uint256));
44        // Guard against stale or replayed calls
45        require(loopID == _loopID, "stale loop");
46        lastTimeStamp = block.timestamp;
47        ++number;
48        ++_loopID;
49    }
50}