helena-network / cron

🕐 Solidity Library to schedule states on Ethereum

Cron

About

This solidity library enable schedule periodical states on the Ethereum Blockchain from a Smart Contract , making it possible for external contracts to lazily allow other state changes on a periodic Basis.

Install

In order to install the library, just run the following commands on your root solidity directory

npm init -y
npm i -E solidity-cron

How to use

There are two different cases where the library could be used:

• Periods: When your DApp just needs an index counting the amount of blocks passed since a certain block-
• Periodic Stages: When your DApp includes also certain actions inside every period.

Using Periods

A periodic Ethereum DApp that needs to handle the current period index.

Importing

Just import the Periodic contract into your Smart Contract, and initialize it.

import "@frontier-token-research/contracts/Period.sol";

Initializing

After that you can define your own period in Blocks, just doing

Period MyDAppPeriod = new Period(T)

Being T the amount of blocks that you want to have as a period.

Getting the current period number

After that, from your Smart Contract you can always reference your current period by calling getCurrentPeriod():

uint256 currentPeriod =  myDappPeriod.getCurrentPeriod();

It will return an incremented value every T blocks.

Using Periodic Stages

Your DApp might have different stages that are repeated over the previously defined period. For example, you might need to give permissions to certain actions only on a certain stage of your period. In this case, instead of creating just a period, it is possible to create a Periodic Stages instance, defininig just the period number :

Importing

import "@frontier-token-research/contracts/Period.sol";

PeriodicStages MyDAppStages = new PeriodicStages(T)

Pushing stages

You can now push any stage using the stages FIFOstack, just defininng the amount of blocks the given stage is going to last:

myDappStages.push(duration)

This will add to your stack a new scheduled Task, filling the period since last pushed stage index to the specified above duration

Getting the current stage

Once the stage has been pushed, you can always get the current stage (by reading the current block), by calling

myDappStages.currentStage()

Testing

You can always use the truffle package to test and contribute to the library. The package needs from a running Ethereum rpc instance in localhost, port 8545. You can run a ganache-cli instance or run geth. You can run the tests by just running:

truffle test

Contributing

If you want to contribute, just open a PR making sure your commits follow Angular Git Commit guidelines, to follow semantic-releaseversioning.

cron's Issues

Move to solidity 0.5

npm scripts