Quick Start

Examples

npm install @arcologynetwork/concurrentlib

1. Vending Machine Example with Cumulative Variables

To better understand cumulative variables work, consider the following example from the Ethereum developers docs:

Original Version

In the original implementation, the cupcakeBalances mapping is a shared variable accessed and modified by multiple functions (refill and purchase), and it is shared among different users interacting with the contract.

Conflict Analysis: Only one transaction will go through due to the obvious conflict caused by the concurrent updates to cupcakeBalances. The parallel execution of transactions interacting with this contract won't bring any performance benefit.

pragma solidity 0.8.7;

contract VendingMachine {

    // Declare state variables of the contract
    address public owner;
    mapping (address => uint) public cupcakeBalances;

    // When 'VendingMachine' contract is deployed:
    // 1. set the deploying address as the owner of the contract
    // 2. set the deployed smart contract's cupcake balance to 100
    constructor() {
        owner = msg.sender;
        cupcakeBalances[address(this)] = 100;
    }

    // Allow the owner to increase the smart contract's cupcake balance
    function refill(uint amount) public {
        require(msg.sender == owner, "Only the owner can refill.");
        cupcakeBalances[address(this)] += amount;
    }

    // Allow anyone to purchase cupcakes
    function purchase(uint amount) public payable {
        require(msg.value >= amount * 1 ether, "You must pay at least 1 ETH per cupcake");
        require(cupcakeBalances[address(this)] >= amount, "Not enough cupcakes in stock to complete this purchase");
        cupcakeBalances[address(this)] -= amount;
        cupcakeBalances[msg.sender] += amount;
    }
}

Parallelized

In the parallelized version, the shared variable cupcakeBalances uses a new data type U256Cum provided by Arcology, enabling concurrent updates. The parallelized contract is as follows:

Parallelized Version: Both transactions will go through because the cupcakeBalances variable is concurrently updatable. Alice and Bob will both receive their cupcakes as long as there are enough in stock.

pragma solidity 0.8.7;

import "@arcologynetwork/concurrentlib/lib/commutative/U256Cum.sol";

contract VendingMachine {

    // Declare state variables of the contract
    address public owner;
    U256Cumulative cupcakeStock;
    mapping (address => uint) public cupcakeBalances;

    // When 'VendingMachine' contract is deployed:
    // 1. set the deploying address as the owner of the contract
    // 2. set the deployed smart contract's cupcake balance to 100
    constructor() {
        owner = msg.sender;
        cupcakeStock = new U256Cum(0, 100);
    }

    // Allow the owner to increase the smart contract's cupcake balance
    function refill(uint amount) public {
        require(msg.sender == owner, "Only the owner can refill.");
        cupcakeStock.add(amount);
    }

    // Allow anyone to purchase cupcakes
    function purchase(uint amount) public payable {
        require(msg.value >= amount * 1 ether, "You must pay at least 1 ETH per cupcake");
        cupcakeStock.sub(amount);
        cupcakeBalances[msg.sender].add(amount);
    }
}

Benchmarking

Info	Configuration
Contract Name	Vending Machine(Parallelized)
Arcology Version	V 1.9.0
Deployment Mode	Standard-alone
Operating System	Ubuntu 22.04
CPU	AMD Ryzen Threadripper 2950X 16-Core Processor
RAM	128G RAM
Storage	2T M2 SSD
Average gas burned/S:	712,118,171.6
Max gas burned/S	1,005,206,703