Welcome to Wonderful-pe

This is a simple payment engine built in Rust.

How to use

You need to set up a Rust development environment. Check this in order to set it up.

Then, you can run the app this way:

cargo run -- ./tests/samples/little.csv

#if you want to save the output to a .csv file
cargo run -- ./tests/samples/little.csv > output.csv

#You can enable logger by setting RUST_LOG env var
RUST_LOG='info'
cargo run -- ./tests/samples/little.csv

Data

Sample input

client,tx,amount,type
1,1,10.0,deposit
2,2,2.0,deposit
1,3,10.0,deposit
1,5,10.0,deposit
1,4,1.5,withdrawal
2,5,3.0,withdrawal
1,3,,dispute
1,5,,dispute
1,3,,resolve
1,5,,chargeback

Sample output

client,available,held,total,locked
2,2.0,0.0,2.0,false
1,18.5,0.0,18.5,true

Implementation info

The code is splitted in a lib (lib.rs) and an executable (main.rs), as suggested in The Rust Programming Language guide

Money amounts

Represented as an u64, wrapped in Amount struct in order to define custom methods like serialiation and deserialization.
Handles 4 decimal digits. Max number is 2^64 / 10^4.
Does not handle negative numbers. Transactions that generate negative numbers are rejected.
Repr: 23.05 ==> 230500_u64

External libraries

csv and serde to handle de/serialization of dsv data.
log and env_logger to handle logs
thiserror to quickly create custom error types with macros, instead of implementing verbose Error trait manually

Tests

Sample input csv files can be found in ./tests/sample/
Some unit tests can be found in files

Ideas

Wrap the engine in using actix::Actor, so that you can read different csv inputs in different threads and a single actor controls the engine.
Move Hashmap to DashMap, so that transactions can can be applied in parallel.

kharenzze/wonderful-pe