transaction-processing-exercice

Made by Clement Guiton

Toy transaction processing engine

The engine implements all the required cases :

• Deposit
• Withdrawal
• Dispute
• Resolve
• Chargeback

Usage

The program takes the path of the input file as a argument, and outputs the result in the console.

Tests

The code is tested all the way through, and the tests can be run with the following command:

cargo test

Tests includes serialization and deserialization of the transactions, file reading, and all the cases of the transaction processing engine.

Safety

Since this is a CLI tool, handling financial transactions, we panic on error. We'd rather fail fast and loud than let a bug go unnoticed, and cause corrutped data. Cases that were documented in the requirements are skipped, for example a dispute on a non-existing transaction.
Otherwise we assert business logic constraits with expects throughout the code Tiger style.

Some cases are also handled gracefully, a deposit on a frozen account will be ignored, but we keep it in a separate queue for further processing in case of unlocking.

Performance

We use the tokio async runtime to parse the file and process the transactions concurrently. This allows us to stream through a large file or handle tcp streams.

We also use a hashmap to store the accounts and a hashmap to store the transactions, which allows us to have a average O(1) complexity for the lookups.