Prevayler-rs

This is a simple implementation of a system prevalance proposed by Klaus Wuestefeld in Rust. Other examples are the prevayler for Java and prevayler-clj for Clojure.

The idea is to save in a redolog all modifications to the prevailed data. If the system restarts, it will re-apply all transactions from the redolog restoring the system state. The system may also write snapshots from time to time to speed-up the recover process.

Here is an example of a program that creates a prevailed state using an u8, increments it, print the value to the screen and closes the program.

```rust use prevayler_rs::{ error::PrevaylerResult, PrevaylerBuilder, Prevayler, serializer::JsonSerializer, Transaction }; use serde::{Deserialize, Serialize};

#[derive(Serialize, Deserialize)] struct Increment { increment: u8 }

impl Transaction for Increment { fn execute(self, data: &mut u8) { *data += self.increment; } }

#[asyncstd::main] async fn main() -> PrevaylerResult<()> { let mut prevayler: Prevayler = PrevaylerBuilder::new() .path(".") .serializer(JsonSerializer::new()) .data(0 as u8) .build().await?; prevayler.executetransaction(Increment{increment: 1}).await?; println!("{}", prevayler.query()); Ok(()) } ```

In most cases, you probably will need more than one transcation. The way that we have to do this now is to use an Enum as a main transaction that will be saved into the redolog. All transactions executed will then be converted into it.

For more examples, take a look at the project tests