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https://github.com/Couragium/qldb-rs

Pure Rust driver for Amazon's QLDB ledger
https://github.com/Couragium/qldb-rs

database driver pure-rust qldb rust

Last synced: 3 months ago
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Pure Rust driver for Amazon's QLDB ledger

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# Amazon's QLDB Driver

Driver for Amazon's QLDB Database implemented in pure rust.

[![Documentation](https://docs.rs/qldb/badge.svg)](https://docs.rs/qldb)
[![Crates.io](https://img.shields.io/crates/v/qldb)](https://crates.io/crates/qldb)
[![Rust](https://github.com/Couragium/qldb-rs/actions/workflows/rust.yml/badge.svg)](https://github.com/Couragium/qldb-rs/actions/workflows/rust.yml)

The driver is fairly tested and should be ready to test in real projects.

## Example

```rust,no_run
use qldb::QldbClient;
use std::collections::HashMap;

let client = QldbClient::default("rust-crate-test", 200).await?;

let mut value_to_insert = HashMap::new();
// This will insert a documents with a key "test_column"
// with the value "IonValue::String(test_value)"
value_to_insert.insert("test_column", "test_value");

client
.transaction_within(|client| async move {
client
.query("INSERT INTO TestTable VALUE ?")
.param(value_to_insert)
.execute()
.await?;
Ok(())
})
.await?;
```

# Session Pool

The driver has a session pool. The second parameter in the
QldbClient::default is the maximum size of the connection pool.

The pool will be auto-populated as parallel transaction are being
requested until it reaches the provided maximum.

The pool uses one independent thread with a single-threaded
executor ([async-executor](https://crates.io/crates/async-executor))
in order to be able to spawn tasks after the session has been returned.

## Alternative session Pool

There is an alternative session pool that will require an spawner
function to be provided. It allows to have the pool running by using
the spawn function of the executor you use. We tested async-std and
tokio, but others should work as well.

This pool will spawn two internal tasks handling the pool.

Use this if you want for this driver to not create a new thread.

Example with async-std:

```rust,no_run
let client = QldbClient::default_with_spawner(
"rust-crate-test",
200,
Arc::new(move |fut| {async_std::task::spawn(Box::pin(fut));})
)
.await?
```

Or, with tokio:

```rust,no_run
let client = QldbClient::default_with_spawner(
"rust-crate-test",
200,
Arc::new(move |fut| {tokio::spawn(Box::pin(fut));})
)
.await?
```

## Select the pool you want to use

By default, both pools are available by using the methods `QldbClient::default`
and `QldbClient::default_with_spawner`. If you don't want the pool to be available
in runtime, you can disable by removing the default features. Still, you will
need to add at least one feature to enable one pool.

This will only enable the default pool, the one that uses one thread.
```toml,no_code
qldb = { version = "3", default_features = false, features = ["internal_pool_with_thread"]}
```

This will only enable the alternative pool, the one that requires an spawner
```toml,no_code
qldb = { version = "3", default_features = false, features = ["internal_pool_with_spawner"]}
```

# Underlying Ion Format Implementation

The library uses [ion-binary-rs](https://crates.io/crates/ion-binary-rs),
which is our own, pure rust, implementation of the format. It is very
well tested and ready to use in production too.

# Test

For tests you will need to have some AWS credentials in your
PC (as env variables or in ~/.aws/credentials). There needs
to be a QLDB database with the name "rust-crate-test" in the
aws account. The tests need to be run sequentially, so in order
to run the tests please run the following command:

```sh
RUST_TEST_THREADS=1 cargo test
```