batched

Rust macro utility for batching expensive async operations.

Installation

cargo add batched

Or add this to your Cargo.toml:

[dependencies]
batched = "0.1.7"

#[batched]

window: Minimum amount of time (in milliseconds) the background thread waits before processing a batch.
limit: Maximum amount of items that can be grouped and processed in a single batch.
concurrent: Maximum amount of concurrent batched tasks running (default: Infinity)
boxed: Automatically wraps the return type in an Arc
iterator_value: Iterator value

The target function must have a single argument, a vector of items (Vec<T>).

The return value of the batched function is propagated (cloned) to all async calls of the batch, unless the batched function returns an iterator (and iterator_value is set), in which case the return value for each call is pulled from the iterator.

If the return value is not an iterator, The target function return type must implement Clone to propagate the result. Use the boxed option to automatically wrap your return type in an Arc.

Prerequisites

Built for async environments (tokio), will not work without a tokio async runtime
Target function must have async, and the function name should end with _batched
Not supported inside structs:

struct A;

impl A {
    // NOT SUPPORTED
    #[batched(window = 1000, limit = 100)]
    fn operation() {
        ...
    }
}

Examples

Simple add batch

#[batched(window = 100, limit = 1000)]
async fn add(numbers: Vec<u32>) -> u32 {
    numbers.iter().sum()
}

async fn main() {
    for _ in 0..99 {
        tokio::task::spawn(async move {
            add(1).await
        });
    }

    let result = add(1).await;
    assert_eq!(result, 100);
}

Batch insert rows

use batched::batched;

// Creates functions [`insert_message`] and [`insert_message_multiple`]
#[batched(window = 100, limit = 100_000, boxed)]
async fn insert_message_batched(messages: Vec<String>) -> Result<(), anyhow::Error> {
    let pool = PgPool::connect("postgres://user:password@localhost/dbname").await?;
    let mut query = String::from("INSERT INTO messages (content) VALUES ");
    ...
}

#[post("/message")]
async fn service(message: String) -> Result<(), anyhow::Error> {
    insert_message(message).await?;
    Ok(())
}

#[post("/bulk_messages")]
async fn service(messages: Vec<String>) -> Result<(), anyhow::Error> {
    insert_message_multiple(messages).await?;
    Ok(())
}

Batch insert rows and return them

use batched::batched;

struct Row {
    pub id: usize,
    pub content: String,
}

// Creates functions [`insert_message`] and [`insert_message_multiple`]
#[batched(window = 100, limit = 100_000, iterator_value = "Row")]
async fn insert_message_batched(messages: Vec<String>) -> Vec<Row> {
    let pool = PgPool::connect("postgres://user:password@localhost/dbname").await?;
    let mut query = String::from("INSERT INTO messages (content) VALUES ");
    ...
}

#[post("/message")]
async fn service(message: String) -> Result<(), anyhow::Error> {
    let message: Row = insert_message(message).await?;
    Ok(())
}

#[post("/bulk_messages")]
async fn service(messages: Vec<String>) -> Result<(), anyhow::Error> {
    let messages: Vec<Row> = insert_message_multiple(messages).await?;
    Ok(())
}

batched_derive 0.1.7