ruststream-sqlx 0.7.1

//! Two subscriptions with workers on SQLite: thumbnails in any order, and ledger postings in
//! order per account through a `partition_key` column.
//!
//! ```text
//! cargo run -p ruststream-sqlx --example sqlx_subscriptions_workers --features inbox,sqlite,chrono,testing
//! ```

use chrono::{DateTime, Utc};
use ruststream::OutgoingMessage;
use serde::{Deserialize, Serialize};
use sqlx::{Sqlite, SqliteConnection};

// --8<-- [start:workers]
use ruststream_sqlx::prelude::*;
use sqlx::Connection;
use sqlx::sqlite::SqlitePoolOptions;

/// One row of `image_jobs`: images resize in any order.
#[derive(Inbox, sqlx::FromRow)]
#[inbox(table = "image_jobs")]
struct Resize {
    #[field(id, generated)]
    id: i64,
    #[field(locked_until)]
    locked_until: Option<DateTime<Utc>>,
    #[field(payload)]
    payload: Vec<u8>,
}

/// One row of `ledger_jobs`: the postings of one account apply in the order they were written.
#[derive(Inbox, sqlx::FromRow)]
#[inbox(table = "ledger_jobs")]
struct Post {
    #[field(id, generated)]
    id: i64,
    #[field(partition_key)]
    account: String,
    #[field(locked_until)]
    locked_until: Option<DateTime<Utc>>,
    #[field(payload)]
    payload: Vec<u8>,
}

#[subscriber(InboxQueue::<Resize>::new("images"))]
async fn resize(image: &Image) -> HandlerOutcome {
    tracing::info!(path = %image.path, "resizing");
    HandlerOutcome::ack()
}

#[subscriber(InboxQueue::<Post>::new("postings"))]
async fn post(posting: &Posting) -> HandlerOutcome {
    tracing::info!(account = %posting.account, posting.n, "posting");
    HandlerOutcome::ack()
}

/// The service on the database `url` names.
fn service(url: &str) -> RustStream {
    let schema_url = url.to_owned();
    // Nothing connects here: the broker builds its pool when the service starts.
    let broker = SqlxBroker::from_url(url, SqlitePoolOptions::new());
    let broker = broker.route::<Resize>("images").route::<Post>("postings");
    RustStream::new(AppInfo::new("back-office", "0.1.0"))
        // The table, created before the subscription checks it.
        .on_startup(async move |()| {
            let mut conn = SqliteConnection::connect(&schema_url).await?;
            sqlx::raw_sql(SCHEMA).execute(&mut conn).await?;
            conn.close().await
        })
        .with_broker(broker, |b| {
            // Up to four images in work at once.
            b.include(resize.workers(nonzero!(4)));
            // Four workers, and the postings of one account on one of them, one after another.
            b.include(post.workers_by_key(nonzero!(4)));
        })
}
// --8<-- [end:workers]

#[ruststream::app]
fn app() -> impl App {
    service("sqlite:back-office.db?mode=rwc")
}

const SCHEMA: &str = "CREATE TABLE IF NOT EXISTS image_jobs (
    id INTEGER PRIMARY KEY,
    locked_until TEXT,
    payload BLOB NOT NULL
);
CREATE TABLE IF NOT EXISTS ledger_jobs (
    id INTEGER PRIMARY KEY,
    account TEXT NOT NULL,
    locked_until TEXT,
    payload BLOB NOT NULL
)";

impl Publish<Sqlite> for Resize {
    async fn publish(
        conn: &mut SqliteConnection,
        message: &OutgoingMessage<'_>,
    ) -> Result<(), sqlx::Error> {
        sqlx::query("INSERT INTO image_jobs (payload) VALUES (?)")
            .bind(message.payload())
            .execute(conn)
            .await?;
        Ok(())
    }
}

/// A publish takes the partition key out of the message: its `account` field.
impl Publish<Sqlite> for Post {
    async fn publish(
        conn: &mut SqliteConnection,
        message: &OutgoingMessage<'_>,
    ) -> Result<(), sqlx::Error> {
        sqlx::query(
            "INSERT INTO ledger_jobs (account, payload) \
             VALUES (json_extract(CAST(?1 AS TEXT), '$.account'), ?1)",
        )
        .bind(message.payload())
        .execute(conn)
        .await?;
        Ok(())
    }
}

#[derive(Debug, PartialEq, Deserialize, Serialize, Outgoing)]
#[outgoing(name = "images")]
struct Image {
    path: String,
}

#[derive(Debug, PartialEq, Deserialize, Serialize, Outgoing)]
#[outgoing(name = "postings")]
struct Posting {
    account: String,
    n: u32,
}

#[cfg(test)]
mod tests {
    use std::error::Error;

    use futures::future::try_join_all;
    use ruststream::testing::TestApp;
    use ruststream_sqlx::prelude::*;
    use sqlx::sqlite::{SqliteConnectOptions, SqlitePoolOptions};
    use sqlx::{Connection, Sqlite, SqliteConnection, SqlitePool};

    use super::{Image, Posting, SCHEMA, service};

    // An in-memory database every connection naming it shares, alive while one of them is open:
    // the test holds one beside the pool it reads the table through.
    async fn database(
        name: &str,
    ) -> Result<(String, SqlitePool, SqliteConnection), Box<dyn Error>> {
        let url = format!("sqlite:file:{name}?mode=memory&cache=shared");
        let options: SqliteConnectOptions = url.parse()?;
        let keeper = SqliteConnection::connect_with(&options).await?;
        let pool = SqlitePoolOptions::new()
            .min_connections(1)
            .idle_timeout(None)
            .connect_with(options)
            .await?;
        sqlx::raw_sql(SCHEMA).execute(&pool).await?;
        Ok((url, pool, keeper))
    }

    #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
    async fn every_image_is_resized_once() -> Result<(), Box<dyn Error>> {
        let (url, _pool, _keeper) = database("sqlx_subscriptions_workers_images").await?;
        let tb = TestApp::start(service(&url)).await?;
        let images: Vec<Image> = (1..=6)
            .map(|n| Image {
                path: format!("upload/{n}.png"),
            })
            .collect();
        let broker = tb.broker::<SqlxBroker<Sqlite>>();
        try_join_all(images.iter().map(|image| broker.message(image).publish())).await?;

        let mut resized: Vec<Image> = broker.subscriber("images").received();
        resized.sort_by(|left, right| left.path.cmp(&right.path));
        assert_eq!(resized, images);
        Ok(())
    }

    #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
    async fn each_accounts_postings_keep_their_order() -> Result<(), Box<dyn Error>> {
        let (url, _pool, _keeper) = database("sqlx_subscriptions_workers_postings").await?;
        let tb = TestApp::start(service(&url)).await?;
        let postings: Vec<Posting> = (1..=8)
            .map(|n| Posting {
                account: if n % 2 == 0 { "acme" } else { "globex" }.to_owned(),
                n,
            })
            .collect();
        let broker = tb.broker::<SqlxBroker<Sqlite>>();
        try_join_all(
            postings
                .iter()
                .map(|posting| broker.message(posting).publish()),
        )
        .await?;

        let received: Vec<Posting> = broker.subscriber("postings").received();
        for account in ["acme", "globex"] {
            let order: Vec<u32> = received
                .iter()
                .filter(|posting| posting.account == account)
                .map(|posting| posting.n)
                .collect();
            let written: Vec<u32> = postings
                .iter()
                .filter(|posting| posting.account == account)
                .map(|posting| posting.n)
                .collect();
            assert_eq!(order, written, "the postings of {account}");
        }
        Ok(())
    }
}