ruststream-sqlx 0.7.1

//! A transactional signup handler on SQLite that reads all three of the inbox's keys: the
//! delivery's transaction, the service's pool and the attempt, in that order.
//!
//! ```text
//! cargo run -p ruststream-sqlx --example sqlx_context --features inbox,sqlite,chrono,testing
//! ```

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

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

/// One row of `signup_jobs`.
#[derive(Inbox, sqlx::FromRow)]
#[inbox(table = "signup_jobs")]
struct OpenAccount {
    #[field(id, generated)]
    id: i64,
    #[field(attempt, generated)]
    attempt: i16,
    #[field(locked_until)]
    locked_until: Option<DateTime<Utc>>,
    #[field(payload)]
    payload: Vec<u8>,
}

#[subscriber(InboxQueue::<OpenAccount>::new("signups"))]
async fn open_account(
    signup: &Signup,
    Ctx(mut tx): Ctx<keys::Tx<Sqlite>>,
    Ctx(pool): Ctx<keys::Pool<Sqlite>>,
    Ctx(attempt): Ctx<keys::Attempt>,
) -> HandlerOutcome {
    // Through the pool: the line stays whatever the outcome. It comes first, because on SQLite
    // the delivery's transaction holds the database's write lock from its first write.
    let _ = sqlx::query("INSERT INTO signup_log (email, attempt) VALUES (?, ?)")
        .bind(&signup.email)
        .bind(attempt.and_then(|attempt| i64::try_from(attempt).ok()))
        .execute(&pool)
        .await;
    // Through the transaction: the account commits with the acknowledgement, or not at all.
    let opened = sqlx::query("INSERT INTO accounts (email) VALUES (?)")
        .bind(&signup.email)
        .execute(&mut *tx)
        .await;
    if opened.is_err() || !register(signup, attempt).await {
        return HandlerOutcome::retry();
    }
    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());
    RustStream::new(AppInfo::new("accounts", "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.route::<OpenAccount>("signups"), |b| {
            b.include(open_account.transactional());
        })
}
// --8<-- [end:context]

/// A stand-in for the CRM: it answers the first call for a signup with a timeout.
async fn register(signup: &Signup, attempt: Option<u64>) -> bool {
    tokio::task::yield_now().await;
    tracing::info!(email = %signup.email, ?attempt, "registering the account");
    attempt != Some(1)
}

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

const SCHEMA: &str = "CREATE TABLE IF NOT EXISTS signup_jobs (
    id INTEGER PRIMARY KEY,
    attempt INTEGER NOT NULL DEFAULT 1,
    locked_until TEXT,
    payload BLOB NOT NULL
);
CREATE TABLE IF NOT EXISTS signup_log (email TEXT NOT NULL, attempt INTEGER);
CREATE TABLE IF NOT EXISTS accounts (email TEXT PRIMARY KEY)";

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

#[derive(Debug, PartialEq, Deserialize, Serialize, Outgoing)]
#[outgoing(name = "signups")]
struct Signup {
    email: String,
}

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

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

    use super::{SCHEMA, Signup, 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 the_log_keeps_every_attempt_and_the_account_commits_once() -> Result<(), Box<dyn Error>>
    {
        let (url, pool, _keeper) = database("sqlx_context").await?;
        let tb = TestApp::start(service(&url)).await?;
        let signup = Signup {
            email: "ada@example.com".to_owned(),
        };
        tb.broker::<SqlxBroker<Sqlite>>()
            .message(&signup)
            .publish()
            .await?;

        let logged: Vec<i64> =
            sqlx::query_scalar("SELECT attempt FROM signup_log ORDER BY attempt")
                .fetch_all(&pool)
                .await?;
        assert_eq!(logged, [1, 2], "the pool's writes outlived the retry");
        let accounts: i64 = sqlx::query_scalar("SELECT count(*) FROM accounts")
            .fetch_one(&pool)
            .await?;
        assert_eq!(accounts, 1, "the retry rolled the first account back");
        Ok(())
    }
}