harmos-runtime 0.1.6

Harmos runtime: managed state, undo, recovery, background work and typed streams.
Documentation 
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/* ***
 *
 * Harmos
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * ***
 */

/* === Modules === */

/* === Re-Exports === */

/* === Imports === */

// Standard Library Imports
use std::sync::{Arc, atomic::Ordering};

// Third Party Imports

// Local Imports
use super::{Fixture, config, metadata};
use harmos_runtime::Identifier;
use harmos_runtime::storage::operations::ResumeFile;
use harmos_runtime::storage::{MutationId, StorageManager};

/* === Constants === */

/* === Macros === */

/* === Type Aliases === */

/* === Structs === */

/* === Enums === */

/* === Traits === */

/* === Implementations === */

/* === Public Functions === */

/* === Private Functions === */

fn identity(storage: &StorageManager, key: &str) -> MutationId {
    MutationId { window: storage.mutation_window().unwrap().id, key: Identifier::new(key).unwrap() }
}

/* === Tests === */

#[tokio::test]
async fn resume_receipt_replays() {
    let f = Fixture::new(config()).await;
    let mut file = f.storage.produce_file(metadata("once")).await.unwrap();
    file.write_all((b"prefix").to_vec()).await.unwrap();
    let token = file.session().unwrap().clone();
    let id = identity(&f.storage, "resume");
    let first = f.storage.resume_file_once(&id, &token).await.unwrap();
    assert_eq!(first.length, 6);
    assert_eq!(first.session.generation, 2);
    assert_eq!(f.storage.resume_file_once(&id, &token).await.unwrap(), first);
    assert!(file.write_all((b"stale").to_vec()).await.is_err());
    let mut later = f.storage.resume_file(&first.session).await.unwrap();
    later.write_all((b"tail").to_vec()).await.unwrap();
    assert_eq!(f.storage.resume_file_once(&id, &token).await.unwrap(), first);
    assert!(f.storage.resume_file_once(&id, later.session().unwrap()).await.is_err());
    assert_eq!(later.session().unwrap().generation, 3);
    later.abort().await.unwrap();
    f.finish().await;
}

#[tokio::test(start_paused = true)]
async fn operation_retries_three() {
    let f = Fixture::new(config()).await;
    harmos_runtime::storage::operations::register(
        &f.runtime.operations,
        "storage",
        crate::storage::operations::Lanes::Open,
        Arc::new(f.storage.clone()),
    )
    .unwrap();
    let file = f.storage.produce_file(metadata("retry")).await.unwrap();
    let request = ResumeFile { mutation: identity(&f.storage, "resume"), session: file.session().unwrap().clone() };
    f.data.control.fence_failures.store(3, Ordering::SeqCst);
    let first = f.runtime.operations.call(request.clone()).await.unwrap();
    assert_eq!(first.session.generation, 2);
    assert_eq!(f.data.control.fence_failures.load(Ordering::SeqCst), 0);
    assert_eq!(*f.runtime.operations.call(request).await.unwrap(), *first);
    f.finish().await;
}

#[tokio::test]
async fn cancelled_resume_replays() {
    let f = Fixture::new(config()).await;
    let file = f.storage.produce_file(metadata("cancelled")).await.unwrap();
    let token = file.session().unwrap().clone();
    let id = identity(&f.storage, "resume");
    f.data.control.block_fence.store(true, Ordering::SeqCst);
    {
        let first = f.storage.resume_file_once(&id, &token);
        tokio::pin!(first);
        tokio::select! { biased; _ = &mut first => panic!("fence must block"), _ = f.data.control.fence_entered.notified() => {} }
    }
    f.data.control.block_fence.store(false, Ordering::SeqCst);
    f.data.control.fence_release.notify_one();
    let result = f.storage.resume_file_once(&id, &token).await.unwrap();
    assert_eq!(result.session.generation, 2);
    assert_eq!(f.storage.resume_file_once(&id, &token).await.unwrap(), result);
    f.finish().await;
}

#[tokio::test]
async fn duplicate_resumes_share() {
    let f = Fixture::new(config()).await;
    let file = f.storage.produce_file(metadata("concurrent")).await.unwrap();
    let token = file.session().unwrap().clone();
    let id = identity(&f.storage, "shared");
    f.data.control.block_fence.store(true, Ordering::SeqCst);
    let first = f.storage.resume_file_once(&id, &token);
    let second = async {
        f.data.control.fence_entered.notified().await;
        let wait = f.storage.resume_file_once(&id, &token);
        tokio::pin!(wait);
        // Poll The Duplicate While The Original Physical Fence Is Still Held.
        std::future::poll_fn(|context| {
            assert!(std::future::Future::poll(wait.as_mut(), context).is_pending());
            std::task::Poll::Ready(())
        })
        .await;
        f.data.control.block_fence.store(false, Ordering::SeqCst);
        f.data.control.fence_release.notify_one();
        wait.await.unwrap()
    };
    let (first, second) = tokio::join!(first, second);
    assert_eq!(first.unwrap(), second);
    assert_eq!(second.session.generation, 2);
    f.finish().await;
}

#[tokio::test(start_paused = true)]
async fn budgets_never_multiply() {
    let f = Fixture::new(config()).await;
    harmos_runtime::storage::operations::register(
        &f.runtime.operations,
        "storage",
        crate::storage::operations::Lanes::Open,
        Arc::new(f.storage.clone()),
    )
    .unwrap();
    let file = f.storage.produce_file(metadata("retry-budget")).await.unwrap();
    let request = ResumeFile { mutation: identity(&f.storage, "resume"), session: file.session().unwrap().clone() };
    f.data.control.fence_failures.store(5, Ordering::SeqCst);
    assert!(f.runtime.operations.call(request.clone()).await.is_err());
    assert_eq!(f.data.control.fence_failures.load(Ordering::SeqCst), 1);
    f.data.control.fence_failures.store(0, Ordering::SeqCst);
    assert_eq!(f.runtime.operations.call(request).await.unwrap().session.generation, 2);
    f.finish().await;
}

#[tokio::test]
async fn ledger_evicts_receipts() {
    // A Small Budget Makes The Ledger Evict Completed Receipts Long Before The Window Ends.
    let mut settings = config();
    settings.budget.read_memory_bytes = std::num::NonZeroUsize::new(1024 * 1024).unwrap();
    settings.response.batch_bytes = std::num::NonZeroUsize::new(64 * 1024).unwrap();
    let budget = settings.budget.read_memory_bytes.get();
    let f = Fixture::new(settings).await;
    let window = f.storage.mutation_window().unwrap();
    let mut last = None;
    for index in 0..2048 {
        let name = format!("small-{index}");
        let create = identity(&f.storage, &format!("create-{index}"));
        let producer = f.storage.create_file_once(&create, &metadata(&name)).await.unwrap();
        let finish = identity(&f.storage, &format!("finish-{index}"));
        let reference = f.storage.finish_file_once(&finish, &producer.session).await.unwrap();
        assert_eq!(reference.length, 0);
        last = Some((finish, producer.session, reference));
    }
    assert_eq!(f.storage.mutation_window().unwrap().id, window.id);
    assert!(f.storage.status().mutation_bytes < budget);

    // The Newest Receipt Still Answers Its Retry With The Original Outcome.
    let (finish, session, reference) = last.unwrap();
    assert_eq!(f.storage.finish_file_once(&finish, &session).await.unwrap(), reference);
    f.finish().await;
}