laburnum 1.17.0

// Copyright Two Neutron Stars Incorporated and contributors
// SPDX-License-Identifier: BlueOak-1.0.0

use {
  super::common::*,
  crate::{
    scheduler::{
      lanes::{
        ASYNC_LANE1,
        DEFAULT_LANE,
        RPC_LANE_3,
        RPC_LANE_HIGH_IDX,
        RPC_LANE_LOW_IDX,
        SYNC_LANE,
      },
      task::LaburnumTask,
    },
    connect::lsp::ClientId,
  },
  macro_rules_attribute::apply,
  std::{
    sync::{
      Arc,
      atomic::{
        AtomicUsize,
        Ordering,
      },
    },
    time::Duration,
  },
};

#[test]
fn rpc_queue_bubbles_up_oldest_tasks() {
  let (scheduler, _conn) = test_scheduler();

  let counter = Arc::new(AtomicUsize::new(0));

  let task_a = {
    let c = counter.clone();
    LaburnumTask::new(
      scheduler.clone(),
      move |_ctx| {
        async move {
          c.fetch_add(1, Ordering::SeqCst);
          None
        }
      },
      RPC_LANE_3,
      ClientId::INTERNAL,
    )
  };

  let task_b = {
    let c = counter.clone();
    LaburnumTask::new(
      scheduler.clone(),
      move |_ctx| {
        async move {
          c.fetch_add(1, Ordering::SeqCst);
          None
        }
      },
      RPC_LANE_3,
      ClientId::INTERNAL,
    )
  };

  let task_c = {
    let c = counter.clone();
    LaburnumTask::new(
      scheduler.clone(),
      move |_ctx| {
        async move {
          c.fetch_add(1, Ordering::SeqCst);
          None
        }
      },
      RPC_LANE_3,
      ClientId::INTERNAL,
    )
  };

  scheduler.queue_rpc_task(task_a.clone());
  scheduler.queue_rpc_task(task_b.clone());
  scheduler.queue_rpc_task(task_c.clone());

  let lane_7_len = scheduler.lane_queues[RPC_LANE_HIGH_IDX].len();
  let lane_8_len = scheduler.lane_queues[RPC_LANE_HIGH_IDX + 1].len();
  let lane_9_len = scheduler.lane_queues[RPC_LANE_HIGH_IDX + 2].len();
  let lane_10_len = scheduler.lane_queues[RPC_LANE_LOW_IDX].len();

  assert_eq!(
    lane_7_len, 0,
    "Lane 7 (highest priority) should be empty - needs 4+ insertions to fill"
  );
  assert_eq!(
    lane_8_len, 1,
    "Lane 8 should have oldest task (A) after 3 insertions"
  );
  assert_eq!(
    lane_9_len, 1,
    "Lane 9 should have middle task (B) after 3 insertions"
  );
  assert_eq!(
    lane_10_len, 1,
    "Lane 10 (lowest priority) should have newest task (C)"
  );
}

#[test]
fn rpc_queue_inserts_at_lowest_priority() {
  let (scheduler, _conn) = test_scheduler();

  let task =
    LaburnumTask::new(scheduler.clone(), |_ctx| async { None }, RPC_LANE_3, ClientId::INTERNAL);

  scheduler.queue_rpc_task(task);

  assert_eq!(
    scheduler.lane_queues[RPC_LANE_LOW_IDX].len(),
    1,
    "New RPC task should be in lowest priority lane (lane 10)"
  );
  assert!(
    scheduler.lane_queues[RPC_LANE_HIGH_IDX].is_empty(),
    "Highest priority lane (lane 7) should be empty for single insertion"
  );
}

#[test]
fn rpc_queue_rotation_is_thread_safe() {
  let (scheduler, _conn) = test_scheduler();
  let scheduler = Arc::new(scheduler);

  let handles: Vec<_> = (0..10)
    .map(|_i| {
      let sched = scheduler.clone();
      std::thread::spawn(move || {
        for _j in 0..100 {
          let task = LaburnumTask::new(
            (*sched).clone(),
            |_ctx| async { None },
            RPC_LANE_3,
            ClientId::INTERNAL,
          );
          sched.queue_rpc_task(task);
        }
      })
    })
    .collect();

  for h in handles {
    h.join().unwrap();
  }

  let total: usize = (RPC_LANE_HIGH_IDX..=RPC_LANE_LOW_IDX)
    .map(|idx| scheduler.lane_queues[idx].len())
    .sum();

  assert_eq!(total, 1000, "All 1000 RPC tasks should be queued");
}

#[test]
fn sync_lane_preempts_rpc_lanes() {
  let (scheduler, _conn) = test_scheduler();

  let rpc_task =
    LaburnumTask::new(scheduler.clone(), |_ctx| async { None }, RPC_LANE_3, ClientId::INTERNAL);
  scheduler.queue_rpc_task(rpc_task);

  let sync_task =
    LaburnumTask::new(scheduler.clone(), |_ctx| async { None }, SYNC_LANE, ClientId::INTERNAL);
  scheduler.queue_task(sync_task);

  let mut first_task_lane = None;
  for lane_idx in 0..31 {
    if let Ok(task) = scheduler.lane_queues[lane_idx].pop() {
      first_task_lane = Some(task.lane);
      break;
    }
  }

  assert_eq!(
    first_task_lane,
    Some(SYNC_LANE),
    "Sync task should be stolen before RPC tasks"
  );
}

#[test]
fn rpc_queue_maintains_fifo_within_priority() {
  let (scheduler, _conn) = test_scheduler();

  for _ in 0..5 {
    let task =
      LaburnumTask::new(scheduler.clone(), |_ctx| async { None }, RPC_LANE_3, ClientId::INTERNAL);
    scheduler.queue_rpc_task(task);
  }

  let lane_7 = scheduler.lane_queues[RPC_LANE_HIGH_IDX].len();
  let lane_8 = scheduler.lane_queues[RPC_LANE_HIGH_IDX + 1].len();
  let lane_9 = scheduler.lane_queues[RPC_LANE_HIGH_IDX + 2].len();
  let lane_10 = scheduler.lane_queues[RPC_LANE_LOW_IDX].len();

  assert_eq!(lane_7, 2, "Lane 7 should have 2 oldest tasks");
  assert_eq!(lane_8, 1, "Lane 8 should have 1 task");
  assert_eq!(lane_9, 1, "Lane 9 should have 1 task");
  assert_eq!(lane_10, 1, "Lane 10 should have 1 newest task");
}

#[apply(smol_macros::test!)]
#[test_log::test]
async fn worker_steals_rpc_tasks_oldest_first() {
  let (scheduler, _conn) = test_scheduler();

  let execution_order = Arc::new(parking_lot::Mutex::new(Vec::new()));

  for i in 0..4 {
    let order = execution_order.clone();
    let task = LaburnumTask::new(
      scheduler.clone(),
      move |_ctx| {
        let order = order.clone();
        async move {
          order.lock().push(i);
          None
        }
      },
      RPC_LANE_3,
      ClientId::INTERNAL,
    );
    scheduler.queue_rpc_task(task);
  }

  scheduler.spawn_workers();

  assert!(
    wait_for(|| execution_order.lock().len() == 4, Duration::from_secs(5))
      .await,
    "Not all RPC tasks completed"
  );

  let order = execution_order.lock().clone();
  assert_eq!(
    order,
    vec![0, 1, 2, 3],
    "RPC tasks should execute oldest first (FIFO via bubble-up)"
  );
}

#[apply(smol_macros::test!)]
#[test_log::test]
async fn worker_processes_standard_lanes_before_rpc() {
  let (scheduler, _conn) = test_scheduler();

  let execution_order = Arc::new(parking_lot::Mutex::new(Vec::new()));

  let order = execution_order.clone();
  let rpc_task = LaburnumTask::new(
    scheduler.clone(),
    move |_ctx| {
      let order = order.clone();
      async move {
        order.lock().push("rpc");
        None
      }
    },
    RPC_LANE_3,
    ClientId::INTERNAL,
  );
  scheduler.queue_rpc_task(rpc_task);

  let order = execution_order.clone();
  scheduler.queue(
    move |_control| {
      let order = order.clone();
      async move {
        order.lock().push("default");
        None
      }
    },
    DEFAULT_LANE,
  );

  let order = execution_order.clone();
  scheduler.queue(
    move |_control| {
      let order = order.clone();
      async move {
        order.lock().push("sync");
        None
      }
    },
    SYNC_LANE,
  );

  scheduler.spawn_workers();

  assert!(
    wait_for(|| execution_order.lock().len() == 3, Duration::from_secs(5))
      .await,
    "Not all tasks completed"
  );

  let order = execution_order.lock().clone();
  assert_eq!(order[0], "sync", "SYNC_LANE should execute first");
  assert_eq!(
    order[1], "default",
    "DEFAULT_LANE should execute before RPC"
  );
  assert_eq!(order[2], "rpc", "RPC should execute last");
}

#[apply(smol_macros::test!)]
#[test_log::test]
async fn worker_processes_rpc_before_async_lanes() {
  let (scheduler, _conn) = test_scheduler();

  let execution_order = Arc::new(parking_lot::Mutex::new(Vec::new()));

  let order = execution_order.clone();
  scheduler.queue(
    move |_control| {
      let order = order.clone();
      async move {
        order.lock().push("async");
        None
      }
    },
    ASYNC_LANE1,
  );

  let order = execution_order.clone();
  let rpc_task = LaburnumTask::new(
    scheduler.clone(),
    move |_ctx| {
      let order = order.clone();
      async move {
        order.lock().push("rpc");
        None
      }
    },
    RPC_LANE_3,
    ClientId::INTERNAL,
  );
  scheduler.queue_rpc_task(rpc_task);

  scheduler.spawn_workers();

  assert!(
    wait_for(|| execution_order.lock().len() == 2, Duration::from_secs(5))
      .await,
    "Not all tasks completed"
  );

  let order = execution_order.lock().clone();
  assert_eq!(order[0], "rpc", "RPC should execute before ASYNC_LANE");
  assert_eq!(order[1], "async", "ASYNC_LANE should execute after RPC");
}

#[apply(smol_macros::test!)]
#[test_log::test]
async fn rpc_task_requeue_interleaves_fairly() {
  let (scheduler, _conn) = test_scheduler();

  let poll_sequence = Arc::new(parking_lot::Mutex::new(Vec::new()));
  let completed = Arc::new(AtomicUsize::new(0));

  let seq_a = poll_sequence.clone();
  let done = completed.clone();
  let task_a = LaburnumTask::new(
    scheduler.clone(),
    move |_ctx| {
      let seq = seq_a.clone();
      let done = done.clone();
      async move {
        for _ in 0..4 {
          seq.lock().push('A');
          futures_lite::future::yield_now().await;
        }
        done.fetch_add(1, Ordering::SeqCst);
        None
      }
    },
    RPC_LANE_3,
    ClientId::INTERNAL,
  );

  let seq_b = poll_sequence.clone();
  let done = completed.clone();
  let task_b = LaburnumTask::new(
    scheduler.clone(),
    move |_ctx| {
      let seq = seq_b.clone();
      let done = done.clone();
      async move {
        for _ in 0..4 {
          seq.lock().push('B');
          futures_lite::future::yield_now().await;
        }
        done.fetch_add(1, Ordering::SeqCst);
        None
      }
    },
    RPC_LANE_3,
    ClientId::INTERNAL,
  );

  scheduler.queue_rpc_task(task_a);
  scheduler.queue_rpc_task(task_b);

  scheduler.spawn_workers();

  assert!(
    wait_for(
      || completed.load(Ordering::SeqCst) == 2,
      Duration::from_secs(5)
    )
    .await,
    "Not all RPC tasks completed"
  );

  let sequence = poll_sequence.lock().clone();

  assert_eq!(
    sequence.len(),
    8,
    "Expected 8 polls total (4 per task), got {}",
    sequence.len()
  );

  let a_count = sequence.iter().filter(|&&c| c == 'A').count();
  let b_count = sequence.iter().filter(|&&c| c == 'B').count();
  assert_eq!(a_count, 4, "Task A should be polled 4 times");
  assert_eq!(b_count, 4, "Task B should be polled 4 times");

  let mut max_consecutive = 1;
  let mut current_consecutive = 1;
  for i in 1..sequence.len() {
    if sequence[i] == sequence[i - 1] {
      current_consecutive += 1;
      max_consecutive = max_consecutive.max(current_consecutive);
    } else {
      current_consecutive = 1;
    }
  }

  assert!(
    max_consecutive <= 2,
    "Tasks should interleave fairly. Max consecutive same-task polls: {}. Sequence: {:?}",
    max_consecutive,
    sequence
  );
}

#[test]
fn rpc_queue_concurrent_push_and_pop() {
  let (scheduler, _conn) = test_scheduler();
  let scheduler = Arc::new(scheduler);

  let total_tasks = 500;
  let stolen = Arc::new(AtomicUsize::new(0));

  let push_handles: Vec<_> = (0..5)
    .map(|_| {
      let sched = scheduler.clone();
      std::thread::spawn(move || {
        for _ in 0..100 {
          let task = LaburnumTask::new(
            (*sched).clone(),
            |_ctx| async { None },
            RPC_LANE_3,
            ClientId::INTERNAL,
          );
          sched.queue_rpc_task(task);
        }
      })
    })
    .collect();

  let pop_handles: Vec<_> = (0..5)
    .map(|_| {
      let sched = scheduler.clone();
      let stolen = stolen.clone();
      std::thread::spawn(move || {
        let mut local_stolen = 0;
        for _ in 0..200 {
          for idx in RPC_LANE_HIGH_IDX..=RPC_LANE_LOW_IDX {
            if sched.lane_queues[idx].pop().is_ok() {
              local_stolen += 1;
            }
          }
          std::thread::yield_now();
        }
        stolen.fetch_add(local_stolen, Ordering::SeqCst);
      })
    })
    .collect();

  for h in push_handles {
    h.join().unwrap();
  }
  for h in pop_handles {
    h.join().unwrap();
  }

  let remaining: usize = (RPC_LANE_HIGH_IDX..=RPC_LANE_LOW_IDX)
    .map(|idx| scheduler.lane_queues[idx].len())
    .sum();
  let total_stolen = stolen.load(Ordering::SeqCst);

  assert_eq!(
    remaining + total_stolen,
    total_tasks,
    "All {} tasks should be accounted for: {} remaining + {} stolen",
    total_tasks,
    remaining,
    total_stolen
  );
}

#[test]
fn rpc_queue_no_task_loss_under_contention() {
  let (scheduler, _conn) = test_scheduler();
  let scheduler = Arc::new(scheduler);

  let task_ids =
    Arc::new(parking_lot::Mutex::new(std::collections::HashSet::new()));
  let completed_ids =
    Arc::new(parking_lot::Mutex::new(std::collections::HashSet::new()));

  for i in 0..100 {
    task_ids.lock().insert(i);
    let completed = completed_ids.clone();
    let task = LaburnumTask::new(
      (*scheduler).clone(),
      move |_ctx| {
        let completed = completed.clone();
        async move {
          completed.lock().insert(i);
          None
        }
      },
      RPC_LANE_3,
      ClientId::INTERNAL,
    );
    scheduler.queue_rpc_task(task);
  }

  let handles: Vec<_> = (0..4)
    .map(|_| {
      let sched = scheduler.clone();
      std::thread::spawn(move || {
        for _ in 0..50 {
          for idx in RPC_LANE_HIGH_IDX..=RPC_LANE_LOW_IDX {
            if let Ok(task) = sched.lane_queues[idx].pop() {
              let _ = task.poll_once();
            }
          }
          std::thread::yield_now();
        }
      })
    })
    .collect();

  for h in handles {
    h.join().unwrap();
  }

  for idx in RPC_LANE_HIGH_IDX..=RPC_LANE_LOW_IDX {
    while let Ok(task) = scheduler.lane_queues[idx].pop() {
      let _ = task.poll_once();
    }
  }

  let original = task_ids.lock().clone();
  let completed = completed_ids.lock().clone();

  assert_eq!(
    original,
    completed,
    "All queued tasks should complete. Missing: {:?}",
    original.difference(&completed).collect::<Vec<_>>()
  );
}