Repository: tokio-rs/tokio
File: tokio/src/runtime/task/list.rs (Rust)

Code before:
            return None;
        }
        shard.push(task);
        Some(notified)
    }

    /// Asserts that the given task is owned by this OwnedTasks and convert it to
    /// a LocalNotified, giving the thread permission to poll this task.
    #[inline]
    pub(crate) fn assert_owner(&self, task: Notified<S>) -> LocalNotified<S> {
        debug_assert_eq!(task.header().get_owner_id(), Some(self.id));
        // safety: All tasks bound to this OwnedTasks are Send, so it is safe
        // to poll it on this thread no matter what thread we are on.
        LocalNotified {
            task: task.0,
            _not_send: PhantomData,
        }
    }

    /// Shuts down all tasks in the collection. This call also closes the
    /// collection, preventing new items from being added.
    ///
    /// The parameter start should be random among different worker threads
    /// to reduce lock conflicts during shutdown.
    /// Initiate shutting down the shard indexed by the start, and reset to 0
    /// once the shar_size is reached, continuing until start - 1, it works like a ring.
    pub(crate) fn close_and_shutdown_all(&self, start: usize)
    where
        S: Schedule,
    {
        self.closed.store(true, Ordering::Release);
        for i in start..self.get_shard_size() + start {
            loop {
                let task = self.list.pop_back(i);
                match task {
                    Some(task) => {
                        task.shutdown();
                    }
                    None => break,
                }
            }
        }
    }

    #[inline]
    pub(crate) fn get_shard_size(&self) -> usize {
        self.list.shard_size()
    }

    pub(crate) fn active_tasks_count(&self) -> usize {
        self.list.len()

Review comment (suggestion):
This sentence is inaccurate if `start == 0`. 
```suggestion
    /// once the `shard_size` is reached, continuing until `start - 1`, it works like a ring.
```

Code after:
            drop(shard);
            task.shutdown();
            return None;
        }
        shard.push(task);
        Some(notified)
    }

    /// Asserts that the given task is owned by this OwnedTasks and convert it to
    /// a LocalNotified, giving the thread permission to poll this task.
    #[inline]
    pub(crate) fn assert_owner(&self, task: Notified<S>) -> LocalNotified<S> {
        debug_assert_eq!(task.header().get_owner_id(), Some(self.id));
        // safety: All tasks bound to this OwnedTasks are Send, so it is safe
        // to poll it on this thread no matter what thread we are on.
        LocalNotified {
            task: task.0,
            _not_send: PhantomData,
        }
    }

    /// Shuts down all tasks in the collection. This call also closes the
    /// collection, preventing new items from being added.
    ///
    /// The parameter start determines which shard this method will start at.
    /// Using different values for each worker thread reduces contention.
    pub(crate) fn close_and_shutdown_all(&self, start: usize)
    where
        S: Schedule,
    {
        self.closed.store(true, Ordering::Release);
        for i in start..self.get_shard_size() + start {
            loop {
                let task = self.list.pop_back(i);
                match task {
                    Some(task) => {
                        task.shutdown();
                    }
                    None => break,
                }
            }
        }
    }

    #[inline]
    pub(crate) fn get_shard_size(&self) -> usize {
        self.list.shard_size()
    }

    pub(crate) fn active_tasks_count(&self) -> usize {
        self.list.len()