Struct NgxQueue

pub struct NgxQueue<T> { /* private fields */ }

A wrapper over a raw ngx_queue_t, an intrusive doubly-linked list.

This wrapper is defined in terms of type T that embeds and can be converted from or to the list entries.

Example:

// We need a wrapper type to define [NgxQueueEntry] on.
#[repr(transparent)]
struct PostedEvent(ngx_event_t);

unsafe impl NgxQueueEntry for PostedEvent {
    fn from_queue(queue: NonNull<ngx_queue_t>) -> NonNull<Self> {
        // We can safely cast obtained ngx_event_t to a transparent wrapper.
        unsafe { ngx_queue_data!(queue, ngx_event_t, queue) }.cast()
    }

    fn to_queue(&mut self) -> &mut ngx_queue_t {
        &mut self.0.queue
    }
}

// SAFETY: `ngx_posted_events` global static is a list of `ngx_event_t` linked via
// `ngx_event_t.queue`.
// NGINX is single-threaded, so we get exclusive access to the static.
let posted: &mut NgxQueue<PostedEvent> =
        unsafe { NgxQueue::from_ptr_mut(addr_of_mut!(ngx_posted_events)) };

See https://nginx.org/en/docs/dev/development_guide.html#queue.

Implementations

impl<T> NgxQueue<T>

where T: NgxQueueEntry,

pub unsafe fn from_ptr<'a>(head: *const ngx_queue_t) -> &'a Self

Creates a queue reference from a pointer to ngx_queue_t.

Safety

head is a valid pointer to a list head, and T::from_queue on the list entries results in valid pointers to T.

pub unsafe fn from_ptr_mut<'a>(head: *mut ngx_queue_t) -> &'a mut Self

Creates a mutable queue reference from a pointer to ngx_queue_t.

Safety

head is a valid pointer to a list head, and T::from_queue on the list entries results in valid pointers to T.

pub fn is_empty(&self) -> bool

Returns true if the queue contains no elements.

pub fn push_back(&mut self, entry: &mut T)

Appends an element to the end of the queue.

pub fn push_front(&mut self, entry: &mut T)

Appends an element to the beginning of the queue.

pub fn iter(&self) -> NgxQueueIter<'_, T>

Returns an iterator over the entries of the queue.

pub fn iter_mut(&mut self) -> NgxQueueIterMut<'_, T>

Returns a mutable iterator over the entries of the queue.

Trait Implementations

impl<T: Debug> Debug for NgxQueue<T>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.