Struct Queue

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

Instance of a queue returning elements of type T.

Example usage:

  use diskqueue::Queue;
  let q: Queue<i32> = Queue::new(path).unwrap();
  q.enqueue(123).unwrap();
  let v = q.dequeue().unwrap();
  assert_eq!(v, Some(123));

Implementations

impl<T> Queue<T>

where T: DeserializeOwned + Serialize,

pub fn open_or_create(path: PathBuf) -> Result<Self, Error>

Try opening a queue at the given location or create a new queue directory.

pub fn new(path: PathBuf) -> Result<Self, Error>

Create a new queue directory at the given path. The path must not exist.

pub fn open(path: PathBuf) -> Result<Self, Error>

Create a new queue instance for the given path. If the path doesn’t follow the queue directory structure an error is returned.

pub fn enqueue(&self, payload: T) -> Result<u64, Error>

Add the given item to the queue. Returns the unique id of the item.

pub fn dequeue(&self) -> Result<Option<T>, Error>

Consume a single item from the queue. Returns Ok(None) if there was no item that could be consumed, otherwise returns Ok(Some(T)). Retries up to 5 times on transient errors e.g. another process having locked or removed the item already. If it fails to read five times Ok(None) is returned.

pub fn dequeue_try_once(&self) -> Result<Option<T>, Error>

Tries to dequeue a single item from the queue. Compared to Queue::dequeue this function doesn’t retry and might return transient errors. Returns Ok(Some(T)) on success and Ok(None) when the queue is empty.