Struct Pool

pub struct Pool<M: Manager, W: From<Object<M>> = Object<M>> { /* private fields */ }

Generic object and connection pool.

This struct can be cloned and transferred across thread boundaries and uses reference counting for its internal state.

Implementations

impl<M: Manager, W: From<Object<M>>> Pool<M, W>

pub fn builder(manager: M) -> PoolBuilder<M, W>

Instantiates a builder for a new Pool.

This is the only way to create a Pool instance.

pub async fn get(&self) -> Result<W, PoolError<M::Error>>

Retrieves an Object from this Pool or waits for one to become available.

Errors

See PoolError for details.

pub async fn timeout_get( &self, timeouts: &Timeouts, ) -> Result<W, PoolError<M::Error>>

Retrieves an Object from this Pool using a different timeout than the configured one.

Errors

See PoolError for details.

pub fn resize(&self, max_size: usize)

Resize the pool. This change the max_size of the pool dropping excess objects and/or making space for new ones.

If the pool is closed this method does nothing. The Pool::status method always reports a max_size of 0 for closed pools.

pub fn retain(&self, f: impl Fn(&M::Type, Metrics) -> bool)

Retains only the objects specified by the given function.

This function is typically used to remove objects from the pool based on their current state or metrics.

Caution: This function blocks the entire pool while it is running. Therefore the given function should not block.

The following example starts a background task that runs every 30 seconds and removes objects from the pool that haven’t been used for more than one minute.

let interval = Duration::from_secs(30);
let max_age = Duration::from_secs(60);
tokio::spawn(async move {
    loop {
        tokio::time::sleep(interval).await;
        pool.retain(|_, metrics| metrics.last_used() < max_age);
    }
});

pub fn timeouts(&self) -> Timeouts

Get current timeout configuration

pub fn close(&self)

Closes this Pool.

All current and future tasks waiting for Objects will return PoolError::Closed immediately.

This operation resizes the pool to 0.

pub fn is_closed(&self) -> bool

Indicates whether this Pool has been closed.

pub fn status(&self) -> Status

Retrieves Status of this Pool.

pub fn manager(&self) -> &M

Returns Manager of this Pool.

Trait Implementations

impl<M: Manager, W: From<Object<M>>> Clone for Pool<M, W>

fn clone(&self) -> Self

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<M, W> Debug for Pool<M, W>

where M: Debug + Manager, M::Type: Debug, W: From<Object<M>>,

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

Formats the value using the given formatter.