Struct bb8::Builder

pub struct Builder<M: ManageConnection> { /* private fields */ }

A builder for a connection pool.

Implementations

impl<M: ManageConnection> Builder<M>

pub fn new() -> Self

Constructs a new Builder.

Parameters are initialized with their default values.

pub fn max_size(self, max_size: u32) -> Self

Sets the maximum number of connections managed by the pool.

Defaults to 10.

Panics

Will panic if max_size is 0.

pub fn min_idle(self, min_idle: impl Into<Option<u32>>) -> Self

Sets the minimum idle connection count maintained by the pool.

If set, the pool will try to maintain at least this many idle connections at all times, while respecting the value of max_size.

Defaults to None.

pub fn test_on_check_out(self, test_on_check_out: bool) -> Self

If true, the health of a connection will be verified through a call to ManageConnection::is_valid before it is provided to a pool user.

Defaults to true.

pub fn max_lifetime(self, max_lifetime: impl Into<Option<Duration>>) -> Self

Sets the maximum lifetime of connections in the pool.

If set, connections will be closed at the next reaping after surviving past this duration.

If a connection reaches its maximum lifetime while checked out it will be closed when it is returned to the pool.

Defaults to 30 minutes.

Panics

Will panic if max_lifetime is 0.

pub fn idle_timeout(self, idle_timeout: impl Into<Option<Duration>>) -> Self

Sets the idle timeout used by the pool.

If set, idle connections in excess of min_idle will be closed at the next reaping after remaining idle past this duration.

Defaults to 10 minutes.

Panics

Will panic if idle_timeout is 0.

pub fn connection_timeout(self, connection_timeout: Duration) -> Self

Sets the connection timeout used by the pool.

Futures returned by Pool::get will wait this long before giving up and resolving with an error.

Defaults to 30 seconds.

Panics

Will panic if connection_timeout is 0.

pub fn retry_connection(self, retry: bool) -> Self

Instructs the pool to automatically retry connection creation if it fails, until the connection_timeout has expired.

Useful for transient connectivity errors like temporary DNS resolution failure or intermittent network failures. Some applications however are smart enough to know that the server is down and retries won’t help (and could actually hurt recovery). In that case, it’s better to disable retries here and let the pool error out.

Defaults to enabled.

pub fn error_sink(self, error_sink: Box<dyn ErrorSink<M::Error>>) -> Self

Set the sink for errors that are not associated with any particular operation on the pool. This can be used to log and monitor failures.

Defaults to NopErrorSink.

pub fn reaper_rate(self, reaper_rate: Duration) -> Self

Used by tests

pub fn queue_strategy(self, queue_strategy: QueueStrategy) -> Self

Sets the queue strategy to be used by the pool

Defaults to Fifo.

pub fn connection_customizer( self, connection_customizer: Box<dyn CustomizeConnection<M::Connection, M::Error>> ) -> Self

Set the connection customizer to customize newly checked out connections

pub async fn build(self, manager: M) -> Result<Pool<M>, M::Error>

Consumes the builder, returning a new, initialized Pool.

The Pool will not be returned until it has established its configured minimum number of connections, or it times out.

pub fn build_unchecked(self, manager: M) -> Pool<M>

Consumes the builder, returning a new, initialized Pool.

Unlike build, this does not wait for any connections to be established before returning.

Trait Implementations

impl<M: Debug + ManageConnection> Debug for Builder<M>

where M::Error: Debug, M::Connection: Debug,

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

Formats the value using the given formatter.

impl<M: ManageConnection> Default for Builder<M>

fn default() -> Self

Returns the “default value” for a type.