Struct PoolConfig 

pub struct PoolConfig {
    pub max_connections: usize,
    pub min_connections: usize,
    pub connect_timeout: Duration,
    pub idle_timeout: Option<Duration>,
    pub max_lifetime: Option<Duration>,
    pub health_check: HealthCheckStrategy,
    pub acquire_timeout: Duration,
    pub after_connect: Option<ConnectCallback>,
    pub before_acquire: Option<AcquireCallback>,
    pub after_release: Option<ReleaseCallback>,
}

Configuration for the connection pool.

Supports lifecycle callbacks for connection setup, validation, and cleanup. All callbacks are optional and default to None.

Fields

max_connections: usize

min_connections: usize

connect_timeout: Duration

idle_timeout: Option<Duration>

max_lifetime: Option<Duration>

health_check: HealthCheckStrategy

acquire_timeout: Duration

after_connect: Option<ConnectCallback>

before_acquire: Option<AcquireCallback>

after_release: Option<ReleaseCallback>

Implementations

impl PoolConfig

pub fn new() -> Self

pub fn max_connections(self, n: usize) -> Self

Maximum number of connections in the pool.

Default: 2 * number of CPUs.

pub fn min_connections(self, n: usize) -> Self

Minimum number of idle connections to maintain.

The pool will create connections in the background to maintain this minimum. Default: 1.

pub fn connect_timeout(self, timeout: Duration) -> Self

Timeout for establishing new connections.

Default: 10 seconds.

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

Maximum time a connection can sit idle before being closed.

Set to None to disable idle timeout. Default: 600 seconds.

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

Maximum total lifetime of a connection before it’s recycled.

Set to None to disable max lifetime. Default: 3600 seconds.

pub fn health_check(self, strategy: HealthCheckStrategy) -> Self

Strategy for checking connection health on checkout.

Default: Fast (flag-based, no query).

pub fn acquire_timeout(self, timeout: Duration) -> Self

Timeout for acquiring a connection from the pool.

If the pool is full and no connection becomes available within this duration, an error is returned. Default: 30 seconds.

pub fn after_connect<F>(self, callback: F) -> Self

where F: Fn(&mut Connection) -> BoxFuture<'_, Result<()>> + Send + Sync + 'static,

Set a callback that runs once per newly created connection.

Called after TCP + TLS + auth completes, before the connection enters the pool. Use for session setup like SET search_path.

If the callback returns an error, the connection is discarded and the pool retries with a new connection.

Example

PoolConfig::new()
    .after_connect(|conn| Box::pin(async move {
        conn.execute("SET search_path TO myapp", &[]).await?;
        Ok(())
    }));

pub fn before_acquire<F>(self, callback: F) -> Self

where F: Fn(&mut Connection) -> BoxFuture<'_, Result<bool>> + Send + Sync + 'static,

Set a callback that runs before returning a connection from the pool.

Called after health check passes. Return false to reject the connection — it will be discarded and the pool tries the next idle connection or creates a new one.

Example

PoolConfig::new()
    .before_acquire(|conn| Box::pin(async move {
        Ok(!conn.is_broken())
    }));

pub fn after_release<F>(self, callback: F) -> Self

where F: Fn(&mut Connection) -> BoxFuture<'_, Result<bool>> + Send + Sync + 'static,

Set a callback that runs when a connection returns to the pool.

Called before the connection enters the idle queue. Return false to discard the connection instead of returning it.

Example

PoolConfig::new()
    .after_release(|conn| Box::pin(async move {
        Ok(true) // always return to pool
    }));

Trait Implementations

impl Clone for PoolConfig

fn clone(&self) -> PoolConfig

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for PoolConfig

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

Formats the value using the given formatter.

impl Default for PoolConfig

fn default() -> Self

Returns the “default value” for a type.