Struct InstancePool 

pub struct InstancePool<T, E>
where
    T: Send + 'static,
    E: PoolResourceLimit + Send + Sync + 'static,
{ /* private fields */ }

A pool of pre-warmed instances for one plugin.

Generic over the pooled instance type T and the loader’s error type E. Production use: InstancePool<extism::Plugin, ExtismError> or InstancePool<wasmtime::component::Instance, WasmError>.

Implementations

impl<T, E> InstancePool<T, E>

where T: Send + 'static, E: PoolResourceLimit + Send + Sync + 'static,

pub fn new( cfg: PoolConfig, factory: impl Fn() -> Result<T, E> + Send + Sync + 'static, ) -> Result<Self, E>

Construct a pool that builds new instances via factory.

Eagerly constructs cfg.warm_count.min(cfg.max_instances) instances at construction time so first-call latency is the pool’s steady-state hit cost, not a fresh wasmtime compile.

Errors

Propagates factory errors from initial warm-up.

pub fn acquire(&self) -> Result<T, E>

Acquire an instance from the pool.

Pops a warm instance if available; otherwise constructs a new one if live < max_instances. Returns a loader-specific resource-limit error if the pool is at capacity.

Errors

• E::resource_limit(...) when max_instances is reached.
• Whatever the factory returns on cold-construction failure.

pub fn release(&self, inst: T)

Release an instance back to the pool.

On overflow (race with reaper), the instance is dropped — its Drop impl is responsible for any cleanup.

pub fn metrics(&self) -> Arc<PoolMetrics>

Snapshot the current metrics.

pub fn config(&self) -> &PoolConfig

Pool configuration, for diagnostics.

Trait Implementations

impl<T, E> Debug for InstancePool<T, E>

where T: Send + 'static, E: PoolResourceLimit + Send + Sync + 'static,

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

Formats the value using the given formatter.