Struct WarmPool 

pub struct WarmPool { /* private fields */ }

A pre-warmed pool of ready-to-use MicroVMs.

The pool maintains min_idle VMs in Ready state. When a VM is acquired, the pool spawns a replacement in the background. Idle VMs that exceed idle_ttl_secs are automatically evicted.

Usage

let pool = WarmPool::start(pool_config, box_config, emitter).await?;
let vm = pool.acquire().await?;  // Instant if pool has capacity
// ... use vm ...
pool.release(vm).await?;         // Return to pool or destroy
pool.drain().await?;             // Graceful shutdown

Implementations

impl WarmPool

pub async fn start( config: PoolConfig, box_config: BoxConfig, event_emitter: EventEmitter, ) -> Result<Self>

Create and start the warm pool.

Spawns min_idle VMs in the background and starts the replenishment/eviction loop.

pub fn set_metrics(&mut self, metrics: RuntimeMetrics)

Attach Prometheus metrics to this pool.

pub async fn acquire(&self) -> Result<VmManager>

Acquire a ready VM from the pool.

If an idle VM is available, returns it immediately. Otherwise, boots a new VM on demand (slower path).

pub async fn release(&self, vm: VmManager) -> Result<()>

Release a VM back to the pool.

If the pool is at capacity, the VM is destroyed instead.

pub async fn stats(&self) -> PoolStats

Get current pool statistics.

pub async fn idle_count(&self) -> usize

Get the number of idle VMs currently in the pool.

pub fn signal_shutdown(&self)

Signal the pool to shutdown. This signals the background task to stop replenishing and sets the shutdown flag. VMs will continue to exist until the pool is drained or dropped.

pub async fn drain(&mut self) -> Result<()>

Gracefully drain all VMs and stop the pool.

pub async fn drain_idle(&self) -> Result<()>

Destroy all idle VMs without consuming the pool (&self), so it can be shut down from behind an Arc (e.g. a daemon serving concurrent requests). Pair with Self::signal_shutdown first to stop the background replenisher; its task then exits on its own (it watches the shutdown channel).