API Reference

UCrimsonObjectPoolSubsystem

A UWorldSubsystem, created for Game and PIE worlds only. Get it with UCrimsonObjectPoolSubsystem::Get(WorldContextObject) in C++ or Get Crimson Object Pool Subsystem in Blueprint.

Function	Returns	Purpose
`AcquireActor(ActorClass, Transform, NewOwner, NewInstigator)`	`AActor*`	Hands out a live instance, recycling or spawning as needed. Null under `HardCap` exhaustion, or on a client for a replicated class.
`AcquireActorDeferred(ActorClass, NewOwner, NewInstigator)`	`AActor*`	Returns the instance still dormant so it can be configured before going live. Pair with `FinishAcquiringActor`.
`FinishAcquiringActor(Actor, Transform)`	`void`	Completes a deferred acquire: positions the instance and brings it into play.
`ReleaseActor(Actor)`	`bool`	Stands the instance down and parks it, or destroys it if the free list is full. False if it was not pool-owned, already parked, or the caller was a client.
`ReleaseActorAfter(Actor, Seconds)`	`void`	Releases after a delay. Cancels itself if the actor is released early or destroyed. Calling it again restarts the delay rather than queueing a second release.
`CancelPendingRelease(Actor)`	`void`	Cancels a pending delayed release.
`RequestActorQueued(ActorClass, Transform, NewOwner, NewInstigator)`	`int32`	Queues an acquire served across frames instead of immediately. Returns a request id.
`CancelQueuedRequest(RequestId)`	`bool`	Drops a queued request before it is served.
`GetQueuedRequestCount()`	`int32`	How many requests are still outstanding.
`OnPooledActorReady`	delegate	`(AActor* Actor, int32 RequestId)`. Fires once per queued request, in order. `Actor` is null if the acquire failed.
`PrewarmPool(ActorClass, Count)`	`void`	Spawns and parks instances up front. Refused with a warning before the world has begun play.
`DrainPool(ActorClass)`	`void`	Destroys every free instance of a class. Checked-out instances are dropped from pool ownership.
`DrainAllPools()`	`void`	As above, for every class.
`GetPoolStats(ActorClass)`	`FCrimsonObjectPoolStats`	One class's counters.
`GetAllPoolStats()`	`TArray<FCrimsonObjectPoolStats>`	Every pool, sorted by class name.
`IsPoolOwnedActor(Actor)`	`bool`	Whether releasing this actor will recycle it rather than do nothing.
`IsBypassEnabled()`	`bool`	Static. Reads the `Crimson.ObjectPool.Bypass` cvar.

ICrimsonPoolable

Ships in CrimsonCommon

Include Pooling/ICrimsonPoolable.h, and depend on CrimsonCommon. It lives there rather than in CrimsonObjectPool so that actors in other Crimson plugins can implement it - no Crimson plugin may reference a sibling.

Member	Audience	Purpose
`OnAcquiredFromPool(const FTransform& Transform)`	Blueprint + C++	Bring the instance back into play. Implementing the interface makes this the only reactivation that happens.
`OnReleasedToPool()`	Blueprint + C++	Stand the instance down. Called while it is still fully active, before the pool applies dormancy.
`GetPoolReleaseDelegate()`	C++ only	Optional. Return a delegate you broadcast when finished and the pool reclaims the actor automatically. Not a `UFUNCTION` - a Blueprint cannot hand out a delegate reference, and should call `Release Actor` instead.
`FCrimsonOnPoolableReleaseRequested`	C++ only	`DECLARE_DYNAMIC_MULTICAST_DELEGATE_OneParam(..., AActor*, Actor)`. The delegate type returned above.

UCrimsonObjectPoolSettings

Project Settings > Crimson > Crimson Object Pool. Config section CrimsonObjectPool.

Setting	Default	Purpose
`DefaultCapacity`	32	Free instances retained for a class with no override.
`DefaultGrowthPolicy`	`Grow`	What happens when the free list is empty.
`bDestroyOnOverCapacityRelease`	true	Destroy rather than pool a release that would exceed capacity.
`ClassOverrides`	empty	`TMap<TSoftClassPtr<AActor>, FCrimsonObjectPoolClassConfig>`. Lookup walks up the class hierarchy.
`MaxSpawnsPerFrame`	2	How many NEW actors a queued request may spawn per frame. Per frame, not per second - a hitch is a frame-cost problem.
`bBatchPooledAcquires`	true	Serve queued requests that a warm pool can fill from its free list immediately, without spending the frame budget.
`PoolPressureWarningRatio`	0.9	Warn once per class when live count reaches this fraction of capacity. 0 disables.
`bUseNetDormancyWhilePooled`	true	Put replicated actors into `DORM_DormantAll` while parked. Leave on - see Concept: Replication and Recycling.

Data types

Type	Members
`FCrimsonObjectPoolClassConfig`	`Capacity`, `GrowthPolicy`, `PrewarmCount`, `bDestroyOnOverCapacityRelease`
`FCrimsonObjectPoolStats`	`ActorClass`, `PooledCount`, `LiveCount`, `TotalCreated`, `SpawnsAvoided`, `HighWaterLive`, `Capacity`
`ECrimsonObjectPoolGrowthPolicy`	`Grow`, `HardCap`

Console commands

Command	Purpose
`Crimson.ObjectPool.Bypass 0\|1`	1 makes every acquire a real `SpawnActor` and every release a real `Destroy`.
`Crimson.ObjectPool.Dump`	Prints per-class pooled / live / high-water / created / spawns-avoided / capacity.

MCP tools

Gated behind Project Settings > Crimson > Crimson MCP > Enable Crimson MCP (requires an editor restart). All operate on the authoritative PIE world.

Tool	Kind	Purpose
`CrimsonObjectPoolToolset.ListPools`	read	Every pool with its full counters.
`CrimsonObjectPoolToolset.SetPoolBypass`	act	Sets the bypass cvar.
`CrimsonObjectPoolToolset.DrainAllPools`	act	Destroys every free instance in every pool.