FCookRand

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A RefCounted RandomStream and a threadlocal global accessor for accessing a currently scoped instance. Intended use is for cook operations to set a scope that can be used for deterministic replacement of random or other fundamentally non-deterministic calculations such as NewGuid.

Like RandomStream, const functions on FCookRand can have the side effect of mutating the RandomSeed to the next random value.

An FCookRand instance is not thread-safe because call order in a threaded environment is in general non-deterministic. Callers that run multithreaded operations using FCookRand should maintain their own FCookRand and should pass exclusive ownership of it to each task thread in a deterministic order.

Example usage:

void HighLevelFunctionWithUserCode() { int32 MySeed = ComputeMyDeterministicSeed(); UE::Cook::FCookRandScope Scope(MySeed, UE::Cook::ECookRandScope::Overwrite);

// ... Call UserCode that uses MyAPI }

FGuid MyAPI::NewGuid() { TRefCountPtr Rand = FCookRand::GetThreadScope(); return Rand ? Rand->RandomGuid() : FGuid::NewGuid(); } float MyAPI::FRand() { TRefCountPtr Rand = FCookRand::GetThreadScope(); return Rand ? Rand->RandomStream().FRand() : FMath::FRand(); }

Syntax

class FCookRand : public FRefCountedObject  
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class FCookRand : public FRefCountedObject

Inheritance Hierarchy

• TAtomicRefCount → FRefCountedObject → FCookRand

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