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TStripedMapBase

The base class of striped maps which is a wrapper that adds thread-safety and contention reduction over regular maps.

API > API/Runtime > API/Runtime/Core

The base class of striped maps which is a wrapper that adds thread-safety and contention reduction over regular maps.

The interface is slightly modified compared to regular maps to avoid some thread-safety issues that would arise if we returned pointers or reference to memory inside the map after the lock on a bucket had been released.

The ByHash() functions are somewhat dangerous but particularly useful in two scenarios: Heterogeneous lookup to avoid creating expensive keys like FString when looking up by const TCHAR*. You must ensure the hash is calculated in the same way as ElementType is hashed. If possible put both ComparableKey and ElementType hash functions next to each other in the same header to avoid bugs when the ElementType hash function is changed. Reducing contention around hash tables protected by a lock. This class manage this automatically so you don't have to work with ByHash function in this case.

   
Name TStripedMapBase
Type class
Header File /Engine/Source/Runtime/Core/Public/Containers/StripedMap.h
Include Path #include "Containers/StripedMap.h"

Syntax

template<int32 BucketCount, typename BaseMapType, typename KeyType, typename ValueType, typename SetAllocator, typename KeyFuncs, typename LockingPolicy>  
class TStripedMapBase

Derived Classes

Structs

Name Remarks
FBucket  
FDebuggableExclusiveLock  
FDebuggableMutex  
FDebuggableSharedLock  

Typedefs

Name Type Remarks Include Path
ExclusiveLockType LockingPolicy::ExclusiveLockType   Containers/StripedMap.h
KeyConstPointerType BaseMapType::KeyConstPointerType   Containers/StripedMap.h
KeyFuncsType KeyFuncs   Containers/StripedMap.h
MapType BaseMapType   Containers/StripedMap.h
MutexType LockingPolicy::MutexType   Containers/StripedMap.h
SharedLockType LockingPolicy::SharedLockType   Containers/StripedMap.h

Functions

Public

Name Remarks Include Path Unreal Specifiers

void Add ( const KeyType& InKey,
ValueType&& InValue
)

 Set the value associated with a key. Containers/StripedMap.h  

void Add ( KeyType&& InKey,
const ValueType& InValue
)

 Set the value associated with a key. Containers/StripedMap.h  

void Add ( KeyType&& InKey,
ValueType&& InValue
)

 Set the value associated with a key. Containers/StripedMap.h  

void Add ( const KeyType& InKey,
const ValueType& InValue
)

 Set the value associated with a key. Containers/StripedMap.h  

void Compact()

 Compacts the pair set to remove holes Containers/StripedMap.h  

bool Contains ( KeyConstPointerType InKey
) const

 Check if map contains the specified key. Containers/StripedMap.h  

void Emplace ( InitKeyType&& InKey,
InitValueType&& InValue
)

 Sets the value associated with a key. Containers/StripedMap.h  

void Empty()

 Removes all elements from the map. Containers/StripedMap.h  

bool FindAndApply ( KeyConstPointerType InKey,
UpdateFunctionType&& InUpdateFunction
)

 Calls a function to update a value if it has been found. Containers/StripedMap.h  

bool FindAndApply ( KeyConstPointerType InKey,
FunctionType&& InFunction
) const

 Calls a function when the value is found while holding a lock on the map. Containers/StripedMap.h  

ValueType FindAndRemoveChecked ( KeyConstPointerType InKey
)

 Find a pair with the specified key, removes it from the map, and returns the value part of the pair. Containers/StripedMap.h  

ValueType FindOrProduce ( const KeyType& InKey,
ProduceFunctionType&& InProduceFunction
)

 Finds or produce a value associated with the key. Containers/StripedMap.h  

void FindOrProduceAndApply ( const KeyType& InKey,
ProduceFunctionType&& InProduceFunction,
ApplyFunctionType&& InApplyFunction
)

 Calls ProduceFunction to produce a value if the key is missing, then calls ApplyFunction on the value. Containers/StripedMap.h  

void FindOrProduceAndApplyForWrite ( const KeyType& InKey,
ProduceFunctionType&& InProduceFunction,
ApplyFunctionType&& InApplyFunction
)

 Calls ProduceFunction to produce a value if the key is missing, then calls ApplyFunction on the value. Containers/StripedMap.h  

bool FindOrTryProduceAndApply ( const KeyType& InKey,
TryProduceFunctionType&& InTryProduceFunction,
ApplyFunctionType&& InApplyFunction
)

 Calls TryProduceFunction to produce a value if the key is missing, then calls ApplyFunction on the value if one exists. Containers/StripedMap.h  

bool FindOrTryProduceAndApplyForWrite ( const KeyType& InKey,
TryProduceFunctionType&& InTryProduceFunction,
ApplyFunctionType&& InApplyFunction
)

 Calls TryProduceFunction to produce a value if the key is missing, then calls ApplyFunction on the value if one exists. Containers/StripedMap.h  

ValueType FindRef ( KeyConstPointerType InKey
) const

 Gets you a copy of the value. Containers/StripedMap.h  

void ForEach ( FunctionType&& InFunction
) const

 Calls a function on all elements of the map with shared access (elements can only be read). Containers/StripedMap.h  

void ForEach ( FunctionType&& InFunction
)

 Calls a function on all elements of the map with exclusive access (elements can be modified). Containers/StripedMap.h  

int32 GetKeys ( TArray< KeyType, Allocator >& OutKeys
) const

 Get the unique keys contained within this map. Containers/StripedMap.h  

int32 Num()

   Containers/StripedMap.h  

int32 Remove ( KeyConstPointerType InKey
)

 Remove all value associations for a key. Containers/StripedMap.h  

bool RemoveAndCopyValue ( KeyConstPointerType InKey,
ValueType& OutRemovedValue
)

 Remove the pair with the specified key and copies the value that was removed to the ref parameter Containers/StripedMap.h  

int32 RemoveByHash ( uint32 InKeyHash,
KeyConstPointerType InKey
)

 See Remove() and class documentation section on ByHash() functions Containers/StripedMap.h  

int32 RemoveIf ( KeyConstPointerType InKey,
PredicateType&& InPredicate
)

 Removes only the element associated by the key if the predicate returns true. Containers/StripedMap.h  

int32 RemoveIf ( PredicateType&& InPredicate
)

 Removes all elements where the predicate returns true. Containers/StripedMap.h  

void Reset()

 Efficiently empties out the map but preserves all allocations and capacities Containers/StripedMap.h  

void Shrink()

 Shrinks the pair set to avoid slack. Containers/StripedMap.h  

Protected

Name Remarks Include Path Unreal Specifiers

decltype(auto) Apply ( KeyConstPointerType InKey,
FunctionType&& InFunction
) const

   Containers/StripedMap.h  

decltype(auto) Apply ( KeyConstPointerType InKey,
FunctionType&& InFunction
)

   Containers/StripedMap.h  

decltype(auto) ApplyByHash ( uint32 InHash,
FunctionType&& InFunction
) const

   Containers/StripedMap.h  

decltype(auto) ApplyByHash ( uint32 InHash,
FunctionType&& InFunction
)

   Containers/StripedMap.h  

decltype(auto) ApplyUnlocked ( KeyConstPointerType InKey,
FunctionType&& InFunction
)

   Containers/StripedMap.h  

decltype(auto) ApplyUnlockedByHash ( uint32 InHash,
FunctionType&& InFunction
)

   Containers/StripedMap.h  

void ForEachMap ( FunctionType&& InFunction
) const

   Containers/StripedMap.h  

void ForEachMap ( FunctionType&& InFunction
)

   Containers/StripedMap.h  

uint32 GetBucketIndex ( uint32 Hash
) const

   Containers/StripedMap.h  

decltype(auto) Read ( KeyConstPointerType InKey,
FunctionType&& InFunction
) const

   Containers/StripedMap.h  

decltype(auto) Read ( KeyConstPointerType InKey,
FunctionType&& InFunction
)

   Containers/StripedMap.h  

decltype(auto) ReadByHash ( uint32 InHash,
KeyConstPointerType InKey,
FunctionType&& InFunction
)

   Containers/StripedMap.h  

decltype(auto) ReadByHash ( uint32 InHash,
KeyConstPointerType InKey,
FunctionType&& InFunction
) const

   Containers/StripedMap.h  

decltype(auto) Write ( KeyConstPointerType InKey,
FunctionType&& InFunction
)

   Containers/StripedMap.h  

decltype(auto) WriteByHash ( uint32 InHash,
KeyConstPointerType InKey,
FunctionType&& InFunction
)

   Containers/StripedMap.h  

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