Diligent::WeakValueHashMap< KeyType, ValueType, Hasher, Keyeq > Class Template Reference

WeakValueHashMap is a thread-safe hash map that holds weak pointers to its values. More...

#include <WeakValueHashMap.hpp>

Classes
class	ValueHandle
	ValueHandle is a handle to a value in the WeakValueHashMap. More...

Public Member Functions
void	GetLiveValues (ValueHandleArray &Values) const

Detailed Description

template<typename KeyType, typename ValueType, typename Hasher = std::hash<KeyType>, typename Keyeq = std::equal_to<KeyType>>
class Diligent::WeakValueHashMap< KeyType, ValueType, Hasher, Keyeq >

WeakValueHashMap is a thread-safe hash map that holds weak pointers to its values.

Template Parameters

KeyType	- Type of the keys in the map. Must be hashable and comparable.
ValueType	- Type of the values in the map.
Hasher	- Hash function for the keys. Default is std::hash<KeyType>.
Keyeq	- Equality comparison function for the keys. Default is std::equal_to<KeyType>.

When a value is requested via GetOrInsert(), a strong pointer (shared_ptr) to the value is returned wrapped in a ValueHandle object. The ValueHandle object is responsible for removing the entry from the map when it is destroyed. If there are no more strong pointers to the value, the entry is removed from the map.

If a value is requested via Get(), a strong pointer to the value is returned wrapped in a ValueHandle object if the entry exists and the value has not expired. Otherwise, an empty ValueHandle is returned.

The map is thread-safe and can be accessed from multiple threads simultaneously.

Example usage:

WeakValueHashMap<int, std::string> Map;
auto Handle = Map.GetOrInsert(1, "Value");
std::cout << *Handle << std::endl; // Outputs "Value"

Member Function Documentation

GetLiveValues()

template<typename KeyType, typename ValueType, typename Hasher = std::hash<KeyType>, typename Keyeq = std::equal_to<KeyType>>

void Diligent::WeakValueHashMap< KeyType, ValueType, Hasher, Keyeq >::GetLiveValues ( ValueHandleArray & Values ) const

inline

Replaces Values with handles to all live values in the map.

Values.clear() is used so that the caller may reuse the vector's capacity across calls. Returned handles retain the values and the corresponding map implementations. Values inserted or removed concurrently may or may not be included. No map mutex is held when this method returns.