util::BlockingCache< ValueType, ErrorType > Class Template Reference

A thread-safe cache that blocks getting operations until the cache is updated. More...

#include <BlockingCache.hpp>

Public Types
enum class	State { NoValue , Updating , HasValue }
	Possible states of the cache.
using	Updater = std::function<std::expected<ValueType, ErrorType>(boost::asio::yield_context)>
	Function type for cache update operations.
using	Verifier = std::function<bool(ValueType const&)>
	Function type to verify if a value should be cached.

Public Member Functions
	BlockingCache ()=default
	Default constructor - creates an empty cache.
	BlockingCache (ValueType initialValue)
	Construct a cache with an initial value.
	BlockingCache (BlockingCache &&)=delete
	BlockingCache (BlockingCache const &)=delete
BlockingCache &	operator= (BlockingCache &&)=delete
BlockingCache &	operator= (BlockingCache const &)=delete
std::expected< ValueType, ErrorType >	asyncGet (boost::asio::yield_context yield, Updater updater, Verifier verifier)
	Asynchronously get a value from the cache, updating if necessary.
std::expected< ValueType, ErrorType >	update (boost::asio::yield_context yield, Updater updater, Verifier verifier)
	Force an update of the cache value.
void	invalidate ()
	Invalidates the currently cached value if present.
State	state () const
	Returns the current state of the cache.

Detailed Description

template<typename ValueType, typename ErrorType>
requires (not std::same_as<ValueType, ErrorType>)
class util::BlockingCache< ValueType, ErrorType >

A thread-safe cache that blocks getting operations until the cache is updated.

Template Parameters

ValueType	The type of value to be cached
ErrorType	The type of error that can occur during updates

Member Typedef Documentation

Updater

template<typename ValueType , typename ErrorType >

using util::BlockingCache< ValueType, ErrorType >::Updater = std::function<std::expected<ValueType, ErrorType>(boost::asio::yield_context)>

Function type for cache update operations.

Called when the cache needs to be populated or refreshed

Verifier

template<typename ValueType , typename ErrorType >

using util::BlockingCache< ValueType, ErrorType >::Verifier = std::function<bool(ValueType const&)>

Function type to verify if a value should be cached.

Returns true if the value should be stored in the cache

Constructor & Destructor Documentation

BlockingCache()

template<typename ValueType , typename ErrorType >

util::BlockingCache< ValueType, ErrorType >::BlockingCache ( ValueType initialValue )

inlineexplicit

Construct a cache with an initial value.

Parameters

initialValue

The value to initialize the cache with

Member Function Documentation

asyncGet()

template<typename ValueType , typename ErrorType >

std::expected< ValueType, ErrorType > util::BlockingCache< ValueType, ErrorType >::asyncGet ( boost::asio::yield_context yield, Updater updater, Verifier verifier )

inlinenodiscard

Asynchronously get a value from the cache, updating if necessary.

Parameters

yield	The asio yield context for coroutine suspension
updater	Function to generate a new value if needed
verifier	Function to validate whether a value should be cached

Returns

std::expected<ValueType, ErrorType> The cached value or an error

Depending on the current cache state, this will either:

• Return the cached value if it's already present
• Wait for an ongoing update to complete
• Trigger a new update if the cache is empty

invalidate()

template<typename ValueType , typename ErrorType >

void util::BlockingCache< ValueType, ErrorType >::invalidate ( )

inline

Invalidates the currently cached value if present.

Clears the cache and sets its state to Empty. Has no effect if the cache is already empty or being updated.

state()

template<typename ValueType , typename ErrorType >

State util::BlockingCache< ValueType, ErrorType >::state ( ) const

inlinenodiscard

Returns the current state of the cache.

Returns

Current cache state (Empty, Updating, or Full)

update()

template<typename ValueType , typename ErrorType >

std::expected< ValueType, ErrorType > util::BlockingCache< ValueType, ErrorType >::update ( boost::asio::yield_context yield, Updater updater, Verifier verifier )

inlinenodiscard

Force an update of the cache value.

Parameters

yield	The ASIO yield context for coroutine suspension
updater	Function to generate a new value
verifier	Function to validate whether a value should be cached

Returns

std::expected<ValueType, ErrorType> The new value or an error

Initiates a cache update operation regardless of current state. If another update is already in progress, waits for it to complete.

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The documentation for this class was generated from the following file:

• /__w/clio/clio/src/util/BlockingCache.hpp