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Class Template resource_guard<T>

Defined in header <siddiqsoft/arrp.hpp> / <siddiqsoft/private/resource_guard.hpp>.

This is a helper class meant to allow your underlying resource to be automatically returned to the resource_pool<T>. - DO NOT extend or derive from this class. It should not be used to store data--use T as your data! - DO NOT share the resource_guard across threads. It is NOT move-able or copy-able so you're supposed to use it in a scope. You can use it across multiple functions but never store this class. - The resource_pool<T> must be in a parent scope or otherwise available to the resource_guard<T>

namespace siddiqsoft::arrp {
    template <NonNumericMoveConstructible T>
    class resource_guard final;
}

resource_guard<T> is a move-only, final RAII handle wrapping a resource borrowed from a resource_pool<T>.

Member Functions

Constructors & Destructor

resource_guard() noexcept;
resource_guard(resource_guard&& source) noexcept;
~resource_guard();
  • Default Constructor: Constructs an invalid guard (error() == pool_error::NoMoreResources).
  • Move Constructor: Transfers ownership of the borrowed resource and callback from source. Leaves source invalid.
  • Destructor: If valid, invokes the return callback to send the resource back to the pool (or discards it if marked abandoned/invalidated).

Validity & Inspection

operator bool / has_value

explicit operator bool() const noexcept;
bool has_value() const noexcept;

Returns true if the guard holds a valid, usable resource; false otherwise.

is_valid

bool is_valid() const noexcept;

Reports whether the destructor will return the resource back to the pool.

error

pool_error error() const noexcept;

Returns the error code associated with an invalid guard (e.g. pool_error::NoMoreResources, pool_error::Timeout, pool_error::ShutdownInitiated).

Accessors & Conversion

operator* & operator->

T& operator*() &;
const T& operator*() const&;
T* operator->() noexcept;
const T* operator->() const noexcept;

Accesses the underlying resource T. - Precondition: operator bool() must be true. operator->() returns nullptr if the guard is invalid.

Mutation & Invalidation

invalidate

void invalidate() noexcept;

Marks the guard invalid/abandoned. When the guard's destructor runs, the resource will be discarded rather than returned to the pool.

to_json

nlohmann::json to_json() const;

Returns a JSON representation of the guard's state. Only compiled when nlohmann/json.hpp is included prior to arrp.hpp.