.. _resource_limiter_cls:

resource_limiter Class

Description

The class resource_limiter<ResourceHandle> represents a Provider that manages one or more resource handles of type ResourceHandle.

It provides exclusive access to managed resources to the consumers -- resource_limited_node instances.

For some resource types, the ResourceHandle represents the resource itself. For other resource types, the ResourceHandle may represent a lightweight entity used to access the resource.

.. code:: cpp

tbb::flow::resource_limiter<int> int_limiter{1, 2, 3};

using db_resource_handle = std::unique_ptr<Database, CloseDatabase>;
tbb::flow::resource_limiter<db_resource_handle> db_limiter{open_database()};

In the example above, int_limiter manages three resources of type int, and db_limiter manages a single handle to a resource of type Database.

All the resource handles managed by the resource_limiter are considered equivalent, and the order in which the access to resources is granted to consumers is unspecified.

API

Header

.. code:: cpp

#define TBB_PREVIEW_FLOW_GRAPH_FEATURES 1
// or
#define TBB_PREVIEW_FLOW_GRAPH_RESOURCE_LIMITING 1

#include <oneapi/tbb/flow_graph.h>

Synopsis

.. code:: cpp

namespace oneapi {
    namespace tbb {
        namespace flow {

            template <typename ResourceHandle>
            class resource_limiter {
            public:
                using resource_handle_type = ResourceHandle;

                template <typename Handle, typename... Handles>
                resource_limiter(Handle&& handle, Handles&&... handles);

                ~resource_limiter();
            }; // class resource_limiter

        } // namespace flow
    } // namespace tbb
} // namespace oneapi

Requirements

ResourceHandle type must meet the MoveConstructible requirements from [moveconstructible] and the MoveAssignable requirements from [moveassignable] sections of the ISO C++ Standard.

Member Types

.. code:: cpp

using resource_handle_type = ResourceHandle;

An alias to the resource handle type.

Member Functions

.. code:: cpp

template <typename Handle, typename... Handles>
resource_limiter(Handle&& handle, Handles&&... handles);

Requirements: ResourceHandle type must be constructible from std::forward<Handle>(handle), and from std::forward<H>(h) for each H in Handles and for each h in handles.

Constructs a resource_limiter that manages at least one resource.

Each resource is constructed from the corresponding argument in handle or handles.

.. code:: cpp

~resource_limiter();

Destroys the resource_limiter.

If there are consumers that still reference the limiter, the behavior is undefined.