join_node

[flow_graph.join_node]

A node that creates a tuple from a set of messages received at its input ports and broadcasts the tuple to all of its successors.

// Defined in header <tbb/flow_graph.h>

namespace tbb {
namespace flow {
    using tag_value = /*implementation-specific*/;

    template<typename OutputTuple, class JoinPolicy = /*implementation-defined*/>
    class join_node : public graph_node, public sender< OutputTuple > {
    public:
        using input_ports_type = /*implementation-defined*/;

        explicit join_node( graph &g );
        join_node( const join_node &src );

        input_ports_type &input_ports( );

        bool try_get( OutputTuple &v );
    };

    template<typename OutputTuple, typename K, class KHash=tbb_hash_compare<K> >
    class join_node< OutputTuple, key_matching<K,KHash> > : public graph_node, public sender< OutputTuple > {
    public:
        using input_ports_type = /*implementation-defined*/;

        explicit join_node( graph &g );
        join_node( const join_node &src );

        template<typename B0, typename B1>
        join_node( graph &g, B0 b0, B1 b1 );
        template<typename B0, typename B1, typename B2>
        join_node( graph &g, B0 b0, B1 b1, B2 b2 );
        template<typename B0, typename B1, typename B2, typename B3>
        join_node( graph &g, B0 b0, B1 b1, B2 b2, B3 b3 );
        template<typename B0, typename B1, typename B2, typename B3, typename B4>
        join_node( graph &g, B0 b0, B1 b1, B2 b2, B3 b3, B4 b4 );
        template<typename B0, typename B1, typename B2, typename B3, typename B5>
        join_node( graph &g, B0 b0, B1 b1, B2 b2, B3 b3, B4 b4, B5 b5 );
        template<typename B0, typename B1, typename B2, typename B3, typename B5, typename B6>
        join_node( graph &g, B0 b0, B1 b1, B2 b2, B3 b3, B4 b4, B5 b5, B6 b6 );
        template<typename B0, typename B1, typename B2, typename B3, typename B5, typename B6, typename B6>
        join_node( graph &g, B0 b0, B1 b1, B2 b2, B3 b3, B4 b4, B5 b5, B6 b6, B7 b7 );
        template<typename B0, typename B1, typename B2, typename B3, typename B5, typename B6, typename B7>
        join_node( graph &g, B0 b0, B1 b1, B2 b2, B3 b3, B4 b4, B5 b5, B6 b6, B7 b7 );
        template<typename B0, typename B1, typename B2, typename B3, typename B5, typename B6, typename B7, typename B8>
        join_node( graph &g, B0 b0, B1 b1, B2 b2, B3 b3, B4 b4, B5 b5, B6 b6, B7 b7, B8 b8 );
        template<typename B0, typename B1, typename B2, typename B3, typename B5, typename B6, typename B7, typename B8, typename B9>
        join_node( graph &g, B0 b0, B1 b1, B2 b2, B3 b3, B4 b4, B5 b5, B6 b6, B7 b7, B8 b8, B9 b9 );

        input_ports_type &input_ports( );

        bool try_get( OutputTuple &v );
    };

} // namespace flow
} // namespace tbb

Requirements:

  • The type OutputTuple must be an instantiation of std::tuple. Each type that the tuple stores must meet the CopyConstructible requirements from [copyconstructible] and CopyAssignable requirements from [copyassignable] ISO C++ Standard sections.

  • The JoinPolicy type must be specified as one of buffering policies for join_node.

  • The KHash type must meet the HashCompare requirements.

  • The Bi types must meet the JoinNodeFunctionObject requirements.

A join_node is a graph_node and a sender<OutputTuple>. It contains a tuple of input ports, each of which is a receiver<Type> for each Type in OutputTuple. It supports multiple input receivers with distinct types and broadcasts a tuple of received messages to all of its successors. All input ports of a join_node must use the same buffering policy.

The behavior of a join_node is based on its buffering policy.

The function template input_port simplifies the syntax for getting a reference to a specific input port.

join_node has a buffering and broadcast-push properties.

Member types

input_ports_type is an alias to a tuple of input ports.

Member functions

explicit join_node( graph &g );

Constructs an empty join_node that belongs to the graph g.


template<typename B0, typename B1>
join_node( graph &g, B0 b0, B1 b1 );
template<typename B0, typename B1, typename B2>
join_node( graph &g, B0 b0, B1 b1, B2 b2 );
template<typename B0, typename B1, , typename B2, typename B3>
join_node( graph &g, B0 b0, B1 b1, B2 b2, B3 b3 );
template<typename B0, typename B1, , typename B2, typename B3, typename B4>
join_node( graph &g, B0 b0, B1 b1, B2 b2, B3 b3, B4 b4 );
template<typename B0, typename B1, , typename B2, typename B3, typename B5>
join_node( graph &g, B0 b0, B1 b1, B2 b2, B3 b3, B4 b4, B5 b5 );
template<typename B0, typename B1, , typename B2, typename B3, typename B5, typename B6>
join_node( graph &g, B0 b0, B1 b1, B2 b2, B3 b3, B4 b4, B5 b5, B6 b6 );
template<typename B0, typename B1, , typename B2, typename B3, typename B5, typename B6, typename B6>
join_node( graph &g, B0 b0, B1 b1, B2 b2, B3 b3, B4 b4, B5 b5, B6 b6, B7 b7 );
template<typename B0, typename B1, , typename B2, typename B3, typename B5, typename B6, typename B7>
join_node( graph &g, B0 b0, B1 b1, B2 b2, B3 b3, B4 b4, B5 b5, B6 b6, B7 b7 );
template<typename B0, typename B1, , typename B2, typename B3, typename B5, typename B6, typename B7, typename B8>
join_node( graph &g, B0 b0, B1 b1, B2 b2, B3 b3, B4 b4, B5 b5, B6 b6, B7 b7, B8 b8 );
template<typename B0, typename B1, , typename B2, typename B3, typename B5, typename B6, typename B7, typename B8, typename B9>
join_node( graph &g, B0 b0, B1 b1, B2 b2, B3 b3, B4 b4, B5 b5, B6 b6, B7 b7, B8 b8, B9 b9 );

A constructor only available in the key_matching specialization of join_node.

Creates a join_node that uses the function objects b0, b1, … , bN to determine that tags for the input ports 0 through N.

Caution

Function objects passed to the join_node constructor must not throw. They are called in parallel, and should be pure, take minimal time, and be non-blocking.


join_node( const join_node &src )

Creates a join_node that has the same initial state that src had at its construction. The list of predecessors, messages in the input ports, and successors are not copied.


input_ports_type &input_ports( )

Returns: a std::tuple of receivers. Each element inherits values from receiver<T>, where T is the type of message expected at that input. Each tuple element can be used like any other receiver<T>. The behavior of the ports is based on the selected join_node policy.


bool try_get( output_type &v )

Attempts to generate a tuple based on the buffering policy of the join_node.

If it can successfully generate a tuple, it copies it to v and returns true. Otherwise, it returns false.

Non-Member Types

using tag_value = /*implementation-specific*/;

tag_value is an unsigned integral type for defining the tag_matching policy.

Deduction Guides

template <typename Body, typename... Bodies>
join_node(graph&, Body, Bodies...)
    ->join_node<std::tuple<std::decay_t<input_t<Body>>, std::decay_t<input_t<Bodies>>...>, key_matching<output_t<Body>>>;

Where:

  • input_t is an alias to the input argument type of the passed function object.

  • output_t is an alias to the return type of the passed function object.