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<a name="multifunc_node_cls"><!-- --></a>
<h1 class="topictitle1">multifunction_node Template Class</h1>
<div>
<div class="section"><h2 class="sectiontitle">Summary</h2>
<p>A template class that is a
receiver<InputType> and has a tuple of sender<T> outputs. This node
may have concurrency limits as set by the user. When the concurrency limit
allows, it executes the user-provided body on incoming messages. The body may
create one or more output messages and broadcast them to successors.
</p>
</div>
<div class="section"><h2 class="sectiontitle">Syntax</h2>
<pre>template <typename Input, typename Output,
graph_buffer_policy = queueing, typename Allocator=cache_aligned_allocator<Input> >
class multifunction_node;</pre>
</div>
<div class="section"><h2 class="sectiontitle">Header</h2>
<pre>#include "tbb/flow_graph.h"</pre>
</div>
<div class="section"><h2 class="sectiontitle">Description</h2>
<p>This type is used for nodes that receive messages
at a single input port and may generate one or more messages that are broadcast
to successors.
</p>
<p>A
<samp class="codeph">multifunction_node</samp>
maintains an internal constant threshold T and an internal counter C. At
construction, C=0 and T is set the value passed in to the constructor. The
behavior of a call to
<samp class="codeph">try_put</samp> is determined
by the value of T and C as shown in the table below.
</p>
<div class="tablenoborder"><a name="tbl50"><!-- --></a><table cellpadding="4" summary="" id="tbl50" frame="border" border="1" cellspacing="0" rules="rows"><caption><span class="tablecap">Behavior of a call to a
multifunction_node's try_put</span></caption>
<thead align="left">
<tr>
<th class="cellrowborder" align="left" valign="top" width="40%" id="d76994e82">
<p>Value of threshold T
</p>
</th>
<th class="cellrowborder" align="left" valign="top" width="20%" id="d76994e88">
<p>Value of counter C
</p>
</th>
<th class="cellrowborder" align="left" valign="top" width="40%" id="d76994e94">
<p>bool try_put( input_type v )
</p>
</th>
</tr>
</thead>
<tbody>
<tr>
<td class="cellrowborder" align="left" valign="top" width="40%" headers="d76994e82 ">
<p><samp class="codeph">T
== graph::unlimited</samp>
</p>
</td>
<td class="cellrowborder" align="left" valign="top" width="20%" headers="d76994e88 ">
<p>NA
</p>
</td>
<td class="cellrowborder" align="left" valign="top" width="40%" headers="d76994e94 ">
<p>A task is spawned that executes body(v).
Returns
<samp class="codeph">true</samp>.
</p>
</td>
</tr>
<tr>
<td class="cellrowborder" align="left" valign="top" width="40%" headers="d76994e82 ">
<p><samp class="codeph">T
!= flow::unlimited</samp>
</p>
</td>
<td class="cellrowborder" align="left" valign="top" width="20%" headers="d76994e88 ">
<p>C < T
</p>
</td>
<td class="cellrowborder" align="left" valign="top" width="40%" headers="d76994e94 ">
<p>Increments C. A task is spawned that
executes body(v) and then decrements C. Returns
<samp class="codeph">true</samp>.
</p>
</td>
</tr>
<tr>
<td class="cellrowborder" align="left" valign="top" width="40%" headers="d76994e82 ">
<p><samp class="codeph">T
!= flow::unlimited</samp>
</p>
</td>
<td class="cellrowborder" align="left" valign="top" width="20%" headers="d76994e88 ">
<p>C >= T
</p>
</td>
<td class="cellrowborder" align="left" valign="top" width="40%" headers="d76994e94 ">
<p>Returns
<samp class="codeph">false</samp>.
</p>
</td>
</tr>
</tbody>
</table>
</div>
<p>A<samp class="codeph">
multifunction_node</samp> has a user-settable concurrency limit. It can have
<samp class="codeph">flow::unlimited
concurrency</samp>, which allows an unlimited number of copies of the node to
execute concurrently. It can have
<samp class="codeph">flow::serial
concurrency</samp>, which allows only a single copy of the node to execute
concurrently. The user can also provide a value of type size_t to limit
concurrency to a value between 1 and unlimited.
</p>
<p>The Body concept for
<samp class="codeph">multifunction_node</samp> is
shown in the table below.
</p>
<div class="tablenoborder"><a name="tbl51"><!-- --></a><table cellpadding="4" summary="" id="tbl51" frame="border" border="1" cellspacing="0" rules="rows"><caption><span class="tablecap">multifunction_node Body Concept</span></caption>
<thead align="left">
<tr>
<th class="cellrowborder" align="center" valign="top" width="50%" id="d76994e216">
<p>Pseudo-Signature
</p>
</th>
<th class="cellrowborder" align="center" valign="top" width="50%" id="d76994e222">
<p>Semantics
</p>
</th>
</tr>
</thead>
<tbody>
<tr>
<td class="cellrowborder" align="left" valign="top" width="50%" headers="d76994e216 ">
<p><samp class="codeph">B::B( const B& )</samp>
</p>
</td>
<td class="cellrowborder" align="left" valign="top" width="50%" headers="d76994e222 ">
<p>Copy constructor.
</p>
</td>
</tr>
<tr>
<td class="cellrowborder" align="left" valign="top" width="50%" headers="d76994e216 ">
<p><samp class="codeph">B::~B()</samp>
</p>
</td>
<td class="cellrowborder" align="left" valign="top" width="50%" headers="d76994e222 ">
<p>Destructor.
</p>
</td>
</tr>
<tr>
<td class="cellrowborder" align="left" valign="top" width="50%" headers="d76994e216 ">
<p><samp class="codeph">void operator=( const B& )</samp>
</p>
</td>
<td class="cellrowborder" align="left" valign="top" width="50%" headers="d76994e222 ">
<p>Assignment
</p>
</td>
</tr>
<tr>
<td class="cellrowborder" align="left" valign="top" width="50%" headers="d76994e216 ">
<p><samp class="codeph">void B::operator()(const input_type &v,
output_ports_type &p)</samp>
</p>
</td>
<td class="cellrowborder" align="left" valign="top" width="50%" headers="d76994e222 ">
<p>Perform operation on
<samp class="codeph">v</samp>. May call
<samp class="codeph">try_put</samp> on
zero or more of the output ports. May call
<samp class="codeph">try_put</samp> on any
output port multiple times.
</p>
</td>
</tr>
</tbody>
</table>
</div>
<div class="Note"><h3 class="NoteTipHead">
Caution</h3>
<p> The body object passed to a
<span class="keyword">multifunction_node</span> is copied. Therefore updates to
member variables will not affect the original object used to construct the
node. If the state held within a body object must be inspected from outside of
the node, the
<span class="keyword">copy_body</span> function can be used to obtain an
updated copy.
</p>
</div>
<div class="Note"><h3 class="NoteTipHead">
Note</h3>
<p> The body object may throw or cancel its enclosing graph. See
task_group_context and Exceptions sections for a description.
</p>
</div>
</div>
<div class="section"><h2 class="sectiontitle">Example</h2>
<p>The example below shows a
<samp class="codeph">multifunction_node</samp>
that separates a stream of integers into odd and even, placing each in the
appropriate output queue.
</p>
<p>The Body method will receive as parameters a
read-only reference to the input value and a reference to the tuple of output
ports. The Body method may put items to one or more output ports.
</p>
<p>The output ports of the
<samp class="codeph">multifunction_node</samp> can
be connected to other graph nodes using the
<samp class="codeph">make_edge</samp> method or by
using
<samp class="codeph">register_successor</samp>:
</p>
<pre>#include "tbb/flow_graph.h"
using namespace tbb::flow;
typedef multifunction_node<int, flow::tuple<int,int> > multi_node;
struct MultiBody {
void operator()(const int &i, multi_node::output_ports_type &op) {
if(i % 2)
std::get<1>(op).try_put(i); // put to odd queue
else
std::get<0>(op).try_put(i); // put to even queue
}
};
int main() {
graph g;
queue_node<int> even_queue(g);
queue_node<int> odd_queue(g);
multi_node node1(g,unlimited,MultiBody());
output_port<0>(node1).register_successor(even_queue);
make_edge(output_port<1>(node1), odd_queue);
for(int i = 0; i < 1000; ++i) {
node1.try_put(i);
}
g.wait_for_all();
}</pre>
</div>
<div class="section"><h2 class="sectiontitle">Members</h2>
<pre>namespace tbb {
template <typename Input, typename Output,
graph_buffer_policy = queueing, typename Allocator=cache_aligned_allocator<Input> >
class multifunction_node : public graph_node, public receiver<Input>
{
public:
template < typename Body >
multifunction_node( graph &g, size_t concurrency, Body body );
multifunction_node( const multifunction_node &other);
~multifunction_node();
// receiver< Input >
typedef Input input_type;
typedef sender<input_type> predecessor_type;
bool try_put( const input_type &v );
bool register_predecessor( predecessor_type &p );
bool remove_predecessor( predecessor_type &p );
typedef <em>implementation-dependent</em> output_ports_type;
output_ports_type& output_ports();
};
}</pre>
<div class="tablenoborder"><table cellpadding="4" summary="" frame="border" border="1" cellspacing="0" rules="all"><span class="tabledesc">The following table provides additional information on the
members of this template class.
</span><thead align="left">
<tr>
<th class="cellrowborder" valign="top" width="33.89830508474576%" id="d76994e384">Member
</th>
<th class="cellrowborder" valign="top" width="66.10169491525423%" id="d76994e387">Description
</th>
</tr>
</thead>
<tbody>
<tr>
<td class="cellrowborder" valign="top" width="33.89830508474576%" headers="d76994e384 ">
<span class="keyword">template < typename Body > multifunction_node(
graph &g, size_t concurrency, Body body )
</span>
</td>
<td class="cellrowborder" valign="top" width="66.10169491525423%" headers="d76994e387 ">
<p>Constructs a
<span class="keyword">multifunction_node</span> with
<span class="keyword">body</span> as its Body. At most
<span class="keyword">concurrency</span> calls to the body may be made
concurrently.
</p>
</td>
</tr>
<tr>
<td class="cellrowborder" valign="top" width="33.89830508474576%" headers="d76994e384 ">
<span class="keyword">multifunction_node( const multifunction_node
&other)</span>
</td>
<td class="cellrowborder" valign="top" width="66.10169491525423%" headers="d76994e387 ">
<p>Constructs a
<span class="keyword">multifunction_node</span> that has the same
initial state that
<span class="keyword">other</span> had when it was constructed. The
<span class="keyword">multifunction_node</span> that is constructed
will have a reference to the same
<span class="keyword">graph</span> object as
<span class="keyword">other</span>, will have a copy of the initial
<span class="keyword">body</span> used by
<span class="keyword">other</span>, and have the same concurrency
threshold as
<span class="keyword">other</span>. The predecessors and successors of
<span class="keyword">other</span> will not be copied.
</p>
<div class="Note"><h3 class="NoteTipHead">
Caution</h3>
<p> The new body object is copy constructed from a copy of
the original body provided to
<span class="keyword">other</span> at its construction. Therefore
changes made to member variables in
<span class="keyword">other</span>'s body after the construction of
<span class="keyword">other</span> will not affect the body of the
new
<span class="keyword">multifunction_node.</span>
</p>
</div>
</td>
</tr>
<tr>
<td class="cellrowborder" valign="top" width="33.89830508474576%" headers="d76994e384 ">
<span class="keyword">~multifunction_node()</span>
</td>
<td class="cellrowborder" valign="top" width="66.10169491525423%" headers="d76994e387 ">
<p>Destructor
</p>
</td>
</tr>
<tr>
<td class="cellrowborder" valign="top" width="33.89830508474576%" headers="d76994e384 ">
<span class="keyword">bool try_put( const input_type &v )</span>
</td>
<td class="cellrowborder" valign="top" width="66.10169491525423%" headers="d76994e387 ">
<p>See the table above describing the behavior of try_put for a
<samp class="codeph">multifunction_node</samp> for more information.
</p>
<p><strong>Returns</strong>:
<span class="keyword">true</span>
</p>
</td>
</tr>
<tr>
<td class="cellrowborder" valign="top" width="33.89830508474576%" headers="d76994e384 "><span class="keyword">bool register_predecessor(
predecessor_type &p )</span>
</td>
<td class="cellrowborder" valign="top" width="66.10169491525423%" headers="d76994e387 ">
<p>Adds
<span class="keyword">p</span> to the set of predecessors.
</p>
<p><strong>Returns</strong>:
<span class="keyword">true</span>
</p>
</td>
</tr>
<tr>
<td class="cellrowborder" valign="top" width="33.89830508474576%" headers="d76994e384 "><span class="keyword">bool remove_predecessor(
predecessor_type &p )</span>
</td>
<td class="cellrowborder" valign="top" width="66.10169491525423%" headers="d76994e387 ">
<p>Removes
<span class="keyword">p</span> from the set of predecessors.
</p>
<p><strong>Returns</strong>:
<span class="keyword">true</span>
</p>
</td>
</tr>
<tr>
<td class="cellrowborder" valign="top" width="33.89830508474576%" headers="d76994e384 "><span class="keyword">output_ports_type&
output_ports();</span>
</td>
<td class="cellrowborder" valign="top" width="66.10169491525423%" headers="d76994e387 ">
<p><strong>Returns</strong>: a tuple of output ports.
</p>
</td>
</tr>
</tbody>
</table>
</div>
</div>
</div>
<div class="familylinks">
<div class="parentlink"><strong>Parent topic:</strong> <a href="../../reference/flow_graph.htm">Flow Graph</a></div>
</div>
<div class="See Also">
<h2>See Also</h2>
<div class="linklist">
<div><a href="make_edge_func.htm">make_edge Template Function
</a></div>
<div><a href="remove_edge_func.htm">remove_edge Template Function
</a></div>
<div><a href="copy_body_func.htm">copy_body Template Function
</a></div>
<div><a href="message_passing_protocol.htm#message_passing_protocol">Message Passing Protocol
</a></div>
<div><a href="../task_scheduler/task_group_context.htm">task_group_context
</a></div>
<div><a href="flow_tuple.htm#flow_tuple">flow::tuple Template Class
</a></div>
<div><a href="../exceptions.htm">Exceptions
</a></div></div>
</div>
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