1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
|
<!DOCTYPE html
PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<!-- saved from url=(0014)about:internet -->
<html xmlns:MSHelp="http://www.microsoft.com/MSHelp/" lang="en-us" xml:lang="en-us"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<meta name="DC.Type" content="reference">
<meta name="DC.Title" content="join_node Template Class">
<meta name="DC.subject" content="join_node Template Class">
<meta name="keywords" content="join_node Template Class">
<meta name="DC.Relation" scheme="URI" content="../../reference/flow_graph.htm">
<meta name="DC.Relation" scheme="URI" content="input_port_func.htm#input_port_func">
<meta name="DC.Relation" scheme="URI" content="message_passing_protocol.htm">
<meta name="DC.Relation" scheme="URI" content="flow_tuple.htm">
<meta name="DC.Format" content="XHTML">
<meta name="DC.Identifier" content="join_node_cls">
<meta name="DC.Language" content="en-US">
<link rel="stylesheet" type="text/css" href="../../intel_css_styles.css">
<title>join_node Template Class</title>
</head>
<body id="join_node_cls">
<!-- ==============(Start:NavScript)================= -->
<script src="..\..\NavScript.js" language="JavaScript1.2" type="text/javascript"></script>
<script language="JavaScript1.2" type="text/javascript">WriteNavLink(2);</script>
<!-- ==============(End:NavScript)================= -->
<a name="join_node_cls"><!-- --></a>
<h1 class="topictitle1">join_node Template Class</h1>
<div>
<div class="section"><h2 class="sectiontitle">Summary</h2>
<p>A node that creates a tuple<T0,T1, ... > from a set of messages
received at its input ports and broadcasts the tuple to all of its successors.
The
<span class="keyword">class</span>
<span class="keyword">join_node</span> supports three buffering policies at its
input ports:
<span class="keyword">reserving</span>,
<span class="keyword">queueing</span> and
<span class="keyword">tag_matching</span>. By default,
<span class="keyword">join_node</span> input ports use the
<span class="keyword">queueing</span> policy.
</p>
</div>
<div class="section"><h2 class="sectiontitle">Syntax</h2>
<pre>
template<typename OutputTuple, graph_buffer_policy JP = queueing>
class join_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>A join_node is a
<span class="keyword">graph_node</span> and a
<span class="keyword">sender< flow::tuple< T0, T1, ... >></span>. It
contains a tuple of input ports, each of which is a
<span class="keyword">receiver<Ti></span> for each of the
<span class="keyword">T0</span> ..
<span class="keyword">TN</span> in
<span class="keyword">OutputTuple</span>. 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
<span class="keyword">join_node</span> must use the same buffering policy. The
behavior of a
<span class="keyword">join_node</span> based on its buffering policy is shown in
the table below.
</p>
<div class="tablenoborder"><a name="tbl28"><!-- --></a><table cellpadding="4" summary="" id="tbl28" frame="border" border="1" cellspacing="0" rules="all"><caption><span class="tablecap">Behavior of a join_node based on the buffering policy of its input
ports.</span></caption>
<thead align="left">
<tr>
<th class="cellrowborder" align="center" valign="top" width="25%" id="d73545e114">
<p>Buffering Policy
</p>
</th>
<th class="cellrowborder" align="center" valign="top" width="75%" id="d73545e120">
<p>Behavior
</p>
</th>
</tr>
</thead>
<tbody>
<tr>
<td class="cellrowborder" valign="top" width="25%" headers="d73545e114 ">
<p>queueing
</p>
</td>
<td class="cellrowborder" valign="top" width="75%" headers="d73545e120 ">
<p>As each input port is put to, the incoming message is added to
an unbounded first-in first-out queue in the port. When there is at least one
message at each input port, the
<span class="keyword">join_node</span> broadcasts a tuple containing the
head of each queue to all successors. If at least one successor accepts the
tuple, the head of each input port's queue is removed; otherwise, the messages
remain in their respective input port queues.
</p>
</td>
</tr>
<tr>
<td class="cellrowborder" valign="top" width="25%" headers="d73545e114 ">
<p>reserving
</p>
</td>
<td class="cellrowborder" valign="top" width="75%" headers="d73545e120 ">
<p>As each input port is put to, the
<span class="keyword">join_node</span> marks that an input may be
available at that port and returns
<span class="keyword">false</span>. When all ports have been marked as
possibly available, the
<span class="keyword">join_node</span> will try to reserve a message at
each port from their known predecessors. If it is unable to reserve a message
at a port, it un-marks that port, and releases all previously acquired
reservations. If it is able to reserve a message at all ports, it broadcasts a
tuple containing these messages to all successors. If at least one successor
accepts the tuple, the reservations are consumed; otherwise, they are released.
</p>
</td>
</tr>
<tr>
<td class="cellrowborder" valign="top" width="25%" headers="d73545e114 ">
<p>tag_matching
</p>
</td>
<td class="cellrowborder" valign="top" width="75%" headers="d73545e120 ">
<p>As each input port is put to, a user-provided function object
is applied to the message to obtain its tag. The message is then added to a
hash table at the input port, using the tag as the key. When there is message
at each input port for a given tag, the
<span class="keyword">join_node</span> broadcasts a tuple containing the
matching messages to all successors. If at least one successor accepts the
tuple, the messages are removed from each input port's hash table; otherwise,
the messages remain in their respective input ports.
</p>
</td>
</tr>
</tbody>
</table>
</div>
<p>Rejection of messages by successors of the
<span class="keyword">join_node</span> and failed gets from predecessors of the
input ports are handled using the protocol in the Message Passing Protocol, see
link below.
</p>
<p>The function template
<span class="keyword">input_port</span> simplifies the syntax for getting a
reference to a specific input port.
</p>
<p><span class="keyword">OutputTuple</span> must be a
<span class="keyword">flow::tuple<T0,T1, ... ></span> where each element is
copy-constructible and assignable.
</p>
</div>
<div class="section"><h2 class="sectiontitle">Example</h2>
<pre>#include<cstdio>
#include "tbb/flow_graph.h"
using namespace tbb::flow;
int main() {
graph g;
function_node<int,int>
f1( g, unlimited, [](const int &i) { return 2*i; } );
function_node<float,float>
f2( g, unlimited, [](const float &f) { return f/2; } );
join_node< flow::tuple<int,float> > j(g);
function_node< flow::tuple<int,float> >
f3( g, unlimited,
[]( const flow::tuple<int,float> &t ) {
printf( "Result is %f\n",
std::get<0>(t) + std::get<1>(t));
} );
make_edge( f1, input_port<0>( j ) );
make_edge( f2, input_port<1>( j ) );
make_edge( j, f3 );
f1.try_put( 3 );
f2.try_put( 3 );
g.wait_for_all( );
return 0;
}</pre>
<p>In the example above, three
<span class="keyword">function_node</span> objects are created:
<span class="keyword">f1</span> multiplies an
<span class="keyword">int i</span> by 2,
<span class="keyword">f2</span> divides a
<span class="keyword">float f</span> by 2, and
<span class="keyword">f3</span> receives a
<span class="keyword">flow::tuple<int,float> t</span>, adds its elements
together and prints the result. The
<span class="keyword">join_node j</span> combines the output of
<span class="keyword">f1</span> and
<span class="keyword">f2</span>, and then forwards the resulting tuple to
<span class="keyword">f3</span>. This example is purely a syntactic demonstration
since there is very little work in the nodes.
</p>
</div>
<div class="section"><h2 class="sectiontitle">Members</h2>
<pre>namespace tbb {
namespace flow {
enum graph_buffer_policy {
rejecting, reserving, queueing, tag_matching };
template<typename OutputTuple, graph_buffer_policy JP = queueing>
class join_node :
public graph_node, public sender< OutputTuple > {
public:
typedef OutputTuple output_type;
typedef receiver<output_type> successor_type;
typedef <em>implementation-dependent-tuple</em> input_ports_tuple_type;
join_node( graph &g );
join_node( const join_node &src );
input_ports_tuple_type &inputs( );
bool register_successor( successor_type &r );
bool remove_successor( successor_type &r );
bool try_get( output_type &v );
bool try_reserve( output_type &v );
bool try_release( );
bool try_consume( );
};
//
// Specialization for tag_matching
//
template<typename OutputTuple>
class join_node<OutputTuple, tag_matching> :
public graph_node, public sender< OutputTuple > {
public:
// Has the same methdods as previous join_node,
// but has constructors to specify the tag_matching
// function objects
template<typename B0, typename B1>
join_node( graph &g, B0 b0, B1 b1 );
// Constructors are defined similarly for
// 3 through 10 elements ...
};
}
}</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="d73545e284">Member
</th>
<th class="cellrowborder" valign="top" width="66.10169491525423%" id="d73545e287">Description
</th>
</tr>
</thead>
<tbody>
<tr>
<td class="cellrowborder" valign="top" width="33.89830508474576%" headers="d73545e284 "><span class="keyword">join_node( graph &g
)</span>
</td>
<td class="cellrowborder" valign="top" width="66.10169491525423%" headers="d73545e287 "> Constructs a
<span class="keyword">join_node</span> that will spawn tasks using the
root task in
<span class="keyword">g</span>.
</td>
</tr>
<tr>
<td class="cellrowborder" valign="top" width="33.89830508474576%" headers="d73545e284 "><span class="keyword">template < typename B0,
typename B1, ... > join_node( graph &g, B0 b0, B1 b1, ... )</span>
</td>
<td class="cellrowborder" valign="top" width="66.10169491525423%" headers="d73545e287 ">
<p>A constructor only available in the
<span class="keyword">tag_matching</span> specialization of
<span class="keyword">join_node</span>.
</p>
<p>Creates a
<span class="keyword">join_node</span> that uses the function objects
<span class="keyword">b0</span>,
<span class="keyword">b1</span>, ... ,
<span class="keyword">bN</span> to determine that tags for the input
ports 0 through N. It will spawn tasks using the root task in
<span class="keyword">g</span>.
</p>
<div class="Note"><h3 class="NoteTipHead">
Caution</h3>
<p> Function objects passed to the join must not throw.
</p>
</div>
</td>
</tr>
<tr>
<td class="cellrowborder" valign="top" width="33.89830508474576%" headers="d73545e284 "><span class="keyword">join_node( const join_node
&src )</span>
</td>
<td class="cellrowborder" valign="top" width="66.10169491525423%" headers="d73545e287 ">
<p>Creates a
<span class="keyword">join_node</span> that has the same initial state
that
<span class="keyword">src</span> had at its construction. The list of
predecessors, messages in the input ports, and successors are NOT copied.
</p>
</td>
</tr>
<tr>
<td class="cellrowborder" valign="top" width="33.89830508474576%" headers="d73545e284 "><span class="keyword">input_ports_tuple_type
&inputs( )</span>
</td>
<td class="cellrowborder" valign="top" width="66.10169491525423%" headers="d73545e287 ">
<p><strong>Returns</strong>: a
<span class="keyword">flow::tuple</span> of receivers. Each element
inherits from
<span class="keyword">tbb::receiver<T></span> where
<span class="keyword">T</span> is the type of message expected at that
input. Each tuple element can be used like any other
<span class="keyword">flow::receiver<T></span>. The behavior of
the ports based on the selected
<span class="keyword">join_node</span> policy is shown in the table
above.
</p>
</td>
</tr>
<tr>
<td class="cellrowborder" valign="top" width="33.89830508474576%" headers="d73545e284 "><span class="keyword">bool register_successor(
successor_type &r )</span>
</td>
<td class="cellrowborder" valign="top" width="66.10169491525423%" headers="d73545e287 ">
<p>Adds
<span class="keyword">r</span> to the set of successors.
</p>
<p><strong>Returns</strong>:
<span class="keyword">true</span>
</p>
</td>
</tr>
<tr>
<td class="cellrowborder" valign="top" width="33.89830508474576%" headers="d73545e284 "><span class="keyword">bool remove_successor(
successor_type &r )</span>
</td>
<td class="cellrowborder" valign="top" width="66.10169491525423%" headers="d73545e287 ">
<p>Removes
<span class="keyword">r</span> from the set of successors.
</p>
<p><strong>Returns</strong>:
<span class="keyword">true</span>
</p>
</td>
</tr>
<tr>
<td class="cellrowborder" valign="top" width="33.89830508474576%" headers="d73545e284 "><span class="keyword">bool try_get( output_type &v
)</span>
</td>
<td class="cellrowborder" valign="top" width="66.10169491525423%" headers="d73545e287 ">
<p>Attempts to generate a tuple based on the buffering policy
of the
<span class="keyword">join_node</span>.
</p>
<p><strong>Returns</strong>: If it can successully generate a tuple, it
copies it to
<span class="keyword">v</span> and returns
<span class="keyword">true</span>. Otherwise it returns
<span class="keyword">false</span>.
</p>
</td>
</tr>
<tr>
<td class="cellrowborder" valign="top" width="33.89830508474576%" headers="d73545e284 "><span class="keyword">bool try_reserve( output_type
&v )</span>
</td>
<td class="cellrowborder" valign="top" width="66.10169491525423%" headers="d73545e287 ">
<p>Does not support reservations.
</p>
<p><strong>Returns</strong>:
<span class="keyword">false</span>.
</p>
</td>
</tr>
<tr>
<td class="cellrowborder" valign="top" width="33.89830508474576%" headers="d73545e284 "><span class="keyword">bool try_release( )</span>
</td>
<td class="cellrowborder" valign="top" width="66.10169491525423%" headers="d73545e287 ">
<p>Does not support reservations.
</p>
<p><strong>Returns</strong>:
<span class="keyword">false</span>.
</p>
</td>
</tr>
<tr>
<td class="cellrowborder" valign="top" width="33.89830508474576%" headers="d73545e284 "><span class="keyword">bool try_consume( )</span>
</td>
<td class="cellrowborder" valign="top" width="66.10169491525423%" headers="d73545e287 ">
<p>Does not support reservations.
</p>
<p><strong>Returns</strong>:
<span class="keyword">false</span>.
</p>
</td>
</tr>
<tr>
<td class="cellrowborder" valign="top" width="33.89830508474576%" headers="d73545e284 "><span class="keyword">template<size_t N, typename
JNT> typename flow::tuple_element<N, typename
JNT::input_ports_tuple_type>::type &input_port( JNT &jn )</span>
</td>
<td class="cellrowborder" valign="top" width="66.10169491525423%" headers="d73545e287 ">
<p>Calling
<span class="keyword">input_port <N>( jn )</span> is equivalent
to calling
<span class="keyword">std::get<N>( jn.inputs() )</span>
</p>
<p><strong>Returns</strong>: the N<sup>th</sup> input port for
<span class="keyword">join_node jn</span>.
</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="input_port_func.htm#input_port_func">input_port Template Function
</a></div>
<div><a href="message_passing_protocol.htm">Message Passing Protocol
</a></div>
<div><a href="flow_tuple.htm">flow::tuple
</a></div></div>
</div>
</body>
</html>
|
