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
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
|
<!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="function_node Template Class">
<meta name="DC.subject" content="function_node Template Class">
<meta name="keywords" content="function_node Template Class">
<meta name="DC.Relation" scheme="URI" content="../../reference/flow_graph.htm">
<meta name="DC.Relation" scheme="URI" content="copy_body_func.htm">
<meta name="DC.Relation" scheme="URI" content="../task_scheduler/task_group_context.htm">
<meta name="DC.Relation" scheme="URI" content="../exceptions.htm">
<meta name="DC.Relation" scheme="URI" content="message_passing_protocol.htm">
<meta name="DC.Format" content="XHTML">
<meta name="DC.Identifier" content="func_node_cls">
<meta name="DC.Language" content="en-US">
<link rel="stylesheet" type="text/css" href="../../intel_css_styles.css">
<title>function_node Template Class</title>
</head>
<body id="func_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="func_node_cls"><!-- --></a>
<h1 class="topictitle1">function_node Template Class</h1>
<div>
<div class="section"><h2 class="sectiontitle">Summary</h2>
<p>A template class that is a
<span class="keyword">graph_node</span>,
<span class="keyword">receiver<Input></span> and a
<span class="keyword">sender<Output></span>. This node may have concurrency
limits as set by the user. By default, a
<span class="keyword">function_node</span> has an internal FIFO buffer at its
input. Messages that cannot be immediately processed due to concurrency limits
are temporarily stored in this FIFO buffer. A template argument can be used to
disable this internal buffer. If the FIFO buffer is disabled, incoming messages
will be rejected if they cannot be processed immediately while respecting the
concurrency limits of the node.
</p>
</div>
<div class="section"><h2 class="sectiontitle">Syntax</h2>
<pre>template < typename Input,
typename Output = continue_msg,
graph_buffer_policy = queueing,
typename A = cache_aligned_allocator<Input> >
class function_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
<span class="keyword">function_node</span> receives messages of type
<span class="keyword">Input</span> at a single input port and generates a single
output message of type
<span class="keyword">Output</span> that is broadcast to all successors.
Rejection of messages by successors is handled using the protocol in Message
Passing Protocol, see link below.
</p>
<p>If
<span class="keyword">graph_buffer_policy == queueing</span>, an internal
unbounded input buffer is maintained using memory obtained through an allocator
of type
<span class="keyword">A</span>.
</p>
<p>A
<span class="keyword">function_node</span> 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
<span class="keyword">try_put</span> is determined by the value of T and C as
shown below.
</p>
<div class="tablenoborder"><a name="tbl23"><!-- --></a><table cellpadding="4" summary="" id="tbl23" frame="border" border="1" cellspacing="0" rules="all"><caption><span class="tablecap">Behavior of a call to a function_node's try_put</span></caption>
<thead align="left">
<tr>
<th class="cellrowborder" align="center" valign="top" width="25%" id="d69978e115">
<p>Value of threshold T
</p>
</th>
<th class="cellrowborder" align="center" valign="top" width="25%" id="d69978e121">
<p>Value of counter C
</p>
</th>
<th class="cellrowborder" align="center" valign="top" width="50%" id="d69978e127">
<p><span class="keyword">bool try_put( const input_type &v )</span>
</p>
</th>
</tr>
</thead>
<tbody>
<tr>
<td class="cellrowborder" valign="top" width="25%" headers="d69978e115 ">
<p>
<pre>T == flow::unlimited</pre>
</p>
</td>
<td class="cellrowborder" valign="top" width="25%" headers="d69978e121 ">
<p>NA
</p>
</td>
<td class="cellrowborder" valign="top" width="50%" headers="d69978e127 ">
<p>A task is spawned that broadcasts the result of
<span class="keyword">body(v)</span> to all successors. Returns
<span class="keyword">true</span>.
</p>
</td>
</tr>
<tr>
<td class="cellrowborder" valign="top" width="25%" headers="d69978e115 ">
<p>
<pre>T != flow::unlimited</pre>
</p>
</td>
<td class="cellrowborder" valign="top" width="25%" headers="d69978e121 ">
<p>C < T
</p>
</td>
<td class="cellrowborder" valign="top" width="50%" headers="d69978e127 ">
<p>Increments C. A task is spawned that broadcasts the result of
<span class="keyword">body(v)</span> to all successors and then
decrements C. Returns
<span class="keyword">true</span>.
</p>
</td>
</tr>
<tr>
<td class="cellrowborder" valign="top" width="25%" headers="d69978e115 ">
<p>
<pre>T != flow::unlimited</pre>
</p>
</td>
<td class="cellrowborder" valign="top" width="25%" headers="d69978e121 ">
<p>C >= T
</p>
</td>
<td class="cellrowborder" valign="top" width="50%" headers="d69978e127 ">
<p>If the template argument
<span class="keyword">graph_buffer_policy==queueing</span>,
<span class="keyword">v</span> is stored in an internal FIFO buffer until
C < T. When T becomes less than C, C is incremented and a task is spawned
that broadcasts the result of
<span class="keyword">body(v)</span> to all successors and then
decrements C. Returns
<span class="keyword">true</span>.
</p>
<p>If the template argument
<span class="keyword">graph_buffer_policy==rejecting</span> and C >=
T, returns
<span class="keyword">false</span>.
</p>
</td>
</tr>
</tbody>
</table>
</div>
<p>A
<span class="keyword">function_node</span> has a user-settable concurrency limit.
It can have
<span class="keyword">flow::unlimited</span> concurrency, which allows an
unlimited number of invocations of the body to execute concurrently. It can
have
<span class="keyword">flow::serial</span> concurrency, which allows only a single
call of body to execute concurrently. The user can also provide a value of type
<span class="keyword">size_t</span> to limit concurrency to a value between 1 and
<span class="keyword">unlimited</span>.
</p>
<p>A
<span class="keyword">function_node</span> with
<span class="keyword">graph_buffer_policy==rejecting</span> will maintain a
predecessor set as described in the Message Passing Protocol, see link below.
If the
<span class="keyword">function_node</span> transitions from a state where C >=
T to a state where C < T, it will try to get new messages from its set of
predecessors until C >= T or there are no valid predecessors left in the
set.
</p>
<div class="Note"><h3 class="NoteTipHead">
Note</h3>
<p>A
<span class="keyword">function_node</span> can serve as a terminal node in the
graph. The convention is to use an
<span class="keyword">Output</span> of
<span class="keyword">continue_msg</span> and attach no successor.
</p>
</div>
<p>The Body concept for
<span class="keyword">function_node</span> is shown in below.
</p>
<div class="tablenoborder"><a name="tbl24"><!-- --></a><table cellpadding="4" summary="" id="tbl24" frame="border" border="1" cellspacing="0" rules="all"><caption><span class="tablecap">function_node<Input, Output> Body Concept</span></caption>
<thead align="left">
<tr>
<th class="cellrowborder" align="center" valign="top" width="50%" id="d69978e311">
<p>Pseudo-Signature
</p>
</th>
<th class="cellrowborder" align="center" valign="top" width="50%" id="d69978e317">
<p>Semantics
</p>
</th>
</tr>
</thead>
<tbody>
<tr>
<td class="cellrowborder" valign="top" width="50%" headers="d69978e311 ">
<p>
<pre>B::B( const B& )</pre>
</p>
</td>
<td class="cellrowborder" valign="top" width="50%" headers="d69978e317 ">
<p>Copy constructor.
</p>
</td>
</tr>
<tr>
<td class="cellrowborder" valign="top" width="50%" headers="d69978e311 ">
<p>
<pre>B::~B()</pre>
</p>
</td>
<td class="cellrowborder" valign="top" width="50%" headers="d69978e317 ">
<p>Destructor.
</p>
</td>
</tr>
<tr>
<td class="cellrowborder" valign="top" width="50%" headers="d69978e311 ">
<p>
<pre>void operator=( const B& )</pre>
</p>
</td>
<td class="cellrowborder" valign="top" width="50%" headers="d69978e317 ">
<p>Assignment. The return type
<samp class="codeph">void</samp> in the pseudo-signature denotes that
<samp class="codeph">operator=</samp> is not required to return a value.
The actual
<samp class="codeph">operator=</samp> can return a value, which will be
ignored.
</p>
</td>
</tr>
<tr>
<td class="cellrowborder" valign="top" width="50%" headers="d69978e311 ">
<p>
<pre>Output B::operator() (const Input &v) const</pre>
</p>
</td>
<td class="cellrowborder" valign="top" width="50%" headers="d69978e317 ">
<p>Perform operation on
<span class="keyword">v</span> and return value of type
<span class="keyword">Output</span>.
</p>
</td>
</tr>
</tbody>
</table>
</div>
<div class="Note"><h3 class="NoteTipHead">
Caution</h3>
<p> The body object passed to a
<span class="keyword">function_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">
Caution</h3>
<p><span class="keyword">Input</span> and
<span class="keyword">Output</span> must be copy-constructible and assignable.
</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">Members</h2>
<pre>namespace tbb {
namespace flow {
enum graph_buffer_policy {
rejecting, reserving, queueing, tag_matching };
template < typename Input, typename Output = continue_msg,
graph_buffer_policy = queueing,
typename A = cache_aligned_allocator<Input> >
class function_node :
public graph_node, public receiver<Input>,
public sender<Output> {
public:
template<typename Body>
function_node( graph &g, size_t concurrency, Body body );
function_node( const function_node &src );
// 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 );
// sender<Output>
typedef Output output_type;
typedef receiver<output_type> successor_type;
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( );
};
}
}</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="d69978e467">Member
</th>
<th class="cellrowborder" valign="top" width="66.10169491525423%" id="d69978e470">Description
</th>
</tr>
</thead>
<tbody>
<tr>
<td class="cellrowborder" valign="top" width="33.89830508474576%" headers="d69978e467 "><span class="keyword">template< typename Body>
function_node(graph &g, size_t concurrency, Body body)</span>
</td>
<td class="cellrowborder" valign="top" width="66.10169491525423%" headers="d69978e470 ">
<p>Constructs a
<span class="keyword">function_node</span> that will invoke a copy of
<span class="keyword">body</span>. At most
<span class="keyword">concurrency</span> calls to
<span class="keyword">body</span> may be made concurrently.
</p>
</td>
</tr>
<tr>
<td class="cellrowborder" valign="top" width="33.89830508474576%" headers="d69978e467 "><span class="keyword">function_node( const function_node
&src )</span>
</td>
<td class="cellrowborder" valign="top" width="66.10169491525423%" headers="d69978e470 ">
<p>Constructs a
<span class="keyword">function_node</span> that has the same initial
state that
<span class="keyword">src</span> had when it was constructed. The
<span class="keyword">function_node</span> that is constructed will
have a reference to the same
<span class="keyword">graph</span> object as
<span class="keyword">src</span>, will have a copy of the initial body
used by
<span class="keyword">src</span>, and have the same concurrency
threshold as
<span class="keyword">src</span>. The predecessors and successors of
<span class="keyword">src</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">src</span> at its construction. Therefore
changes made to member variables in
<span class="keyword">src</span>'s body after the construction of
<span class="keyword">src</span> will not affect the body of the new
<span class="keyword">function_node.</span>
</p>
</div>
</td>
</tr>
<tr>
<td class="cellrowborder" valign="top" width="33.89830508474576%" headers="d69978e467 "><span class="keyword">bool try_put( const input_type
&v )</span>
</td>
<td class="cellrowborder" valign="top" width="66.10169491525423%" headers="d69978e470 ">
<p>See the table above, "Behavior of a call to a
<samp class="codeph">function_node</samp>'s <samp class="codeph">try_put</samp>," for more
information.
</p>
<p><strong>Returns</strong>:
<span class="keyword">true</span> if the input was accepted; and
<span class="keyword">false</span> otherwise.
</p>
</td>
</tr>
<tr>
<td class="cellrowborder" valign="top" width="33.89830508474576%" headers="d69978e467 "><span class="keyword">bool register_predecessor(
predecessor_type &p )</span>
</td>
<td class="cellrowborder" valign="top" width="66.10169491525423%" headers="d69978e470 ">
<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="d69978e467 "><span class="keyword">bool remove_predecessor(
predecessor_type &p )</span>
</td>
<td class="cellrowborder" valign="top" width="66.10169491525423%" headers="d69978e470 ">
<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="d69978e467 "><span class="keyword">bool register_successor(
successor_type &r )</span>
</td>
<td class="cellrowborder" valign="top" width="66.10169491525423%" headers="d69978e470 ">
<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="d69978e467 "><span class="keyword">bool remove_successor(
successor_type &r )</span>
</td>
<td class="cellrowborder" valign="top" width="66.10169491525423%" headers="d69978e470 ">
<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="d69978e467 "><span class="keyword">bool try_get( output_type &v
)</span>
</td>
<td class="cellrowborder" valign="top" width="66.10169491525423%" headers="d69978e470 ">
<p>A
<span class="keyword">function_node</span> does not contain buffering
of its output. Therefore it always rejects
<span class="keyword">try_get</span> calls.
</p>
<p><strong>Returns</strong>:
<span class="keyword">false</span>
</p>
</td>
</tr>
<tr>
<td class="cellrowborder" valign="top" width="33.89830508474576%" headers="d69978e467 "><span class="keyword">bool try_reserve( output_type
&v )</span>
</td>
<td class="cellrowborder" valign="top" width="66.10169491525423%" headers="d69978e470 ">
<p>A
<span class="keyword">function_node</span> does not contain buffering
of its output. Therefore it cannot be reserved.
</p>
<p><strong>Returns</strong>:
<span class="keyword">false</span>
</p>
</td>
</tr>
<tr>
<td class="cellrowborder" valign="top" width="33.89830508474576%" headers="d69978e467 "><span class="keyword">bool try_release( )</span>
</td>
<td class="cellrowborder" valign="top" width="66.10169491525423%" headers="d69978e470 ">
<p>A
<span class="keyword">function_node</span> does not contain buffering
of its output. Therefore it cannot be reserved.
</p>
<p><strong>Returns</strong>:
<span class="keyword">false</span>
</p>
</td>
</tr>
<tr>
<td class="cellrowborder" valign="top" width="33.89830508474576%" headers="d69978e467 "><span class="keyword">bool try_consume( )</span>
</td>
<td class="cellrowborder" valign="top" width="66.10169491525423%" headers="d69978e470 ">
<p>A
<span class="keyword">function_node</span> does not contain buffering
of its output. Therefore it cannot be reserved.
</p>
<p><strong>Returns</strong>:
<span class="keyword">false</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="copy_body_func.htm">copy_body Template Function
</a></div>
<div><a href="../task_scheduler/task_group_context.htm">task_group_context
</a></div>
<div><a href="../exceptions.htm">Exceptions
</a></div>
<div><a href="message_passing_protocol.htm">Message Passing Protocol
</a></div></div>
</div>
</body>
</html>
|
