Skip to content
Navigation Menu
{{ message }}
-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathArrayPrefixHelpers.java
More file actions
696 lines (670 loc) · 30.8 KB
/
Copy pathArrayPrefixHelpers.java
File metadata and controls
696 lines (670 loc) · 30.8 KB
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
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
/*
* Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*/
package java.util;
/*
* Written by Doug Lea with assistance from members of JCP JSR-166
* Expert Group and released to the public domain, as explained at
* http://creativecommons.org/publicdomain/zero/1.0/
*/
import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.CountedCompleter;
import java.util.function.BinaryOperator;
import java.util.function.IntBinaryOperator;
import java.util.function.LongBinaryOperator;
import java.util.function.DoubleBinaryOperator;
/**
* ForkJoin tasks to perform Arrays.parallelPrefix operations.
*
* @author Doug Lea
* @since 1.8
*/
class ArrayPrefixHelpers {
private ArrayPrefixHelpers() {}; // non-instantiable
/*
* Parallel prefix (aka cumulate, scan) task classes
* are based loosely on Guy Blelloch's original
* algorithm (http://www.cs.cmu.edu/~scandal/alg/scan.html):
* Keep dividing by two to threshold segment size, and then:
* Pass 1: Create tree of partial sums for each segment
* Pass 2: For each segment, cumulate with offset of left sibling
*
* This version improves performance within FJ framework mainly by
* allowing the second pass of ready left-hand sides to proceed
* even if some right-hand side first passes are still executing.
* It also combines first and second pass for leftmost segment,
* and skips the first pass for rightmost segment (whose result is
* not needed for second pass). It similarly manages to avoid
* requiring that users supply an identity basis for accumulations
* by tracking those segments/subtasks for which the first
* existing element is used as base.
*
* Managing this relies on ORing some bits in the pendingCount for
* phases/states: CUMULATE, SUMMED, and FINISHED. CUMULATE is the
* main phase bit. When false, segments compute only their sum.
* When true, they cumulate array elements. CUMULATE is set at
* root at beginning of second pass and then propagated down. But
* it may also be set earlier for subtrees with lo==0 (the left
* spine of tree). SUMMED is a one bit join count. For leafs, it
* is set when summed. For internal nodes, it becomes true when
* one child is summed. When the second child finishes summing,
* we then moves up tree to trigger the cumulate phase. FINISHED
* is also a one bit join count. For leafs, it is set when
* cumulated. For internal nodes, it becomes true when one child
* is cumulated. When the second child finishes cumulating, it
* then moves up tree, completing at the root.
*
* To better exploit locality and reduce overhead, the compute
* method loops starting with the current task, moving if possible
* to one of its subtasks rather than forking.
*
* As usual for this sort of utility, there are 4 versions, that
* are simple copy/paste/adapt variants of each other. (The
* double and int versions differ from long version soley by
* replacing "long" (with case-matching)).
*/
// see above
static final int CUMULATE = 1;
static final int SUMMED = 2;
static final int FINISHED = 4;
/** The smallest subtask array partition size to use as threshold */
static final int MIN_PARTITION = 16;
static final class CumulateTask<T> extends CountedCompleter<Void> {
final T[] array;
final BinaryOperator<T> function;
CumulateTask<T> left, right;
T in, out;
final int lo, hi, origin, fence, threshold;
/** Root task constructor */
public CumulateTask(CumulateTask<T> parent,
BinaryOperator<T> function,
T[] array, int lo, int hi) {
super(parent);
this.function = function; this.array = array;
this.lo = this.origin = lo; this.hi = this.fence = hi;
int p;
this.threshold =
(p = (hi - lo) / (ForkJoinPool.getCommonPoolParallelism() << 3))
<= MIN_PARTITION ? MIN_PARTITION : p;
}
/** Subtask constructor */
CumulateTask(CumulateTask<T> parent, BinaryOperator<T> function,
T[] array, int origin, int fence, int threshold,
int lo, int hi) {
super(parent);
this.function = function; this.array = array;
this.origin = origin; this.fence = fence;
this.threshold = threshold;
this.lo = lo; this.hi = hi;
}
@SuppressWarnings("unchecked")
public final void compute() {
final BinaryOperator<T> fn;
final T[] a;
if ((fn = this.function) == null || (a = this.array) == null)
throw new NullPointerException(); // hoist checks
int th = threshold, org = origin, fnc = fence, l, h;
CumulateTask<T> t = this;
outer: while ((l = t.lo) >= 0 && (h = t.hi) <= a.length) {
if (h - l > th) {
CumulateTask<T> lt = t.left, rt = t.right, f;
if (lt == null) { // first pass
int mid = (l + h) >>> 1;
f = rt = t.right =
new CumulateTask<T>(t, fn, a, org, fnc, th, mid, h);
t = lt = t.left =
new CumulateTask<T>(t, fn, a, org, fnc, th, l, mid);
}
else { // possibly refork
T pin = t.in;
lt.in = pin;
f = t = null;
if (rt != null) {
T lout = lt.out;
rt.in = (l == org ? lout :
fn.apply(pin, lout));
for (int c;;) {
if (((c = rt.getPendingCount()) & CUMULATE) != 0)
break;
if (rt.compareAndSetPendingCount(c, c|CUMULATE)){
t = rt;
break;
}
}
}
for (int c;;) {
if (((c = lt.getPendingCount()) & CUMULATE) != 0)
break;
if (lt.compareAndSetPendingCount(c, c|CUMULATE)) {
if (t != null)
f = t;
t = lt;
break;
}
}
if (t == null)
break;
}
if (f != null)
f.fork();
}
else {
int state; // Transition to sum, cumulate, or both
for (int b;;) {
if (((b = t.getPendingCount()) & FINISHED) != 0)
break outer; // already done
state = ((b & CUMULATE) != 0? FINISHED :
(l > org) ? SUMMED : (SUMMED|FINISHED));
if (t.compareAndSetPendingCount(b, b|state))
break;
}
T sum;
if (state != SUMMED) {
int first;
if (l == org) { // leftmost; no in
sum = a[org];
first = org + 1;
}
else {
sum = t.in;
first = l;
}
for (int i = first; i < h; ++i) // cumulate
a[i] = sum = fn.apply(sum, a[i]);
}
else if (h < fnc) { // skip rightmost
sum = a[l];
for (int i = l + 1; i < h; ++i) // sum only
sum = fn.apply(sum, a[i]);
}
else
sum = t.in;
t.out = sum;
for (CumulateTask<T> par;;) { // propagate
if ((par = (CumulateTask<T>)t.getCompleter()) == null) {
if ((state & FINISHED) != 0) // enable join
t.quietlyComplete();
break outer;
}
int b = par.getPendingCount();
if ((b & state & FINISHED) != 0)
t = par; // both done
else if ((b & state & SUMMED) != 0) { // both summed
int nextState; CumulateTask<T> lt, rt;
if ((lt = par.left) != null &&
(rt = par.right) != null) {
T lout = lt.out;
par.out = (rt.hi == fnc ? lout :
fn.apply(lout, rt.out));
}
int refork = (((b & CUMULATE) == 0 &&
par.lo == org) ? CUMULATE : 0);
if ((nextState = b|state|refork) == b ||
par.compareAndSetPendingCount(b, nextState)) {
state = SUMMED; // drop finished
t = par;
if (refork != 0)
par.fork();
}
}
else if (par.compareAndSetPendingCount(b, b|state))
break outer; // sib not ready
}
}
}
}
}
static final class LongCumulateTask extends CountedCompleter<Void> {
final long[] array;
final LongBinaryOperator function;
LongCumulateTask left, right;
long in, out;
final int lo, hi, origin, fence, threshold;
/** Root task constructor */
public LongCumulateTask(LongCumulateTask parent,
LongBinaryOperator function,
long[] array, int lo, int hi) {
super(parent);
this.function = function; this.array = array;
this.lo = this.origin = lo; this.hi = this.fence = hi;
int p;
this.threshold =
(p = (hi - lo) / (ForkJoinPool.getCommonPoolParallelism() << 3))
<= MIN_PARTITION ? MIN_PARTITION : p;
}
/** Subtask constructor */
LongCumulateTask(LongCumulateTask parent, LongBinaryOperator function,
long[] array, int origin, int fence, int threshold,
int lo, int hi) {
super(parent);
this.function = function; this.array = array;
this.origin = origin; this.fence = fence;
this.threshold = threshold;
this.lo = lo; this.hi = hi;
}
public final void compute() {
final LongBinaryOperator fn;
final long[] a;
if ((fn = this.function) == null || (a = this.array) == null)
throw new NullPointerException(); // hoist checks
int th = threshold, org = origin, fnc = fence, l, h;
LongCumulateTask t = this;
outer: while ((l = t.lo) >= 0 && (h = t.hi) <= a.length) {
if (h - l > th) {
LongCumulateTask lt = t.left, rt = t.right, f;
if (lt == null) { // first pass
int mid = (l + h) >>> 1;
f = rt = t.right =
new LongCumulateTask(t, fn, a, org, fnc, th, mid, h);
t = lt = t.left =
new LongCumulateTask(t, fn, a, org, fnc, th, l, mid);
}
else { // possibly refork
long pin = t.in;
lt.in = pin;
f = t = null;
if (rt != null) {
long lout = lt.out;
rt.in = (l == org ? lout :
fn.applyAsLong(pin, lout));
for (int c;;) {
if (((c = rt.getPendingCount()) & CUMULATE) != 0)
break;
if (rt.compareAndSetPendingCount(c, c|CUMULATE)){
t = rt;
break;
}
}
}
for (int c;;) {
if (((c = lt.getPendingCount()) & CUMULATE) != 0)
break;
if (lt.compareAndSetPendingCount(c, c|CUMULATE)) {
if (t != null)
f = t;
t = lt;
break;
}
}
if (t == null)
break;
}
if (f != null)
f.fork();
}
else {
int state; // Transition to sum, cumulate, or both
for (int b;;) {
if (((b = t.getPendingCount()) & FINISHED) != 0)
break outer; // already done
state = ((b & CUMULATE) != 0? FINISHED :
(l > org) ? SUMMED : (SUMMED|FINISHED));
if (t.compareAndSetPendingCount(b, b|state))
break;
}
long sum;
if (state != SUMMED) {
int first;
if (l == org) { // leftmost; no in
sum = a[org];
first = org + 1;
}
else {
sum = t.in;
first = l;
}
for (int i = first; i < h; ++i) // cumulate
a[i] = sum = fn.applyAsLong(sum, a[i]);
}
else if (h < fnc) { // skip rightmost
sum = a[l];
for (int i = l + 1; i < h; ++i) // sum only
sum = fn.applyAsLong(sum, a[i]);
}
else
sum = t.in;
t.out = sum;
for (LongCumulateTask par;;) { // propagate
if ((par = (LongCumulateTask)t.getCompleter()) == null) {
if ((state & FINISHED) != 0) // enable join
t.quietlyComplete();
break outer;
}
int b = par.getPendingCount();
if ((b & state & FINISHED) != 0)
t = par; // both done
else if ((b & state & SUMMED) != 0) { // both summed
int nextState; LongCumulateTask lt, rt;
if ((lt = par.left) != null &&
(rt = par.right) != null) {
long lout = lt.out;
par.out = (rt.hi == fnc ? lout :
fn.applyAsLong(lout, rt.out));
}
int refork = (((b & CUMULATE) == 0 &&
par.lo == org) ? CUMULATE : 0);
if ((nextState = b|state|refork) == b ||
par.compareAndSetPendingCount(b, nextState)) {
state = SUMMED; // drop finished
t = par;
if (refork != 0)
par.fork();
}
}
else if (par.compareAndSetPendingCount(b, b|state))
break outer; // sib not ready
}
}
}
}
}
static final class DoubleCumulateTask extends CountedCompleter<Void> {
final double[] array;
final DoubleBinaryOperator function;
DoubleCumulateTask left, right;
double in, out;
final int lo, hi, origin, fence, threshold;
/** Root task constructor */
public DoubleCumulateTask(DoubleCumulateTask parent,
DoubleBinaryOperator function,
double[] array, int lo, int hi) {
super(parent);
this.function = function; this.array = array;
this.lo = this.origin = lo; this.hi = this.fence = hi;
int p;
this.threshold =
(p = (hi - lo) / (ForkJoinPool.getCommonPoolParallelism() << 3))
<= MIN_PARTITION ? MIN_PARTITION : p;
}
/** Subtask constructor */
DoubleCumulateTask(DoubleCumulateTask parent, DoubleBinaryOperator function,
double[] array, int origin, int fence, int threshold,
int lo, int hi) {
super(parent);
this.function = function; this.array = array;
this.origin = origin; this.fence = fence;
this.threshold = threshold;
this.lo = lo; this.hi = hi;
}
public final void compute() {
final DoubleBinaryOperator fn;
final double[] a;
if ((fn = this.function) == null || (a = this.array) == null)
throw new NullPointerException(); // hoist checks
int th = threshold, org = origin, fnc = fence, l, h;
DoubleCumulateTask t = this;
outer: while ((l = t.lo) >= 0 && (h = t.hi) <= a.length) {
if (h - l > th) {
DoubleCumulateTask lt = t.left, rt = t.right, f;
if (lt == null) { // first pass
int mid = (l + h) >>> 1;
f = rt = t.right =
new DoubleCumulateTask(t, fn, a, org, fnc, th, mid, h);
t = lt = t.left =
new DoubleCumulateTask(t, fn, a, org, fnc, th, l, mid);
}
else { // possibly refork
double pin = t.in;
lt.in = pin;
f = t = null;
if (rt != null) {
double lout = lt.out;
rt.in = (l == org ? lout :
fn.applyAsDouble(pin, lout));
for (int c;;) {
if (((c = rt.getPendingCount()) & CUMULATE) != 0)
break;
if (rt.compareAndSetPendingCount(c, c|CUMULATE)){
t = rt;
break;
}
}
}
for (int c;;) {
if (((c = lt.getPendingCount()) & CUMULATE) != 0)
break;
if (lt.compareAndSetPendingCount(c, c|CUMULATE)) {
if (t != null)
f = t;
t = lt;
break;
}
}
if (t == null)
break;
}
if (f != null)
f.fork();
}
else {
int state; // Transition to sum, cumulate, or both
for (int b;;) {
if (((b = t.getPendingCount()) & FINISHED) != 0)
break outer; // already done
state = ((b & CUMULATE) != 0? FINISHED :
(l > org) ? SUMMED : (SUMMED|FINISHED));
if (t.compareAndSetPendingCount(b, b|state))
break;
}
double sum;
if (state != SUMMED) {
int first;
if (l == org) { // leftmost; no in
sum = a[org];
first = org + 1;
}
else {
sum = t.in;
first = l;
}
for (int i = first; i < h; ++i) // cumulate
a[i] = sum = fn.applyAsDouble(sum, a[i]);
}
else if (h < fnc) { // skip rightmost
sum = a[l];
for (int i = l + 1; i < h; ++i) // sum only
sum = fn.applyAsDouble(sum, a[i]);
}
else
sum = t.in;
t.out = sum;
for (DoubleCumulateTask par;;) { // propagate
if ((par = (DoubleCumulateTask)t.getCompleter()) == null) {
if ((state & FINISHED) != 0) // enable join
t.quietlyComplete();
break outer;
}
int b = par.getPendingCount();
if ((b & state & FINISHED) != 0)
t = par; // both done
else if ((b & state & SUMMED) != 0) { // both summed
int nextState; DoubleCumulateTask lt, rt;
if ((lt = par.left) != null &&
(rt = par.right) != null) {
double lout = lt.out;
par.out = (rt.hi == fnc ? lout :
fn.applyAsDouble(lout, rt.out));
}
int refork = (((b & CUMULATE) == 0 &&
par.lo == org) ? CUMULATE : 0);
if ((nextState = b|state|refork) == b ||
par.compareAndSetPendingCount(b, nextState)) {
state = SUMMED; // drop finished
t = par;
if (refork != 0)
par.fork();
}
}
else if (par.compareAndSetPendingCount(b, b|state))
break outer; // sib not ready
}
}
}
}
}
static final class IntCumulateTask extends CountedCompleter<Void> {
final int[] array;
final IntBinaryOperator function;
IntCumulateTask left, right;
int in, out;
final int lo, hi, origin, fence, threshold;
/** Root task constructor */
public IntCumulateTask(IntCumulateTask parent,
IntBinaryOperator function,
int[] array, int lo, int hi) {
super(parent);
this.function = function; this.array = array;
this.lo = this.origin = lo; this.hi = this.fence = hi;
int p;
this.threshold =
(p = (hi - lo) / (ForkJoinPool.getCommonPoolParallelism() << 3))
<= MIN_PARTITION ? MIN_PARTITION : p;
}
/** Subtask constructor */
IntCumulateTask(IntCumulateTask parent, IntBinaryOperator function,
int[] array, int origin, int fence, int threshold,
int lo, int hi) {
super(parent);
this.function = function; this.array = array;
this.origin = origin; this.fence = fence;
this.threshold = threshold;
this.lo = lo; this.hi = hi;
}
public final void compute() {
final IntBinaryOperator fn;
final int[] a;
if ((fn = this.function) == null || (a = this.array) == null)
throw new NullPointerException(); // hoist checks
int th = threshold, org = origin, fnc = fence, l, h;
IntCumulateTask t = this;
outer: while ((l = t.lo) >= 0 && (h = t.hi) <= a.length) {
if (h - l > th) {
IntCumulateTask lt = t.left, rt = t.right, f;
if (lt == null) { // first pass
int mid = (l + h) >>> 1;
f = rt = t.right =
new IntCumulateTask(t, fn, a, org, fnc, th, mid, h);
t = lt = t.left =
new IntCumulateTask(t, fn, a, org, fnc, th, l, mid);
}
else { // possibly refork
int pin = t.in;
lt.in = pin;
f = t = null;
if (rt != null) {
int lout = lt.out;
rt.in = (l == org ? lout :
fn.applyAsInt(pin, lout));
for (int c;;) {
if (((c = rt.getPendingCount()) & CUMULATE) != 0)
break;
if (rt.compareAndSetPendingCount(c, c|CUMULATE)){
t = rt;
break;
}
}
}
for (int c;;) {
if (((c = lt.getPendingCount()) & CUMULATE) != 0)
break;
if (lt.compareAndSetPendingCount(c, c|CUMULATE)) {
if (t != null)
f = t;
t = lt;
break;
}
}
if (t == null)
break;
}
if (f != null)
f.fork();
}
else {
int state; // Transition to sum, cumulate, or both
for (int b;;) {
if (((b = t.getPendingCount()) & FINISHED) != 0)
break outer; // already done
state = ((b & CUMULATE) != 0? FINISHED :
(l > org) ? SUMMED : (SUMMED|FINISHED));
if (t.compareAndSetPendingCount(b, b|state))
break;
}
int sum;
if (state != SUMMED) {
int first;
if (l == org) { // leftmost; no in
sum = a[org];
first = org + 1;
}
else {
sum = t.in;
first = l;
}
for (int i = first; i < h; ++i) // cumulate
a[i] = sum = fn.applyAsInt(sum, a[i]);
}
else if (h < fnc) { // skip rightmost
sum = a[l];
for (int i = l + 1; i < h; ++i) // sum only
sum = fn.applyAsInt(sum, a[i]);
}
else
sum = t.in;
t.out = sum;
for (IntCumulateTask par;;) { // propagate
if ((par = (IntCumulateTask)t.getCompleter()) == null) {
if ((state & FINISHED) != 0) // enable join
t.quietlyComplete();
break outer;
}
int b = par.getPendingCount();
if ((b & state & FINISHED) != 0)
t = par; // both done
else if ((b & state & SUMMED) != 0) { // both summed
int nextState; IntCumulateTask lt, rt;
if ((lt = par.left) != null &&
(rt = par.right) != null) {
int lout = lt.out;
par.out = (rt.hi == fnc ? lout :
fn.applyAsInt(lout, rt.out));
}
int refork = (((b & CUMULATE) == 0 &&
par.lo == org) ? CUMULATE : 0);
if ((nextState = b|state|refork) == b ||
par.compareAndSetPendingCount(b, nextState)) {
state = SUMMED; // drop finished
t = par;
if (refork != 0)
par.fork();
}
}
else if (par.compareAndSetPendingCount(b, b|state))
break outer; // sib not ready
}
}
}
}
}
}
You can’t perform that action at this time.