| 1 |
/* |
| 2 |
* Written by Doug Lea with assistance from members of JCP JSR-166 |
| 3 |
* Expert Group and released to the public domain, as explained at |
| 4 |
* http://creativecommons.org/publicdomain/zero/1.0/ |
| 5 |
*/ |
| 6 |
|
| 7 |
package java.util; |
| 8 |
import java.util.concurrent.ForkJoinPool; |
| 9 |
import java.util.concurrent.CountedCompleter; |
| 10 |
import java.util.function.BinaryOperator; |
| 11 |
import java.util.function.IntBinaryOperator; |
| 12 |
import java.util.function.LongBinaryOperator; |
| 13 |
import java.util.function.DoubleBinaryOperator; |
| 14 |
|
| 15 |
/** |
| 16 |
* ForkJoin tasks to perform Arrays.parallelPrefix operations. |
| 17 |
* |
| 18 |
* @author Doug Lea |
| 19 |
* @since 1.8 |
| 20 |
*/ |
| 21 |
class ArrayPrefixHelpers { |
| 22 |
private ArrayPrefixHelpers() {} // non-instantiable |
| 23 |
|
| 24 |
/* |
| 25 |
* Parallel prefix (aka cumulate, scan) task classes |
| 26 |
* are based loosely on Guy Blelloch's original |
| 27 |
* algorithm (http://www.cs.cmu.edu/~scandal/alg/scan.html): |
| 28 |
* Keep dividing by two to threshold segment size, and then: |
| 29 |
* Pass 1: Create tree of partial sums for each segment |
| 30 |
* Pass 2: For each segment, cumulate with offset of left sibling |
| 31 |
* |
| 32 |
* This version improves performance within FJ framework mainly by |
| 33 |
* allowing the second pass of ready left-hand sides to proceed |
| 34 |
* even if some right-hand side first passes are still executing. |
| 35 |
* It also combines first and second pass for leftmost segment, |
| 36 |
* and skips the first pass for rightmost segment (whose result is |
| 37 |
* not needed for second pass). It similarly manages to avoid |
| 38 |
* requiring that users supply an identity basis for accumulations |
| 39 |
* by tracking those segments/subtasks for which the first |
| 40 |
* existing element is used as base. |
| 41 |
* |
| 42 |
* Managing this relies on ORing some bits in the pendingCount for |
| 43 |
* phases/states: CUMULATE, SUMMED, and FINISHED. CUMULATE is the |
| 44 |
* main phase bit. When false, segments compute only their sum. |
| 45 |
* When true, they cumulate array elements. CUMULATE is set at |
| 46 |
* root at beginning of second pass and then propagated down. But |
| 47 |
* it may also be set earlier for subtrees with lo==0 (the left |
| 48 |
* spine of tree). SUMMED is a one bit join count. For leafs, it |
| 49 |
* is set when summed. For internal nodes, it becomes true when |
| 50 |
* one child is summed. When the second child finishes summing, |
| 51 |
* we then moves up tree to trigger the cumulate phase. FINISHED |
| 52 |
* is also a one bit join count. For leafs, it is set when |
| 53 |
* cumulated. For internal nodes, it becomes true when one child |
| 54 |
* is cumulated. When the second child finishes cumulating, it |
| 55 |
* then moves up tree, completing at the root. |
| 56 |
* |
| 57 |
* To better exploit locality and reduce overhead, the compute |
| 58 |
* method loops starting with the current task, moving if possible |
| 59 |
* to one of its subtasks rather than forking. |
| 60 |
* |
| 61 |
* As usual for this sort of utility, there are 4 versions, that |
| 62 |
* are simple copy/paste/adapt variants of each other. (The |
| 63 |
* double and int versions differ from long version solely by |
| 64 |
* replacing "long" (with case-matching)). |
| 65 |
*/ |
| 66 |
|
| 67 |
// see above |
| 68 |
static final int CUMULATE = 1; |
| 69 |
static final int SUMMED = 2; |
| 70 |
static final int FINISHED = 4; |
| 71 |
|
| 72 |
/** The smallest subtask array partition size to use as threshold */ |
| 73 |
static final int MIN_PARTITION = 16; |
| 74 |
|
| 75 |
static final class CumulateTask<T> extends CountedCompleter<Void> { |
| 76 |
final T[] array; |
| 77 |
final BinaryOperator<T> function; |
| 78 |
CumulateTask<T> left, right; |
| 79 |
T in, out; |
| 80 |
final int lo, hi, origin, fence, threshold; |
| 81 |
|
| 82 |
/** Root task constructor */ |
| 83 |
public CumulateTask(CumulateTask<T> parent, |
| 84 |
BinaryOperator<T> function, |
| 85 |
T[] array, int lo, int hi) { |
| 86 |
super(parent); |
| 87 |
this.function = function; this.array = array; |
| 88 |
this.lo = this.origin = lo; this.hi = this.fence = hi; |
| 89 |
int p; |
| 90 |
this.threshold = |
| 91 |
(p = (hi - lo) / (ForkJoinPool.getCommonPoolParallelism() << 3)) |
| 92 |
<= MIN_PARTITION ? MIN_PARTITION : p; |
| 93 |
} |
| 94 |
|
| 95 |
/** Subtask constructor */ |
| 96 |
CumulateTask(CumulateTask<T> parent, BinaryOperator<T> function, |
| 97 |
T[] array, int origin, int fence, int threshold, |
| 98 |
int lo, int hi) { |
| 99 |
super(parent); |
| 100 |
this.function = function; this.array = array; |
| 101 |
this.origin = origin; this.fence = fence; |
| 102 |
this.threshold = threshold; |
| 103 |
this.lo = lo; this.hi = hi; |
| 104 |
} |
| 105 |
|
| 106 |
public final void compute() { |
| 107 |
final BinaryOperator<T> fn; |
| 108 |
final T[] a; |
| 109 |
if ((fn = this.function) == null || (a = this.array) == null) |
| 110 |
throw new NullPointerException(); // hoist checks |
| 111 |
int th = threshold, org = origin, fnc = fence, l, h; |
| 112 |
CumulateTask<T> t = this; |
| 113 |
outer: while ((l = t.lo) >= 0 && (h = t.hi) <= a.length) { |
| 114 |
if (h - l > th) { |
| 115 |
CumulateTask<T> lt = t.left, rt = t.right, f; |
| 116 |
if (lt == null) { // first pass |
| 117 |
int mid = (l + h) >>> 1; |
| 118 |
f = rt = t.right = |
| 119 |
new CumulateTask<T>(t, fn, a, org, fnc, th, mid, h); |
| 120 |
t = lt = t.left = |
| 121 |
new CumulateTask<T>(t, fn, a, org, fnc, th, l, mid); |
| 122 |
} |
| 123 |
else { // possibly refork |
| 124 |
T pin = t.in; |
| 125 |
lt.in = pin; |
| 126 |
f = t = null; |
| 127 |
if (rt != null) { |
| 128 |
T lout = lt.out; |
| 129 |
rt.in = (l == org ? lout : |
| 130 |
fn.apply(pin, lout)); |
| 131 |
for (int c;;) { |
| 132 |
if (((c = rt.getPendingCount()) & CUMULATE) != 0) |
| 133 |
break; |
| 134 |
if (rt.compareAndSetPendingCount(c, c|CUMULATE)){ |
| 135 |
t = rt; |
| 136 |
break; |
| 137 |
} |
| 138 |
} |
| 139 |
} |
| 140 |
for (int c;;) { |
| 141 |
if (((c = lt.getPendingCount()) & CUMULATE) != 0) |
| 142 |
break; |
| 143 |
if (lt.compareAndSetPendingCount(c, c|CUMULATE)) { |
| 144 |
if (t != null) |
| 145 |
f = t; |
| 146 |
t = lt; |
| 147 |
break; |
| 148 |
} |
| 149 |
} |
| 150 |
if (t == null) |
| 151 |
break; |
| 152 |
} |
| 153 |
if (f != null) |
| 154 |
f.fork(); |
| 155 |
} |
| 156 |
else { |
| 157 |
int state; // Transition to sum, cumulate, or both |
| 158 |
for (int b;;) { |
| 159 |
if (((b = t.getPendingCount()) & FINISHED) != 0) |
| 160 |
break outer; // already done |
| 161 |
state = ((b & CUMULATE) != 0 ? FINISHED : |
| 162 |
(l > org) ? SUMMED : (SUMMED|FINISHED)); |
| 163 |
if (t.compareAndSetPendingCount(b, b|state)) |
| 164 |
break; |
| 165 |
} |
| 166 |
|
| 167 |
T sum; |
| 168 |
if (state != SUMMED) { |
| 169 |
int first; |
| 170 |
if (l == org) { // leftmost; no in |
| 171 |
sum = a[org]; |
| 172 |
first = org + 1; |
| 173 |
} |
| 174 |
else { |
| 175 |
sum = t.in; |
| 176 |
first = l; |
| 177 |
} |
| 178 |
for (int i = first; i < h; ++i) // cumulate |
| 179 |
a[i] = sum = fn.apply(sum, a[i]); |
| 180 |
} |
| 181 |
else if (h < fnc) { // skip rightmost |
| 182 |
sum = a[l]; |
| 183 |
for (int i = l + 1; i < h; ++i) // sum only |
| 184 |
sum = fn.apply(sum, a[i]); |
| 185 |
} |
| 186 |
else |
| 187 |
sum = t.in; |
| 188 |
t.out = sum; |
| 189 |
for (CumulateTask<T> par;;) { // propagate |
| 190 |
@SuppressWarnings("unchecked") CumulateTask<T> partmp |
| 191 |
= (CumulateTask<T>)t.getCompleter(); |
| 192 |
if ((par = partmp) == null) { |
| 193 |
if ((state & FINISHED) != 0) // enable join |
| 194 |
t.quietlyComplete(); |
| 195 |
break outer; |
| 196 |
} |
| 197 |
int b = par.getPendingCount(); |
| 198 |
if ((b & state & FINISHED) != 0) |
| 199 |
t = par; // both done |
| 200 |
else if ((b & state & SUMMED) != 0) { // both summed |
| 201 |
int nextState; CumulateTask<T> lt, rt; |
| 202 |
if ((lt = par.left) != null && |
| 203 |
(rt = par.right) != null) { |
| 204 |
T lout = lt.out; |
| 205 |
par.out = (rt.hi == fnc ? lout : |
| 206 |
fn.apply(lout, rt.out)); |
| 207 |
} |
| 208 |
int refork = (((b & CUMULATE) == 0 && |
| 209 |
par.lo == org) ? CUMULATE : 0); |
| 210 |
if ((nextState = b|state|refork) == b || |
| 211 |
par.compareAndSetPendingCount(b, nextState)) { |
| 212 |
state = SUMMED; // drop finished |
| 213 |
t = par; |
| 214 |
if (refork != 0) |
| 215 |
par.fork(); |
| 216 |
} |
| 217 |
} |
| 218 |
else if (par.compareAndSetPendingCount(b, b|state)) |
| 219 |
break outer; // sib not ready |
| 220 |
} |
| 221 |
} |
| 222 |
} |
| 223 |
} |
| 224 |
private static final long serialVersionUID = 5293554502939613543L; |
| 225 |
} |
| 226 |
|
| 227 |
static final class LongCumulateTask extends CountedCompleter<Void> { |
| 228 |
final long[] array; |
| 229 |
final LongBinaryOperator function; |
| 230 |
LongCumulateTask left, right; |
| 231 |
long in, out; |
| 232 |
final int lo, hi, origin, fence, threshold; |
| 233 |
|
| 234 |
/** Root task constructor */ |
| 235 |
public LongCumulateTask(LongCumulateTask parent, |
| 236 |
LongBinaryOperator function, |
| 237 |
long[] array, int lo, int hi) { |
| 238 |
super(parent); |
| 239 |
this.function = function; this.array = array; |
| 240 |
this.lo = this.origin = lo; this.hi = this.fence = hi; |
| 241 |
int p; |
| 242 |
this.threshold = |
| 243 |
(p = (hi - lo) / (ForkJoinPool.getCommonPoolParallelism() << 3)) |
| 244 |
<= MIN_PARTITION ? MIN_PARTITION : p; |
| 245 |
} |
| 246 |
|
| 247 |
/** Subtask constructor */ |
| 248 |
LongCumulateTask(LongCumulateTask parent, LongBinaryOperator function, |
| 249 |
long[] array, int origin, int fence, int threshold, |
| 250 |
int lo, int hi) { |
| 251 |
super(parent); |
| 252 |
this.function = function; this.array = array; |
| 253 |
this.origin = origin; this.fence = fence; |
| 254 |
this.threshold = threshold; |
| 255 |
this.lo = lo; this.hi = hi; |
| 256 |
} |
| 257 |
|
| 258 |
public final void compute() { |
| 259 |
final LongBinaryOperator fn; |
| 260 |
final long[] a; |
| 261 |
if ((fn = this.function) == null || (a = this.array) == null) |
| 262 |
throw new NullPointerException(); // hoist checks |
| 263 |
int th = threshold, org = origin, fnc = fence, l, h; |
| 264 |
LongCumulateTask t = this; |
| 265 |
outer: while ((l = t.lo) >= 0 && (h = t.hi) <= a.length) { |
| 266 |
if (h - l > th) { |
| 267 |
LongCumulateTask lt = t.left, rt = t.right, f; |
| 268 |
if (lt == null) { // first pass |
| 269 |
int mid = (l + h) >>> 1; |
| 270 |
f = rt = t.right = |
| 271 |
new LongCumulateTask(t, fn, a, org, fnc, th, mid, h); |
| 272 |
t = lt = t.left = |
| 273 |
new LongCumulateTask(t, fn, a, org, fnc, th, l, mid); |
| 274 |
} |
| 275 |
else { // possibly refork |
| 276 |
long pin = t.in; |
| 277 |
lt.in = pin; |
| 278 |
f = t = null; |
| 279 |
if (rt != null) { |
| 280 |
long lout = lt.out; |
| 281 |
rt.in = (l == org ? lout : |
| 282 |
fn.applyAsLong(pin, lout)); |
| 283 |
for (int c;;) { |
| 284 |
if (((c = rt.getPendingCount()) & CUMULATE) != 0) |
| 285 |
break; |
| 286 |
if (rt.compareAndSetPendingCount(c, c|CUMULATE)){ |
| 287 |
t = rt; |
| 288 |
break; |
| 289 |
} |
| 290 |
} |
| 291 |
} |
| 292 |
for (int c;;) { |
| 293 |
if (((c = lt.getPendingCount()) & CUMULATE) != 0) |
| 294 |
break; |
| 295 |
if (lt.compareAndSetPendingCount(c, c|CUMULATE)) { |
| 296 |
if (t != null) |
| 297 |
f = t; |
| 298 |
t = lt; |
| 299 |
break; |
| 300 |
} |
| 301 |
} |
| 302 |
if (t == null) |
| 303 |
break; |
| 304 |
} |
| 305 |
if (f != null) |
| 306 |
f.fork(); |
| 307 |
} |
| 308 |
else { |
| 309 |
int state; // Transition to sum, cumulate, or both |
| 310 |
for (int b;;) { |
| 311 |
if (((b = t.getPendingCount()) & FINISHED) != 0) |
| 312 |
break outer; // already done |
| 313 |
state = ((b & CUMULATE) != 0 ? FINISHED : |
| 314 |
(l > org) ? SUMMED : (SUMMED|FINISHED)); |
| 315 |
if (t.compareAndSetPendingCount(b, b|state)) |
| 316 |
break; |
| 317 |
} |
| 318 |
|
| 319 |
long sum; |
| 320 |
if (state != SUMMED) { |
| 321 |
int first; |
| 322 |
if (l == org) { // leftmost; no in |
| 323 |
sum = a[org]; |
| 324 |
first = org + 1; |
| 325 |
} |
| 326 |
else { |
| 327 |
sum = t.in; |
| 328 |
first = l; |
| 329 |
} |
| 330 |
for (int i = first; i < h; ++i) // cumulate |
| 331 |
a[i] = sum = fn.applyAsLong(sum, a[i]); |
| 332 |
} |
| 333 |
else if (h < fnc) { // skip rightmost |
| 334 |
sum = a[l]; |
| 335 |
for (int i = l + 1; i < h; ++i) // sum only |
| 336 |
sum = fn.applyAsLong(sum, a[i]); |
| 337 |
} |
| 338 |
else |
| 339 |
sum = t.in; |
| 340 |
t.out = sum; |
| 341 |
for (LongCumulateTask par;;) { // propagate |
| 342 |
if ((par = (LongCumulateTask)t.getCompleter()) == null) { |
| 343 |
if ((state & FINISHED) != 0) // enable join |
| 344 |
t.quietlyComplete(); |
| 345 |
break outer; |
| 346 |
} |
| 347 |
int b = par.getPendingCount(); |
| 348 |
if ((b & state & FINISHED) != 0) |
| 349 |
t = par; // both done |
| 350 |
else if ((b & state & SUMMED) != 0) { // both summed |
| 351 |
int nextState; LongCumulateTask lt, rt; |
| 352 |
if ((lt = par.left) != null && |
| 353 |
(rt = par.right) != null) { |
| 354 |
long lout = lt.out; |
| 355 |
par.out = (rt.hi == fnc ? lout : |
| 356 |
fn.applyAsLong(lout, rt.out)); |
| 357 |
} |
| 358 |
int refork = (((b & CUMULATE) == 0 && |
| 359 |
par.lo == org) ? CUMULATE : 0); |
| 360 |
if ((nextState = b|state|refork) == b || |
| 361 |
par.compareAndSetPendingCount(b, nextState)) { |
| 362 |
state = SUMMED; // drop finished |
| 363 |
t = par; |
| 364 |
if (refork != 0) |
| 365 |
par.fork(); |
| 366 |
} |
| 367 |
} |
| 368 |
else if (par.compareAndSetPendingCount(b, b|state)) |
| 369 |
break outer; // sib not ready |
| 370 |
} |
| 371 |
} |
| 372 |
} |
| 373 |
} |
| 374 |
private static final long serialVersionUID = -5074099945909284273L; |
| 375 |
} |
| 376 |
|
| 377 |
static final class DoubleCumulateTask extends CountedCompleter<Void> { |
| 378 |
final double[] array; |
| 379 |
final DoubleBinaryOperator function; |
| 380 |
DoubleCumulateTask left, right; |
| 381 |
double in, out; |
| 382 |
final int lo, hi, origin, fence, threshold; |
| 383 |
|
| 384 |
/** Root task constructor */ |
| 385 |
public DoubleCumulateTask(DoubleCumulateTask parent, |
| 386 |
DoubleBinaryOperator function, |
| 387 |
double[] array, int lo, int hi) { |
| 388 |
super(parent); |
| 389 |
this.function = function; this.array = array; |
| 390 |
this.lo = this.origin = lo; this.hi = this.fence = hi; |
| 391 |
int p; |
| 392 |
this.threshold = |
| 393 |
(p = (hi - lo) / (ForkJoinPool.getCommonPoolParallelism() << 3)) |
| 394 |
<= MIN_PARTITION ? MIN_PARTITION : p; |
| 395 |
} |
| 396 |
|
| 397 |
/** Subtask constructor */ |
| 398 |
DoubleCumulateTask(DoubleCumulateTask parent, DoubleBinaryOperator function, |
| 399 |
double[] array, int origin, int fence, int threshold, |
| 400 |
int lo, int hi) { |
| 401 |
super(parent); |
| 402 |
this.function = function; this.array = array; |
| 403 |
this.origin = origin; this.fence = fence; |
| 404 |
this.threshold = threshold; |
| 405 |
this.lo = lo; this.hi = hi; |
| 406 |
} |
| 407 |
|
| 408 |
public final void compute() { |
| 409 |
final DoubleBinaryOperator fn; |
| 410 |
final double[] a; |
| 411 |
if ((fn = this.function) == null || (a = this.array) == null) |
| 412 |
throw new NullPointerException(); // hoist checks |
| 413 |
int th = threshold, org = origin, fnc = fence, l, h; |
| 414 |
DoubleCumulateTask t = this; |
| 415 |
outer: while ((l = t.lo) >= 0 && (h = t.hi) <= a.length) { |
| 416 |
if (h - l > th) { |
| 417 |
DoubleCumulateTask lt = t.left, rt = t.right, f; |
| 418 |
if (lt == null) { // first pass |
| 419 |
int mid = (l + h) >>> 1; |
| 420 |
f = rt = t.right = |
| 421 |
new DoubleCumulateTask(t, fn, a, org, fnc, th, mid, h); |
| 422 |
t = lt = t.left = |
| 423 |
new DoubleCumulateTask(t, fn, a, org, fnc, th, l, mid); |
| 424 |
} |
| 425 |
else { // possibly refork |
| 426 |
double pin = t.in; |
| 427 |
lt.in = pin; |
| 428 |
f = t = null; |
| 429 |
if (rt != null) { |
| 430 |
double lout = lt.out; |
| 431 |
rt.in = (l == org ? lout : |
| 432 |
fn.applyAsDouble(pin, lout)); |
| 433 |
for (int c;;) { |
| 434 |
if (((c = rt.getPendingCount()) & CUMULATE) != 0) |
| 435 |
break; |
| 436 |
if (rt.compareAndSetPendingCount(c, c|CUMULATE)){ |
| 437 |
t = rt; |
| 438 |
break; |
| 439 |
} |
| 440 |
} |
| 441 |
} |
| 442 |
for (int c;;) { |
| 443 |
if (((c = lt.getPendingCount()) & CUMULATE) != 0) |
| 444 |
break; |
| 445 |
if (lt.compareAndSetPendingCount(c, c|CUMULATE)) { |
| 446 |
if (t != null) |
| 447 |
f = t; |
| 448 |
t = lt; |
| 449 |
break; |
| 450 |
} |
| 451 |
} |
| 452 |
if (t == null) |
| 453 |
break; |
| 454 |
} |
| 455 |
if (f != null) |
| 456 |
f.fork(); |
| 457 |
} |
| 458 |
else { |
| 459 |
int state; // Transition to sum, cumulate, or both |
| 460 |
for (int b;;) { |
| 461 |
if (((b = t.getPendingCount()) & FINISHED) != 0) |
| 462 |
break outer; // already done |
| 463 |
state = ((b & CUMULATE) != 0 ? FINISHED : |
| 464 |
(l > org) ? SUMMED : (SUMMED|FINISHED)); |
| 465 |
if (t.compareAndSetPendingCount(b, b|state)) |
| 466 |
break; |
| 467 |
} |
| 468 |
|
| 469 |
double sum; |
| 470 |
if (state != SUMMED) { |
| 471 |
int first; |
| 472 |
if (l == org) { // leftmost; no in |
| 473 |
sum = a[org]; |
| 474 |
first = org + 1; |
| 475 |
} |
| 476 |
else { |
| 477 |
sum = t.in; |
| 478 |
first = l; |
| 479 |
} |
| 480 |
for (int i = first; i < h; ++i) // cumulate |
| 481 |
a[i] = sum = fn.applyAsDouble(sum, a[i]); |
| 482 |
} |
| 483 |
else if (h < fnc) { // skip rightmost |
| 484 |
sum = a[l]; |
| 485 |
for (int i = l + 1; i < h; ++i) // sum only |
| 486 |
sum = fn.applyAsDouble(sum, a[i]); |
| 487 |
} |
| 488 |
else |
| 489 |
sum = t.in; |
| 490 |
t.out = sum; |
| 491 |
for (DoubleCumulateTask par;;) { // propagate |
| 492 |
if ((par = (DoubleCumulateTask)t.getCompleter()) == null) { |
| 493 |
if ((state & FINISHED) != 0) // enable join |
| 494 |
t.quietlyComplete(); |
| 495 |
break outer; |
| 496 |
} |
| 497 |
int b = par.getPendingCount(); |
| 498 |
if ((b & state & FINISHED) != 0) |
| 499 |
t = par; // both done |
| 500 |
else if ((b & state & SUMMED) != 0) { // both summed |
| 501 |
int nextState; DoubleCumulateTask lt, rt; |
| 502 |
if ((lt = par.left) != null && |
| 503 |
(rt = par.right) != null) { |
| 504 |
double lout = lt.out; |
| 505 |
par.out = (rt.hi == fnc ? lout : |
| 506 |
fn.applyAsDouble(lout, rt.out)); |
| 507 |
} |
| 508 |
int refork = (((b & CUMULATE) == 0 && |
| 509 |
par.lo == org) ? CUMULATE : 0); |
| 510 |
if ((nextState = b|state|refork) == b || |
| 511 |
par.compareAndSetPendingCount(b, nextState)) { |
| 512 |
state = SUMMED; // drop finished |
| 513 |
t = par; |
| 514 |
if (refork != 0) |
| 515 |
par.fork(); |
| 516 |
} |
| 517 |
} |
| 518 |
else if (par.compareAndSetPendingCount(b, b|state)) |
| 519 |
break outer; // sib not ready |
| 520 |
} |
| 521 |
} |
| 522 |
} |
| 523 |
} |
| 524 |
private static final long serialVersionUID = -586947823794232033L; |
| 525 |
} |
| 526 |
|
| 527 |
static final class IntCumulateTask extends CountedCompleter<Void> { |
| 528 |
final int[] array; |
| 529 |
final IntBinaryOperator function; |
| 530 |
IntCumulateTask left, right; |
| 531 |
int in, out; |
| 532 |
final int lo, hi, origin, fence, threshold; |
| 533 |
|
| 534 |
/** Root task constructor */ |
| 535 |
public IntCumulateTask(IntCumulateTask parent, |
| 536 |
IntBinaryOperator function, |
| 537 |
int[] array, int lo, int hi) { |
| 538 |
super(parent); |
| 539 |
this.function = function; this.array = array; |
| 540 |
this.lo = this.origin = lo; this.hi = this.fence = hi; |
| 541 |
int p; |
| 542 |
this.threshold = |
| 543 |
(p = (hi - lo) / (ForkJoinPool.getCommonPoolParallelism() << 3)) |
| 544 |
<= MIN_PARTITION ? MIN_PARTITION : p; |
| 545 |
} |
| 546 |
|
| 547 |
/** Subtask constructor */ |
| 548 |
IntCumulateTask(IntCumulateTask parent, IntBinaryOperator function, |
| 549 |
int[] array, int origin, int fence, int threshold, |
| 550 |
int lo, int hi) { |
| 551 |
super(parent); |
| 552 |
this.function = function; this.array = array; |
| 553 |
this.origin = origin; this.fence = fence; |
| 554 |
this.threshold = threshold; |
| 555 |
this.lo = lo; this.hi = hi; |
| 556 |
} |
| 557 |
|
| 558 |
public final void compute() { |
| 559 |
final IntBinaryOperator fn; |
| 560 |
final int[] a; |
| 561 |
if ((fn = this.function) == null || (a = this.array) == null) |
| 562 |
throw new NullPointerException(); // hoist checks |
| 563 |
int th = threshold, org = origin, fnc = fence, l, h; |
| 564 |
IntCumulateTask t = this; |
| 565 |
outer: while ((l = t.lo) >= 0 && (h = t.hi) <= a.length) { |
| 566 |
if (h - l > th) { |
| 567 |
IntCumulateTask lt = t.left, rt = t.right, f; |
| 568 |
if (lt == null) { // first pass |
| 569 |
int mid = (l + h) >>> 1; |
| 570 |
f = rt = t.right = |
| 571 |
new IntCumulateTask(t, fn, a, org, fnc, th, mid, h); |
| 572 |
t = lt = t.left = |
| 573 |
new IntCumulateTask(t, fn, a, org, fnc, th, l, mid); |
| 574 |
} |
| 575 |
else { // possibly refork |
| 576 |
int pin = t.in; |
| 577 |
lt.in = pin; |
| 578 |
f = t = null; |
| 579 |
if (rt != null) { |
| 580 |
int lout = lt.out; |
| 581 |
rt.in = (l == org ? lout : |
| 582 |
fn.applyAsInt(pin, lout)); |
| 583 |
for (int c;;) { |
| 584 |
if (((c = rt.getPendingCount()) & CUMULATE) != 0) |
| 585 |
break; |
| 586 |
if (rt.compareAndSetPendingCount(c, c|CUMULATE)){ |
| 587 |
t = rt; |
| 588 |
break; |
| 589 |
} |
| 590 |
} |
| 591 |
} |
| 592 |
for (int c;;) { |
| 593 |
if (((c = lt.getPendingCount()) & CUMULATE) != 0) |
| 594 |
break; |
| 595 |
if (lt.compareAndSetPendingCount(c, c|CUMULATE)) { |
| 596 |
if (t != null) |
| 597 |
f = t; |
| 598 |
t = lt; |
| 599 |
break; |
| 600 |
} |
| 601 |
} |
| 602 |
if (t == null) |
| 603 |
break; |
| 604 |
} |
| 605 |
if (f != null) |
| 606 |
f.fork(); |
| 607 |
} |
| 608 |
else { |
| 609 |
int state; // Transition to sum, cumulate, or both |
| 610 |
for (int b;;) { |
| 611 |
if (((b = t.getPendingCount()) & FINISHED) != 0) |
| 612 |
break outer; // already done |
| 613 |
state = ((b & CUMULATE) != 0 ? FINISHED : |
| 614 |
(l > org) ? SUMMED : (SUMMED|FINISHED)); |
| 615 |
if (t.compareAndSetPendingCount(b, b|state)) |
| 616 |
break; |
| 617 |
} |
| 618 |
|
| 619 |
int sum; |
| 620 |
if (state != SUMMED) { |
| 621 |
int first; |
| 622 |
if (l == org) { // leftmost; no in |
| 623 |
sum = a[org]; |
| 624 |
first = org + 1; |
| 625 |
} |
| 626 |
else { |
| 627 |
sum = t.in; |
| 628 |
first = l; |
| 629 |
} |
| 630 |
for (int i = first; i < h; ++i) // cumulate |
| 631 |
a[i] = sum = fn.applyAsInt(sum, a[i]); |
| 632 |
} |
| 633 |
else if (h < fnc) { // skip rightmost |
| 634 |
sum = a[l]; |
| 635 |
for (int i = l + 1; i < h; ++i) // sum only |
| 636 |
sum = fn.applyAsInt(sum, a[i]); |
| 637 |
} |
| 638 |
else |
| 639 |
sum = t.in; |
| 640 |
t.out = sum; |
| 641 |
for (IntCumulateTask par;;) { // propagate |
| 642 |
if ((par = (IntCumulateTask)t.getCompleter()) == null) { |
| 643 |
if ((state & FINISHED) != 0) // enable join |
| 644 |
t.quietlyComplete(); |
| 645 |
break outer; |
| 646 |
} |
| 647 |
int b = par.getPendingCount(); |
| 648 |
if ((b & state & FINISHED) != 0) |
| 649 |
t = par; // both done |
| 650 |
else if ((b & state & SUMMED) != 0) { // both summed |
| 651 |
int nextState; IntCumulateTask lt, rt; |
| 652 |
if ((lt = par.left) != null && |
| 653 |
(rt = par.right) != null) { |
| 654 |
int lout = lt.out; |
| 655 |
par.out = (rt.hi == fnc ? lout : |
| 656 |
fn.applyAsInt(lout, rt.out)); |
| 657 |
} |
| 658 |
int refork = (((b & CUMULATE) == 0 && |
| 659 |
par.lo == org) ? CUMULATE : 0); |
| 660 |
if ((nextState = b|state|refork) == b || |
| 661 |
par.compareAndSetPendingCount(b, nextState)) { |
| 662 |
state = SUMMED; // drop finished |
| 663 |
t = par; |
| 664 |
if (refork != 0) |
| 665 |
par.fork(); |
| 666 |
} |
| 667 |
} |
| 668 |
else if (par.compareAndSetPendingCount(b, b|state)) |
| 669 |
break outer; // sib not ready |
| 670 |
} |
| 671 |
} |
| 672 |
} |
| 673 |
} |
| 674 |
private static final long serialVersionUID = 3731755594596840961L; |
| 675 |
} |
| 676 |
|
| 677 |
} |
