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*
* This code is free software; you can redistribute it and/or modify it
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* published by the Free Software Foundation.
*
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
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* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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/*
* This file is available under and governed by the GNU General Public
* License version 2 only, as published by the Free Software Foundation.
* However, the following notice accompanied the original version of this
* file:
*
* 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/
*/
/*
* @test
* @bug 6865571
* @summary Numerical Integration using fork/join
* @run main Integrate reps=1 forkPolicy=dynamic
* @run main Integrate reps=1 forkPolicy=serial
* @run main Integrate reps=1 forkPolicy=fork
*/
import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.RecursiveAction;
/**
* Sample program using Gaussian Quadrature for numerical integration.
* This version uses a simplified hardwired function. Inspired by a
* <A href="http://www.cs.uga.edu/~dkl/filaments/dist.html">
* Filaments</A> demo program.
*/
public final class Integrate {
static final double errorTolerance = 1.0e-11;
/** for time conversion */
static final long NPS = (1000L * 1000 * 1000);
static final int SERIAL = -1;
static final int DYNAMIC = 0;
static final int FORK = 1;
/** the function to integrate */
static double computeFunction(double x) {
return (x * x + 1.0) * x;
}
static final double start = 0.0;
static final double end = 1536.0;
/**
* The number of recursive calls for
* integrate from start to end.
* (Empirically determined)
*/
static final int calls = 263479047;
static String keywordValue(String[] args, String keyword) {
for (String arg : args)
if (arg.startsWith(keyword))
return arg.substring(keyword.length() + 1);
return null;
}
static int intArg(String[] args, String keyword, int defaultValue) {
String val = keywordValue(args, keyword);
return (val == null) ? defaultValue : Integer.parseInt(val);
}
static int policyArg(String[] args, String keyword, int defaultPolicy) {
String val = keywordValue(args, keyword);
if (val == null) return defaultPolicy;
if (val.equals("dynamic")) return DYNAMIC;
if (val.equals("serial")) return SERIAL;
if (val.equals("fork")) return FORK;
throw new Error();
}
/**
* Usage: Integrate [procs=N] [reps=N] forkPolicy=serial|dynamic|fork
*/
public static void main(String[] args) throws Exception {
final int procs = intArg(args, "procs",
Runtime.getRuntime().availableProcessors());
final int forkPolicy = policyArg(args, "forkPolicy", DYNAMIC);
ForkJoinPool g = new ForkJoinPool(procs);
System.out.println("Integrating from " + start + " to " + end +
" forkPolicy = " + forkPolicy);
long lastTime = System.nanoTime();
for (int reps = intArg(args, "reps", 10); reps > 0; reps--) {
double a;
if (forkPolicy == SERIAL)
a = SQuad.computeArea(g, start, end);
else if (forkPolicy == FORK)
a = FQuad.computeArea(g, start, end);
else
a = DQuad.computeArea(g, start, end);
long now = System.nanoTime();
double s = (double) (now - lastTime) / NPS;
lastTime = now;
System.out.printf("Calls/sec: %12d", (long) (calls / s));
System.out.printf(" Time: %7.3f", s);
System.out.printf(" Area: %12.1f", a);
System.out.println();
}
System.out.println(g);
g.shutdown();
}
// Sequential version
static final class SQuad extends RecursiveAction {
static double computeArea(ForkJoinPool pool, double l, double r) {
SQuad q = new SQuad(l, r, 0);
pool.invoke(q);
return q.area;
}
final double left; // lower bound
final double right; // upper bound
double area;
SQuad(double l, double r, double a) {
this.left = l; this.right = r; this.area = a;
}
public final void compute() {
double l = left;
double r = right;
area = recEval(l, r, (l * l + 1.0) * l, (r * r + 1.0) * r, area);
}
static final double recEval(double l, double r, double fl,
double fr, double a) {
double h = (r - l) * 0.5;
double c = l + h;
double fc = (c * c + 1.0) * c;
double hh = h * 0.5;
double al = (fl + fc) * hh;
double ar = (fr + fc) * hh;
double alr = al + ar;
if (Math.abs(alr - a) <= errorTolerance)
return alr;
else
return recEval(c, r, fc, fr, ar) + recEval(l, c, fl, fc, al);
}
}
//....................................
// ForkJoin version
static final class FQuad extends RecursiveAction {
static double computeArea(ForkJoinPool pool, double l, double r) {
FQuad q = new FQuad(l, r, 0);
pool.invoke(q);
return q.area;
}
final double left; // lower bound
final double right; // upper bound
double area;
FQuad(double l, double r, double a) {
this.left = l; this.right = r; this.area = a;
}
public final void compute() {
double l = left;
double r = right;
area = recEval(l, r, (l * l + 1.0) * l, (r * r + 1.0) * r, area);
}
static final double recEval(double l, double r, double fl,
double fr, double a) {
double h = (r - l) * 0.5;
double c = l + h;
double fc = (c * c + 1.0) * c;
double hh = h * 0.5;
double al = (fl + fc) * hh;
double ar = (fr + fc) * hh;
double alr = al + ar;
if (Math.abs(alr - a) <= errorTolerance)
return alr;
FQuad q = new FQuad(l, c, al);
q.fork();
ar = recEval(c, r, fc, fr, ar);
if (!q.tryUnfork()) {
q.quietlyJoin();
return ar + q.area;
}
return ar + recEval(l, c, fl, fc, al);
}
}
// ...........................
// Version using on-demand Fork
static final class DQuad extends RecursiveAction {
static double computeArea(ForkJoinPool pool, double l, double r) {
DQuad q = new DQuad(l, r, 0);
pool.invoke(q);
return q.area;
}
final double left; // lower bound
final double right; // upper bound
double area;
DQuad(double l, double r, double a) {
this.left = l; this.right = r; this.area = a;
}
public final void compute() {
double l = left;
double r = right;
area = recEval(l, r, (l * l + 1.0) * l, (r * r + 1.0) * r, area);
}
static final double recEval(double l, double r, double fl,
double fr, double a) {
double h = (r - l) * 0.5;
double c = l + h;
double fc = (c * c + 1.0) * c;
double hh = h * 0.5;
double al = (fl + fc) * hh;
double ar = (fr + fc) * hh;
double alr = al + ar;
if (Math.abs(alr - a) <= errorTolerance)
return alr;
DQuad q = null;
if (getSurplusQueuedTaskCount() <= 3)
(q = new DQuad(l, c, al)).fork();
ar = recEval(c, r, fc, fr, ar);
if (q != null && !q.tryUnfork()) {
q.quietlyJoin();
return ar + q.area;
}
return ar + recEval(l, c, fl, fc, al);
}
}
}