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@cberzan
Created Jun 3, 2014
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benchmark cost of checking boolean flags on every call
import java.util.Random;
public class Benchmark {
public Benchmark() {
rng = new Random();
hasLower = false;
hasUpper = false;
}
public void setParams(Double lower, Double upper) {
if (lower != null) {
this.lower = lower;
this.hasLower = true;
}
if (upper != null) {
this.upper = upper;
this.hasUpper = true;
}
if (this.hasLower && this.hasUpper && this.lower >= this.upper) {
throw new IllegalArgumentException("lower >= upper");
}
}
private void checkHasParams() {
if (!hasLower) {
throw new IllegalArgumentException("lower not provided");
}
if (!hasUpper) {
throw new IllegalArgumentException("upper not provided");
}
}
public double sampleWithoutCheck() {
return lower + (rng.nextDouble() * (upper - lower));
}
public double sampleWithCheck() {
checkHasParams();
return lower + (rng.nextDouble() * (upper - lower));
}
public double getLogProbWithCheck(double value) {
checkHasParams();
if ((value >= lower) && (value < upper)) {
return Math.log(1.0 / (upper - lower));
} else {
return Double.NEGATIVE_INFINITY;
}
}
public double getLogProbWithoutCheck(double value) {
if ((value >= lower) && (value < upper)) {
return Math.log(1.0 / (upper - lower));
} else {
return Double.NEGATIVE_INFINITY;
}
}
private Random rng;
private boolean hasLower;
private boolean hasUpper;
private double lower;
private double upper;
/////////////////////////////////////////////////////////////////////////////
public static void main(String[] args) {
Benchmark b = new Benchmark();
b.setParams(5.0, 6.0);
// Warm up the jit.
final int numWarmupTrials = 1000000;
for (int i = 0; i < numWarmupTrials; i++) {
b.sampleWithoutCheck();
b.sampleWithCheck();
b.getLogProbWithoutCheck(5.5);
b.getLogProbWithCheck(5.5);
}
// Now benchmark.
final int numTrials = 10000000;
long sampleWithoutCheckNanos = System.nanoTime();
for (int i = 0; i < numTrials; i++) {
b.sampleWithoutCheck();
}
sampleWithoutCheckNanos = System.nanoTime() - sampleWithoutCheckNanos;
System.out.println("sampleWithoutCheck: " +
sampleWithoutCheckNanos / 1e9 / numTrials + " seconds");
long sampleWithCheckNanos = System.nanoTime();
for (int i = 0; i < numTrials; i++) {
b.sampleWithCheck();
}
sampleWithCheckNanos = System.nanoTime() - sampleWithCheckNanos;
System.out.println("sampleWithCheck: " +
sampleWithCheckNanos / 1e9 / numTrials + " seconds");
long getLogProbWithoutCheckNanos = System.nanoTime();
for (int i = 0; i < numTrials; i++) {
b.getLogProbWithoutCheck(5.5);
}
getLogProbWithoutCheckNanos = System.nanoTime() - getLogProbWithoutCheckNanos;
System.out.println("getLogProbWithoutCheck: " +
getLogProbWithoutCheckNanos / 1e9 / numTrials + " seconds");
long getLogProbWithCheckNanos = System.nanoTime();
for (int i = 0; i < numTrials; i++) {
b.getLogProbWithCheck(5.5);
}
getLogProbWithCheckNanos = System.nanoTime() - getLogProbWithCheckNanos;
System.out.println("getLogProbWithCheck: " +
getLogProbWithCheckNanos / 1e9 / numTrials + " seconds");
}
}
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