org.petitparser.utils.Profiler Maven / Gradle / Ivy
package org.petitparser.utils;
import org.petitparser.context.Result;
import org.petitparser.parser.Parser;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.function.Consumer;
/**
* Profiles the run-time of parsers.
*/
public class Profiler {
private Profiler() {}
/**
* Returns a parser that calls the provided consumer with a {@link Profile} of
* every parser.
*/
public static Parser on(Parser source, Consumer consumer) {
Map builders = new LinkedHashMap<>();
return Mirror.of(source).transform(parser -> {
ProfileBuilder builder = new ProfileBuilder(parser);
builders.put(parser, builder);
return parser.callCC((continuation, context) -> {
builder.start();
Result result = continuation.apply(context);
builder.stop();
return result;
});
}).callCC((continuation, context) -> {
builders.values().forEach(ProfileBuilder::reset);
Result result = continuation.apply(context);
builders.values().stream().map(ProfileBuilder::build).forEach(consumer);
return result;
});
}
/**
* The profile information about a parser.
*/
public static class Profile {
/**
* The parser being profiled.
*/
public final Parser parser;
/**
* The number of times the parser got activated on the top-level.
*/
public final int activationCount;
/**
* The number of times the parser got activated in total (including nested
* calls).
*/
public final int totalActivationCount;
/**
* The total time this parser or any of its children has been active.
*/
public final long elapsedNanoseconds;
private Profile(
Parser parser, int activationCount, int totalActivationCount,
long elapsedNanoseconds) {
this.parser = parser;
this.activationCount = activationCount;
this.totalActivationCount = totalActivationCount;
this.elapsedNanoseconds = elapsedNanoseconds;
}
@Override
public String toString() {
return activationCount + "\t" + totalActivationCount + "\t" +
elapsedNanoseconds + "\t" + parser;
}
}
/**
* Internal builder for profile information.
*/
private static class ProfileBuilder {
private final Parser parser;
private int activationCount;
private int totalActivationCount;
private long elapsedNanoseconds;
private int nestingLevel;
private long startTime;
private ProfileBuilder(Parser parser) {
this.parser = parser;
}
private void reset() {
activationCount = 0;
totalActivationCount = 0;
elapsedNanoseconds = 0;
nestingLevel = 0;
startTime = 0;
}
private void start() {
nestingLevel++;
totalActivationCount++;
if (nestingLevel == 1) {
activationCount++;
startTime = System.nanoTime();
}
}
private void stop() {
if (nestingLevel == 1) {
elapsedNanoseconds += System.nanoTime() - startTime;
}
nestingLevel--;
}
private Profile build() {
return new Profile(parser, activationCount, totalActivationCount,
elapsedNanoseconds);
}
}
}