Benchmark.java
/*
* Janino - An embedded Java[TM] compiler
*
* Copyright (c) 2001-2010 Arno Unkrig. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification, are permitted provided that the
* following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the
* following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the
* following disclaimer in the documentation and/or other materials provided with the distribution.
* 3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote
* products derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package org.codehaus.commons.compiler.util;
import java.util.Stack;
import org.codehaus.commons.nullanalysis.Nullable;
/**
* Implements a scheme for benchmarking, i.e. for determining and/or reporting the time elapsed between the beginning
* and the end of an activity.
* <p>
* The measurement is done by invoking {@link #begin()} and later calling {@link #end()} whichs returns the time
* elapsed since the call to {@link #begin()}.
* </p>
* <p>
* Notice that calls to {@link #begin()} and {@link #end()} can be nested, and each call to {@link #end()} refers to
* the matching {@link #begin()} call. To ensure that all calls match, the preferred way to write a benchmark is
* </p>
* <pre>
* ...
* Benchmark b = new Benchmark();
* ...
* b.begin();
* try {
* ....
* } finally {
* long ms = b.end();
* }
* </pre>
* <p>
* This code layout also makes it visually easy to write correct pairs of {@link #begin()} / {@link #end()} pairs.
* </p>
* <p>
* The pair {@link #beginReporting()} and {@link #endReporting()} do basically the same, but report the benchmarking
* information through an internal {@link Reporter} object. The default {@link Reporter} prints its messages by
* {@code System.out.println()}.
* </p>
* <p>
* Reporting is only enabled if the Benchmark object was created through {@link #Benchmark(boolean)} with a {@code
* true} argument.
* </p>
*/
public
class Benchmark {
private final Stack<Long> beginTimes = new Stack<>();
/**
* @see Benchmark
*/
public void
begin() { this.beginTimes.push(Long.valueOf(System.currentTimeMillis())); }
/**
* @see Benchmark
*/
public long
end() { return System.currentTimeMillis() - ((Long) this.beginTimes.pop()).longValue(); }
// Reporting-related methods and fields.
/**
* Sets up a {@link Benchmark} with a default {@link Reporter} that reports to {@code System.out}.
*/
public
Benchmark(boolean reportingEnabled) {
this.reportingEnabled = reportingEnabled;
this.reporter = new Reporter() {
@Override public void report(String message) { System.out.println(message); }
};
}
/**
* Sets up a {@link Benchmark} with a custom {@link Reporter}.
*/
public
Benchmark(boolean reportingEnabled, Reporter reporter) {
this.reportingEnabled = reportingEnabled;
this.reporter = reporter;
}
private final boolean reportingEnabled;
private final Reporter reporter;
/**
* Interface used to report messages.
*/
public
interface Reporter {
/**
* Reports the given <var>message</var>.
*/
void report(String message);
}
/**
* Begins a benchmark (see {@link #begin()}) and report the fact.
*/
public void
beginReporting() {
if (!this.reportingEnabled) return;
this.reportIndented("Beginning...");
this.begin();
}
/**
* Begins a benchmark (see {@link #begin()}) and report the fact.
*/
public void
beginReporting(String message) {
if (!this.reportingEnabled) return;
this.reportIndented(message + "...");
this.begin();
}
/**
* End a benchmark (see {@link #end()}) and report the fact.
*/
public void
endReporting() {
if (!this.reportingEnabled) return;
this.reportIndented("... took " + this.end() + " ms");
}
/**
* Ends a benchmark (see {@link #begin()}) and report the fact.
*/
public void
endReporting(String message) {
if (!this.reportingEnabled) return;
this.reportIndented("... took " + this.end() + " ms: " + message);
}
/**
* Reports the given message.
*/
public void
report(String message) {
if (!this.reportingEnabled) return;
this.reportIndented(message);
}
/**
* Reports the {@code title}, a colon, a space, and the pretty-printed {@link Object}.
*/
public void
report(@Nullable String title, @Nullable Object o) {
if (!this.reportingEnabled) return;
String prefix = title == null ? "" : (
title
+ ": "
+ (title.length() < Benchmark.PAD.length() ? Benchmark.PAD.substring(title.length()) : "")
);
if (o == null) {
this.reportIndented(prefix + "(undefined)");
} else
if (o.getClass().isArray()) {
Object[] oa = (Object[]) o;
if (oa.length == 0) {
this.reportIndented(prefix + "(empty)");
} else
if (oa.length == 1) {
this.reportIndented(prefix + oa[0].toString());
} else {
this.reportIndented(title == null ? "Array:" : title + ':');
this.begin();
try {
for (Object o2 : oa) this.report(null, o2);
} finally {
this.end();
}
}
} else
{
this.reportIndented(prefix + o.toString());
}
}
private static final String PAD = " ";
/**
* Reports a message through {@link #reporter}, indent by N spaces where N is the current benchmark stack depth.
*/
private void
reportIndented(String message) {
StringBuilder sb = new StringBuilder();
for (int i = this.beginTimes.size(); i > 0; --i) sb.append(" ");
sb.append(message);
this.reporter.report(sb.toString());
}
}