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 * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * 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
 * accompanied this code).
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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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package org.graalvm.compiler.debug.internal;

import java.io.PrintStream;
import java.util.Arrays;
import java.util.List;

import org.graalvm.compiler.debug.DebugHistogram;
import org.graalvm.compiler.debug.DebugHistogram.CountedValue;
import org.graalvm.compiler.debug.DebugHistogram.Printer;

Renders a textual representation of a histogram to a given print stream.
/** * Renders a textual representation of a histogram to a given print stream. */
public class DebugHistogramAsciiPrinter implements Printer { public static final int NumberSize = 10; public static final int DefaultNameSize = 50; public static final int DefaultBarSize = 100; public static final int DefaultScale = 1; private final PrintStream os; private final int limit; private final int nameSize; private final int barSize; private final int scale; public DebugHistogramAsciiPrinter(PrintStream os) { this(os, Integer.MAX_VALUE, DefaultNameSize, DefaultBarSize, DefaultScale); }
Params:
  • os – where to print
  • limit – limits printing to the limit most frequent values
  • nameSize – the width of the value names column
  • barSize – the width of the value frequency column
  • scale – a factor by which every result is divided
/** * @param os where to print * @param limit limits printing to the {@code limit} most frequent values * @param nameSize the width of the value names column * @param barSize the width of the value frequency column * @param scale a factor by which every result is divided */
public DebugHistogramAsciiPrinter(PrintStream os, int limit, int nameSize, int barSize, int scale) { this.os = os; this.limit = limit; this.nameSize = nameSize; this.barSize = barSize; this.scale = scale; } @Override public void print(DebugHistogram histogram) { List<CountedValue> list = histogram.getValues(); if (list.isEmpty()) { os.printf("%s is empty.%n", histogram.getName()); return; } // Sum up the total number of elements. long total = list.stream().mapToLong(CountedValue::getCount).sum(); // Print header. os.printf("%s has %d unique elements and %d total elements:%n", histogram.getName(), list.size(), total / scale); long max = list.get(0).getCount() / scale; final int lineSize = nameSize + NumberSize + barSize + 10; printLine(os, '-', lineSize); String formatString = "| %-" + nameSize + "s | %-" + NumberSize + "d | %-" + barSize + "s |\n"; for (int i = 0; i < list.size() && i < limit; ++i) { CountedValue cv = list.get(i); long value = cv.getCount() / scale; char[] bar = new char[(int) (((double) value / (double) max) * barSize)]; Arrays.fill(bar, '='); String objectString = String.valueOf(cv.getValue()); if (objectString.length() > nameSize) { objectString = objectString.substring(0, nameSize - 3) + "..."; } os.printf(formatString, objectString, value, new String(bar)); } printLine(os, '-', lineSize); } private static void printLine(PrintStream printStream, char c, int lineSize) { char[] charArr = new char[lineSize]; Arrays.fill(charArr, c); printStream.printf("%s%n", new String(charArr)); } }