com.facebook.presto.jdbc.internal.jol.info.ClassLayout Maven / Gradle / Ivy
/*
* Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* 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).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package com.facebook.presto.jdbc.internal.jol.info;
import com.facebook.presto.jdbc.internal.jol.layouters.CurrentLayouter;
import com.facebook.presto.jdbc.internal.jol.layouters.Layouter;
import com.facebook.presto.jdbc.internal.jol.util.VMSupport;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.util.SortedSet;
/**
* Handles the class data *with* the layout information.
*/
public class ClassLayout {
/**
* Produce the class layout for the given class.
* This produces the layout for the current VM.
*
* @param klass class to work on
* @return class layout
*/
public static ClassLayout parseClass(Class klass) {
return parseClass(klass, new CurrentLayouter());
}
/**
* Produce the class layout for the given class, and given layouter.
*
* @param klass class to work on
* @param layouter class layouter
* @return class layout
*/
public static ClassLayout parseClass(Class klass, Layouter layouter) {
return layouter.layout(ClassData.parseClass(klass));
}
private final ClassData classData;
private final SortedSet fields;
private final int headerSize;
private final int size;
/**
* Builds the class layout.
*
* @param classData class data
* @param fields field layouts
* @param headerSize header size
* @param instanceSize instance size
* @param check whether to check important invariants
*/
public ClassLayout(ClassData classData, SortedSet fields, int headerSize, int instanceSize, boolean check) {
this.classData = classData;
this.fields = fields;
this.headerSize = headerSize;
this.size = instanceSize;
if (check) {
checkInvariants();
}
}
private void checkInvariants() {
long lastOffset = 0;
for (FieldLayout f : fields) {
if (f.offset() % f.size() != 0) {
throw new IllegalStateException("Field " + f + " is not aligned");
}
if (f.offset() + f.size() > instanceSize()) {
throw new IllegalStateException("Field " + f + " is overflowing the object of size " + instanceSize());
}
if (f.offset() < lastOffset) {
throw new IllegalStateException("Field " + f + " overlaps with the previous field");
}
lastOffset = f.offset() + f.size();
}
}
/**
* Answer the set of fields, including those in superclasses
*
* @return sorted set of fields
*/
public SortedSet fields() {
return fields;
}
/**
* Answer instance size
*
* @return instance size
*/
public int instanceSize() {
return size;
}
/**
* Answer header size
*
* @return header size
*/
public int headerSize() {
return headerSize;
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
for (FieldLayout f : fields()) {
sb.append(f).append("\n");
}
sb.append("size = ").append(size).append("\n");
return sb.toString();
}
/**
* Produce printable stringly representation of class layout.
* This method does not require alive instance, just the class.
*
* @return human-readable layout info
*/
public String toPrintable() {
return toPrintable(null);
}
/**
* Produce printable stringly representation of class layout.
* This method accepts instance to read the actual data from.
*
* @param instance instance to work on
* @return human-readable layout info
*/
public String toPrintable(Object instance) {
StringWriter sw = new StringWriter();
PrintWriter pw = new PrintWriter(sw);
int maxTypeLen = 5;
for (FieldLayout f : fields()) {
maxTypeLen = Math.max(f.typeClass().length(), maxTypeLen);
}
int maxDescrLen = 30;
for (FieldLayout f : fields()) {
maxDescrLen = Math.max((f.hostClass() + "" + f.name()).length(), maxDescrLen);
}
pw.println(classData.name() + " object internals:");
pw.printf(" %6s %5s %" + maxTypeLen + "s %-" + maxDescrLen + "s %s%n", "OFFSET", "SIZE", "TYPE", "DESCRIPTION", "VALUE");
if (instance != null) {
for (long off = 0; off < headerSize(); off += 4) {
pw.printf(" %6d %5d %" + maxTypeLen + "s %-" + maxDescrLen + "s %s%n", off, 4, "", "(object header)",
toHex(VMSupport.U.getByte(instance, off + 0) & 0xFF) + " " +
toHex(VMSupport.U.getByte(instance, off + 1) & 0xFF) + " " +
toHex(VMSupport.U.getByte(instance, off + 2) & 0xFF) + " " +
toHex(VMSupport.U.getByte(instance, off + 3) & 0xFF) + " " +
"(" +
toBinary(VMSupport.U.getByte(instance, off + 0) & 0xFF) + " " +
toBinary(VMSupport.U.getByte(instance, off + 1) & 0xFF) + " " +
toBinary(VMSupport.U.getByte(instance, off + 2) & 0xFF) + " " +
toBinary(VMSupport.U.getByte(instance, off + 3) & 0xFF) + ")"
);
}
} else {
pw.printf(" %6d %5d %" + maxTypeLen + "s %-" + maxDescrLen + "s %s%n", 0, headerSize(), "", "(object header)", "N/A");
}
int nextFree = headerSize();
int interLoss = 0;
int exterLoss = 0;
for (FieldLayout f : fields()) {
if (f.offset() > nextFree) {
pw.printf(" %6d %5d %" + maxTypeLen + "s %-" + maxDescrLen + "s %s%n", nextFree, (f.offset() - nextFree), "", "(alignment/padding gap)", "N/A");
interLoss += (f.offset() - nextFree);
}
pw.printf(" %6d %5d %" + maxTypeLen + "s %-" + maxDescrLen + "s %s%n",
f.offset(),
f.size(),
f.typeClass(),
f.hostClass() + "." + f.name(),
(instance != null) ? f.safeValue(instance) : "N/A"
);
nextFree = f.offset() + f.size();
}
VMSupport.SizeInfo info = VMSupport.tryExactObjectSize(instance, this);
if (info.instanceSize() != nextFree) {
exterLoss = info.instanceSize() - nextFree;
pw.printf(" %6d %5s %" + maxTypeLen + "s %s%n", nextFree, exterLoss, "", "(loss due to the next object alignment)");
}
if (info.exactSize()) {
pw.printf("Instance size: %d bytes (reported by VM agent)%n", info.instanceSize());
} else {
if (instance != null) {
pw.printf("Instance size: %d bytes (estimated, add this JAR via -javaagent: to get accurate result)%n", info.instanceSize());
} else {
pw.printf("Instance size: %d bytes (estimated, the sample instance is not available)%n", info.instanceSize());
}
}
pw.printf("Space losses: %d bytes internal + %d bytes external = %d bytes total%n", interLoss, exterLoss, interLoss + exterLoss);
pw.close();
return sw.toString();
}
// very ineffective, so what?
private static String toBinary(int x) {
String s = Integer.toBinaryString(x);
int deficit = 8 - s.length();
for (int c = 0; c < deficit; c++) {
s = "0" + s;
}
return s.substring(0, 4) + " " + s.substring(4);
}
// very ineffective, so what?
private static String toHex(int x) {
String s = Integer.toHexString(x);
int deficit = 2 - s.length();
for (int c = 0; c < deficit; c++) {
s = "0" + s;
}
return s;
}
}
© 2015 - 2024 Weber Informatics LLC | Privacy Policy