com.facebook.presto.jdbc.internal.jol.util.VMSupport Maven / Gradle / Ivy
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* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
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*
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* 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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package com.facebook.presto.jdbc.internal.jol.util;
import com.facebook.presto.jdbc.internal.jol.info.ClassData;
import com.facebook.presto.jdbc.internal.jol.info.ClassLayout;
import com.facebook.presto.jdbc.internal.jol.layouters.CurrentLayouter;
import sun.misc.Unsafe;
import javax.management.MBeanServer;
import javax.management.ObjectName;
import javax.management.RuntimeMBeanException;
import javax.management.openmbean.CompositeDataSupport;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.lang.instrument.Instrumentation;
import java.lang.management.ManagementFactory;
import java.lang.reflect.Field;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.Arrays;
import java.util.Random;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
* VM support doorway.
* Contains all the special tricks and methods to poll VM about it's secrets.
*
* @author Aleksey Shipilev
*/
public class VMSupport {
private static Instrumentation INSTRUMENTATION;
public static final Unsafe U;
public static final String VM_NAME;
public static final int ADDRESS_SIZE;
public static final int OBJ_ALIGNMENT;
public static final int OBJ_HEADER_SIZE;
public static final boolean USE_COMPRESSED_REFS;
public static final int COMPRESSED_REF_SHIFT;
public static final int REF_SIZE;
public static final int BOOLEAN_SIZE;
public static final int BYTE_SIZE;
public static final int CHAR_SIZE;
public static final int DOUBLE_SIZE;
public static final int FLOAT_SIZE;
public static final int INT_SIZE;
public static final int LONG_SIZE;
public static final int SHORT_SIZE;
private static final ThreadLocal BUFFERS;
private static final long OBJECT_ARRAY_BASE;
static {
U = AccessController.doPrivileged(
new PrivilegedAction() {
public Unsafe run() {
try {
Field unsafe = Unsafe.class.getDeclaredField("theUnsafe");
unsafe.setAccessible(true);
return (Unsafe) unsafe.get(null);
} catch (NoSuchFieldException e) {
throw new IllegalStateException(e);
} catch (IllegalAccessException e) {
throw new IllegalStateException(e);
}
}
}
);
OBJECT_ARRAY_BASE = U.arrayBaseOffset(Object[].class);
BUFFERS = new ThreadLocal() {
@Override
protected Object[] initialValue() {
return new Object[1];
}
};
int headerSize;
try {
long off1 = U.objectFieldOffset(HeaderClass.class.getField("b1"));
headerSize = (int) off1;
} catch (NoSuchFieldException e) {
headerSize = -1;
}
VMOptions opts = VMOptions.getOptions();
ADDRESS_SIZE = U.addressSize();
OBJ_HEADER_SIZE = headerSize;
VM_NAME = opts.name;
USE_COMPRESSED_REFS = opts.compressedRef;
COMPRESSED_REF_SHIFT = opts.compressRefShift;
OBJ_ALIGNMENT = opts.objectAlignment;
REF_SIZE = opts.sizeReference;
BOOLEAN_SIZE = opts.sizeBoolean;
BYTE_SIZE = opts.sizeByte;
CHAR_SIZE = opts.sizeChar;
DOUBLE_SIZE = opts.sizeDouble;
FLOAT_SIZE = opts.sizeFloat;
INT_SIZE = opts.sizeInt;
LONG_SIZE = opts.sizeLong;
SHORT_SIZE = opts.sizeShort;
}
public static long toNativeAddress(long address) {
if (USE_COMPRESSED_REFS) {
return address << COMPRESSED_REF_SHIFT;
} else {
return address;
}
}
public static int align(int addr) {
return align(addr, OBJ_ALIGNMENT);
}
public static int align(int addr, int align) {
if ((addr % align) == 0) {
return addr;
} else {
return ((addr / align) + 1) * align;
}
}
public static String vmDetails() {
StringWriter sw = new StringWriter();
PrintWriter out = new PrintWriter(sw);
out.println("Running " + (ADDRESS_SIZE * 8) + "-bit " + VM_NAME + " VM.");
if (USE_COMPRESSED_REFS)
out.println("Using compressed references with " + COMPRESSED_REF_SHIFT + "-bit shift.");
out.println("Objects are " + OBJ_ALIGNMENT + " bytes aligned.");
out.printf("%-19s: %d, %d, %d, %d, %d, %d, %d, %d, %d [bytes]%n",
"Field sizes by type",
REF_SIZE,
BOOLEAN_SIZE,
BYTE_SIZE,
CHAR_SIZE,
SHORT_SIZE,
INT_SIZE,
FLOAT_SIZE,
LONG_SIZE,
DOUBLE_SIZE
);
out.printf("%-19s: %d, %d, %d, %d, %d, %d, %d, %d, %d [bytes]%n",
"Array element sizes",
U.arrayIndexScale(Object[].class),
U.arrayIndexScale(boolean[].class),
U.arrayIndexScale(byte[].class),
U.arrayIndexScale(char[].class),
U.arrayIndexScale(short[].class),
U.arrayIndexScale(int[].class),
U.arrayIndexScale(float[].class),
U.arrayIndexScale(long[].class),
U.arrayIndexScale(double[].class)
);
out.close();
return sw.toString();
}
private static Object instantiateType(int type) {
switch (type) {
case 0: return new MyObject1();
case 1: return new MyObject2();
case 2: return new MyObject3();
case 3: return new MyObject4();
case 4: return new MyObject5();
default:
throw new IllegalStateException();
}
}
private static int guessAlignment(int oopSize) {
final int COUNT = 100000;
Random r = new Random();
long min = -1;
for (int c = 0; c < COUNT; c++) {
Object o1 = instantiateType(r.nextInt(5));
Object o2 = instantiateType(r.nextInt(5));
long diff = Math.abs(addressOf(o2, oopSize) - addressOf(o1, oopSize));
if (min == -1) {
min = diff;
} else {
min = MathUtil.gcd(min, diff);
}
}
return (int) min;
}
public static long addressOf(Object o) {
return addressOf(o, REF_SIZE);
}
public static long addressOf(Object o, int oopSize) {
Object[] array = BUFFERS.get();
array[0] = o;
long objectAddress;
switch (oopSize) {
case 4:
objectAddress = U.getInt(array, OBJECT_ARRAY_BASE) & 0xFFFFFFFFL;
break;
case 8:
objectAddress = U.getLong(array, OBJECT_ARRAY_BASE);
break;
default:
throw new Error("unsupported address size: " + oopSize);
}
array[0] = null;
return toNativeAddress(objectAddress);
}
public static void premain(String agentArgs, Instrumentation inst) {
INSTRUMENTATION = inst;
}
public static SizeInfo tryExactObjectSize(Object o, ClassLayout layout) {
return new SizeInfo(o, layout);
}
public static class SizeInfo {
private final int size;
private final boolean exactSizeAvail;
public SizeInfo(Object o, ClassLayout layout) {
exactSizeAvail = VMSupport.INSTRUMENTATION != null && o != null;
size = exactSizeAvail ? (int) VMSupport.INSTRUMENTATION.getObjectSize(o) : layout.instanceSize();
}
public int instanceSize() {
return size;
}
public boolean exactSize() {
return exactSizeAvail;
}
}
private static class VMOptions {
private final String name;
private final boolean compressedRef;
private final int compressRefShift;
private final int objectAlignment;
private final int sizeReference;
private final int sizeBoolean = getMinDiff(MyBooleans4.class);
private final int sizeByte = getMinDiff(MyBytes4.class);
private final int sizeShort = getMinDiff(MyShorts4.class);
private final int sizeChar = getMinDiff(MyChars4.class);
private final int sizeFloat = getMinDiff(MyFloats4.class);
private final int sizeInt = getMinDiff(MyInts4.class);
private final int sizeLong = getMinDiff(MyLongs4.class);
private final int sizeDouble = getMinDiff(MyDoubles4.class);
public static int getMinDiff(Class klass) {
try {
int off1 = (int) U.objectFieldOffset(klass.getDeclaredField("f1"));
int off2 = (int) U.objectFieldOffset(klass.getDeclaredField("f2"));
int off3 = (int) U.objectFieldOffset(klass.getDeclaredField("f3"));
int off4 = (int) U.objectFieldOffset(klass.getDeclaredField("f4"));
return MathUtil.minDiff(off1, off2, off3, off4);
} catch (NoSuchFieldException e) {
throw new IllegalStateException("Infrastructure failure, klass = " + klass, e);
}
}
public VMOptions(String name) {
this.name = name;
this.sizeReference = U.addressSize();
this.objectAlignment = guessAlignment(this.sizeReference);
this.compressedRef = false;
this.compressRefShift = 1;
}
public VMOptions(String name, int align) {
this.name = name;
this.sizeReference = 4;
this.objectAlignment = align;
this.compressedRef = true;
this.compressRefShift = MathUtil.log2p(align);
}
public VMOptions(String name, int align, int compRefShift) {
this.name = name;
this.sizeReference = 4;
this.objectAlignment = align;
this.compressedRef = true;
this.compressRefShift = compRefShift;
}
private static VMOptions getOptions() {
// try Hotspot
VMOptions hsOpts = getHotspotSpecifics();
if (hsOpts != null) return hsOpts;
// try JRockit
VMOptions jrOpts = getJRockitSpecifics();
if (jrOpts != null) return jrOpts;
// When running with CompressedOops on 64-bit platform, the address size
// reported by Unsafe is still 8, while the real reference fields are 4 bytes long.
// Try to guess the reference field size with this naive trick.
int oopSize;
try {
long off1 = U.objectFieldOffset(CompressedOopsClass.class.getField("obj1"));
long off2 = U.objectFieldOffset(CompressedOopsClass.class.getField("obj2"));
oopSize = (int) Math.abs(off2 - off1);
} catch (NoSuchFieldException e) {
throw new IllegalStateException("Infrastructure failure", e);
}
if (oopSize != U.addressSize()) {
return new VMOptions("Auto-detected", 3); // assume compressed references have << 3 shift
} else {
return new VMOptions("Auto-detected");
}
}
private static VMOptions getHotspotSpecifics() {
String name = System.getProperty("java.vm.name");
if (!name.contains("HotSpot") && !name.contains("OpenJDK")) {
return null;
}
try {
MBeanServer server = ManagementFactory.getPlatformMBeanServer();
try {
ObjectName mbean = new ObjectName("com.sun.management:type=HotSpotDiagnostic");
CompositeDataSupport compressedOopsValue = (CompositeDataSupport) server.invoke(mbean, "getVMOption", new Object[]{"UseCompressedOops"}, new String[]{"java.lang.String"});
boolean compressedOops = Boolean.valueOf(compressedOopsValue.get("value").toString());
if (compressedOops) {
// if compressed oops are enabled, then this option is also accessible
CompositeDataSupport alignmentValue = (CompositeDataSupport) server.invoke(mbean, "getVMOption", new Object[]{"ObjectAlignmentInBytes"}, new String[]{"java.lang.String"});
int align = Integer.valueOf(alignmentValue.get("value").toString());
return new VMOptions("HotSpot", align);
} else {
return new VMOptions("HotSpot");
}
} catch (RuntimeMBeanException iae) {
return new VMOptions("HotSpot");
}
} catch (RuntimeException re) {
System.err.println("Failed to read HotSpot-specific configuration properly, please report this as the bug");
re.printStackTrace();
return null;
} catch (Exception exp) {
System.err.println("Failed to read HotSpot-specific configuration properly, please report this as the bug");
exp.printStackTrace();
return null;
}
}
private static VMOptions getJRockitSpecifics() {
String name = System.getProperty("java.vm.name");
if (!name.contains("JRockit")) {
return null;
}
try {
MBeanServer server = ManagementFactory.getPlatformMBeanServer();
String str = (String) server.invoke(new ObjectName("oracle.jrockit.management:type=DiagnosticCommand"), "execute", new Object[]{"print_vm_state"}, new String[]{"java.lang.String"});
String[] split = str.split("\n");
for (String s : split) {
if (s.contains("CompRefs")) {
Pattern pattern = Pattern.compile("(.*?)References are compressed, with heap base (.*?) and shift (.*?)\\.");
Matcher matcher = pattern.matcher(s);
if (matcher.matches()) {
return new VMOptions("JRockit (experimental)", 8, Integer.valueOf(matcher.group(3)));
} else {
return new VMOptions("JRockit (experimental)");
}
}
}
return null;
} catch (RuntimeException re) {
System.err.println("Failed to read JRockit-specific configuration properly, please report this as the bug");
re.printStackTrace();
return null;
} catch (Exception exp) {
System.err.println("Failed to read JRockit-specific configuration properly, please report this as the bug");
exp.printStackTrace();
return null;
}
}
}
public static int sizeOf(Object o) {
if (VMSupport.INSTRUMENTATION != null) {
return VMSupport.align((int) VMSupport.INSTRUMENTATION.getObjectSize(o));
}
return new CurrentLayouter().layout(ClassData.parseInstance(o)).instanceSize();
}
/**
* Produces the toString string, only calling toString() on known types,
* which do not mutate the instance.
*
* @param o object to process
* @return toString
*/
public static String safeToString(Object o) {
if (o == null) return "null";
if (o.getClass().isArray()) {
Class type = o.getClass().getComponentType();
if (type == boolean.class) return Arrays.toString((boolean[]) o);
if (type == byte.class) return Arrays.toString((byte[]) o);
if (type == short.class) return Arrays.toString((short[]) o);
if (type == char.class) return Arrays.toString((char[]) o);
if (type == int.class) return Arrays.toString((int[]) o);
if (type == float.class) return Arrays.toString((float[]) o);
if (type == long.class) return Arrays.toString((long[]) o);
if (type == double.class) return Arrays.toString((double[]) o);
Object[] oos = (Object[]) o;
String[] strs = new String[oos.length];
for (int i = 0; i < oos.length; i++) {
strs[i] = (oos[i] == null) ? "null" : safeToString(oos[i]);
}
return Arrays.toString(strs);
}
if (o.getClass().isPrimitive()) return o.toString();
if (o.getClass() == Boolean.class) return o.toString();
if (o.getClass() == Byte.class) return o.toString();
if (o.getClass() == Short.class) return o.toString();
if (o.getClass() == Character.class) return o.toString();
if (o.getClass() == Integer.class) return o.toString();
if (o.getClass() == Float.class) return o.toString();
if (o.getClass() == Long.class) return o.toString();
if (o.getClass() == Double.class) return o.toString();
return "(object)";
}
static class CompressedOopsClass {
public Object obj1;
public Object obj2;
}
static class HeaderClass {
public boolean b1;
}
static class MyObject1 {
}
static class MyObject2 {
private boolean b;
}
static class MyObject3 {
private int i;
}
static class MyObject4 {
private long l;
}
static class MyObject5 {
private Object o;
}
static class MyBooleans4 {
private boolean f1, f2, f3, f4;
}
static class MyBytes4 {
private byte f1, f2, f3, f4;
}
static class MyShorts4 {
private short f1, f2, f3, f4;
}
static class MyChars4 {
private char f1, f2, f3, f4;
}
static class MyInts4 {
private int f1, f2, f3, f4;
}
static class MyFloats4 {
private float f1, f2, f3, f4;
}
static class MyLongs4 {
private long f1, f2, f3, f4;
}
static class MyDoubles4 {
private double f1, f2, f3, f4;
}
}
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