package com.carrotsearch.sizeof;
import java.lang.reflect.Field;
import java.nio.ByteOrder;
import java.util.Locale;
import java.util.Map;
import java.util.TreeMap;
import sun.misc.Unsafe;
/**
* This class contains black magic stuff based mostly on proprietary
* APIs and hacks. Use at your own risk.
*/
@SuppressWarnings({"restriction"})
public final class BlackMagic {
/**
* Returns Unsafe if available or throw a RuntimeException.
*/
public static sun.misc.Unsafe getUnsafe() {
try {
final Class<?> unsafeClass = Class.forName("sun.misc.Unsafe");
final Field unsafeField = unsafeClass.getDeclaredField("theUnsafe");
unsafeField.setAccessible(true);
return (sun.misc.Unsafe) unsafeField.get(null);
} catch (Throwable t) {
throw new RuntimeException("Unsafe not available.", t);
}
}
/**
* Attempts to dump physical object's memory as a string.
*/
public static String objectMemoryAsString(Object o) {
final Unsafe unsafe = getUnsafe();
final ByteOrder byteOrder = ByteOrder.nativeOrder();
StringBuilder b = new StringBuilder();
final int obSize = (int) RamUsageEstimator.shallowSizeOf(o);
for (int i = 0; i < obSize; i += 2) {
if ((i & 0xf) == 0) {
if (i > 0) b.append("\n");
b.append(String.format(Locale.ENGLISH, "%#06x", i));
}
// we go short by short because J9 fails on odd addresses (everything is aligned,
// including byte fields.
int shortValue = unsafe.getShort(o, (long) i);
if (byteOrder == ByteOrder.BIG_ENDIAN) {
b.append(String.format(Locale.ENGLISH, " %02x", (shortValue >>> 8) & 0xff));
b.append(String.format(Locale.ENGLISH, " %02x", (shortValue & 0xff)));
} else {
b.append(String.format(Locale.ENGLISH, " %02x", (shortValue & 0xff)));
b.append(String.format(Locale.ENGLISH, " %02x", (shortValue >>> 8) & 0xff));
}
}
return b.toString();
}
/**
* Attempts to dump a layout of a class's fields in memory
* (offsets from base object pointer).
*/
@SuppressWarnings({"unchecked"})
public static String fieldsLayoutAsString(Class<?> clazz) {
Unsafe unsafe = getUnsafe();
TreeMap<Long, String> fields = new TreeMap<Long, String>();
for (Class<?> c = clazz; c != null; c = c.getSuperclass()) {
for (Field f : c.getDeclaredFields()) {
fields.put(
unsafe.objectFieldOffset(f),
f.getDeclaringClass().getSimpleName() + "." + f.getName());
}
}
fields.put(
RamUsageEstimator.shallowSizeOfInstance(clazz), "#shallowSizeOfInstance(" + clazz.getName() + ")");
StringBuilder b = new StringBuilder();
Object [] entries = fields.entrySet().toArray();
for (int i = 0; i < entries.length; i++) {
Map.Entry<Long, String> e = (Map.Entry<Long, String>) entries[i];
Map.Entry<Long, String> next = (i + 1 < entries.length ? (Map.Entry<Long, String>) entries[i + 1] : null);
b.append(String.format(Locale.ENGLISH,
"@%02d %2s %s\n",
e.getKey(),
next == null ? "" : next.getKey() - e.getKey(),
e.getValue()));
}
return b.toString();
}
}