jdk/src/share/classes/sun/misc/Unsafe.java
changeset 2 90ce3da70b43
child 2707 5a17df307cbc
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/classes/sun/misc/Unsafe.java	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,984 @@
+/*
+ * Copyright 2000-2006 Sun Microsystems, Inc.  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.  Sun designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+package sun.misc;
+
+import java.security.*;
+import java.lang.reflect.*;
+
+
+/**
+ * A collection of methods for performing low-level, unsafe operations.
+ * Although the class and all methods are public, use of this class is
+ * limited because only trusted code can obtain instances of it.
+ *
+ * @author John R. Rose
+ * @see #getUnsafe
+ */
+
+public final class Unsafe {
+
+    private static native void registerNatives();
+    static {
+        registerNatives();
+        sun.reflect.Reflection.registerMethodsToFilter(Unsafe.class, "getUnsafe");
+    }
+
+    private Unsafe() {}
+
+    private static final Unsafe theUnsafe = new Unsafe();
+
+    /**
+     * Provides the caller with the capability of performing unsafe
+     * operations.
+     *
+     * <p> The returned <code>Unsafe</code> object should be carefully guarded
+     * by the caller, since it can be used to read and write data at arbitrary
+     * memory addresses.  It must never be passed to untrusted code.
+     *
+     * <p> Most methods in this class are very low-level, and correspond to a
+     * small number of hardware instructions (on typical machines).  Compilers
+     * are encouraged to optimize these methods accordingly.
+     *
+     * <p> Here is a suggested idiom for using unsafe operations:
+     *
+     * <blockquote><pre>
+     * class MyTrustedClass {
+     *   private static final Unsafe unsafe = Unsafe.getUnsafe();
+     *   ...
+     *   private long myCountAddress = ...;
+     *   public int getCount() { return unsafe.getByte(myCountAddress); }
+     * }
+     * </pre></blockquote>
+     *
+     * (It may assist compilers to make the local variable be
+     * <code>final</code>.)
+     *
+     * @exception  SecurityException  if a security manager exists and its
+     *             <code>checkPropertiesAccess</code> method doesn't allow
+     *             access to the system properties.
+     */
+    public static Unsafe getUnsafe() {
+        Class cc = sun.reflect.Reflection.getCallerClass(2);
+        if (cc.getClassLoader() != null)
+            throw new SecurityException("Unsafe");
+        return theUnsafe;
+    }
+
+    /// peek and poke operations
+    /// (compilers should optimize these to memory ops)
+
+    // These work on object fields in the Java heap.
+    // They will not work on elements of packed arrays.
+
+    /**
+     * Fetches a value from a given Java variable.
+     * More specifically, fetches a field or array element within the given
+     * object <code>o</code> at the given offset, or (if <code>o</code> is
+     * null) from the memory address whose numerical value is the given
+     * offset.
+     * <p>
+     * The results are undefined unless one of the following cases is true:
+     * <ul>
+     * <li>The offset was obtained from {@link #objectFieldOffset} on
+     * the {@link java.lang.reflect.Field} of some Java field and the object
+     * referred to by <code>o</code> is of a class compatible with that
+     * field's class.
+     *
+     * <li>The offset and object reference <code>o</code> (either null or
+     * non-null) were both obtained via {@link #staticFieldOffset}
+     * and {@link #staticFieldBase} (respectively) from the
+     * reflective {@link Field} representation of some Java field.
+     *
+     * <li>The object referred to by <code>o</code> is an array, and the offset
+     * is an integer of the form <code>B+N*S</code>, where <code>N</code> is
+     * a valid index into the array, and <code>B</code> and <code>S</code> are
+     * the values obtained by {@link #arrayBaseOffset} and {@link
+     * #arrayIndexScale} (respectively) from the array's class.  The value
+     * referred to is the <code>N</code><em>th</em> element of the array.
+     *
+     * </ul>
+     * <p>
+     * If one of the above cases is true, the call references a specific Java
+     * variable (field or array element).  However, the results are undefined
+     * if that variable is not in fact of the type returned by this method.
+     * <p>
+     * This method refers to a variable by means of two parameters, and so
+     * it provides (in effect) a <em>double-register</em> addressing mode
+     * for Java variables.  When the object reference is null, this method
+     * uses its offset as an absolute address.  This is similar in operation
+     * to methods such as {@link #getInt(long)}, which provide (in effect) a
+     * <em>single-register</em> addressing mode for non-Java variables.
+     * However, because Java variables may have a different layout in memory
+     * from non-Java variables, programmers should not assume that these
+     * two addressing modes are ever equivalent.  Also, programmers should
+     * remember that offsets from the double-register addressing mode cannot
+     * be portably confused with longs used in the single-register addressing
+     * mode.
+     *
+     * @param o Java heap object in which the variable resides, if any, else
+     *        null
+     * @param offset indication of where the variable resides in a Java heap
+     *        object, if any, else a memory address locating the variable
+     *        statically
+     * @return the value fetched from the indicated Java variable
+     * @throws RuntimeException No defined exceptions are thrown, not even
+     *         {@link NullPointerException}
+     */
+    public native int getInt(Object o, long offset);
+
+    /**
+     * Stores a value into a given Java variable.
+     * <p>
+     * The first two parameters are interpreted exactly as with
+     * {@link #getInt(Object, long)} to refer to a specific
+     * Java variable (field or array element).  The given value
+     * is stored into that variable.
+     * <p>
+     * The variable must be of the same type as the method
+     * parameter <code>x</code>.
+     *
+     * @param o Java heap object in which the variable resides, if any, else
+     *        null
+     * @param offset indication of where the variable resides in a Java heap
+     *        object, if any, else a memory address locating the variable
+     *        statically
+     * @param x the value to store into the indicated Java variable
+     * @throws RuntimeException No defined exceptions are thrown, not even
+     *         {@link NullPointerException}
+     */
+    public native void putInt(Object o, long offset, int x);
+
+    /**
+     * Fetches a reference value from a given Java variable.
+     * @see #getInt(Object, long)
+     */
+    public native Object getObject(Object o, long offset);
+
+    /**
+     * Stores a reference value into a given Java variable.
+     * <p>
+     * Unless the reference <code>x</code> being stored is either null
+     * or matches the field type, the results are undefined.
+     * If the reference <code>o</code> is non-null, car marks or
+     * other store barriers for that object (if the VM requires them)
+     * are updated.
+     * @see #putInt(Object, int, int)
+     */
+    public native void putObject(Object o, long offset, Object x);
+
+    /** @see #getInt(Object, long) */
+    public native boolean getBoolean(Object o, long offset);
+    /** @see #putInt(Object, int, int) */
+    public native void    putBoolean(Object o, long offset, boolean x);
+    /** @see #getInt(Object, long) */
+    public native byte    getByte(Object o, long offset);
+    /** @see #putInt(Object, int, int) */
+    public native void    putByte(Object o, long offset, byte x);
+    /** @see #getInt(Object, long) */
+    public native short   getShort(Object o, long offset);
+    /** @see #putInt(Object, int, int) */
+    public native void    putShort(Object o, long offset, short x);
+    /** @see #getInt(Object, long) */
+    public native char    getChar(Object o, long offset);
+    /** @see #putInt(Object, int, int) */
+    public native void    putChar(Object o, long offset, char x);
+    /** @see #getInt(Object, long) */
+    public native long    getLong(Object o, long offset);
+    /** @see #putInt(Object, int, int) */
+    public native void    putLong(Object o, long offset, long x);
+    /** @see #getInt(Object, long) */
+    public native float   getFloat(Object o, long offset);
+    /** @see #putInt(Object, int, int) */
+    public native void    putFloat(Object o, long offset, float x);
+    /** @see #getInt(Object, long) */
+    public native double  getDouble(Object o, long offset);
+    /** @see #putInt(Object, int, int) */
+    public native void    putDouble(Object o, long offset, double x);
+
+    /**
+     * This method, like all others with 32-bit offsets, was native
+     * in a previous release but is now a wrapper which simply casts
+     * the offset to a long value.  It provides backward compatibility
+     * with bytecodes compiled against 1.4.
+     * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long.
+     * See {@link #staticFieldOffset}.
+     */
+    @Deprecated
+    public int getInt(Object o, int offset) {
+        return getInt(o, (long)offset);
+    }
+
+    /**
+     * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long.
+     * See {@link #staticFieldOffset}.
+     */
+    @Deprecated
+    public void putInt(Object o, int offset, int x) {
+        putInt(o, (long)offset, x);
+    }
+
+    /**
+     * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long.
+     * See {@link #staticFieldOffset}.
+     */
+    @Deprecated
+    public Object getObject(Object o, int offset) {
+        return getObject(o, (long)offset);
+    }
+
+    /**
+     * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long.
+     * See {@link #staticFieldOffset}.
+     */
+    @Deprecated
+    public void putObject(Object o, int offset, Object x) {
+        putObject(o, (long)offset, x);
+    }
+
+    /**
+     * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long.
+     * See {@link #staticFieldOffset}.
+     */
+    @Deprecated
+    public boolean getBoolean(Object o, int offset) {
+        return getBoolean(o, (long)offset);
+    }
+
+    /**
+     * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long.
+     * See {@link #staticFieldOffset}.
+     */
+    @Deprecated
+    public void putBoolean(Object o, int offset, boolean x) {
+        putBoolean(o, (long)offset, x);
+    }
+
+    /**
+     * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long.
+     * See {@link #staticFieldOffset}.
+     */
+    @Deprecated
+    public byte getByte(Object o, int offset) {
+        return getByte(o, (long)offset);
+    }
+
+    /**
+     * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long.
+     * See {@link #staticFieldOffset}.
+     */
+    @Deprecated
+    public void putByte(Object o, int offset, byte x) {
+        putByte(o, (long)offset, x);
+    }
+
+    /**
+     * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long.
+     * See {@link #staticFieldOffset}.
+     */
+    @Deprecated
+    public short getShort(Object o, int offset) {
+        return getShort(o, (long)offset);
+    }
+
+    /**
+     * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long.
+     * See {@link #staticFieldOffset}.
+     */
+    @Deprecated
+    public void putShort(Object o, int offset, short x) {
+        putShort(o, (long)offset, x);
+    }
+
+    /**
+     * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long.
+     * See {@link #staticFieldOffset}.
+     */
+    @Deprecated
+    public char getChar(Object o, int offset) {
+        return getChar(o, (long)offset);
+    }
+
+    /**
+     * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long.
+     * See {@link #staticFieldOffset}.
+     */
+    @Deprecated
+    public void putChar(Object o, int offset, char x) {
+        putChar(o, (long)offset, x);
+    }
+
+    /**
+     * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long.
+     * See {@link #staticFieldOffset}.
+     */
+    @Deprecated
+    public long getLong(Object o, int offset) {
+        return getLong(o, (long)offset);
+    }
+
+    /**
+     * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long.
+     * See {@link #staticFieldOffset}.
+     */
+    @Deprecated
+    public void putLong(Object o, int offset, long x) {
+        putLong(o, (long)offset, x);
+    }
+
+    /**
+     * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long.
+     * See {@link #staticFieldOffset}.
+     */
+    @Deprecated
+    public float getFloat(Object o, int offset) {
+        return getFloat(o, (long)offset);
+    }
+
+    /**
+     * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long.
+     * See {@link #staticFieldOffset}.
+     */
+    @Deprecated
+    public void putFloat(Object o, int offset, float x) {
+        putFloat(o, (long)offset, x);
+    }
+
+    /**
+     * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long.
+     * See {@link #staticFieldOffset}.
+     */
+    @Deprecated
+    public double getDouble(Object o, int offset) {
+        return getDouble(o, (long)offset);
+    }
+
+    /**
+     * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long.
+     * See {@link #staticFieldOffset}.
+     */
+    @Deprecated
+    public void putDouble(Object o, int offset, double x) {
+        putDouble(o, (long)offset, x);
+    }
+
+    // These work on values in the C heap.
+
+    /**
+     * Fetches a value from a given memory address.  If the address is zero, or
+     * does not point into a block obtained from {@link #allocateMemory}, the
+     * results are undefined.
+     *
+     * @see #allocateMemory
+     */
+    public native byte    getByte(long address);
+
+    /**
+     * Stores a value into a given memory address.  If the address is zero, or
+     * does not point into a block obtained from {@link #allocateMemory}, the
+     * results are undefined.
+     *
+     * @see #getByte(long)
+     */
+    public native void    putByte(long address, byte x);
+
+    /** @see #getByte(long) */
+    public native short   getShort(long address);
+    /** @see #putByte(long, byte) */
+    public native void    putShort(long address, short x);
+    /** @see #getByte(long) */
+    public native char    getChar(long address);
+    /** @see #putByte(long, byte) */
+    public native void    putChar(long address, char x);
+    /** @see #getByte(long) */
+    public native int     getInt(long address);
+    /** @see #putByte(long, byte) */
+    public native void    putInt(long address, int x);
+    /** @see #getByte(long) */
+    public native long    getLong(long address);
+    /** @see #putByte(long, byte) */
+    public native void    putLong(long address, long x);
+    /** @see #getByte(long) */
+    public native float   getFloat(long address);
+    /** @see #putByte(long, byte) */
+    public native void    putFloat(long address, float x);
+    /** @see #getByte(long) */
+    public native double  getDouble(long address);
+    /** @see #putByte(long, byte) */
+    public native void    putDouble(long address, double x);
+
+    /**
+     * Fetches a native pointer from a given memory address.  If the address is
+     * zero, or does not point into a block obtained from {@link
+     * #allocateMemory}, the results are undefined.
+     *
+     * <p> If the native pointer is less than 64 bits wide, it is extended as
+     * an unsigned number to a Java long.  The pointer may be indexed by any
+     * given byte offset, simply by adding that offset (as a simple integer) to
+     * the long representing the pointer.  The number of bytes actually read
+     * from the target address maybe determined by consulting {@link
+     * #addressSize}.
+     *
+     * @see #allocateMemory
+     */
+    public native long getAddress(long address);
+
+    /**
+     * Stores a native pointer into a given memory address.  If the address is
+     * zero, or does not point into a block obtained from {@link
+     * #allocateMemory}, the results are undefined.
+     *
+     * <p> The number of bytes actually written at the target address maybe
+     * determined by consulting {@link #addressSize}.
+     *
+     * @see #getAddress(long)
+     */
+    public native void putAddress(long address, long x);
+
+    /// wrappers for malloc, realloc, free:
+
+    /**
+     * Allocates a new block of native memory, of the given size in bytes.  The
+     * contents of the memory are uninitialized; they will generally be
+     * garbage.  The resulting native pointer will never be zero, and will be
+     * aligned for all value types.  Dispose of this memory by calling {@link
+     * #freeMemory}, or resize it with {@link #reallocateMemory}.
+     *
+     * @throws IllegalArgumentException if the size is negative or too large
+     *         for the native size_t type
+     *
+     * @throws OutOfMemoryError if the allocation is refused by the system
+     *
+     * @see #getByte(long)
+     * @see #putByte(long, byte)
+     */
+    public native long allocateMemory(long bytes);
+
+    /**
+     * Resizes a new block of native memory, to the given size in bytes.  The
+     * contents of the new block past the size of the old block are
+     * uninitialized; they will generally be garbage.  The resulting native
+     * pointer will be zero if and only if the requested size is zero.  The
+     * resulting native pointer will be aligned for all value types.  Dispose
+     * of this memory by calling {@link #freeMemory}, or resize it with {@link
+     * #reallocateMemory}.  The address passed to this method may be null, in
+     * which case an allocation will be performed.
+     *
+     * @throws IllegalArgumentException if the size is negative or too large
+     *         for the native size_t type
+     *
+     * @throws OutOfMemoryError if the allocation is refused by the system
+     *
+     * @see #allocateMemory
+     */
+    public native long reallocateMemory(long address, long bytes);
+
+    /**
+     * Sets all bytes in a given block of memory to a fixed value
+     * (usually zero).
+     *
+     * <p>This method determines a block's base address by means of two parameters,
+     * and so it provides (in effect) a <em>double-register</em> addressing mode,
+     * as discussed in {@link #getInt(Object,long)}.  When the object reference is null,
+     * the offset supplies an absolute base address.
+     *
+     * <p>The stores are in coherent (atomic) units of a size determined
+     * by the address and length parameters.  If the effective address and
+     * length are all even modulo 8, the stores take place in 'long' units.
+     * If the effective address and length are (resp.) even modulo 4 or 2,
+     * the stores take place in units of 'int' or 'short'.
+     *
+     * @since 1.7
+     */
+    public native void setMemory(Object o, long offset, long bytes, byte value);
+
+    /**
+     * Sets all bytes in a given block of memory to a fixed value
+     * (usually zero).  This provides a <em>single-register</em> addressing mode,
+     * as discussed in {@link #getInt(Object,long)}.
+     *
+     * <p>Equivalent to <code>setMemory(null, address, bytes, value)</code>.
+     */
+    public void setMemory(long address, long bytes, byte value) {
+        setMemory(null, address, bytes, value);
+    }
+
+    /**
+     * Sets all bytes in a given block of memory to a copy of another
+     * block.
+     *
+     * <p>This method determines each block's base address by means of two parameters,
+     * and so it provides (in effect) a <em>double-register</em> addressing mode,
+     * as discussed in {@link #getInt(Object,long)}.  When the object reference is null,
+     * the offset supplies an absolute base address.
+     *
+     * <p>The transfers are in coherent (atomic) units of a size determined
+     * by the address and length parameters.  If the effective addresses and
+     * length are all even modulo 8, the transfer takes place in 'long' units.
+     * If the effective addresses and length are (resp.) even modulo 4 or 2,
+     * the transfer takes place in units of 'int' or 'short'.
+     *
+     * @since 1.7
+     */
+    public native void copyMemory(Object srcBase, long srcOffset,
+                                  Object destBase, long destOffset,
+                                  long bytes);
+    /**
+     * Sets all bytes in a given block of memory to a copy of another
+     * block.  This provides a <em>single-register</em> addressing mode,
+     * as discussed in {@link #getInt(Object,long)}.
+     *
+     * Equivalent to <code>copyMemory(null, srcAddress, null, destAddress, bytes)</code>.
+     */
+    public void copyMemory(long srcAddress, long destAddress, long bytes) {
+        copyMemory(null, srcAddress, null, destAddress, bytes);
+    }
+
+    /**
+     * Disposes of a block of native memory, as obtained from {@link
+     * #allocateMemory} or {@link #reallocateMemory}.  The address passed to
+     * this method may be null, in which case no action is taken.
+     *
+     * @see #allocateMemory
+     */
+    public native void freeMemory(long address);
+
+    /// random queries
+
+    /**
+     * This constant differs from all results that will ever be returned from
+     * {@link #staticFieldOffset}, {@link #objectFieldOffset},
+     * or {@link #arrayBaseOffset}.
+     */
+    public static final int INVALID_FIELD_OFFSET   = -1;
+
+    /**
+     * Returns the offset of a field, truncated to 32 bits.
+     * This method is implemented as follows:
+     * <blockquote><pre>
+     * public int fieldOffset(Field f) {
+     *     if (Modifier.isStatic(f.getModifiers()))
+     *         return (int) staticFieldOffset(f);
+     *     else
+     *         return (int) objectFieldOffset(f);
+     * }
+     * </pre></blockquote>
+     * @deprecated As of 1.4.1, use {@link #staticFieldOffset} for static
+     * fields and {@link #objectFieldOffset} for non-static fields.
+     */
+    @Deprecated
+    public int fieldOffset(Field f) {
+        if (Modifier.isStatic(f.getModifiers()))
+            return (int) staticFieldOffset(f);
+        else
+            return (int) objectFieldOffset(f);
+    }
+
+    /**
+     * Returns the base address for accessing some static field
+     * in the given class.  This method is implemented as follows:
+     * <blockquote><pre>
+     * public Object staticFieldBase(Class c) {
+     *     Field[] fields = c.getDeclaredFields();
+     *     for (int i = 0; i < fields.length; i++) {
+     *         if (Modifier.isStatic(fields[i].getModifiers())) {
+     *             return staticFieldBase(fields[i]);
+     *         }
+     *     }
+     *     return null;
+     * }
+     * </pre></blockquote>
+     * @deprecated As of 1.4.1, use {@link #staticFieldBase(Field)}
+     * to obtain the base pertaining to a specific {@link Field}.
+     * This method works only for JVMs which store all statics
+     * for a given class in one place.
+     */
+    @Deprecated
+    public Object staticFieldBase(Class c) {
+        Field[] fields = c.getDeclaredFields();
+        for (int i = 0; i < fields.length; i++) {
+            if (Modifier.isStatic(fields[i].getModifiers())) {
+                return staticFieldBase(fields[i]);
+            }
+        }
+        return null;
+    }
+
+    /**
+     * Report the location of a given field in the storage allocation of its
+     * class.  Do not expect to perform any sort of arithmetic on this offset;
+     * it is just a cookie which is passed to the unsafe heap memory accessors.
+     *
+     * <p>Any given field will always have the same offset and base, and no
+     * two distinct fields of the same class will ever have the same offset
+     * and base.
+     *
+     * <p>As of 1.4.1, offsets for fields are represented as long values,
+     * although the Sun JVM does not use the most significant 32 bits.
+     * However, JVM implementations which store static fields at absolute
+     * addresses can use long offsets and null base pointers to express
+     * the field locations in a form usable by {@link #getInt(Object,long)}.
+     * Therefore, code which will be ported to such JVMs on 64-bit platforms
+     * must preserve all bits of static field offsets.
+     * @see #getInt(Object, long)
+     */
+    public native long staticFieldOffset(Field f);
+
+    /**
+     * Report the location of a given static field, in conjunction with {@link
+     * #staticFieldBase}.
+     * <p>Do not expect to perform any sort of arithmetic on this offset;
+     * it is just a cookie which is passed to the unsafe heap memory accessors.
+     *
+     * <p>Any given field will always have the same offset, and no two distinct
+     * fields of the same class will ever have the same offset.
+     *
+     * <p>As of 1.4.1, offsets for fields are represented as long values,
+     * although the Sun JVM does not use the most significant 32 bits.
+     * It is hard to imagine a JVM technology which needs more than
+     * a few bits to encode an offset within a non-array object,
+     * However, for consistency with other methods in this class,
+     * this method reports its result as a long value.
+     * @see #getInt(Object, long)
+     */
+    public native long objectFieldOffset(Field f);
+
+    /**
+     * Report the location of a given static field, in conjunction with {@link
+     * #staticFieldOffset}.
+     * <p>Fetch the base "Object", if any, with which static fields of the
+     * given class can be accessed via methods like {@link #getInt(Object,
+     * long)}.  This value may be null.  This value may refer to an object
+     * which is a "cookie", not guaranteed to be a real Object, and it should
+     * not be used in any way except as argument to the get and put routines in
+     * this class.
+     */
+    public native Object staticFieldBase(Field f);
+
+    /**
+     * Ensure the given class has been initialized. This is often
+     * needed in conjunction with obtaining the static field base of a
+     * class.
+     */
+    public native void ensureClassInitialized(Class c);
+
+    /**
+     * Report the offset of the first element in the storage allocation of a
+     * given array class.  If {@link #arrayIndexScale} returns a non-zero value
+     * for the same class, you may use that scale factor, together with this
+     * base offset, to form new offsets to access elements of arrays of the
+     * given class.
+     *
+     * @see #getInt(Object, long)
+     * @see #putInt(Object, long, int)
+     */
+    public native int arrayBaseOffset(Class arrayClass);
+
+    /** The value of {@code arrayBaseOffset(boolean[].class)} */
+    public static final int ARRAY_BOOLEAN_BASE_OFFSET
+            = theUnsafe.arrayBaseOffset(boolean[].class);
+
+    /** The value of {@code arrayBaseOffset(byte[].class)} */
+    public static final int ARRAY_BYTE_BASE_OFFSET
+            = theUnsafe.arrayBaseOffset(byte[].class);
+
+    /** The value of {@code arrayBaseOffset(short[].class)} */
+    public static final int ARRAY_SHORT_BASE_OFFSET
+            = theUnsafe.arrayBaseOffset(short[].class);
+
+    /** The value of {@code arrayBaseOffset(char[].class)} */
+    public static final int ARRAY_CHAR_BASE_OFFSET
+            = theUnsafe.arrayBaseOffset(char[].class);
+
+    /** The value of {@code arrayBaseOffset(int[].class)} */
+    public static final int ARRAY_INT_BASE_OFFSET
+            = theUnsafe.arrayBaseOffset(int[].class);
+
+    /** The value of {@code arrayBaseOffset(long[].class)} */
+    public static final int ARRAY_LONG_BASE_OFFSET
+            = theUnsafe.arrayBaseOffset(long[].class);
+
+    /** The value of {@code arrayBaseOffset(float[].class)} */
+    public static final int ARRAY_FLOAT_BASE_OFFSET
+            = theUnsafe.arrayBaseOffset(float[].class);
+
+    /** The value of {@code arrayBaseOffset(double[].class)} */
+    public static final int ARRAY_DOUBLE_BASE_OFFSET
+            = theUnsafe.arrayBaseOffset(double[].class);
+
+    /** The value of {@code arrayBaseOffset(Object[].class)} */
+    public static final int ARRAY_OBJECT_BASE_OFFSET
+            = theUnsafe.arrayBaseOffset(Object[].class);
+
+    /**
+     * Report the scale factor for addressing elements in the storage
+     * allocation of a given array class.  However, arrays of "narrow" types
+     * will generally not work properly with accessors like {@link
+     * #getByte(Object, int)}, so the scale factor for such classes is reported
+     * as zero.
+     *
+     * @see #arrayBaseOffset
+     * @see #getInt(Object, long)
+     * @see #putInt(Object, long, int)
+     */
+    public native int arrayIndexScale(Class arrayClass);
+
+    /** The value of {@code arrayIndexScale(boolean[].class)} */
+    public static final int ARRAY_BOOLEAN_INDEX_SCALE
+            = theUnsafe.arrayIndexScale(boolean[].class);
+
+    /** The value of {@code arrayIndexScale(byte[].class)} */
+    public static final int ARRAY_BYTE_INDEX_SCALE
+            = theUnsafe.arrayIndexScale(byte[].class);
+
+    /** The value of {@code arrayIndexScale(short[].class)} */
+    public static final int ARRAY_SHORT_INDEX_SCALE
+            = theUnsafe.arrayIndexScale(short[].class);
+
+    /** The value of {@code arrayIndexScale(char[].class)} */
+    public static final int ARRAY_CHAR_INDEX_SCALE
+            = theUnsafe.arrayIndexScale(char[].class);
+
+    /** The value of {@code arrayIndexScale(int[].class)} */
+    public static final int ARRAY_INT_INDEX_SCALE
+            = theUnsafe.arrayIndexScale(int[].class);
+
+    /** The value of {@code arrayIndexScale(long[].class)} */
+    public static final int ARRAY_LONG_INDEX_SCALE
+            = theUnsafe.arrayIndexScale(long[].class);
+
+    /** The value of {@code arrayIndexScale(float[].class)} */
+    public static final int ARRAY_FLOAT_INDEX_SCALE
+            = theUnsafe.arrayIndexScale(float[].class);
+
+    /** The value of {@code arrayIndexScale(double[].class)} */
+    public static final int ARRAY_DOUBLE_INDEX_SCALE
+            = theUnsafe.arrayIndexScale(double[].class);
+
+    /** The value of {@code arrayIndexScale(Object[].class)} */
+    public static final int ARRAY_OBJECT_INDEX_SCALE
+            = theUnsafe.arrayIndexScale(Object[].class);
+
+    /**
+     * Report the size in bytes of a native pointer, as stored via {@link
+     * #putAddress}.  This value will be either 4 or 8.  Note that the sizes of
+     * other primitive types (as stored in native memory blocks) is determined
+     * fully by their information content.
+     */
+    public native int addressSize();
+
+    /** The value of {@code addressSize()} */
+    public static final int ADDRESS_SIZE = theUnsafe.addressSize();
+
+    /**
+     * Report the size in bytes of a native memory page (whatever that is).
+     * This value will always be a power of two.
+     */
+    public native int pageSize();
+
+
+    /// random trusted operations from JNI:
+
+    /**
+     * Tell the VM to define a class, without security checks.  By default, the
+     * class loader and protection domain come from the caller's class.
+     */
+    public native Class defineClass(String name, byte[] b, int off, int len,
+                                    ClassLoader loader,
+                                    ProtectionDomain protectionDomain);
+
+    public native Class defineClass(String name, byte[] b, int off, int len);
+
+    /** Allocate an instance but do not run any constructor.
+        Initializes the class if it has not yet been. */
+    public native Object allocateInstance(Class cls)
+        throws InstantiationException;
+
+    /** Lock the object.  It must get unlocked via {@link #monitorExit}. */
+    public native void monitorEnter(Object o);
+
+    /**
+     * Unlock the object.  It must have been locked via {@link
+     * #monitorEnter}.
+     */
+    public native void monitorExit(Object o);
+
+    /**
+     * Tries to lock the object.  Returns true or false to indicate
+     * whether the lock succeeded.  If it did, the object must be
+     * unlocked via {@link #monitorExit}.
+     */
+    public native boolean tryMonitorEnter(Object o);
+
+    /** Throw the exception without telling the verifier. */
+    public native void throwException(Throwable ee);
+
+
+    /**
+     * Atomically update Java variable to <tt>x</tt> if it is currently
+     * holding <tt>expected</tt>.
+     * @return <tt>true</tt> if successful
+     */
+    public final native boolean compareAndSwapObject(Object o, long offset,
+                                                     Object expected,
+                                                     Object x);
+
+    /**
+     * Atomically update Java variable to <tt>x</tt> if it is currently
+     * holding <tt>expected</tt>.
+     * @return <tt>true</tt> if successful
+     */
+    public final native boolean compareAndSwapInt(Object o, long offset,
+                                                  int expected,
+                                                  int x);
+
+    /**
+     * Atomically update Java variable to <tt>x</tt> if it is currently
+     * holding <tt>expected</tt>.
+     * @return <tt>true</tt> if successful
+     */
+    public final native boolean compareAndSwapLong(Object o, long offset,
+                                                   long expected,
+                                                   long x);
+
+    /**
+     * Fetches a reference value from a given Java variable, with volatile
+     * load semantics. Otherwise identical to {@link #getObject(Object, long)}
+     */
+    public native Object getObjectVolatile(Object o, long offset);
+
+    /**
+     * Stores a reference value into a given Java variable, with
+     * volatile store semantics. Otherwise identical to {@link #putObject(Object, long, Object)}
+     */
+    public native void    putObjectVolatile(Object o, long offset, Object x);
+
+    /** Volatile version of {@link #getInt(Object, long)}  */
+    public native int     getIntVolatile(Object o, long offset);
+
+    /** Volatile version of {@link #putInt(Object, long, int)}  */
+    public native void    putIntVolatile(Object o, long offset, int x);
+
+    /** Volatile version of {@link #getBoolean(Object, long)}  */
+    public native boolean getBooleanVolatile(Object o, long offset);
+
+    /** Volatile version of {@link #putBoolean(Object, long, boolean)}  */
+    public native void    putBooleanVolatile(Object o, long offset, boolean x);
+
+    /** Volatile version of {@link #getByte(Object, long)}  */
+    public native byte    getByteVolatile(Object o, long offset);
+
+    /** Volatile version of {@link #putByte(Object, long, byte)}  */
+    public native void    putByteVolatile(Object o, long offset, byte x);
+
+    /** Volatile version of {@link #getShort(Object, long)}  */
+    public native short   getShortVolatile(Object o, long offset);
+
+    /** Volatile version of {@link #putShort(Object, long, short)}  */
+    public native void    putShortVolatile(Object o, long offset, short x);
+
+    /** Volatile version of {@link #getChar(Object, long)}  */
+    public native char    getCharVolatile(Object o, long offset);
+
+    /** Volatile version of {@link #putChar(Object, long, char)}  */
+    public native void    putCharVolatile(Object o, long offset, char x);
+
+    /** Volatile version of {@link #getLong(Object, long)}  */
+    public native long    getLongVolatile(Object o, long offset);
+
+    /** Volatile version of {@link #putLong(Object, long, long)}  */
+    public native void    putLongVolatile(Object o, long offset, long x);
+
+    /** Volatile version of {@link #getFloat(Object, long)}  */
+    public native float   getFloatVolatile(Object o, long offset);
+
+    /** Volatile version of {@link #putFloat(Object, long, float)}  */
+    public native void    putFloatVolatile(Object o, long offset, float x);
+
+    /** Volatile version of {@link #getDouble(Object, long)}  */
+    public native double  getDoubleVolatile(Object o, long offset);
+
+    /** Volatile version of {@link #putDouble(Object, long, double)}  */
+    public native void    putDoubleVolatile(Object o, long offset, double x);
+
+    /**
+     * Version of {@link #putObjectVolatile(Object, long, Object)}
+     * that does not guarantee immediate visibility of the store to
+     * other threads. This method is generally only useful if the
+     * underlying field is a Java volatile (or if an array cell, one
+     * that is otherwise only accessed using volatile accesses).
+     */
+    public native void    putOrderedObject(Object o, long offset, Object x);
+
+    /** Ordered/Lazy version of {@link #putIntVolatile(Object, long, int)}  */
+    public native void    putOrderedInt(Object o, long offset, int x);
+
+    /** Ordered/Lazy version of {@link #putLongVolatile(Object, long, long)} */
+    public native void    putOrderedLong(Object o, long offset, long x);
+
+    /**
+     * Unblock the given thread blocked on <tt>park</tt>, or, if it is
+     * not blocked, cause the subsequent call to <tt>park</tt> not to
+     * block.  Note: this operation is "unsafe" solely because the
+     * caller must somehow ensure that the thread has not been
+     * destroyed. Nothing special is usually required to ensure this
+     * when called from Java (in which there will ordinarily be a live
+     * reference to the thread) but this is not nearly-automatically
+     * so when calling from native code.
+     * @param thread the thread to unpark.
+     *
+     */
+    public native void unpark(Object thread);
+
+    /**
+     * Block current thread, returning when a balancing
+     * <tt>unpark</tt> occurs, or a balancing <tt>unpark</tt> has
+     * already occurred, or the thread is interrupted, or, if not
+     * absolute and time is not zero, the given time nanoseconds have
+     * elapsed, or if absolute, the given deadline in milliseconds
+     * since Epoch has passed, or spuriously (i.e., returning for no
+     * "reason"). Note: This operation is in the Unsafe class only
+     * because <tt>unpark</tt> is, so it would be strange to place it
+     * elsewhere.
+     */
+    public native void park(boolean isAbsolute, long time);
+
+    /**
+     * Gets the load average in the system run queue assigned
+     * to the available processors averaged over various periods of time.
+     * This method retrieves the given <tt>nelem</tt> samples and
+     * assigns to the elements of the given <tt>loadavg</tt> array.
+     * The system imposes a maximum of 3 samples, representing
+     * averages over the last 1,  5,  and  15 minutes, respectively.
+     *
+     * @params loadavg an array of double of size nelems
+     * @params nelems the number of samples to be retrieved and
+     *         must be 1 to 3.
+     *
+     * @return the number of samples actually retrieved; or -1
+     *         if the load average is unobtainable.
+     */
+    public native int getLoadAverage(double[] loadavg, int nelems);
+}