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   /*
    * Copyright (c) 2000, 2009, 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 sun.misc;
  
  import java.security.*;
  
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(s):
John R. Rose
See also:
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.

The returned Unsafe 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.

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.

Here is a suggested idiom for using unsafe operations:

 class MyTrustedClass {
   private static final Unsafe unsafe = Unsafe.getUnsafe();
   ...
   private long myCountAddress = ...;
   public int getCount() { return unsafe.getByte(myCountAddress); }
 }
 
(It may assist compilers to make the local variable be final.)

Throws:
java.lang.SecurityException if a security manager exists and its checkPropertiesAccess method doesn't allow access to the system properties.
  
      @CallerSensitive
      public static Unsafe getUnsafe() {
          Class cc = Reflection.getCallerClass();
          if (cc.getClassLoader() != null)
              throw new SecurityException("Unsafe");
          return ;
      }
  
      /// 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 o at the given offset, or (if o is null) from the memory address whose numerical value is the given offset.

The results are undefined unless one of the following cases is true:

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.

This method refers to a variable by means of two parameters, and so it provides (in effect) a double-register 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 getInt(long), which provide (in effect) a single-register 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.

Parameters:
o Java heap object in which the variable resides, if any, else null
offset indication of where the variable resides in a Java heap object, if any, else a memory address locating the variable statically
Returns:
the value fetched from the indicated Java variable
Throws:
java.lang.RuntimeException No defined exceptions are thrown, not even java.lang.NullPointerException
 
     public native int getInt(Object olong offset);

    
Stores a value into a given Java variable.

The first two parameters are interpreted exactly as with getInt(java.lang.Object,long) to refer to a specific Java variable (field or array element). The given value is stored into that variable.

The variable must be of the same type as the method parameter x.

Parameters:
o Java heap object in which the variable resides, if any, else null
offset indication of where the variable resides in a Java heap object, if any, else a memory address locating the variable statically
x the value to store into the indicated Java variable
Throws:
java.lang.RuntimeException No defined exceptions are thrown, not even java.lang.NullPointerException
 
     public native void putInt(Object olong offsetint x);

    
Fetches a reference value from a given Java variable.

 
     public native Object getObject(Object olong offset);

    
Stores a reference value into a given Java variable.

Unless the reference x being stored is either null or matches the field type, the results are undefined. If the reference o is non-null, car marks or other store barriers for that object (if the VM requires them) are updated.

 
     public native void putObject(Object olong offsetObject x);

    
 
     public native boolean getBoolean(Object olong offset);
    
 
     public native void    putBoolean(Object olong offsetboolean x);
    
 
     public native byte    getByte(Object olong offset);
    
 
     public native void    putByte(Object olong offsetbyte x);
    
 
     public native short   getShort(Object olong offset);
    
 
     public native void    putShort(Object olong offsetshort x);
    
 
     public native char    getChar(Object olong offset);
    
 
     public native void    putChar(Object olong offsetchar x);
    
 
     public native long    getLong(Object olong offset);
    
 
     public native void    putLong(Object olong offsetlong x);
    
 
     public native float   getFloat(Object olong offset);
    
 
     public native void    putFloat(Object olong offsetfloat x);
    
 
     public native double  getDouble(Object olong offset);
    
 
     public native void    putDouble(Object olong offsetdouble 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 staticFieldOffset(java.lang.reflect.Field).
 
     @Deprecated
     public int getInt(Object oint offset) {
         return getInt(o, (long)offset);
     }

    

Deprecated:
As of 1.4.1, cast the 32-bit offset argument to a long. See staticFieldOffset(java.lang.reflect.Field).
 
     @Deprecated
     public void putInt(Object oint offsetint x) {
         putInt(o, (long)offsetx);
     }

    

Deprecated:
As of 1.4.1, cast the 32-bit offset argument to a long. See staticFieldOffset(java.lang.reflect.Field).
 
     @Deprecated
     public Object getObject(Object oint offset) {
         return getObject(o, (long)offset);
     }

    

Deprecated:
As of 1.4.1, cast the 32-bit offset argument to a long. See staticFieldOffset(java.lang.reflect.Field).
 
     @Deprecated
     public void putObject(Object oint offsetObject x) {
         putObject(o, (long)offsetx);
     }

    

Deprecated:
As of 1.4.1, cast the 32-bit offset argument to a long. See staticFieldOffset(java.lang.reflect.Field).
 
     @Deprecated
     public boolean getBoolean(Object oint offset) {
         return getBoolean(o, (long)offset);
     }

    

Deprecated:
As of 1.4.1, cast the 32-bit offset argument to a long. See staticFieldOffset(java.lang.reflect.Field).
 
     @Deprecated
     public void putBoolean(Object oint offsetboolean x) {
         putBoolean(o, (long)offsetx);
     }

    

Deprecated:
As of 1.4.1, cast the 32-bit offset argument to a long. See staticFieldOffset(java.lang.reflect.Field).
 
     @Deprecated
     public byte getByte(Object oint offset) {
         return getByte(o, (long)offset);
     }

    

Deprecated:
As of 1.4.1, cast the 32-bit offset argument to a long. See staticFieldOffset(java.lang.reflect.Field).
 
     @Deprecated
     public void putByte(Object oint offsetbyte x) {
         putByte(o, (long)offsetx);
     }

    

Deprecated:
As of 1.4.1, cast the 32-bit offset argument to a long. See staticFieldOffset(java.lang.reflect.Field).
 
     @Deprecated
     public short getShort(Object oint offset) {
         return getShort(o, (long)offset);
     }

    

Deprecated:
As of 1.4.1, cast the 32-bit offset argument to a long. See staticFieldOffset(java.lang.reflect.Field).
 
     @Deprecated
     public void putShort(Object oint offsetshort x) {
         putShort(o, (long)offsetx);
     }

    

Deprecated:
As of 1.4.1, cast the 32-bit offset argument to a long. See staticFieldOffset(java.lang.reflect.Field).
 
     @Deprecated
     public char getChar(Object oint offset) {
         return getChar(o, (long)offset);
     }

    

Deprecated:
As of 1.4.1, cast the 32-bit offset argument to a long. See staticFieldOffset(java.lang.reflect.Field).
 
     @Deprecated
     public void putChar(Object oint offsetchar x) {
         putChar(o, (long)offsetx);
     }

    

Deprecated:
As of 1.4.1, cast the 32-bit offset argument to a long. See staticFieldOffset(java.lang.reflect.Field).
 
     @Deprecated
     public long getLong(Object oint offset) {
         return getLong(o, (long)offset);
     }

    

Deprecated:
As of 1.4.1, cast the 32-bit offset argument to a long. See staticFieldOffset(java.lang.reflect.Field).
 
     @Deprecated
     public void putLong(Object oint offsetlong x) {
         putLong(o, (long)offsetx);
     }

    

Deprecated:
As of 1.4.1, cast the 32-bit offset argument to a long. See staticFieldOffset(java.lang.reflect.Field).
 
     @Deprecated
     public float getFloat(Object oint offset) {
         return getFloat(o, (long)offset);
     }

    

Deprecated:
As of 1.4.1, cast the 32-bit offset argument to a long. See staticFieldOffset(java.lang.reflect.Field).
 
     @Deprecated
     public void putFloat(Object oint offsetfloat x) {
         putFloat(o, (long)offsetx);
     }

    

Deprecated:
As of 1.4.1, cast the 32-bit offset argument to a long. See staticFieldOffset(java.lang.reflect.Field).
 
     @Deprecated
     public double getDouble(Object oint offset) {
         return getDouble(o, (long)offset);
     }

    

Deprecated:
As of 1.4.1, cast the 32-bit offset argument to a long. See staticFieldOffset(java.lang.reflect.Field).
 
     @Deprecated
     public void putDouble(Object oint offsetdouble x) {
         putDouble(o, (long)offsetx);
     }
 
     // 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 allocateMemory(long), the results are undefined.

 
     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 allocateMemory(long), the results are undefined.

See also:
getByte(long)
 
     public native void    putByte(long addressbyte x);

    

See also:
getByte(long)
 
     public native short   getShort(long address);
    
 
     public native void    putShort(long addressshort x);
    

See also:
getByte(long)
 
     public native char    getChar(long address);
    
 
     public native void    putChar(long addresschar x);
    

See also:
getByte(long)
 
     public native int     getInt(long address);
    
 
     public native void    putInt(long addressint x);
    

See also:
getByte(long)
 
     public native long    getLong(long address);
    
 
     public native void    putLong(long addresslong x);
    

See also:
getByte(long)
 
     public native float   getFloat(long address);
    
 
     public native void    putFloat(long addressfloat x);
    

See also:
getByte(long)
 
     public native double  getDouble(long address);
    
 
     public native void    putDouble(long addressdouble x);

    
Fetches a native pointer from a given memory address. If the address is zero, or does not point into a block obtained from allocateMemory(long), the results are undefined.

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 addressSize().

 
     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 allocateMemory(long), the results are undefined.

The number of bytes actually written at the target address maybe determined by consulting addressSize().

 
     public native void putAddress(long addresslong 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 freeMemory(long), or resize it with reallocateMemory(long,long).

Throws:
java.lang.IllegalArgumentException if the size is negative or too large for the native size_t type
java.lang.OutOfMemoryError if the allocation is refused by the system
See also:
getByte(long)
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 freeMemory(long), or resize it with reallocateMemory(long,long). The address passed to this method may be null, in which case an allocation will be performed.

Throws:
java.lang.IllegalArgumentException if the size is negative or too large for the native size_t type
java.lang.OutOfMemoryError if the allocation is refused by the system
See also:
allocateMemory(long)
 
     public native long reallocateMemory(long addresslong bytes);

    
Sets all bytes in a given block of memory to a fixed value (usually zero).

This method determines a block's base address by means of two parameters, and so it provides (in effect) a double-register addressing mode, as discussed in getInt(java.lang.Object,long). When the object reference is null, the offset supplies an absolute base address.

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 olong offsetlong bytesbyte value);

    
Sets all bytes in a given block of memory to a fixed value (usually zero). This provides a single-register addressing mode, as discussed in getInt(java.lang.Object,long).

Equivalent to setMemory(null, address, bytes, value).

 
     public void setMemory(long addresslong bytesbyte value) {
         setMemory(nulladdressbytesvalue);
     }

    
Sets all bytes in a given block of memory to a copy of another block.

This method determines each block's base address by means of two parameters, and so it provides (in effect) a double-register addressing mode, as discussed in getInt(java.lang.Object,long). When the object reference is null, the offset supplies an absolute base address.

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 srcBaselong srcOffset,
                                   Object destBaselong destOffset,
                                   long bytes);
    
Sets all bytes in a given block of memory to a copy of another block. This provides a single-register addressing mode, as discussed in getInt(java.lang.Object,long). Equivalent to copyMemory(null, srcAddress, null, destAddress, bytes).
 
     public void copyMemory(long srcAddresslong destAddresslong bytes) {
         copyMemory(nullsrcAddressnulldestAddressbytes);
     }

    
Disposes of a block of native memory, as obtained from allocateMemory(long) or reallocateMemory(long,long). The address passed to this method may be null, in which case no action is taken.

 
     public native void freeMemory(long address);
 
     /// random queries
 
    
This constant differs from all results that will ever be returned from staticFieldOffset(java.lang.reflect.Field), objectFieldOffset(java.lang.reflect.Field), or arrayBaseOffset(java.lang.Class).
 
     public static final int INVALID_FIELD_OFFSET   = -1;

    
Returns the offset of a field, truncated to 32 bits. This method is implemented as follows:
 public int fieldOffset(Field f) {
     if (Modifier.isStatic(f.getModifiers()))
         return (int) staticFieldOffset(f);
     else
         return (int) objectFieldOffset(f);
 }
 

Deprecated:
As of 1.4.1, use staticFieldOffset(java.lang.reflect.Field) for static fields and objectFieldOffset(java.lang.reflect.Field) for non-static fields.
 
     @Deprecated
     public int fieldOffset(Field f) {
         if (Modifier.isStatic(f.getModifiers()))
             return (intstaticFieldOffset(f);
         else
             return (intobjectFieldOffset(f);
     }

    
Returns the base address for accessing some static field in the given class. This method is implemented as follows:
 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;
 }
 

Deprecated:
As of 1.4.1, use staticFieldBase(java.lang.reflect.Field) to obtain the base pertaining to a specific java.lang.reflect.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.lengthi++) {
             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.

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.

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 getInt(java.lang.Object,long). Therefore, code which will be ported to such JVMs on 64-bit platforms must preserve all bits of static field offsets.

 
     public native long staticFieldOffset(Field f);

    
Report the location of a given static field, in conjunction with staticFieldBase(java.lang.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.

Any given field will always have the same offset, and no two distinct fields of the same class will ever have the same offset.

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.

 
     public native long objectFieldOffset(Field f);

    
Report the location of a given static field, in conjunction with staticFieldOffset(java.lang.reflect.Field).

Fetch the base "Object", if any, with which static fields of the given class can be accessed via methods like getInt(java.lang.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);

    
Detect if the given class may need to be initialized. This is often needed in conjunction with obtaining the static field base of a class.

Returns:
false only if a call to ensureClassInitialized would have no effect
 
     public native boolean shouldBeInitialized(Class<?> c);

    
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 arrayIndexScale(java.lang.Class) 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.

 
     public native int arrayBaseOffset(Class arrayClass);

    
The value of arrayBaseOffset(boolean[].class)
 
     public static final int ARRAY_BOOLEAN_BASE_OFFSET
             = .arrayBaseOffset(boolean[].class);

    
The value of arrayBaseOffset(byte[].class)
 
     public static final int ARRAY_BYTE_BASE_OFFSET
             = .arrayBaseOffset(byte[].class);

    
The value of arrayBaseOffset(short[].class)
 
     public static final int ARRAY_SHORT_BASE_OFFSET
             = .arrayBaseOffset(short[].class);

    
The value of arrayBaseOffset(char[].class)
 
     public static final int ARRAY_CHAR_BASE_OFFSET
             = .arrayBaseOffset(char[].class);

    
The value of arrayBaseOffset(int[].class)
 
     public static final int ARRAY_INT_BASE_OFFSET
             = .arrayBaseOffset(int[].class);

    
The value of arrayBaseOffset(long[].class)
 
     public static final int ARRAY_LONG_BASE_OFFSET
             = .arrayBaseOffset(long[].class);

    
The value of arrayBaseOffset(float[].class)
 
     public static final int ARRAY_FLOAT_BASE_OFFSET
             = .arrayBaseOffset(float[].class);

    
The value of arrayBaseOffset(double[].class)
 
     public static final int ARRAY_DOUBLE_BASE_OFFSET
             = .arrayBaseOffset(double[].class);

    
The value of arrayBaseOffset(Object[].class)
 
     public static final int ARRAY_OBJECT_BASE_OFFSET
             = .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 getByte(java.lang.Object,int), so the scale factor for such classes is reported as zero.

 
     public native int arrayIndexScale(Class arrayClass);

    
The value of arrayIndexScale(boolean[].class)
 
     public static final int ARRAY_BOOLEAN_INDEX_SCALE
             = .arrayIndexScale(boolean[].class);

    
The value of arrayIndexScale(byte[].class)
 
     public static final int ARRAY_BYTE_INDEX_SCALE
             = .arrayIndexScale(byte[].class);

    
The value of arrayIndexScale(short[].class)
 
     public static final int ARRAY_SHORT_INDEX_SCALE
             = .arrayIndexScale(short[].class);

    
The value of arrayIndexScale(char[].class)
 
     public static final int ARRAY_CHAR_INDEX_SCALE
             = .arrayIndexScale(char[].class);

    
The value of arrayIndexScale(int[].class)
 
     public static final int ARRAY_INT_INDEX_SCALE
             = .arrayIndexScale(int[].class);

    
The value of arrayIndexScale(long[].class)
 
     public static final int ARRAY_LONG_INDEX_SCALE
             = .arrayIndexScale(long[].class);

    
The value of arrayIndexScale(float[].class)
 
     public static final int ARRAY_FLOAT_INDEX_SCALE
             = .arrayIndexScale(float[].class);

    
The value of arrayIndexScale(double[].class)
 
     public static final int ARRAY_DOUBLE_INDEX_SCALE
             = .arrayIndexScale(double[].class);

    
The value of arrayIndexScale(Object[].class)
 
     public static final int ARRAY_OBJECT_INDEX_SCALE
             = .arrayIndexScale(Object[].class);

    
Report the size in bytes of a native pointer, as stored via putAddress(long,long). 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 addressSize()
 
     public static final int ADDRESS_SIZE = .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 namebyte[] bint offint len,
                                     ClassLoader loader,
                                     ProtectionDomain protectionDomain);

    

Deprecated:
Use defineClass(String, byte[], int, int, ClassLoader, ProtectionDomain) instead. This method will be removed in JDK 8.
 
     @Deprecated
     public native Class defineClass(String namebyte[] bint offint len);

    
Define a class but do not make it known to the class loader or system dictionary.

For each CP entry, the corresponding CP patch must either be null or have the a format that matches its tag:

  • Integer, Long, Float, Double: the corresponding wrapper object type from java.lang
  • Utf8: a string (must have suitable syntax if used as signature or name)
  • Class: any java.lang.Class object
  • String: any object (not just a java.lang.String)
  • InterfaceMethodRef: (NYI) a method handle to invoke on that call site's arguments

Params:
hostClass context for linkage, access control, protection domain, and class loader
Params:
data bytes of a class file
Params:
cpPatches where non-null entries exist, they replace corresponding CP entries in data
 
     public native Class defineAnonymousClass(Class hostClassbyte[] dataObject[] cpPatches);


    
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 monitorExit(java.lang.Object).
 
     public native void monitorEnter(Object o);

    
Unlock the object. It must have been locked via monitorEnter(java.lang.Object).
 
     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 monitorExit(java.lang.Object).
 
     public native boolean tryMonitorEnter(Object o);

    
Throw the exception without telling the verifier.
 
     public native void throwException(Throwable ee);


    
Atomically update Java variable to x if it is currently holding expected.

Returns:
true if successful
 
     public final native boolean compareAndSwapObject(Object olong offset,
                                                      Object expected,
                                                      Object x);

    
Atomically update Java variable to x if it is currently holding expected.

Returns:
true if successful
 
     public final native boolean compareAndSwapInt(Object olong offset,
                                                   int expected,
                                                   int x);

    
Atomically update Java variable to x if it is currently holding expected.

Returns:
true if successful
 
     public final native boolean compareAndSwapLong(Object olong offset,
                                                    long expected,
                                                    long x);

    
Fetches a reference value from a given Java variable, with volatile load semantics. Otherwise identical to getObject(java.lang.Object,long)
 
     public native Object getObjectVolatile(Object olong offset);

    
Stores a reference value into a given Java variable, with volatile store semantics. Otherwise identical to putObject(java.lang.Object,long,java.lang.Object)
 
     public native void    putObjectVolatile(Object olong offsetObject x);

    
Volatile version of getInt(java.lang.Object,long)
 
     public native int     getIntVolatile(Object olong offset);

    
 
     public native void    putIntVolatile(Object olong offsetint x);

    
 
     public native boolean getBooleanVolatile(Object olong offset);

    
 
     public native void    putBooleanVolatile(Object olong offsetboolean x);

    
Volatile version of getByte(java.lang.Object,long)
 
     public native byte    getByteVolatile(Object olong offset);

    
 
     public native void    putByteVolatile(Object olong offsetbyte x);

    
Volatile version of getShort(java.lang.Object,long)
 
     public native short   getShortVolatile(Object olong offset);

    
 
     public native void    putShortVolatile(Object olong offsetshort x);

    
Volatile version of getChar(java.lang.Object,long)
 
     public native char    getCharVolatile(Object olong offset);

    
 
     public native void    putCharVolatile(Object olong offsetchar x);

    
Volatile version of getLong(java.lang.Object,long)
 
     public native long    getLongVolatile(Object olong offset);

    
 
     public native void    putLongVolatile(Object olong offsetlong x);

    
Volatile version of getFloat(java.lang.Object,long)
 
     public native float   getFloatVolatile(Object olong offset);

    
 
     public native void    putFloatVolatile(Object olong offsetfloat x);

    
 
     public native double  getDoubleVolatile(Object olong offset);

    
 
     public native void    putDoubleVolatile(Object olong offsetdouble x);

    
Version of putObjectVolatile(java.lang.Object,long,java.lang.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 olong offsetObject x);

    
 
     public native void    putOrderedInt(Object olong offsetint x);

    
 
     public native void    putOrderedLong(Object olong offsetlong x);

    
Unblock the given thread blocked on park, or, if it is not blocked, cause the subsequent call to park 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.

Parameters:
thread the thread to unpark.
 
     public native void unpark(Object thread);

    
Block current thread, returning when a balancing unpark occurs, or a balancing unpark 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 unpark is, so it would be strange to place it elsewhere.
    public native void park(boolean isAbsolutelong 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 nelem samples and assigns to the elements of the given loadavg array. The system imposes a maximum of 3 samples, representing averages over the last 1, 5, and 15 minutes, respectively.

Returns:
the number of samples actually retrieved; or -1 if the load average is unobtainable.
Params:
loadavg an array of double of size nelems
Params:
nelems the number of samples to be retrieved and must be 1 to 3.
    public native int getLoadAverage(double[] loadavgint nelems);
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