Public Member Functions | Static Public Member Functions | Static Public Attributes | Static Package Functions

sun.misc.Unsafe Class Reference

List of all members.

Public Member Functions

native int getInt (Object o, long offset)
native void putInt (Object o, long offset, int x)
native Object getObject (Object o, long offset)
native void putObject (Object o, long offset, Object x)
native boolean getBoolean (Object o, long offset)
native void putBoolean (Object o, long offset, boolean x)
native byte getByte (Object o, long offset)
native void putByte (Object o, long offset, byte x)
native short getShort (Object o, long offset)
native void putShort (Object o, long offset, short x)
native char getChar (Object o, long offset)
native void putChar (Object o, long offset, char x)
native long getLong (Object o, long offset)
native void putLong (Object o, long offset, long x)
native float getFloat (Object o, long offset)
native void putFloat (Object o, long offset, float x)
native double getDouble (Object o, long offset)
native void putDouble (Object o, long offset, double x)
int getInt (Object o, int offset)
void putInt (Object o, int offset, int x)
Object getObject (Object o, int offset)
void putObject (Object o, int offset, Object x)
boolean getBoolean (Object o, int offset)
void putBoolean (Object o, int offset, boolean x)
byte getByte (Object o, int offset)
void putByte (Object o, int offset, byte x)
short getShort (Object o, int offset)
void putShort (Object o, int offset, short x)
char getChar (Object o, int offset)
void putChar (Object o, int offset, char x)
long getLong (Object o, int offset)
void putLong (Object o, int offset, long x)
float getFloat (Object o, int offset)
void putFloat (Object o, int offset, float x)
double getDouble (Object o, int offset)
void putDouble (Object o, int offset, double x)
native byte getByte (long address)
native void putByte (long address, byte x)
native short getShort (long address)
native void putShort (long address, short x)
native char getChar (long address)
native void putChar (long address, char x)
native int getInt (long address)
native void putInt (long address, int x)
native long getLong (long address)
native void putLong (long address, long x)
native float getFloat (long address)
native void putFloat (long address, float x)
native double getDouble (long address)
native void putDouble (long address, double x)
native long getAddress (long address)
native void putAddress (long address, long x)
native long allocateMemory (long bytes)
 wrappers for malloc, realloc, free:
native long reallocateMemory (long address, long bytes)
native void setMemory (Object o, long offset, long bytes, byte value)
void setMemory (long address, long bytes, byte value)
native void copyMemory (Object srcBase, long srcOffset, Object destBase, long destOffset, long bytes)
void copyMemory (long srcAddress, long destAddress, long bytes)
native void freeMemory (long address)
int fieldOffset (Field f)
Object staticFieldBase (Class c)
native long staticFieldOffset (Field f)
native long objectFieldOffset (Field f)
native Object staticFieldBase (Field f)
native void ensureClassInitialized (Class c)
native int arrayBaseOffset (Class arrayClass)
native int arrayIndexScale (Class arrayClass)
native int addressSize ()
native int pageSize ()
native Class defineClass (String name, byte[] b, int off, int len, ClassLoader loader, ProtectionDomain protectionDomain)
 random trusted operations from JNI:
native Class defineClass (String name, byte[] b, int off, int len)
native Class defineAnonymousClass (Class hostClass, byte[] data, Object[] cpPatches)
native Object allocateInstance (Class cls) throws InstantiationException
native void monitorEnter (Object o)
native void monitorExit (Object o)
native boolean tryMonitorEnter (Object o)
native void throwException (Throwable ee)
final native boolean compareAndSwapObject (Object o, long offset, Object expected, Object x)
final native boolean compareAndSwapInt (Object o, long offset, int expected, int x)
final native boolean compareAndSwapLong (Object o, long offset, long expected, long x)
native Object getObjectVolatile (Object o, long offset)
native void putObjectVolatile (Object o, long offset, Object x)
native int getIntVolatile (Object o, long offset)
native void putIntVolatile (Object o, long offset, int x)
native boolean getBooleanVolatile (Object o, long offset)
native void putBooleanVolatile (Object o, long offset, boolean x)
native byte getByteVolatile (Object o, long offset)
native void putByteVolatile (Object o, long offset, byte x)
native short getShortVolatile (Object o, long offset)
native void putShortVolatile (Object o, long offset, short x)
native char getCharVolatile (Object o, long offset)
native void putCharVolatile (Object o, long offset, char x)
native long getLongVolatile (Object o, long offset)
native void putLongVolatile (Object o, long offset, long x)
native float getFloatVolatile (Object o, long offset)
native void putFloatVolatile (Object o, long offset, float x)
native double getDoubleVolatile (Object o, long offset)
native void putDoubleVolatile (Object o, long offset, double x)
native void putOrderedObject (Object o, long offset, Object x)
native void putOrderedInt (Object o, long offset, int x)
native void putOrderedLong (Object o, long offset, long x)
native void unpark (Object thread)
native void park (boolean isAbsolute, long time)
native int getLoadAverage (double[] loadavg, int nelems)

Static Public Member Functions

static Unsafe getUnsafe ()

Static Public Attributes

static final int INVALID_FIELD_OFFSET = -1
 random queries
static final int ARRAY_BOOLEAN_BASE_OFFSET = theUnsafe.arrayBaseOffset(boolean[].class)
static final int ARRAY_BYTE_BASE_OFFSET = theUnsafe.arrayBaseOffset(byte[].class)
static final int ARRAY_SHORT_BASE_OFFSET = theUnsafe.arrayBaseOffset(short[].class)
static final int ARRAY_CHAR_BASE_OFFSET = theUnsafe.arrayBaseOffset(char[].class)
static final int ARRAY_INT_BASE_OFFSET = theUnsafe.arrayBaseOffset(int[].class)
static final int ARRAY_LONG_BASE_OFFSET = theUnsafe.arrayBaseOffset(long[].class)
static final int ARRAY_FLOAT_BASE_OFFSET = theUnsafe.arrayBaseOffset(float[].class)
static final int ARRAY_DOUBLE_BASE_OFFSET = theUnsafe.arrayBaseOffset(double[].class)
static final int ARRAY_OBJECT_BASE_OFFSET = theUnsafe.arrayBaseOffset(Object[].class)
static final int ARRAY_BOOLEAN_INDEX_SCALE = theUnsafe.arrayIndexScale(boolean[].class)
static final int ARRAY_BYTE_INDEX_SCALE = theUnsafe.arrayIndexScale(byte[].class)
static final int ARRAY_SHORT_INDEX_SCALE = theUnsafe.arrayIndexScale(short[].class)
static final int ARRAY_CHAR_INDEX_SCALE = theUnsafe.arrayIndexScale(char[].class)
static final int ARRAY_INT_INDEX_SCALE = theUnsafe.arrayIndexScale(int[].class)
static final int ARRAY_LONG_INDEX_SCALE = theUnsafe.arrayIndexScale(long[].class)
static final int ARRAY_FLOAT_INDEX_SCALE = theUnsafe.arrayIndexScale(float[].class)
static final int ARRAY_DOUBLE_INDEX_SCALE = theUnsafe.arrayIndexScale(double[].class)
static final int ARRAY_OBJECT_INDEX_SCALE = theUnsafe.arrayIndexScale(Object[].class)
static final int ADDRESS_SIZE = theUnsafe.addressSize()

Static Package Functions

 [static initializer]

Detailed Description

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 also:
getUnsafe

Definition at line 41 of file Unsafe.java.


Member Function Documentation

sun.misc.Unsafe.[static initializer] (  )  [static, package]
native int sun.misc.Unsafe.addressSize (  ) 

Report the size in bytes of a native pointer, as stored via 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.

native Object sun.misc.Unsafe.allocateInstance ( Class  cls  )  throws InstantiationException

Allocate an instance but do not run any constructor. Initializes the class if it has not yet been.

native long sun.misc.Unsafe.allocateMemory ( long  bytes  ) 

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, or resize it with reallocateMemory.

Exceptions:
IllegalArgumentException if the size is negative or too large for the native size_t type
OutOfMemoryError if the allocation is refused by the system
See also:
getByte(long)
putByte(long, byte)
native int sun.misc.Unsafe.arrayBaseOffset ( Class  arrayClass  ) 

Report the offset of the first element in the storage allocation of a given array class. If 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 also:
getInt(Object, long)
putInt(Object, long, int)
native int sun.misc.Unsafe.arrayIndexScale ( Class  arrayClass  ) 

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(Object, int), so the scale factor for such classes is reported as zero.

See also:
arrayBaseOffset
getInt(Object, long)
putInt(Object, long, int)
final native boolean sun.misc.Unsafe.compareAndSwapInt ( Object  o,
long  offset,
int  expected,
int  x 
)

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

Returns:
true if successful
final native boolean sun.misc.Unsafe.compareAndSwapLong ( Object  o,
long  offset,
long  expected,
long  x 
)

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

Returns:
true if successful
final native boolean sun.misc.Unsafe.compareAndSwapObject ( Object  o,
long  offset,
Object  expected,
Object  x 
)

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

Returns:
true if successful
native void sun.misc.Unsafe.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 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(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
void sun.misc.Unsafe.copyMemory ( long  srcAddress,
long  destAddress,
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(Object,long).

Equivalent to copyMemory(null, srcAddress, null, destAddress, bytes).

Definition at line 555 of file Unsafe.java.

native Class sun.misc.Unsafe.defineAnonymousClass ( Class  hostClass,
byte[]  data,
Object[]  cpPatches 
)

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

hostClass context for linkage, access control, protection domain, and class loader data bytes of a class file cpPatches where non-null entries exist, they replace corresponding CP entries in data

native Class sun.misc.Unsafe.defineClass ( String  name,
byte[]  b,
int  off,
int  len,
ClassLoader  loader,
ProtectionDomain  protectionDomain 
)

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.

native Class sun.misc.Unsafe.defineClass ( String  name,
byte[]  b,
int  off,
int  len 
)
native void sun.misc.Unsafe.ensureClassInitialized ( Class  c  ) 

Ensure the given class has been initialized. This is often needed in conjunction with obtaining the static field base of a class.

int sun.misc.Unsafe.fieldOffset ( Field  f  ) 

Returns the offset of a field, truncated to 32 bits. This method is implemented as follows: <blockquote>

 public int fieldOffset(Field f) {
     if (Modifier.isStatic(f.getModifiers()))
         return (int) staticFieldOffset(f);
     else
         return (int) objectFieldOffset(f);
 }
 

</blockquote>

Deprecated:
As of 1.4.1, use staticFieldOffset for static fields and objectFieldOffset for non-static fields.

Definition at line 592 of file Unsafe.java.

native void sun.misc.Unsafe.freeMemory ( long  address  ) 

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

See also:
allocateMemory
native long sun.misc.Unsafe.getAddress ( long  address  ) 

Fetches a native pointer from a given memory address. If the address is zero, or does not point into a block obtained from allocateMemory, 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.

See also:
allocateMemory
native boolean sun.misc.Unsafe.getBoolean ( Object  o,
long  offset 
)
boolean sun.misc.Unsafe.getBoolean ( Object  o,
int  offset 
)
Deprecated:
As of 1.4.1, cast the 32-bit offset argument to a long. See staticFieldOffset.

Definition at line 266 of file Unsafe.java.

native boolean sun.misc.Unsafe.getBooleanVolatile ( Object  o,
long  offset 
)

Volatile version of getBoolean(Object, long)

native byte sun.misc.Unsafe.getByte ( long  address  ) 

Fetches a value from a given memory address. If the address is zero, or does not point into a block obtained from allocateMemory, the results are undefined.

See also:
allocateMemory
native byte sun.misc.Unsafe.getByte ( Object  o,
long  offset 
)
byte sun.misc.Unsafe.getByte ( Object  o,
int  offset 
)
Deprecated:
As of 1.4.1, cast the 32-bit offset argument to a long. See staticFieldOffset.

Definition at line 284 of file Unsafe.java.

native byte sun.misc.Unsafe.getByteVolatile ( Object  o,
long  offset 
)

Volatile version of getByte(Object, long)

native char sun.misc.Unsafe.getChar ( long  address  ) 
See also:
getByte(long)
native char sun.misc.Unsafe.getChar ( Object  o,
long  offset 
)
char sun.misc.Unsafe.getChar ( Object  o,
int  offset 
)
Deprecated:
As of 1.4.1, cast the 32-bit offset argument to a long. See staticFieldOffset.

Definition at line 320 of file Unsafe.java.

native char sun.misc.Unsafe.getCharVolatile ( Object  o,
long  offset 
)

Volatile version of getChar(Object, long)

native double sun.misc.Unsafe.getDouble ( Object  o,
long  offset 
)
double sun.misc.Unsafe.getDouble ( Object  o,
int  offset 
)
Deprecated:
As of 1.4.1, cast the 32-bit offset argument to a long. See staticFieldOffset.

Definition at line 374 of file Unsafe.java.

native double sun.misc.Unsafe.getDouble ( long  address  ) 
See also:
getByte(long)
native double sun.misc.Unsafe.getDoubleVolatile ( Object  o,
long  offset 
)

Volatile version of getDouble(Object, long)

float sun.misc.Unsafe.getFloat ( Object  o,
int  offset 
)
Deprecated:
As of 1.4.1, cast the 32-bit offset argument to a long. See staticFieldOffset.

Definition at line 356 of file Unsafe.java.

native float sun.misc.Unsafe.getFloat ( Object  o,
long  offset 
)
native float sun.misc.Unsafe.getFloat ( long  address  ) 
See also:
getByte(long)
native float sun.misc.Unsafe.getFloatVolatile ( Object  o,
long  offset 
)

Volatile version of getFloat(Object, long)

int sun.misc.Unsafe.getInt ( Object  o,
int  offset 
)

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.

Definition at line 230 of file Unsafe.java.

native int sun.misc.Unsafe.getInt ( long  address  ) 
See also:
getByte(long)
native int sun.misc.Unsafe.getInt ( Object  o,
long  offset 
)

peek and poke operations (compilers should optimize these to memory ops) 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:

  • The offset was obtained from objectFieldOffset on the java.lang.reflect.Field of some Java field and the object referred to by o is of a class compatible with that field's class.

  • The offset and object reference o (either null or non-null) were both obtained via staticFieldOffset and staticFieldBase (respectively) from the reflective Field representation of some Java field.

  • The object referred to by o is an array, and the offset is an integer of the form B+N*S, where N is a valid index into the array, and B and S are the values obtained by arrayBaseOffset and arrayIndexScale (respectively) from the array's class. The value referred to is the Nth element of the array.

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
Exceptions:
RuntimeException No defined exceptions are thrown, not even NullPointerException
native int sun.misc.Unsafe.getIntVolatile ( Object  o,
long  offset 
)

Volatile version of getInt(Object, long)

native int sun.misc.Unsafe.getLoadAverage ( double[]  loadavg,
int  nelems 
)

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.

loadavg an array of double of size nelems nelems the number of samples to be retrieved and must be 1 to 3.

Returns:
the number of samples actually retrieved; or -1 if the load average is unobtainable.
long sun.misc.Unsafe.getLong ( Object  o,
int  offset 
)
Deprecated:
As of 1.4.1, cast the 32-bit offset argument to a long. See staticFieldOffset.

Definition at line 338 of file Unsafe.java.

native long sun.misc.Unsafe.getLong ( long  address  ) 
See also:
getByte(long)
native long sun.misc.Unsafe.getLong ( Object  o,
long  offset 
)
native long sun.misc.Unsafe.getLongVolatile ( Object  o,
long  offset 
)

Volatile version of getLong(Object, long)

native Object sun.misc.Unsafe.getObject ( Object  o,
long  offset 
)

Fetches a reference value from a given Java variable.

See also:
getInt(Object, long)
Object sun.misc.Unsafe.getObject ( Object  o,
int  offset 
)
Deprecated:
As of 1.4.1, cast the 32-bit offset argument to a long. See staticFieldOffset.

Definition at line 248 of file Unsafe.java.

native Object sun.misc.Unsafe.getObjectVolatile ( Object  o,
long  offset 
)

Fetches a reference value from a given Java variable, with volatile load semantics. Otherwise identical to getObject(Object, long)

native short sun.misc.Unsafe.getShort ( long  address  ) 
See also:
getByte(long)
native short sun.misc.Unsafe.getShort ( Object  o,
long  offset 
)
short sun.misc.Unsafe.getShort ( Object  o,
int  offset 
)
Deprecated:
As of 1.4.1, cast the 32-bit offset argument to a long. See staticFieldOffset.

Definition at line 302 of file Unsafe.java.

native short sun.misc.Unsafe.getShortVolatile ( Object  o,
long  offset 
)

Volatile version of getShort(Object, long)

static Unsafe sun.misc.Unsafe.getUnsafe (  )  [static]

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:

<blockquote>

 class MyTrustedClass {
   private static final Unsafe unsafe = Unsafe.getUnsafe();
   ...
   private long myCountAddress = ...;
   public int getCount() { return unsafe.getByte(myCountAddress); }
 }
 

</blockquote>

(It may assist compilers to make the local variable be final.)

Exceptions:
SecurityException if a security manager exists and its checkPropertiesAccess method doesn't allow access to the system properties.

Definition at line 83 of file Unsafe.java.

native void sun.misc.Unsafe.monitorEnter ( Object  o  ) 

Lock the object. It must get unlocked via monitorExit.

native void sun.misc.Unsafe.monitorExit ( Object  o  ) 

Unlock the object. It must have been locked via monitorEnter.

native long sun.misc.Unsafe.objectFieldOffset ( Field  f  ) 

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

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.

See also:
getInt(Object, long)
native int sun.misc.Unsafe.pageSize (  ) 

Report the size in bytes of a native memory page (whatever that is). This value will always be a power of two.

native void sun.misc.Unsafe.park ( boolean  isAbsolute,
long  time 
)

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.

native void sun.misc.Unsafe.putAddress ( long  address,
long  x 
)

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

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

See also:
getAddress(long)
native void sun.misc.Unsafe.putBoolean ( Object  o,
long  offset,
boolean  x 
)
void sun.misc.Unsafe.putBoolean ( Object  o,
int  offset,
boolean  x 
)
Deprecated:
As of 1.4.1, cast the 32-bit offset argument to a long. See staticFieldOffset.

Definition at line 275 of file Unsafe.java.

native void sun.misc.Unsafe.putBooleanVolatile ( Object  o,
long  offset,
boolean  x 
)

Volatile version of putBoolean(Object, long, boolean)

native void sun.misc.Unsafe.putByte ( long  address,
byte  x 
)

Stores a value into a given memory address. If the address is zero, or does not point into a block obtained from allocateMemory, the results are undefined.

See also:
getByte(long)
native void sun.misc.Unsafe.putByte ( Object  o,
long  offset,
byte  x 
)
void sun.misc.Unsafe.putByte ( Object  o,
int  offset,
byte  x 
)
Deprecated:
As of 1.4.1, cast the 32-bit offset argument to a long. See staticFieldOffset.

Definition at line 293 of file Unsafe.java.

native void sun.misc.Unsafe.putByteVolatile ( Object  o,
long  offset,
byte  x 
)

Volatile version of putByte(Object, long, byte)

void sun.misc.Unsafe.putChar ( Object  o,
int  offset,
char  x 
)
Deprecated:
As of 1.4.1, cast the 32-bit offset argument to a long. See staticFieldOffset.

Definition at line 329 of file Unsafe.java.

native void sun.misc.Unsafe.putChar ( long  address,
char  x 
)
native void sun.misc.Unsafe.putChar ( Object  o,
long  offset,
char  x 
)
native void sun.misc.Unsafe.putCharVolatile ( Object  o,
long  offset,
char  x 
)

Volatile version of putChar(Object, long, char)

native void sun.misc.Unsafe.putDouble ( long  address,
double  x 
)
void sun.misc.Unsafe.putDouble ( Object  o,
int  offset,
double  x 
)
Deprecated:
As of 1.4.1, cast the 32-bit offset argument to a long. See staticFieldOffset.

Definition at line 383 of file Unsafe.java.

native void sun.misc.Unsafe.putDouble ( Object  o,
long  offset,
double  x 
)
native void sun.misc.Unsafe.putDoubleVolatile ( Object  o,
long  offset,
double  x 
)

Volatile version of putDouble(Object, long, double)

void sun.misc.Unsafe.putFloat ( Object  o,
int  offset,
float  x 
)
Deprecated:
As of 1.4.1, cast the 32-bit offset argument to a long. See staticFieldOffset.

Definition at line 365 of file Unsafe.java.

native void sun.misc.Unsafe.putFloat ( Object  o,
long  offset,
float  x 
)
native void sun.misc.Unsafe.putFloat ( long  address,
float  x 
)
native void sun.misc.Unsafe.putFloatVolatile ( Object  o,
long  offset,
float  x 
)

Volatile version of putFloat(Object, long, float)

void sun.misc.Unsafe.putInt ( Object  o,
int  offset,
int  x 
)
Deprecated:
As of 1.4.1, cast the 32-bit offset argument to a long. See staticFieldOffset.

Definition at line 239 of file Unsafe.java.

native void sun.misc.Unsafe.putInt ( Object  o,
long  offset,
int  x 
)

Stores a value into a given Java variable.

The first two parameters are interpreted exactly as with getInt(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
Exceptions:
RuntimeException No defined exceptions are thrown, not even NullPointerException
native void sun.misc.Unsafe.putInt ( long  address,
int  x 
)
native void sun.misc.Unsafe.putIntVolatile ( Object  o,
long  offset,
int  x 
)

Volatile version of putInt(Object, long, int)

native void sun.misc.Unsafe.putLong ( Object  o,
long  offset,
long  x 
)
void sun.misc.Unsafe.putLong ( Object  o,
int  offset,
long  x 
)
Deprecated:
As of 1.4.1, cast the 32-bit offset argument to a long. See staticFieldOffset.

Definition at line 347 of file Unsafe.java.

native void sun.misc.Unsafe.putLong ( long  address,
long  x 
)
native void sun.misc.Unsafe.putLongVolatile ( Object  o,
long  offset,
long  x 
)

Volatile version of putLong(Object, long, long)

void sun.misc.Unsafe.putObject ( Object  o,
int  offset,
Object  x 
)
Deprecated:
As of 1.4.1, cast the 32-bit offset argument to a long. See staticFieldOffset.

Definition at line 257 of file Unsafe.java.

native void sun.misc.Unsafe.putObject ( Object  o,
long  offset,
Object  x 
)

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.

See also:
putInt(Object, int, int)
native void sun.misc.Unsafe.putObjectVolatile ( Object  o,
long  offset,
Object  x 
)

Stores a reference value into a given Java variable, with volatile store semantics. Otherwise identical to putObject(Object, long, Object)

native void sun.misc.Unsafe.putOrderedInt ( Object  o,
long  offset,
int  x 
)

Ordered/Lazy version of putIntVolatile(Object, long, int)

native void sun.misc.Unsafe.putOrderedLong ( Object  o,
long  offset,
long  x 
)

Ordered/Lazy version of putLongVolatile(Object, long, long)

native void sun.misc.Unsafe.putOrderedObject ( Object  o,
long  offset,
Object  x 
)

Version of 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).

native void sun.misc.Unsafe.putShort ( Object  o,
long  offset,
short  x 
)
void sun.misc.Unsafe.putShort ( Object  o,
int  offset,
short  x 
)
Deprecated:
As of 1.4.1, cast the 32-bit offset argument to a long. See staticFieldOffset.

Definition at line 311 of file Unsafe.java.

native void sun.misc.Unsafe.putShort ( long  address,
short  x 
)
native void sun.misc.Unsafe.putShortVolatile ( Object  o,
long  offset,
short  x 
)

Volatile version of putShort(Object, long, short)

native long sun.misc.Unsafe.reallocateMemory ( long  address,
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, or resize it with reallocateMemory. The address passed to this method may be null, in which case an allocation will be performed.

Exceptions:
IllegalArgumentException if the size is negative or too large for the native size_t type
OutOfMemoryError if the allocation is refused by the system
See also:
allocateMemory
native void sun.misc.Unsafe.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 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(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
void sun.misc.Unsafe.setMemory ( long  address,
long  bytes,
byte  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(Object,long).

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

Definition at line 524 of file Unsafe.java.

Object sun.misc.Unsafe.staticFieldBase ( Class  c  ) 

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

 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;
 }
 

</blockquote>

Deprecated:
As of 1.4.1, use staticFieldBase(Field) to obtain the base pertaining to a specific Field. This method works only for JVMs which store all statics for a given class in one place.

Definition at line 619 of file Unsafe.java.

native Object sun.misc.Unsafe.staticFieldBase ( Field  f  ) 

Report the location of a given static field, in conjunction with staticFieldOffset.

Fetch the base "Object", if any, with which static fields of the given class can be accessed via methods like 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.

native long sun.misc.Unsafe.staticFieldOffset ( Field  f  ) 

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

See also:
getInt(Object, long)
native void sun.misc.Unsafe.throwException ( Throwable  ee  ) 

Throw the exception without telling the verifier.

native boolean sun.misc.Unsafe.tryMonitorEnter ( 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.

native void sun.misc.Unsafe.unpark ( Object  thread  ) 

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.

Member Data Documentation

final int sun.misc.Unsafe.ADDRESS_SIZE = theUnsafe.addressSize() [static]

The value of

Definition at line 793 of file Unsafe.java.

final int sun.misc.Unsafe.ARRAY_BOOLEAN_BASE_OFFSET = theUnsafe.arrayBaseOffset(boolean[].class) [static]

The value of

 arrayBaseOffset(boolean[].class) 

Definition at line 701 of file Unsafe.java.

final int sun.misc.Unsafe.ARRAY_BOOLEAN_INDEX_SCALE = theUnsafe.arrayIndexScale(boolean[].class) [static]

The value of

 arrayIndexScale(boolean[].class) 

Definition at line 750 of file Unsafe.java.

final int sun.misc.Unsafe.ARRAY_BYTE_BASE_OFFSET = theUnsafe.arrayBaseOffset(byte[].class) [static]

The value of

 arrayBaseOffset(byte[].class) 

Definition at line 705 of file Unsafe.java.

final int sun.misc.Unsafe.ARRAY_BYTE_INDEX_SCALE = theUnsafe.arrayIndexScale(byte[].class) [static]

The value of

 arrayIndexScale(byte[].class) 

Definition at line 754 of file Unsafe.java.

final int sun.misc.Unsafe.ARRAY_CHAR_BASE_OFFSET = theUnsafe.arrayBaseOffset(char[].class) [static]

The value of

 arrayBaseOffset(char[].class) 

Definition at line 713 of file Unsafe.java.

final int sun.misc.Unsafe.ARRAY_CHAR_INDEX_SCALE = theUnsafe.arrayIndexScale(char[].class) [static]

The value of

 arrayIndexScale(char[].class) 

Definition at line 762 of file Unsafe.java.

final int sun.misc.Unsafe.ARRAY_DOUBLE_BASE_OFFSET = theUnsafe.arrayBaseOffset(double[].class) [static]

The value of

 arrayBaseOffset(double[].class) 

Definition at line 729 of file Unsafe.java.

final int sun.misc.Unsafe.ARRAY_DOUBLE_INDEX_SCALE = theUnsafe.arrayIndexScale(double[].class) [static]

The value of

 arrayIndexScale(double[].class) 

Definition at line 778 of file Unsafe.java.

final int sun.misc.Unsafe.ARRAY_FLOAT_BASE_OFFSET = theUnsafe.arrayBaseOffset(float[].class) [static]

The value of

 arrayBaseOffset(float[].class) 

Definition at line 725 of file Unsafe.java.

final int sun.misc.Unsafe.ARRAY_FLOAT_INDEX_SCALE = theUnsafe.arrayIndexScale(float[].class) [static]

The value of

 arrayIndexScale(float[].class) 

Definition at line 774 of file Unsafe.java.

final int sun.misc.Unsafe.ARRAY_INT_BASE_OFFSET = theUnsafe.arrayBaseOffset(int[].class) [static]

The value of

 arrayBaseOffset(int[].class) 

Definition at line 717 of file Unsafe.java.

final int sun.misc.Unsafe.ARRAY_INT_INDEX_SCALE = theUnsafe.arrayIndexScale(int[].class) [static]

The value of

 arrayIndexScale(int[].class) 

Definition at line 766 of file Unsafe.java.

final int sun.misc.Unsafe.ARRAY_LONG_BASE_OFFSET = theUnsafe.arrayBaseOffset(long[].class) [static]

The value of

 arrayBaseOffset(long[].class) 

Definition at line 721 of file Unsafe.java.

final int sun.misc.Unsafe.ARRAY_LONG_INDEX_SCALE = theUnsafe.arrayIndexScale(long[].class) [static]

The value of

 arrayIndexScale(long[].class) 

Definition at line 770 of file Unsafe.java.

final int sun.misc.Unsafe.ARRAY_OBJECT_BASE_OFFSET = theUnsafe.arrayBaseOffset(Object[].class) [static]

The value of

 arrayBaseOffset(Object[].class) 

Definition at line 733 of file Unsafe.java.

final int sun.misc.Unsafe.ARRAY_OBJECT_INDEX_SCALE = theUnsafe.arrayIndexScale(Object[].class) [static]

The value of

 arrayIndexScale(Object[].class) 

Definition at line 782 of file Unsafe.java.

final int sun.misc.Unsafe.ARRAY_SHORT_BASE_OFFSET = theUnsafe.arrayBaseOffset(short[].class) [static]

The value of

 arrayBaseOffset(short[].class) 

Definition at line 709 of file Unsafe.java.

final int sun.misc.Unsafe.ARRAY_SHORT_INDEX_SCALE = theUnsafe.arrayIndexScale(short[].class) [static]

The value of

 arrayIndexScale(short[].class) 

Definition at line 758 of file Unsafe.java.

final int sun.misc.Unsafe.INVALID_FIELD_OFFSET = -1 [static]

random queries

This constant differs from all results that will ever be returned from staticFieldOffset, objectFieldOffset, or arrayBaseOffset.

Definition at line 575 of file Unsafe.java.


The documentation for this class was generated from the following file:
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