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); }
+ * }
+ * final.)
+ *
+ * @exception SecurityException if a security manager exists and its
+ * checkPropertiesAccess 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 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: + *
o is of a class compatible with that
+ * field's class.
+ *
+ * o (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.
+ *
+ * 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 {@link #arrayBaseOffset} and {@link
+ * #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 {@link #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. + * + * @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. + *
+ * 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. + *
+ * The variable must be of the same type as the method
+ * parameter x.
+ *
+ * @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.
+ *
+ * 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 #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.
+ *
+ *
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. + * + *
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). + * + *
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 {@link #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 + */ + 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 single-register addressing mode, + * as discussed in {@link #getInt(Object,long)}. + * + *
Equivalent to setMemory(null, address, bytes, value).
+ */
+ 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.
+ *
+ *
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 {@link #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
+ */
+ 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 single-register addressing mode,
+ * as discussed in {@link #getInt(Object,long)}.
+ *
+ * Equivalent to copyMemory(null, srcAddress, null, destAddress, bytes).
+ */
+ 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:
+ *
+ * public int fieldOffset(Field f) {
+ * if (Modifier.isStatic(f.getModifiers()))
+ * return (int) staticFieldOffset(f);
+ * else
+ * return (int) objectFieldOffset(f);
+ * }
+ *
+ * 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;
+ * }
+ * 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 {@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}. + *
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 #getInt(Object, long) + */ + public native long objectFieldOffset(Field f); + + /** + * Report the location of a given static field, in conjunction with {@link + * #staticFieldOffset}. + *
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 x if it is currently + * holding expected. + * @return true if successful + */ + public final native boolean compareAndSwapObject(Object o, long offset, + Object expected, + Object x); + + /** + * Atomically update Java variable to x if it is currently + * holding expected. + * @return true if successful + */ + public final native boolean compareAndSwapInt(Object o, long offset, + int expected, + int x); + + /** + * Atomically update Java variable to x if it is currently + * holding expected. + * @return true 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 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. + * @param 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 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 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. + * + * @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); +}