JDK 17 jdk.unsupported.jmod - Unsupported Module
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⏎ sun/misc/Unsafe.java
/*
* Copyright (c) 2000, 2021, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*
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*/
package sun.misc;
import jdk.internal.vm.annotation.ForceInline;
import jdk.internal.misc.VM;
import jdk.internal.reflect.CallerSensitive;
import jdk.internal.reflect.Reflection;
import java.lang.invoke.MethodHandles;
import java.lang.reflect.Field;
import java.util.Set;
/**
* 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.
*
* <em>Note:</em> It is the responsibility of the caller to make sure
* arguments are checked before methods of this class are
* called. While some rudimentary checks are performed on the input,
* the checks are best effort and when performance is an overriding
* priority, as when methods of this class are optimized by the
* runtime compiler, some or all checks (if any) may be elided. Hence,
* the caller must not rely on the checks and corresponding
* exceptions!
*
* @author John R. Rose
* @see #getUnsafe
*/
public final class Unsafe {
static {
Reflection.registerMethodsToFilter(Unsafe.class, Set.of("getUnsafe"));
}
private Unsafe() {}
private static final Unsafe theUnsafe = new Unsafe();
private static final jdk.internal.misc.Unsafe theInternalUnsafe = jdk.internal.misc.Unsafe.getUnsafe();
/**
* Provides the caller with the capability of performing unsafe
* operations.
*
* <p>The returned {@code 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.
*
* <p>Most methods in this class are very low-level, and correspond to a
* small number of hardware instructions (on typical machines). Compilers
* are encouraged to optimize these methods accordingly.
*
* <p>Here is a suggested idiom for using unsafe operations:
*
* <pre> {@code
* class MyTrustedClass {
* private static final Unsafe unsafe = Unsafe.getUnsafe();
* ...
* private long myCountAddress = ...;
* public int getCount() { return unsafe.getByte(myCountAddress); }
* }}</pre>
*
* (It may assist compilers to make the local variable {@code final}.)
*
* @throws SecurityException if the class loader of the caller
* class is not in the system domain in which all permissions
* are granted.
*/
@CallerSensitive
public static Unsafe getUnsafe() {
Class<?> caller = Reflection.getCallerClass();
if (!VM.isSystemDomainLoader(caller.getClassLoader()))
throw new SecurityException("Unsafe");
return theUnsafe;
}
/// peek and poke operations
/// (compilers should optimize these to memory ops)
// These work on object fields in the Java heap.
// They will not work on elements of packed arrays.
/**
* Fetches a value from a given Java variable.
* More specifically, fetches a field or array element within the given
* object {@code o} at the given offset, or (if {@code o} is null)
* from the memory address whose numerical value is the given offset.
* <p>
* The results are undefined unless one of the following cases is true:
* <ul>
* <li>The offset was obtained from {@link #objectFieldOffset} on
* the {@link java.lang.reflect.Field} of some Java field and the object
* referred to by {@code o} is of a class compatible with that
* field's class.
*
* <li>The offset and object reference {@code 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.
*
* <li>The object referred to by {@code o} is an array, and the offset
* is an integer of the form {@code B+N*S}, where {@code N} is
* a valid index into the array, and {@code B} and {@code S} are
* the values obtained by {@link #arrayBaseOffset} and {@link
* #arrayIndexScale} (respectively) from the array's class. The value
* referred to is the {@code N}<em>th</em> element of the array.
*
* </ul>
* <p>
* If one of the above cases is true, the call references a specific Java
* variable (field or array element). However, the results are undefined
* if that variable is not in fact of the type returned by this method.
* <p>
* This method refers to a variable by means of two parameters, and so
* it provides (in effect) a <em>double-register</em> addressing mode
* for Java variables. When the object reference is null, this method
* uses its offset as an absolute address. This is similar in operation
* to methods such as {@link #getInt(long)}, which provide (in effect) a
* <em>single-register</em> addressing mode for non-Java variables.
* However, because Java variables may have a different layout in memory
* from non-Java variables, programmers should not assume that these
* two addressing modes are ever equivalent. Also, programmers should
* remember that offsets from the double-register addressing mode cannot
* be portably confused with longs used in the single-register addressing
* mode.
*
* @param o Java heap object in which the variable resides, if any, else
* null
* @param offset indication of where the variable resides in a Java heap
* object, if any, else a memory address locating the variable
* statically
* @return the value fetched from the indicated Java variable
* @throws RuntimeException No defined exceptions are thrown, not even
* {@link NullPointerException}
*/
@ForceInline
public int getInt(Object o, long offset) {
return theInternalUnsafe.getInt(o, offset);
}
/**
* Stores a value into a given Java variable.
* <p>
* The first two parameters are interpreted exactly as with
* {@link #getInt(Object, long)} to refer to a specific
* Java variable (field or array element). The given value
* is stored into that variable.
* <p>
* The variable must be of the same type as the method
* parameter {@code x}.
*
* @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}
*/
@ForceInline
public void putInt(Object o, long offset, int x) {
theInternalUnsafe.putInt(o, offset, x);
}
/**
* Fetches a reference value from a given Java variable.
* @see #getInt(Object, long)
*/
@ForceInline
public Object getObject(Object o, long offset) {
return theInternalUnsafe.getReference(o, offset);
}
/**
* Stores a reference value into a given Java variable.
* <p>
* Unless the reference {@code x} being stored is either null
* or matches the field type, the results are undefined.
* If the reference {@code o} is non-null, card marks or
* other store barriers for that object (if the VM requires them)
* are updated.
* @see #putInt(Object, long, int)
*/
@ForceInline
public void putObject(Object o, long offset, Object x) {
theInternalUnsafe.putReference(o, offset, x);
}
/** @see #getInt(Object, long) */
@ForceInline
public boolean getBoolean(Object o, long offset) {
return theInternalUnsafe.getBoolean(o, offset);
}
/** @see #putInt(Object, long, int) */
@ForceInline
public void putBoolean(Object o, long offset, boolean x) {
theInternalUnsafe.putBoolean(o, offset, x);
}
/** @see #getInt(Object, long) */
@ForceInline
public byte getByte(Object o, long offset) {
return theInternalUnsafe.getByte(o, offset);
}
/** @see #putInt(Object, long, int) */
@ForceInline
public void putByte(Object o, long offset, byte x) {
theInternalUnsafe.putByte(o, offset, x);
}
/** @see #getInt(Object, long) */
@ForceInline
public short getShort(Object o, long offset) {
return theInternalUnsafe.getShort(o, offset);
}
/** @see #putInt(Object, long, int) */
@ForceInline
public void putShort(Object o, long offset, short x) {
theInternalUnsafe.putShort(o, offset, x);
}
/** @see #getInt(Object, long) */
@ForceInline
public char getChar(Object o, long offset) {
return theInternalUnsafe.getChar(o, offset);
}
/** @see #putInt(Object, long, int) */
@ForceInline
public void putChar(Object o, long offset, char x) {
theInternalUnsafe.putChar(o, offset, x);
}
/** @see #getInt(Object, long) */
@ForceInline
public long getLong(Object o, long offset) {
return theInternalUnsafe.getLong(o, offset);
}
/** @see #putInt(Object, long, int) */
@ForceInline
public void putLong(Object o, long offset, long x) {
theInternalUnsafe.putLong(o, offset, x);
}
/** @see #getInt(Object, long) */
@ForceInline
public float getFloat(Object o, long offset) {
return theInternalUnsafe.getFloat(o, offset);
}
/** @see #putInt(Object, long, int) */
@ForceInline
public void putFloat(Object o, long offset, float x) {
theInternalUnsafe.putFloat(o, offset, x);
}
/** @see #getInt(Object, long) */
@ForceInline
public double getDouble(Object o, long offset) {
return theInternalUnsafe.getDouble(o, offset);
}
/** @see #putInt(Object, long, int) */
@ForceInline
public void putDouble(Object o, long offset, double x) {
theInternalUnsafe.putDouble(o, 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
*/
@ForceInline
public byte getByte(long address) {
return theInternalUnsafe.getByte(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)
*/
@ForceInline
public void putByte(long address, byte x) {
theInternalUnsafe.putByte(address, x);
}
/** @see #getByte(long) */
@ForceInline
public short getShort(long address) {
return theInternalUnsafe.getShort(address);
}
/** @see #putByte(long, byte) */
@ForceInline
public void putShort(long address, short x) {
theInternalUnsafe.putShort(address, x);
}
/** @see #getByte(long) */
@ForceInline
public char getChar(long address) {
return theInternalUnsafe.getChar(address);
}
/** @see #putByte(long, byte) */
@ForceInline
public void putChar(long address, char x) {
theInternalUnsafe.putChar(address, x);
}
/** @see #getByte(long) */
@ForceInline
public int getInt(long address) {
return theInternalUnsafe.getInt(address);
}
/** @see #putByte(long, byte) */
@ForceInline
public void putInt(long address, int x) {
theInternalUnsafe.putInt(address, x);
}
/** @see #getByte(long) */
@ForceInline
public long getLong(long address) {
return theInternalUnsafe.getLong(address);
}
/** @see #putByte(long, byte) */
@ForceInline
public void putLong(long address, long x) {
theInternalUnsafe.putLong(address, x);
}
/** @see #getByte(long) */
@ForceInline
public float getFloat(long address) {
return theInternalUnsafe.getFloat(address);
}
/** @see #putByte(long, byte) */
@ForceInline
public void putFloat(long address, float x) {
theInternalUnsafe.putFloat(address, x);
}
/** @see #getByte(long) */
@ForceInline
public double getDouble(long address) {
return theInternalUnsafe.getDouble(address);
}
/** @see #putByte(long, byte) */
@ForceInline
public void putDouble(long address, double x) {
theInternalUnsafe.putDouble(address, x);
}
/**
* Fetches a native pointer from a given memory address. If the address is
* zero, or does not point into a block obtained from {@link
* #allocateMemory}, the results are undefined.
*
* <p>If the native pointer is less than 64 bits wide, it is extended as
* an unsigned number to a Java long. The pointer may be indexed by any
* given byte offset, simply by adding that offset (as a simple integer) to
* the long representing the pointer. The number of bytes actually read
* from the target address may be determined by consulting {@link
* #addressSize}.
*
* @see #allocateMemory
*/
@ForceInline
public long getAddress(long address) {
return theInternalUnsafe.getAddress(address);
}
/**
* Stores a native pointer into a given memory address. If the address is
* zero, or does not point into a block obtained from {@link
* #allocateMemory}, the results are undefined.
*
* <p>The number of bytes actually written at the target address may be
* determined by consulting {@link #addressSize}.
*
* @see #getAddress(long)
*/
@ForceInline
public void putAddress(long address, long x) {
theInternalUnsafe.putAddress(address, 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}.
*
* <em>Note:</em> It is the responsibility of the caller to make
* sure arguments are checked before the methods are called. While
* some rudimentary checks are performed on the input, the checks
* are best effort and when performance is an overriding priority,
* as when methods of this class are optimized by the runtime
* compiler, some or all checks (if any) may be elided. Hence, the
* caller must not rely on the checks and corresponding
* exceptions!
*
* @throws RuntimeException 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)
*/
@ForceInline
public long allocateMemory(long bytes) {
return theInternalUnsafe.allocateMemory(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.
*
* <em>Note:</em> It is the responsibility of the caller to make
* sure arguments are checked before the methods are called. While
* some rudimentary checks are performed on the input, the checks
* are best effort and when performance is an overriding priority,
* as when methods of this class are optimized by the runtime
* compiler, some or all checks (if any) may be elided. Hence, the
* caller must not rely on the checks and corresponding
* exceptions!
*
* @throws RuntimeException 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
*/
@ForceInline
public long reallocateMemory(long address, long bytes) {
return theInternalUnsafe.reallocateMemory(address, bytes);
}
/**
* Sets all bytes in a given block of memory to a fixed value
* (usually zero).
*
* <p>This method determines a block's base address by means of two parameters,
* and so it provides (in effect) a <em>double-register</em> addressing mode,
* as discussed in {@link #getInt(Object,long)}. When the object reference is null,
* the offset supplies an absolute base address.
*
* <p>The stores are in coherent (atomic) units of a size determined
* by the address and length parameters. If the effective address and
* length are all even modulo 8, the stores take place in 'long' units.
* If the effective address and length are (resp.) even modulo 4 or 2,
* the stores take place in units of 'int' or 'short'.
*
* <em>Note:</em> It is the responsibility of the caller to make
* sure arguments are checked before the methods are called. While
* some rudimentary checks are performed on the input, the checks
* are best effort and when performance is an overriding priority,
* as when methods of this class are optimized by the runtime
* compiler, some or all checks (if any) may be elided. Hence, the
* caller must not rely on the checks and corresponding
* exceptions!
*
* @throws RuntimeException if any of the arguments is invalid
*
* @since 1.7
*/
@ForceInline
public void setMemory(Object o, long offset, long bytes, byte value) {
theInternalUnsafe.setMemory(o, offset, bytes, value);
}
/**
* Sets all bytes in a given block of memory to a fixed value
* (usually zero). This provides a <em>single-register</em> addressing mode,
* as discussed in {@link #getInt(Object,long)}.
*
* <p>Equivalent to {@code setMemory(null, address, bytes, value)}.
*/
@ForceInline
public void setMemory(long address, long bytes, byte value) {
theInternalUnsafe.setMemory(address, bytes, value);
}
/**
* Sets all bytes in a given block of memory to a copy of another
* block.
*
* <p>This method determines each block's base address by means of two parameters,
* and so it provides (in effect) a <em>double-register</em> addressing mode,
* as discussed in {@link #getInt(Object,long)}. When the object reference is null,
* the offset supplies an absolute base address.
*
* <p>The transfers are in coherent (atomic) units of a size determined
* by the address and length parameters. If the effective addresses and
* length are all even modulo 8, the transfer takes place in 'long' units.
* If the effective addresses and length are (resp.) even modulo 4 or 2,
* the transfer takes place in units of 'int' or 'short'.
*
* <em>Note:</em> It is the responsibility of the caller to make
* sure arguments are checked before the methods are called. While
* some rudimentary checks are performed on the input, the checks
* are best effort and when performance is an overriding priority,
* as when methods of this class are optimized by the runtime
* compiler, some or all checks (if any) may be elided. Hence, the
* caller must not rely on the checks and corresponding
* exceptions!
*
* @throws RuntimeException if any of the arguments is invalid
*
* @since 1.7
*/
@ForceInline
public void copyMemory(Object srcBase, long srcOffset,
Object destBase, long destOffset,
long bytes) {
theInternalUnsafe.copyMemory(srcBase, srcOffset, destBase, destOffset, bytes);
}
/**
* Sets all bytes in a given block of memory to a copy of another
* block. This provides a <em>single-register</em> addressing mode,
* as discussed in {@link #getInt(Object,long)}.
*
* Equivalent to {@code copyMemory(null, srcAddress, null, destAddress, bytes)}.
*/
@ForceInline
public void copyMemory(long srcAddress, long destAddress, long bytes) {
theInternalUnsafe.copyMemory(srcAddress, 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.
*
* <em>Note:</em> It is the responsibility of the caller to make
* sure arguments are checked before the methods are called. While
* some rudimentary checks are performed on the input, the checks
* are best effort and when performance is an overriding priority,
* as when methods of this class are optimized by the runtime
* compiler, some or all checks (if any) may be elided. Hence, the
* caller must not rely on the checks and corresponding
* exceptions!
*
* @throws RuntimeException if any of the arguments is invalid
*
* @see #allocateMemory
*/
@ForceInline
public void freeMemory(long address) {
theInternalUnsafe.freeMemory(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 = jdk.internal.misc.Unsafe.INVALID_FIELD_OFFSET;
/**
* Reports the location of a given field in the storage allocation of its
* class. Do not expect to perform any sort of arithmetic on this offset;
* it is just a cookie which is passed to the unsafe heap memory accessors.
*
* <p>Any given field will always have the same offset and base, and no
* two distinct fields of the same class will ever have the same offset
* and base.
*
* <p>As of 1.4.1, offsets for fields are represented as long values,
* although the Sun JVM does not use the most significant 32 bits.
* However, JVM implementations which store static fields at absolute
* addresses can use long offsets and null base pointers to express
* the field locations in a form usable by {@link #getInt(Object,long)}.
* Therefore, code which will be ported to such JVMs on 64-bit platforms
* must preserve all bits of static field offsets.
* @see #getInt(Object, long)
*/
@ForceInline
public long objectFieldOffset(Field f) {
if (f == null) {
throw new NullPointerException();
}
Class<?> declaringClass = f.getDeclaringClass();
if (declaringClass.isHidden()) {
throw new UnsupportedOperationException("can't get field offset on a hidden class: " + f);
}
if (declaringClass.isRecord()) {
throw new UnsupportedOperationException("can't get field offset on a record class: " + f);
}
return theInternalUnsafe.objectFieldOffset(f);
}
/**
* Reports the location of a given static field, in conjunction with {@link
* #staticFieldBase}.
* <p>Do not expect to perform any sort of arithmetic on this offset;
* it is just a cookie which is passed to the unsafe heap memory accessors.
*
* <p>Any given field will always have the same offset, and no two distinct
* fields of the same class will ever have the same offset.
*
* <p>As of 1.4.1, offsets for fields are represented as long values,
* although the Sun JVM does not use the most significant 32 bits.
* It is hard to imagine a JVM technology which needs more than
* a few bits to encode an offset within a non-array object,
* However, for consistency with other methods in this class,
* this method reports its result as a long value.
* @see #getInt(Object, long)
*/
@ForceInline
public long staticFieldOffset(Field f) {
if (f == null) {
throw new NullPointerException();
}
Class<?> declaringClass = f.getDeclaringClass();
if (declaringClass.isHidden()) {
throw new UnsupportedOperationException("can't get field offset on a hidden class: " + f);
}
if (declaringClass.isRecord()) {
throw new UnsupportedOperationException("can't get field offset on a record class: " + f);
}
return theInternalUnsafe.staticFieldOffset(f);
}
/**
* Reports the location of a given static field, in conjunction with {@link
* #staticFieldOffset}.
* <p>Fetch the base "Object", if any, with which static fields of the
* given class can be accessed via methods like {@link #getInt(Object,
* long)}. This value may be null. This value may refer to an object
* which is a "cookie", not guaranteed to be a real Object, and it should
* not be used in any way except as argument to the get and put routines in
* this class.
*/
@ForceInline
public Object staticFieldBase(Field f) {
if (f == null) {
throw new NullPointerException();
}
Class<?> declaringClass = f.getDeclaringClass();
if (declaringClass.isHidden()) {
throw new UnsupportedOperationException("can't get base address on a hidden class: " + f);
}
if (declaringClass.isRecord()) {
throw new UnsupportedOperationException("can't get base address on a record class: " + f);
}
return theInternalUnsafe.staticFieldBase(f);
}
/**
* Detects if the given class may need to be initialized. This is often
* needed in conjunction with obtaining the static field base of a
* class.
*
* @deprecated No replacement API for this method. As multiple threads
* may be trying to initialize the same class or interface at the same time.
* The only reliable result returned by this method is {@code false}
* indicating that the given class has been initialized. Instead, simply
* call {@link java.lang.invoke.MethodHandles.Lookup#ensureInitialized(Class)}
* that does nothing if the given class has already been initialized.
* This method is subject to removal in a future version of JDK.
*
* @return false only if a call to {@code ensureClassInitialized} would have no effect
*
*/
@Deprecated(since = "15", forRemoval = true)
@ForceInline
public boolean shouldBeInitialized(Class<?> c) {
return theInternalUnsafe.shouldBeInitialized(c);
}
/**
* Ensures the given class has been initialized. This is often
* needed in conjunction with obtaining the static field base of a
* class.
*
* @deprecated Use the {@link java.lang.invoke.MethodHandles.Lookup#ensureInitialized(Class)}
* method instead. This method is subject to removal in a future version of JDK.
*/
@Deprecated(since = "15", forRemoval = true)
@ForceInline
public void ensureClassInitialized(Class<?> c) {
theInternalUnsafe.ensureClassInitialized(c);
}
/**
* Reports 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)
*/
@ForceInline
public int arrayBaseOffset(Class<?> arrayClass) {
return theInternalUnsafe.arrayBaseOffset(arrayClass);
}
/** The value of {@code arrayBaseOffset(boolean[].class)} */
public static final int ARRAY_BOOLEAN_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_BOOLEAN_BASE_OFFSET;
/** The value of {@code arrayBaseOffset(byte[].class)} */
public static final int ARRAY_BYTE_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_BYTE_BASE_OFFSET;
/** The value of {@code arrayBaseOffset(short[].class)} */
public static final int ARRAY_SHORT_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_SHORT_BASE_OFFSET;
/** The value of {@code arrayBaseOffset(char[].class)} */
public static final int ARRAY_CHAR_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_CHAR_BASE_OFFSET;
/** The value of {@code arrayBaseOffset(int[].class)} */
public static final int ARRAY_INT_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_INT_BASE_OFFSET;
/** The value of {@code arrayBaseOffset(long[].class)} */
public static final int ARRAY_LONG_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_LONG_BASE_OFFSET;
/** The value of {@code arrayBaseOffset(float[].class)} */
public static final int ARRAY_FLOAT_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_FLOAT_BASE_OFFSET;
/** The value of {@code arrayBaseOffset(double[].class)} */
public static final int ARRAY_DOUBLE_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_DOUBLE_BASE_OFFSET;
/** The value of {@code arrayBaseOffset(Object[].class)} */
public static final int ARRAY_OBJECT_BASE_OFFSET = jdk.internal.misc.Unsafe.ARRAY_OBJECT_BASE_OFFSET;
/**
* Reports 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, long)}, so the scale factor for such classes is reported
* as zero.
*
* @see #arrayBaseOffset
* @see #getInt(Object, long)
* @see #putInt(Object, long, int)
*/
@ForceInline
public int arrayIndexScale(Class<?> arrayClass) {
return theInternalUnsafe.arrayIndexScale(arrayClass);
}
/** The value of {@code arrayIndexScale(boolean[].class)} */
public static final int ARRAY_BOOLEAN_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_BOOLEAN_INDEX_SCALE;
/** The value of {@code arrayIndexScale(byte[].class)} */
public static final int ARRAY_BYTE_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_BYTE_INDEX_SCALE;
/** The value of {@code arrayIndexScale(short[].class)} */
public static final int ARRAY_SHORT_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_SHORT_INDEX_SCALE;
/** The value of {@code arrayIndexScale(char[].class)} */
public static final int ARRAY_CHAR_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_CHAR_INDEX_SCALE;
/** The value of {@code arrayIndexScale(int[].class)} */
public static final int ARRAY_INT_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_INT_INDEX_SCALE;
/** The value of {@code arrayIndexScale(long[].class)} */
public static final int ARRAY_LONG_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_LONG_INDEX_SCALE;
/** The value of {@code arrayIndexScale(float[].class)} */
public static final int ARRAY_FLOAT_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_FLOAT_INDEX_SCALE;
/** The value of {@code arrayIndexScale(double[].class)} */
public static final int ARRAY_DOUBLE_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_DOUBLE_INDEX_SCALE;
/** The value of {@code arrayIndexScale(Object[].class)} */
public static final int ARRAY_OBJECT_INDEX_SCALE = jdk.internal.misc.Unsafe.ARRAY_OBJECT_INDEX_SCALE;
/**
* Reports 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.
*/
@ForceInline
public int addressSize() {
return theInternalUnsafe.addressSize();
}
/** The value of {@code addressSize()} */
public static final int ADDRESS_SIZE = theInternalUnsafe.addressSize();
/**
* Reports the size in bytes of a native memory page (whatever that is).
* This value will always be a power of two.
*/
@ForceInline
public int pageSize() {
return theInternalUnsafe.pageSize();
}
/// random trusted operations from JNI:
/**
* Allocates an instance but does not run any constructor.
* Initializes the class if it has not yet been.
*/
@ForceInline
public Object allocateInstance(Class<?> cls)
throws InstantiationException {
return theInternalUnsafe.allocateInstance(cls);
}
/** Throws the exception without telling the verifier. */
@ForceInline
public void throwException(Throwable ee) {
theInternalUnsafe.throwException(ee);
}
/**
* Atomically updates Java variable to {@code x} if it is currently
* holding {@code expected}.
*
* <p>This operation has memory semantics of a {@code volatile} read
* and write. Corresponds to C11 atomic_compare_exchange_strong.
*
* @return {@code true} if successful
*/
@ForceInline
public final boolean compareAndSwapObject(Object o, long offset,
Object expected,
Object x) {
return theInternalUnsafe.compareAndSetReference(o, offset, expected, x);
}
/**
* Atomically updates Java variable to {@code x} if it is currently
* holding {@code expected}.
*
* <p>This operation has memory semantics of a {@code volatile} read
* and write. Corresponds to C11 atomic_compare_exchange_strong.
*
* @return {@code true} if successful
*/
@ForceInline
public final boolean compareAndSwapInt(Object o, long offset,
int expected,
int x) {
return theInternalUnsafe.compareAndSetInt(o, offset, expected, x);
}
/**
* Atomically updates Java variable to {@code x} if it is currently
* holding {@code expected}.
*
* <p>This operation has memory semantics of a {@code volatile} read
* and write. Corresponds to C11 atomic_compare_exchange_strong.
*
* @return {@code true} if successful
*/
@ForceInline
public final boolean compareAndSwapLong(Object o, long offset,
long expected,
long x) {
return theInternalUnsafe.compareAndSetLong(o, offset, expected, x);
}
/**
* Fetches a reference value from a given Java variable, with volatile
* load semantics. Otherwise identical to {@link #getObject(Object, long)}
*/
@ForceInline
public Object getObjectVolatile(Object o, long offset) {
return theInternalUnsafe.getReferenceVolatile(o, offset);
}
/**
* Stores a reference value into a given Java variable, with
* volatile store semantics. Otherwise identical to {@link #putObject(Object, long, Object)}
*/
@ForceInline
public void putObjectVolatile(Object o, long offset, Object x) {
theInternalUnsafe.putReferenceVolatile(o, offset, x);
}
/** Volatile version of {@link #getInt(Object, long)} */
@ForceInline
public int getIntVolatile(Object o, long offset) {
return theInternalUnsafe.getIntVolatile(o, offset);
}
/** Volatile version of {@link #putInt(Object, long, int)} */
@ForceInline
public void putIntVolatile(Object o, long offset, int x) {
theInternalUnsafe.putIntVolatile(o, offset, x);
}
/** Volatile version of {@link #getBoolean(Object, long)} */
@ForceInline
public boolean getBooleanVolatile(Object o, long offset) {
return theInternalUnsafe.getBooleanVolatile(o, offset);
}
/** Volatile version of {@link #putBoolean(Object, long, boolean)} */
@ForceInline
public void putBooleanVolatile(Object o, long offset, boolean x) {
theInternalUnsafe.putBooleanVolatile(o, offset, x);
}
/** Volatile version of {@link #getByte(Object, long)} */
@ForceInline
public byte getByteVolatile(Object o, long offset) {
return theInternalUnsafe.getByteVolatile(o, offset);
}
/** Volatile version of {@link #putByte(Object, long, byte)} */
@ForceInline
public void putByteVolatile(Object o, long offset, byte x) {
theInternalUnsafe.putByteVolatile(o, offset, x);
}
/** Volatile version of {@link #getShort(Object, long)} */
@ForceInline
public short getShortVolatile(Object o, long offset) {
return theInternalUnsafe.getShortVolatile(o, offset);
}
/** Volatile version of {@link #putShort(Object, long, short)} */
@ForceInline
public void putShortVolatile(Object o, long offset, short x) {
theInternalUnsafe.putShortVolatile(o, offset, x);
}
/** Volatile version of {@link #getChar(Object, long)} */
@ForceInline
public char getCharVolatile(Object o, long offset) {
return theInternalUnsafe.getCharVolatile(o, offset);
}
/** Volatile version of {@link #putChar(Object, long, char)} */
@ForceInline
public void putCharVolatile(Object o, long offset, char x) {
theInternalUnsafe.putCharVolatile(o, offset, x);
}
/** Volatile version of {@link #getLong(Object, long)} */
@ForceInline
public long getLongVolatile(Object o, long offset) {
return theInternalUnsafe.getLongVolatile(o, offset);
}
/** Volatile version of {@link #putLong(Object, long, long)} */
@ForceInline
public void putLongVolatile(Object o, long offset, long x) {
theInternalUnsafe.putLongVolatile(o, offset, x);
}
/** Volatile version of {@link #getFloat(Object, long)} */
@ForceInline
public float getFloatVolatile(Object o, long offset) {
return theInternalUnsafe.getFloatVolatile(o, offset);
}
/** Volatile version of {@link #putFloat(Object, long, float)} */
@ForceInline
public void putFloatVolatile(Object o, long offset, float x) {
theInternalUnsafe.putFloatVolatile(o, offset, x);
}
/** Volatile version of {@link #getDouble(Object, long)} */
@ForceInline
public double getDoubleVolatile(Object o, long offset) {
return theInternalUnsafe.getDoubleVolatile(o, offset);
}
/** Volatile version of {@link #putDouble(Object, long, double)} */
@ForceInline
public void putDoubleVolatile(Object o, long offset, double x) {
theInternalUnsafe.putDoubleVolatile(o, offset, 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).
*
* Corresponds to C11 atomic_store_explicit(..., memory_order_release).
*/
@ForceInline
public void putOrderedObject(Object o, long offset, Object x) {
theInternalUnsafe.putReferenceRelease(o, offset, x);
}
/** Ordered/Lazy version of {@link #putIntVolatile(Object, long, int)} */
@ForceInline
public void putOrderedInt(Object o, long offset, int x) {
theInternalUnsafe.putIntRelease(o, offset, x);
}
/** Ordered/Lazy version of {@link #putLongVolatile(Object, long, long)} */
@ForceInline
public void putOrderedLong(Object o, long offset, long x) {
theInternalUnsafe.putLongRelease(o, offset, x);
}
/**
* Unblocks the given thread blocked on {@code park}, or, if it is
* not blocked, causes the subsequent call to {@code 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.
*/
@ForceInline
public void unpark(Object thread) {
theInternalUnsafe.unpark(thread);
}
/**
* Blocks current thread, returning when a balancing
* {@code unpark} occurs, or a balancing {@code 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 {@code unpark} is, so it would be strange to place it
* elsewhere.
*/
@ForceInline
public void park(boolean isAbsolute, long time) {
theInternalUnsafe.park(isAbsolute, 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 {@code nelem} samples and
* assigns to the elements of the given {@code loadavg} array.
* The system imposes a maximum of 3 samples, representing
* averages over the last 1, 5, and 15 minutes, respectively.
*
* @param loadavg an array of double of size nelems
* @param 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.
*/
@ForceInline
public int getLoadAverage(double[] loadavg, int nelems) {
return theInternalUnsafe.getLoadAverage(loadavg, nelems);
}
// The following contain CAS-based Java implementations used on
// platforms not supporting native instructions
/**
* Atomically adds the given value to the current value of a field
* or array element within the given object {@code o}
* at the given {@code offset}.
*
* @param o object/array to update the field/element in
* @param offset field/element offset
* @param delta the value to add
* @return the previous value
* @since 1.8
*/
@ForceInline
public final int getAndAddInt(Object o, long offset, int delta) {
return theInternalUnsafe.getAndAddInt(o, offset, delta);
}
/**
* Atomically adds the given value to the current value of a field
* or array element within the given object {@code o}
* at the given {@code offset}.
*
* @param o object/array to update the field/element in
* @param offset field/element offset
* @param delta the value to add
* @return the previous value
* @since 1.8
*/
@ForceInline
public final long getAndAddLong(Object o, long offset, long delta) {
return theInternalUnsafe.getAndAddLong(o, offset, delta);
}
/**
* Atomically exchanges the given value with the current value of
* a field or array element within the given object {@code o}
* at the given {@code offset}.
*
* @param o object/array to update the field/element in
* @param offset field/element offset
* @param newValue new value
* @return the previous value
* @since 1.8
*/
@ForceInline
public final int getAndSetInt(Object o, long offset, int newValue) {
return theInternalUnsafe.getAndSetInt(o, offset, newValue);
}
/**
* Atomically exchanges the given value with the current value of
* a field or array element within the given object {@code o}
* at the given {@code offset}.
*
* @param o object/array to update the field/element in
* @param offset field/element offset
* @param newValue new value
* @return the previous value
* @since 1.8
*/
@ForceInline
public final long getAndSetLong(Object o, long offset, long newValue) {
return theInternalUnsafe.getAndSetLong(o, offset, newValue);
}
/**
* Atomically exchanges the given reference value with the current
* reference value of a field or array element within the given
* object {@code o} at the given {@code offset}.
*
* @param o object/array to update the field/element in
* @param offset field/element offset
* @param newValue new value
* @return the previous value
* @since 1.8
*/
@ForceInline
public final Object getAndSetObject(Object o, long offset, Object newValue) {
return theInternalUnsafe.getAndSetReference(o, offset, newValue);
}
/**
* Ensures that loads before the fence will not be reordered with loads and
* stores after the fence; a "LoadLoad plus LoadStore barrier".
*
* Corresponds to C11 atomic_thread_fence(memory_order_acquire)
* (an "acquire fence").
*
* A pure LoadLoad fence is not provided, since the addition of LoadStore
* is almost always desired, and most current hardware instructions that
* provide a LoadLoad barrier also provide a LoadStore barrier for free.
* @since 1.8
*/
@ForceInline
public void loadFence() {
theInternalUnsafe.loadFence();
}
/**
* Ensures that loads and stores before the fence will not be reordered with
* stores after the fence; a "StoreStore plus LoadStore barrier".
*
* Corresponds to C11 atomic_thread_fence(memory_order_release)
* (a "release fence").
*
* A pure StoreStore fence is not provided, since the addition of LoadStore
* is almost always desired, and most current hardware instructions that
* provide a StoreStore barrier also provide a LoadStore barrier for free.
* @since 1.8
*/
@ForceInline
public void storeFence() {
theInternalUnsafe.storeFence();
}
/**
* Ensures that loads and stores before the fence will not be reordered
* with loads and stores after the fence. Implies the effects of both
* loadFence() and storeFence(), and in addition, the effect of a StoreLoad
* barrier.
*
* Corresponds to C11 atomic_thread_fence(memory_order_seq_cst).
* @since 1.8
*/
@ForceInline
public void fullFence() {
theInternalUnsafe.fullFence();
}
/**
* Invokes the given direct byte buffer's cleaner, if any.
*
* @param directBuffer a direct byte buffer
* @throws NullPointerException if {@code directBuffer} is null
* @throws IllegalArgumentException if {@code directBuffer} is non-direct,
* or is a {@link java.nio.Buffer#slice slice}, or is a
* {@link java.nio.Buffer#duplicate duplicate}
* @since 9
*/
public void invokeCleaner(java.nio.ByteBuffer directBuffer) {
if (!directBuffer.isDirect())
throw new IllegalArgumentException("buffer is non-direct");
theInternalUnsafe.invokeCleaner(directBuffer);
}
}
⏎ sun/misc/Unsafe.java
Or download all of them as a single archive file:
File name: jdk.unsupported-17.0.5-src.zip File size: 18533 bytes Release date: 2022-09-13 Download
⇒ JDK 17 jdk.unsupported.desktop.jmod - Unsupported Desktop Module
2022-11-07, 1054👍, 0💬
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