2362N/A * Copyright (c) 2000, 2009, Oracle and/or its affiliates. All rights reserved. 0N/A * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 0N/A * This code is free software; you can redistribute it and/or modify it 0N/A * under the terms of the GNU General Public License version 2 only, as 2362N/A * published by the Free Software Foundation. Oracle designates this 0N/A * particular file as subject to the "Classpath" exception as provided 2362N/A * by Oracle in the LICENSE file that accompanied this code. 0N/A * This code is distributed in the hope that it will be useful, but WITHOUT 0N/A * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 0N/A * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 0N/A * version 2 for more details (a copy is included in the LICENSE file that 0N/A * accompanied this code). 0N/A * You should have received a copy of the GNU General Public License version 0N/A * 2 along with this work; if not, write to the Free Software Foundation, 0N/A * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 2362N/A * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 2362N/A * or visit www.oracle.com if you need additional information or have any 0N/A * A collection of methods for performing low-level, unsafe operations. 0N/A * Although the class and all methods are public, use of this class is 0N/A * limited because only trusted code can obtain instances of it. 0N/A * @author John R. Rose 0N/A * Provides the caller with the capability of performing unsafe 0N/A * <p> The returned <code>Unsafe</code> object should be carefully guarded 0N/A * by the caller, since it can be used to read and write data at arbitrary 0N/A * memory addresses. It must never be passed to untrusted code. 0N/A * <p> Most methods in this class are very low-level, and correspond to a 0N/A * small number of hardware instructions (on typical machines). Compilers 0N/A * are encouraged to optimize these methods accordingly. 0N/A * <p> Here is a suggested idiom for using unsafe operations: 0N/A * class MyTrustedClass { 0N/A * private static final Unsafe unsafe = Unsafe.getUnsafe(); 0N/A * private long myCountAddress = ...; 0N/A * public int getCount() { return unsafe.getByte(myCountAddress); } 0N/A * </pre></blockquote> 0N/A * (It may assist compilers to make the local variable be 0N/A * <code>final</code>.) 0N/A * @exception SecurityException if a security manager exists and its 0N/A * <code>checkPropertiesAccess</code> method doesn't allow 0N/A * access to the system properties. 0N/A /// peek and poke operations 0N/A /// (compilers should optimize these to memory ops) 0N/A // These work on object fields in the Java heap. 0N/A // They will not work on elements of packed arrays. 0N/A * Fetches a value from a given Java variable. 0N/A * More specifically, fetches a field or array element within the given 0N/A * object <code>o</code> at the given offset, or (if <code>o</code> is 0N/A * null) from the memory address whose numerical value is the given 0N/A * The results are undefined unless one of the following cases is true: 0N/A * <li>The offset was obtained from {@link #objectFieldOffset} on 0N/A * the {@link java.lang.reflect.Field} of some Java field and the object 0N/A * referred to by <code>o</code> is of a class compatible with that 0N/A * <li>The offset and object reference <code>o</code> (either null or 0N/A * non-null) were both obtained via {@link #staticFieldOffset} 0N/A * and {@link #staticFieldBase} (respectively) from the 0N/A * reflective {@link Field} representation of some Java field. 0N/A * <li>The object referred to by <code>o</code> is an array, and the offset 0N/A * is an integer of the form <code>B+N*S</code>, where <code>N</code> is 0N/A * a valid index into the array, and <code>B</code> and <code>S</code> are 0N/A * the values obtained by {@link #arrayBaseOffset} and {@link 0N/A * #arrayIndexScale} (respectively) from the array's class. The value 0N/A * referred to is the <code>N</code><em>th</em> element of the array. 0N/A * If one of the above cases is true, the call references a specific Java 0N/A * variable (field or array element). However, the results are undefined 0N/A * if that variable is not in fact of the type returned by this method. 0N/A * This method refers to a variable by means of two parameters, and so 0N/A * it provides (in effect) a <em>double-register</em> addressing mode 0N/A * for Java variables. When the object reference is null, this method 0N/A * uses its offset as an absolute address. This is similar in operation 0N/A * to methods such as {@link #getInt(long)}, which provide (in effect) a 0N/A * <em>single-register</em> addressing mode for non-Java variables. 0N/A * However, because Java variables may have a different layout in memory 0N/A * from non-Java variables, programmers should not assume that these 0N/A * two addressing modes are ever equivalent. Also, programmers should 0N/A * remember that offsets from the double-register addressing mode cannot 0N/A * be portably confused with longs used in the single-register addressing 0N/A * @param o Java heap object in which the variable resides, if any, else 0N/A * @param offset indication of where the variable resides in a Java heap 0N/A * object, if any, else a memory address locating the variable 0N/A * @return the value fetched from the indicated Java variable 0N/A * @throws RuntimeException No defined exceptions are thrown, not even 0N/A * {@link NullPointerException} 0N/A * Stores a value into a given Java variable. 0N/A * The first two parameters are interpreted exactly as with 0N/A * {@link #getInt(Object, long)} to refer to a specific 0N/A * Java variable (field or array element). The given value 0N/A * is stored into that variable. 0N/A * The variable must be of the same type as the method 0N/A * parameter <code>x</code>. 0N/A * @param o Java heap object in which the variable resides, if any, else 0N/A * @param offset indication of where the variable resides in a Java heap 0N/A * object, if any, else a memory address locating the variable 0N/A * @param x the value to store into the indicated Java variable 0N/A * @throws RuntimeException No defined exceptions are thrown, not even 0N/A * {@link NullPointerException} 0N/A * Fetches a reference value from a given Java variable. 0N/A * @see #getInt(Object, long) 0N/A * Stores a reference value into a given Java variable. 0N/A * Unless the reference <code>x</code> being stored is either null 0N/A * or matches the field type, the results are undefined. 0N/A * If the reference <code>o</code> is non-null, car marks or 0N/A * other store barriers for that object (if the VM requires them) 0N/A * @see #putInt(Object, int, int) 0N/A /** @see #getInt(Object, long) */ 0N/A /** @see #putInt(Object, int, int) */ 0N/A /** @see #getInt(Object, long) */ 0N/A /** @see #putInt(Object, int, int) */ 0N/A /** @see #getInt(Object, long) */ 0N/A /** @see #putInt(Object, int, int) */ 0N/A /** @see #getInt(Object, long) */ 0N/A /** @see #putInt(Object, int, int) */ 0N/A /** @see #getInt(Object, long) */ 0N/A /** @see #putInt(Object, int, int) */ 0N/A /** @see #getInt(Object, long) */ 0N/A /** @see #putInt(Object, int, int) */ 0N/A /** @see #getInt(Object, long) */ 0N/A /** @see #putInt(Object, int, int) */ 0N/A * This method, like all others with 32-bit offsets, was native 0N/A * in a previous release but is now a wrapper which simply casts 0N/A * the offset to a long value. It provides backward compatibility 0N/A * with bytecodes compiled against 1.4. 0N/A * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long. 0N/A * See {@link #staticFieldOffset}. 0N/A * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long. 0N/A * See {@link #staticFieldOffset}. 0N/A * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long. 0N/A * See {@link #staticFieldOffset}. 0N/A * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long. 0N/A * See {@link #staticFieldOffset}. 0N/A * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long. 0N/A * See {@link #staticFieldOffset}. 0N/A * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long. 0N/A * See {@link #staticFieldOffset}. 0N/A * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long. 0N/A * See {@link #staticFieldOffset}. 0N/A * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long. 0N/A * See {@link #staticFieldOffset}. 0N/A * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long. 0N/A * See {@link #staticFieldOffset}. 0N/A * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long. 0N/A * See {@link #staticFieldOffset}. 0N/A * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long. 0N/A * See {@link #staticFieldOffset}. 0N/A * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long. 0N/A * See {@link #staticFieldOffset}. 0N/A * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long. 0N/A * See {@link #staticFieldOffset}. 0N/A * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long. 0N/A * See {@link #staticFieldOffset}. 0N/A * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long. 0N/A * See {@link #staticFieldOffset}. 0N/A * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long. 0N/A * See {@link #staticFieldOffset}. 0N/A * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long. 0N/A * See {@link #staticFieldOffset}. 0N/A * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long. 0N/A * See {@link #staticFieldOffset}. 0N/A // These work on values in the C heap. 0N/A * Fetches a value from a given memory address. If the address is zero, or 0N/A * does not point into a block obtained from {@link #allocateMemory}, the 0N/A * results are undefined. 0N/A * @see #allocateMemory 0N/A * Stores a value into a given memory address. If the address is zero, or 0N/A * does not point into a block obtained from {@link #allocateMemory}, the 0N/A * results are undefined. 0N/A * @see #getByte(long) 0N/A /** @see #getByte(long) */ 0N/A /** @see #putByte(long, byte) */ 0N/A /** @see #getByte(long) */ 0N/A /** @see #putByte(long, byte) */ 0N/A /** @see #getByte(long) */ 0N/A /** @see #putByte(long, byte) */ 0N/A /** @see #getByte(long) */ 0N/A /** @see #putByte(long, byte) */ 0N/A /** @see #getByte(long) */ 0N/A /** @see #putByte(long, byte) */ 0N/A /** @see #getByte(long) */ 0N/A /** @see #putByte(long, byte) */ 0N/A * Fetches a native pointer from a given memory address. If the address is 0N/A * zero, or does not point into a block obtained from {@link 0N/A * #allocateMemory}, the results are undefined. 0N/A * <p> If the native pointer is less than 64 bits wide, it is extended as 0N/A * an unsigned number to a Java long. The pointer may be indexed by any 0N/A * given byte offset, simply by adding that offset (as a simple integer) to 0N/A * the long representing the pointer. The number of bytes actually read 0N/A * from the target address maybe determined by consulting {@link 0N/A * @see #allocateMemory 0N/A * Stores a native pointer into a given memory address. If the address is 0N/A * zero, or does not point into a block obtained from {@link 0N/A * #allocateMemory}, the results are undefined. 0N/A * <p> The number of bytes actually written at the target address maybe 0N/A * determined by consulting {@link #addressSize}. 0N/A * @see #getAddress(long) 0N/A /// wrappers for malloc, realloc, free: 0N/A * Allocates a new block of native memory, of the given size in bytes. The 0N/A * contents of the memory are uninitialized; they will generally be 0N/A * garbage. The resulting native pointer will never be zero, and will be 0N/A * aligned for all value types. Dispose of this memory by calling {@link 0N/A * #freeMemory}, or resize it with {@link #reallocateMemory}. 0N/A * @throws IllegalArgumentException if the size is negative or too large 0N/A * for the native size_t type 0N/A * @throws OutOfMemoryError if the allocation is refused by the system 0N/A * @see #getByte(long) 0N/A * @see #putByte(long, byte) 0N/A * Resizes a new block of native memory, to the given size in bytes. The 0N/A * contents of the new block past the size of the old block are 0N/A * uninitialized; they will generally be garbage. The resulting native 0N/A * pointer will be zero if and only if the requested size is zero. The 0N/A * resulting native pointer will be aligned for all value types. Dispose 0N/A * of this memory by calling {@link #freeMemory}, or resize it with {@link 0N/A * #reallocateMemory}. The address passed to this method may be null, in 0N/A * which case an allocation will be performed. 0N/A * @throws IllegalArgumentException if the size is negative or too large 0N/A * for the native size_t type 0N/A * @throws OutOfMemoryError if the allocation is refused by the system 0N/A * @see #allocateMemory 0N/A * Sets all bytes in a given block of memory to a fixed value 0N/A * <p>This method determines a block's base address by means of two parameters, 0N/A * and so it provides (in effect) a <em>double-register</em> addressing mode, 0N/A * as discussed in {@link #getInt(Object,long)}. When the object reference is null, 0N/A * the offset supplies an absolute base address. 0N/A * <p>The stores are in coherent (atomic) units of a size determined 0N/A * by the address and length parameters. If the effective address and 0N/A * length are all even modulo 8, the stores take place in 'long' units. 0N/A * If the effective address and length are (resp.) even modulo 4 or 2, 0N/A * the stores take place in units of 'int' or 'short'. 0N/A * Sets all bytes in a given block of memory to a fixed value 0N/A * (usually zero). This provides a <em>single-register</em> addressing mode, 0N/A * as discussed in {@link #getInt(Object,long)}. 0N/A * <p>Equivalent to <code>setMemory(null, address, bytes, value)</code>. 0N/A * Sets all bytes in a given block of memory to a copy of another 0N/A * <p>This method determines each block's base address by means of two parameters, 0N/A * and so it provides (in effect) a <em>double-register</em> addressing mode, 0N/A * as discussed in {@link #getInt(Object,long)}. When the object reference is null, 0N/A * the offset supplies an absolute base address. 0N/A * <p>The transfers are in coherent (atomic) units of a size determined 0N/A * by the address and length parameters. If the effective addresses and 0N/A * length are all even modulo 8, the transfer takes place in 'long' units. 0N/A * If the effective addresses and length are (resp.) even modulo 4 or 2, 0N/A * the transfer takes place in units of 'int' or 'short'. 0N/A * Sets all bytes in a given block of memory to a copy of another 0N/A * block. This provides a <em>single-register</em> addressing mode, 0N/A * as discussed in {@link #getInt(Object,long)}. 0N/A * Equivalent to <code>copyMemory(null, srcAddress, null, destAddress, bytes)</code>. 0N/A * Disposes of a block of native memory, as obtained from {@link 0N/A * #allocateMemory} or {@link #reallocateMemory}. The address passed to 0N/A * this method may be null, in which case no action is taken. 0N/A * @see #allocateMemory 0N/A * This constant differs from all results that will ever be returned from 0N/A * {@link #staticFieldOffset}, {@link #objectFieldOffset}, 0N/A * or {@link #arrayBaseOffset}. 0N/A * Returns the offset of a field, truncated to 32 bits. 0N/A * This method is implemented as follows: 0N/A * public int fieldOffset(Field f) { 0N/A * if (Modifier.isStatic(f.getModifiers())) 0N/A * return (int) staticFieldOffset(f); 0N/A * return (int) objectFieldOffset(f); 0N/A * </pre></blockquote> 0N/A * @deprecated As of 1.4.1, use {@link #staticFieldOffset} for static 0N/A * fields and {@link #objectFieldOffset} for non-static fields. 0N/A * Returns the base address for accessing some static field 0N/A * in the given class. This method is implemented as follows: 0N/A * public Object staticFieldBase(Class c) { 0N/A * Field[] fields = c.getDeclaredFields(); 0N/A * for (int i = 0; i < fields.length; i++) { 0N/A * if (Modifier.isStatic(fields[i].getModifiers())) { 0N/A * return staticFieldBase(fields[i]); 0N/A * </pre></blockquote> 0N/A * @deprecated As of 1.4.1, use {@link #staticFieldBase(Field)} 0N/A * to obtain the base pertaining to a specific {@link Field}. 0N/A * This method works only for JVMs which store all statics 0N/A * for a given class in one place. 0N/A * Report the location of a given field in the storage allocation of its 0N/A * class. Do not expect to perform any sort of arithmetic on this offset; 0N/A * it is just a cookie which is passed to the unsafe heap memory accessors. 0N/A * <p>Any given field will always have the same offset and base, and no 0N/A * two distinct fields of the same class will ever have the same offset 0N/A * <p>As of 1.4.1, offsets for fields are represented as long values, 0N/A * although the Sun JVM does not use the most significant 32 bits. 0N/A * However, JVM implementations which store static fields at absolute 0N/A * addresses can use long offsets and null base pointers to express 0N/A * the field locations in a form usable by {@link #getInt(Object,long)}. 0N/A * Therefore, code which will be ported to such JVMs on 64-bit platforms 0N/A * must preserve all bits of static field offsets. 0N/A * @see #getInt(Object, long) 0N/A * Report the location of a given static field, in conjunction with {@link 0N/A * #staticFieldBase}. 0N/A * <p>Do not expect to perform any sort of arithmetic on this offset; 0N/A * it is just a cookie which is passed to the unsafe heap memory accessors. 0N/A * <p>Any given field will always have the same offset, and no two distinct 0N/A * fields of the same class will ever have the same offset. 0N/A * <p>As of 1.4.1, offsets for fields are represented as long values, 0N/A * although the Sun JVM does not use the most significant 32 bits. 0N/A * It is hard to imagine a JVM technology which needs more than 0N/A * a few bits to encode an offset within a non-array object, 0N/A * However, for consistency with other methods in this class, 0N/A * this method reports its result as a long value. 0N/A * @see #getInt(Object, long) 0N/A * Report the location of a given static field, in conjunction with {@link 0N/A * #staticFieldOffset}. 0N/A * <p>Fetch the base "Object", if any, with which static fields of the 0N/A * given class can be accessed via methods like {@link #getInt(Object, 0N/A * long)}. This value may be null. This value may refer to an object 0N/A * which is a "cookie", not guaranteed to be a real Object, and it should 0N/A * not be used in any way except as argument to the get and put routines in 5459N/A * Detect if the given class may need to be initialized. This is often 5459N/A * needed in conjunction with obtaining the static field base of a 5459N/A * @return false only if a call to {@code ensureClassInitialized} would have no effect 0N/A * Ensure the given class has been initialized. This is often 0N/A * needed in conjunction with obtaining the static field base of a 0N/A * Report the offset of the first element in the storage allocation of a 0N/A * given array class. If {@link #arrayIndexScale} returns a non-zero value 0N/A * for the same class, you may use that scale factor, together with this 0N/A * base offset, to form new offsets to access elements of arrays of the 0N/A * @see #getInt(Object, long) 0N/A * @see #putInt(Object, long, int) 0N/A /** The value of {@code arrayBaseOffset(boolean[].class)} */ 0N/A /** The value of {@code arrayBaseOffset(byte[].class)} */ 0N/A /** The value of {@code arrayBaseOffset(short[].class)} */ 0N/A /** The value of {@code arrayBaseOffset(char[].class)} */ 0N/A /** The value of {@code arrayBaseOffset(int[].class)} */ 0N/A /** The value of {@code arrayBaseOffset(long[].class)} */ 0N/A /** The value of {@code arrayBaseOffset(float[].class)} */ 0N/A /** The value of {@code arrayBaseOffset(double[].class)} */ 0N/A /** The value of {@code arrayBaseOffset(Object[].class)} */ 0N/A * Report the scale factor for addressing elements in the storage 0N/A * allocation of a given array class. However, arrays of "narrow" types 0N/A * will generally not work properly with accessors like {@link 0N/A * #getByte(Object, int)}, so the scale factor for such classes is reported 0N/A * @see #arrayBaseOffset 0N/A * @see #getInt(Object, long) 0N/A * @see #putInt(Object, long, int) 0N/A /** The value of {@code arrayIndexScale(boolean[].class)} */ 0N/A /** The value of {@code arrayIndexScale(byte[].class)} */ 0N/A /** The value of {@code arrayIndexScale(short[].class)} */ 0N/A /** The value of {@code arrayIndexScale(char[].class)} */ 0N/A /** The value of {@code arrayIndexScale(int[].class)} */ 0N/A /** The value of {@code arrayIndexScale(long[].class)} */ 0N/A /** The value of {@code arrayIndexScale(float[].class)} */ 0N/A /** The value of {@code arrayIndexScale(double[].class)} */ 0N/A /** The value of {@code arrayIndexScale(Object[].class)} */ 0N/A * Report the size in bytes of a native pointer, as stored via {@link 0N/A * #putAddress}. This value will be either 4 or 8. Note that the sizes of 0N/A * other primitive types (as stored in native memory blocks) is determined 0N/A * fully by their information content. 0N/A /** The value of {@code addressSize()} */ 0N/A * Report the size in bytes of a native memory page (whatever that is). 0N/A * This value will always be a power of two. 0N/A /// random trusted operations from JNI: 0N/A * Tell the VM to define a class, without security checks. By default, the 0N/A * class loader and protection domain come from the caller's class. 6338N/A * @deprecated Use defineClass(String, byte[], int, int, ClassLoader, ProtectionDomain) 6338N/A * instead. This method will be removed in JDK 8. 1193N/A * Define a class but do not make it known to the class loader or system dictionary. 1193N/A * For each CP entry, the corresponding CP patch must either be null or have 1193N/A * the a format that matches its tag: 1193N/A * <li>Integer, Long, Float, Double: the corresponding wrapper object type from java.lang 1193N/A * <li>Utf8: a string (must have suitable syntax if used as signature or name) 1193N/A * <li>Class: any java.lang.Class object 1193N/A * <li>String: any object (not just a java.lang.String) 1193N/A * <li>InterfaceMethodRef: (NYI) a method handle to invoke on that call site's arguments 1193N/A * @params hostClass context for linkage, access control, protection domain, and class loader 1193N/A * @params data bytes of a class file 1193N/A * @params cpPatches where non-null entries exist, they replace corresponding CP entries in data 0N/A /** Allocate an instance but do not run any constructor. 0N/A Initializes the class if it has not yet been. */ 0N/A /** Lock the object. It must get unlocked via {@link #monitorExit}. */ 0N/A * Unlock the object. It must have been locked via {@link 0N/A * Tries to lock the object. Returns true or false to indicate 0N/A * whether the lock succeeded. If it did, the object must be 0N/A * unlocked via {@link #monitorExit}. 0N/A /** Throw the exception without telling the verifier. */ 0N/A * Atomically update Java variable to <tt>x</tt> if it is currently 0N/A * holding <tt>expected</tt>. 0N/A * @return <tt>true</tt> if successful 0N/A * Atomically update Java variable to <tt>x</tt> if it is currently 0N/A * holding <tt>expected</tt>. 0N/A * @return <tt>true</tt> if successful 0N/A * Atomically update Java variable to <tt>x</tt> if it is currently 0N/A * holding <tt>expected</tt>. 0N/A * @return <tt>true</tt> if successful 0N/A * Fetches a reference value from a given Java variable, with volatile 0N/A * load semantics. Otherwise identical to {@link #getObject(Object, long)} 0N/A * Stores a reference value into a given Java variable, with 0N/A * volatile store semantics. Otherwise identical to {@link #putObject(Object, long, Object)} 0N/A /** Volatile version of {@link #getInt(Object, long)} */ 0N/A /** Volatile version of {@link #putInt(Object, long, int)} */ 0N/A /** Volatile version of {@link #getBoolean(Object, long)} */ 0N/A /** Volatile version of {@link #putBoolean(Object, long, boolean)} */ 0N/A /** Volatile version of {@link #getByte(Object, long)} */ 0N/A /** Volatile version of {@link #putByte(Object, long, byte)} */ 0N/A /** Volatile version of {@link #getShort(Object, long)} */ 0N/A /** Volatile version of {@link #putShort(Object, long, short)} */ 0N/A /** Volatile version of {@link #getChar(Object, long)} */ 0N/A /** Volatile version of {@link #putChar(Object, long, char)} */ 0N/A /** Volatile version of {@link #getLong(Object, long)} */ 0N/A /** Volatile version of {@link #putLong(Object, long, long)} */ 0N/A /** Volatile version of {@link #getFloat(Object, long)} */ 0N/A /** Volatile version of {@link #putFloat(Object, long, float)} */ 0N/A /** Volatile version of {@link #getDouble(Object, long)} */ 0N/A /** Volatile version of {@link #putDouble(Object, long, double)} */ 0N/A * Version of {@link #putObjectVolatile(Object, long, Object)} 0N/A * that does not guarantee immediate visibility of the store to 0N/A * other threads. This method is generally only useful if the 0N/A * underlying field is a Java volatile (or if an array cell, one 0N/A * that is otherwise only accessed using volatile accesses). 0N/A /** Ordered/Lazy version of {@link #putIntVolatile(Object, long, int)} */ 0N/A /** Ordered/Lazy version of {@link #putLongVolatile(Object, long, long)} */ 0N/A * Unblock the given thread blocked on <tt>park</tt>, or, if it is 0N/A * not blocked, cause the subsequent call to <tt>park</tt> not to 0N/A * block. Note: this operation is "unsafe" solely because the 0N/A * caller must somehow ensure that the thread has not been 0N/A * destroyed. Nothing special is usually required to ensure this 0N/A * when called from Java (in which there will ordinarily be a live 0N/A * reference to the thread) but this is not nearly-automatically 0N/A * so when calling from native code. 0N/A * @param thread the thread to unpark. 0N/A * Block current thread, returning when a balancing 0N/A * <tt>unpark</tt> occurs, or a balancing <tt>unpark</tt> has 0N/A * already occurred, or the thread is interrupted, or, if not 0N/A * absolute and time is not zero, the given time nanoseconds have 0N/A * elapsed, or if absolute, the given deadline in milliseconds 0N/A * since Epoch has passed, or spuriously (i.e., returning for no 0N/A * "reason"). Note: This operation is in the Unsafe class only 0N/A * because <tt>unpark</tt> is, so it would be strange to place it 0N/A * Gets the load average in the system run queue assigned 0N/A * to the available processors averaged over various periods of time. 0N/A * This method retrieves the given <tt>nelem</tt> samples and 0N/A * assigns to the elements of the given <tt>loadavg</tt> array. 0N/A * The system imposes a maximum of 3 samples, representing 0N/A * averages over the last 1, 5, and 15 minutes, respectively. 0N/A * @params loadavg an array of double of size nelems 0N/A * @params nelems the number of samples to be retrieved and 0N/A * @return the number of samples actually retrieved; or -1 0N/A * if the load average is unobtainable.