diff -r 836adbf7a2cd -r 3317bb8137f4 jdk/src/java.base/share/classes/java/util/concurrent/atomic/AtomicLongFieldUpdater.java --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/jdk/src/java.base/share/classes/java/util/concurrent/atomic/AtomicLongFieldUpdater.java Sun Aug 17 15:54:13 2014 +0100 @@ -0,0 +1,608 @@ +/* + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This code is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 only, as + * published by the Free Software Foundation. Oracle designates this + * particular file as subject to the "Classpath" exception as provided + * by Oracle in the LICENSE file that accompanied this code. + * + * This code is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * version 2 for more details (a copy is included in the LICENSE file that + * accompanied this code). + * + * You should have received a copy of the GNU General Public License version + * 2 along with this work; if not, write to the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. + * + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA + * or visit www.oracle.com if you need additional information or have any + * questions. + */ + +/* + * This file is available under and governed by the GNU General Public + * License version 2 only, as published by the Free Software Foundation. + * However, the following notice accompanied the original version of this + * file: + * + * Written by Doug Lea with assistance from members of JCP JSR-166 + * Expert Group and released to the public domain, as explained at + * http://creativecommons.org/publicdomain/zero/1.0/ + */ + +package java.util.concurrent.atomic; +import java.util.function.LongUnaryOperator; +import java.util.function.LongBinaryOperator; +import sun.misc.Unsafe; +import java.lang.reflect.Field; +import java.lang.reflect.Modifier; +import java.security.AccessController; +import java.security.PrivilegedExceptionAction; +import java.security.PrivilegedActionException; +import sun.reflect.CallerSensitive; +import sun.reflect.Reflection; + +/** + * A reflection-based utility that enables atomic updates to + * designated {@code volatile long} fields of designated classes. + * This class is designed for use in atomic data structures in which + * several fields of the same node are independently subject to atomic + * updates. + * + *

Note that the guarantees of the {@code compareAndSet} + * method in this class are weaker than in other atomic classes. + * Because this class cannot ensure that all uses of the field + * are appropriate for purposes of atomic access, it can + * guarantee atomicity only with respect to other invocations of + * {@code compareAndSet} and {@code set} on the same updater. + * + * @since 1.5 + * @author Doug Lea + * @param The type of the object holding the updatable field + */ +public abstract class AtomicLongFieldUpdater { + /** + * Creates and returns an updater for objects with the given field. + * The Class argument is needed to check that reflective types and + * generic types match. + * + * @param tclass the class of the objects holding the field + * @param fieldName the name of the field to be updated + * @param the type of instances of tclass + * @return the updater + * @throws IllegalArgumentException if the field is not a + * volatile long type + * @throws RuntimeException with a nested reflection-based + * exception if the class does not hold field or is the wrong type, + * or the field is inaccessible to the caller according to Java language + * access control + */ + @CallerSensitive + public static AtomicLongFieldUpdater newUpdater(Class tclass, + String fieldName) { + Class caller = Reflection.getCallerClass(); + if (AtomicLong.VM_SUPPORTS_LONG_CAS) + return new CASUpdater(tclass, fieldName, caller); + else + return new LockedUpdater(tclass, fieldName, caller); + } + + /** + * Protected do-nothing constructor for use by subclasses. + */ + protected AtomicLongFieldUpdater() { + } + + /** + * Atomically sets the field of the given object managed by this updater + * to the given updated value if the current value {@code ==} the + * expected value. This method is guaranteed to be atomic with respect to + * other calls to {@code compareAndSet} and {@code set}, but not + * necessarily with respect to other changes in the field. + * + * @param obj An object whose field to conditionally set + * @param expect the expected value + * @param update the new value + * @return {@code true} if successful + * @throws ClassCastException if {@code obj} is not an instance + * of the class possessing the field established in the constructor + */ + public abstract boolean compareAndSet(T obj, long expect, long update); + + /** + * Atomically sets the field of the given object managed by this updater + * to the given updated value if the current value {@code ==} the + * expected value. This method is guaranteed to be atomic with respect to + * other calls to {@code compareAndSet} and {@code set}, but not + * necessarily with respect to other changes in the field. + * + *

May fail + * spuriously and does not provide ordering guarantees, so is + * only rarely an appropriate alternative to {@code compareAndSet}. + * + * @param obj An object whose field to conditionally set + * @param expect the expected value + * @param update the new value + * @return {@code true} if successful + * @throws ClassCastException if {@code obj} is not an instance + * of the class possessing the field established in the constructor + */ + public abstract boolean weakCompareAndSet(T obj, long expect, long update); + + /** + * Sets the field of the given object managed by this updater to the + * given updated value. This operation is guaranteed to act as a volatile + * store with respect to subsequent invocations of {@code compareAndSet}. + * + * @param obj An object whose field to set + * @param newValue the new value + */ + public abstract void set(T obj, long newValue); + + /** + * Eventually sets the field of the given object managed by this + * updater to the given updated value. + * + * @param obj An object whose field to set + * @param newValue the new value + * @since 1.6 + */ + public abstract void lazySet(T obj, long newValue); + + /** + * Gets the current value held in the field of the given object managed + * by this updater. + * + * @param obj An object whose field to get + * @return the current value + */ + public abstract long get(T obj); + + /** + * Atomically sets the field of the given object managed by this updater + * to the given value and returns the old value. + * + * @param obj An object whose field to get and set + * @param newValue the new value + * @return the previous value + */ + public long getAndSet(T obj, long newValue) { + long prev; + do { + prev = get(obj); + } while (!compareAndSet(obj, prev, newValue)); + return prev; + } + + /** + * Atomically increments by one the current value of the field of the + * given object managed by this updater. + * + * @param obj An object whose field to get and set + * @return the previous value + */ + public long getAndIncrement(T obj) { + long prev, next; + do { + prev = get(obj); + next = prev + 1; + } while (!compareAndSet(obj, prev, next)); + return prev; + } + + /** + * Atomically decrements by one the current value of the field of the + * given object managed by this updater. + * + * @param obj An object whose field to get and set + * @return the previous value + */ + public long getAndDecrement(T obj) { + long prev, next; + do { + prev = get(obj); + next = prev - 1; + } while (!compareAndSet(obj, prev, next)); + return prev; + } + + /** + * Atomically adds the given value to the current value of the field of + * the given object managed by this updater. + * + * @param obj An object whose field to get and set + * @param delta the value to add + * @return the previous value + */ + public long getAndAdd(T obj, long delta) { + long prev, next; + do { + prev = get(obj); + next = prev + delta; + } while (!compareAndSet(obj, prev, next)); + return prev; + } + + /** + * Atomically increments by one the current value of the field of the + * given object managed by this updater. + * + * @param obj An object whose field to get and set + * @return the updated value + */ + public long incrementAndGet(T obj) { + long prev, next; + do { + prev = get(obj); + next = prev + 1; + } while (!compareAndSet(obj, prev, next)); + return next; + } + + /** + * Atomically decrements by one the current value of the field of the + * given object managed by this updater. + * + * @param obj An object whose field to get and set + * @return the updated value + */ + public long decrementAndGet(T obj) { + long prev, next; + do { + prev = get(obj); + next = prev - 1; + } while (!compareAndSet(obj, prev, next)); + return next; + } + + /** + * Atomically adds the given value to the current value of the field of + * the given object managed by this updater. + * + * @param obj An object whose field to get and set + * @param delta the value to add + * @return the updated value + */ + public long addAndGet(T obj, long delta) { + long prev, next; + do { + prev = get(obj); + next = prev + delta; + } while (!compareAndSet(obj, prev, next)); + return next; + } + + /** + * Atomically updates the field of the given object managed by this updater + * with the results of applying the given function, returning the previous + * value. The function should be side-effect-free, since it may be + * re-applied when attempted updates fail due to contention among threads. + * + * @param obj An object whose field to get and set + * @param updateFunction a side-effect-free function + * @return the previous value + * @since 1.8 + */ + public final long getAndUpdate(T obj, LongUnaryOperator updateFunction) { + long prev, next; + do { + prev = get(obj); + next = updateFunction.applyAsLong(prev); + } while (!compareAndSet(obj, prev, next)); + return prev; + } + + /** + * Atomically updates the field of the given object managed by this updater + * with the results of applying the given function, returning the updated + * value. The function should be side-effect-free, since it may be + * re-applied when attempted updates fail due to contention among threads. + * + * @param obj An object whose field to get and set + * @param updateFunction a side-effect-free function + * @return the updated value + * @since 1.8 + */ + public final long updateAndGet(T obj, LongUnaryOperator updateFunction) { + long prev, next; + do { + prev = get(obj); + next = updateFunction.applyAsLong(prev); + } while (!compareAndSet(obj, prev, next)); + return next; + } + + /** + * Atomically updates the field of the given object managed by this + * updater with the results of applying the given function to the + * current and given values, returning the previous value. The + * function should be side-effect-free, since it may be re-applied + * when attempted updates fail due to contention among threads. The + * function is applied with the current value as its first argument, + * and the given update as the second argument. + * + * @param obj An object whose field to get and set + * @param x the update value + * @param accumulatorFunction a side-effect-free function of two arguments + * @return the previous value + * @since 1.8 + */ + public final long getAndAccumulate(T obj, long x, + LongBinaryOperator accumulatorFunction) { + long prev, next; + do { + prev = get(obj); + next = accumulatorFunction.applyAsLong(prev, x); + } while (!compareAndSet(obj, prev, next)); + return prev; + } + + /** + * Atomically updates the field of the given object managed by this + * updater with the results of applying the given function to the + * current and given values, returning the updated value. The + * function should be side-effect-free, since it may be re-applied + * when attempted updates fail due to contention among threads. The + * function is applied with the current value as its first argument, + * and the given update as the second argument. + * + * @param obj An object whose field to get and set + * @param x the update value + * @param accumulatorFunction a side-effect-free function of two arguments + * @return the updated value + * @since 1.8 + */ + public final long accumulateAndGet(T obj, long x, + LongBinaryOperator accumulatorFunction) { + long prev, next; + do { + prev = get(obj); + next = accumulatorFunction.applyAsLong(prev, x); + } while (!compareAndSet(obj, prev, next)); + return next; + } + + private static class CASUpdater extends AtomicLongFieldUpdater { + private static final Unsafe unsafe = Unsafe.getUnsafe(); + private final long offset; + private final Class tclass; + private final Class cclass; + + CASUpdater(final Class tclass, final String fieldName, + final Class caller) { + final Field field; + final int modifiers; + try { + field = AccessController.doPrivileged( + new PrivilegedExceptionAction() { + public Field run() throws NoSuchFieldException { + return tclass.getDeclaredField(fieldName); + } + }); + modifiers = field.getModifiers(); + sun.reflect.misc.ReflectUtil.ensureMemberAccess( + caller, tclass, null, modifiers); + ClassLoader cl = tclass.getClassLoader(); + ClassLoader ccl = caller.getClassLoader(); + if ((ccl != null) && (ccl != cl) && + ((cl == null) || !isAncestor(cl, ccl))) { + sun.reflect.misc.ReflectUtil.checkPackageAccess(tclass); + } + } catch (PrivilegedActionException pae) { + throw new RuntimeException(pae.getException()); + } catch (Exception ex) { + throw new RuntimeException(ex); + } + + Class fieldt = field.getType(); + if (fieldt != long.class) + throw new IllegalArgumentException("Must be long type"); + + if (!Modifier.isVolatile(modifiers)) + throw new IllegalArgumentException("Must be volatile type"); + + this.cclass = (Modifier.isProtected(modifiers) && + caller != tclass) ? caller : null; + this.tclass = tclass; + offset = unsafe.objectFieldOffset(field); + } + + private void fullCheck(T obj) { + if (!tclass.isInstance(obj)) + throw new ClassCastException(); + if (cclass != null) + ensureProtectedAccess(obj); + } + + public boolean compareAndSet(T obj, long expect, long update) { + if (obj == null || obj.getClass() != tclass || cclass != null) fullCheck(obj); + return unsafe.compareAndSwapLong(obj, offset, expect, update); + } + + public boolean weakCompareAndSet(T obj, long expect, long update) { + if (obj == null || obj.getClass() != tclass || cclass != null) fullCheck(obj); + return unsafe.compareAndSwapLong(obj, offset, expect, update); + } + + public void set(T obj, long newValue) { + if (obj == null || obj.getClass() != tclass || cclass != null) fullCheck(obj); + unsafe.putLongVolatile(obj, offset, newValue); + } + + public void lazySet(T obj, long newValue) { + if (obj == null || obj.getClass() != tclass || cclass != null) fullCheck(obj); + unsafe.putOrderedLong(obj, offset, newValue); + } + + public long get(T obj) { + if (obj == null || obj.getClass() != tclass || cclass != null) fullCheck(obj); + return unsafe.getLongVolatile(obj, offset); + } + + public long getAndSet(T obj, long newValue) { + if (obj == null || obj.getClass() != tclass || cclass != null) fullCheck(obj); + return unsafe.getAndSetLong(obj, offset, newValue); + } + + public long getAndIncrement(T obj) { + return getAndAdd(obj, 1); + } + + public long getAndDecrement(T obj) { + return getAndAdd(obj, -1); + } + + public long getAndAdd(T obj, long delta) { + if (obj == null || obj.getClass() != tclass || cclass != null) fullCheck(obj); + return unsafe.getAndAddLong(obj, offset, delta); + } + + public long incrementAndGet(T obj) { + return getAndAdd(obj, 1) + 1; + } + + public long decrementAndGet(T obj) { + return getAndAdd(obj, -1) - 1; + } + + public long addAndGet(T obj, long delta) { + return getAndAdd(obj, delta) + delta; + } + + private void ensureProtectedAccess(T obj) { + if (cclass.isInstance(obj)) { + return; + } + throw new RuntimeException( + new IllegalAccessException("Class " + + cclass.getName() + + " can not access a protected member of class " + + tclass.getName() + + " using an instance of " + + obj.getClass().getName() + ) + ); + } + } + + + private static class LockedUpdater extends AtomicLongFieldUpdater { + private static final Unsafe unsafe = Unsafe.getUnsafe(); + private final long offset; + private final Class tclass; + private final Class cclass; + + LockedUpdater(final Class tclass, final String fieldName, + final Class caller) { + Field field = null; + int modifiers = 0; + try { + field = AccessController.doPrivileged( + new PrivilegedExceptionAction() { + public Field run() throws NoSuchFieldException { + return tclass.getDeclaredField(fieldName); + } + }); + modifiers = field.getModifiers(); + sun.reflect.misc.ReflectUtil.ensureMemberAccess( + caller, tclass, null, modifiers); + ClassLoader cl = tclass.getClassLoader(); + ClassLoader ccl = caller.getClassLoader(); + if ((ccl != null) && (ccl != cl) && + ((cl == null) || !isAncestor(cl, ccl))) { + sun.reflect.misc.ReflectUtil.checkPackageAccess(tclass); + } + } catch (PrivilegedActionException pae) { + throw new RuntimeException(pae.getException()); + } catch (Exception ex) { + throw new RuntimeException(ex); + } + + Class fieldt = field.getType(); + if (fieldt != long.class) + throw new IllegalArgumentException("Must be long type"); + + if (!Modifier.isVolatile(modifiers)) + throw new IllegalArgumentException("Must be volatile type"); + + this.cclass = (Modifier.isProtected(modifiers) && + caller != tclass) ? caller : null; + this.tclass = tclass; + offset = unsafe.objectFieldOffset(field); + } + + private void fullCheck(T obj) { + if (!tclass.isInstance(obj)) + throw new ClassCastException(); + if (cclass != null) + ensureProtectedAccess(obj); + } + + public boolean compareAndSet(T obj, long expect, long update) { + if (obj == null || obj.getClass() != tclass || cclass != null) fullCheck(obj); + synchronized (this) { + long v = unsafe.getLong(obj, offset); + if (v != expect) + return false; + unsafe.putLong(obj, offset, update); + return true; + } + } + + public boolean weakCompareAndSet(T obj, long expect, long update) { + return compareAndSet(obj, expect, update); + } + + public void set(T obj, long newValue) { + if (obj == null || obj.getClass() != tclass || cclass != null) fullCheck(obj); + synchronized (this) { + unsafe.putLong(obj, offset, newValue); + } + } + + public void lazySet(T obj, long newValue) { + set(obj, newValue); + } + + public long get(T obj) { + if (obj == null || obj.getClass() != tclass || cclass != null) fullCheck(obj); + synchronized (this) { + return unsafe.getLong(obj, offset); + } + } + + private void ensureProtectedAccess(T obj) { + if (cclass.isInstance(obj)) { + return; + } + throw new RuntimeException( + new IllegalAccessException("Class " + + cclass.getName() + + " can not access a protected member of class " + + tclass.getName() + + " using an instance of " + + obj.getClass().getName() + ) + ); + } + } + + /** + * Returns true if the second classloader can be found in the first + * classloader's delegation chain. + * Equivalent to the inaccessible: first.isAncestor(second). + */ + private static boolean isAncestor(ClassLoader first, ClassLoader second) { + ClassLoader acl = first; + do { + acl = acl.getParent(); + if (second == acl) { + return true; + } + } while (acl != null); + return false; + } +}