1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/rt/emul/compact/src/main/java/java/lang/ClassValue.java Tue Jan 17 07:04:06 2017 +0100
1.3 @@ -0,0 +1,179 @@
1.4 +/*
1.5 + * Copyright (c) 2010, 2011, Oracle and/or its affiliates. All rights reserved.
1.6 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 + *
1.8 + * This code is free software; you can redistribute it and/or modify it
1.9 + * under the terms of the GNU General Public License version 2 only, as
1.10 + * published by the Free Software Foundation. Oracle designates this
1.11 + * particular file as subject to the "Classpath" exception as provided
1.12 + * by Oracle in the LICENSE file that accompanied this code.
1.13 + *
1.14 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.15 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.16 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.17 + * version 2 for more details (a copy is included in the LICENSE file that
1.18 + * accompanied this code).
1.19 + *
1.20 + * You should have received a copy of the GNU General Public License version
1.21 + * 2 along with this work; if not, write to the Free Software Foundation,
1.22 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.23 + *
1.24 + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
1.25 + * or visit www.oracle.com if you need additional information or have any
1.26 + * questions.
1.27 + */
1.28 +
1.29 +package java.lang;
1.30 +
1.31 +import java.lang.Class;
1.32 +import org.apidesign.bck2brwsr.core.JavaScriptBody;
1.33 +
1.34 +/**
1.35 + * Lazily associate a computed value with (potentially) every type.
1.36 + * For example, if a dynamic language needs to construct a message dispatch
1.37 + * table for each class encountered at a message send call site,
1.38 + * it can use a {@code ClassValue} to cache information needed to
1.39 + * perform the message send quickly, for each class encountered.
1.40 + * @author John Rose, JSR 292 EG
1.41 + * @since 1.7
1.42 + */
1.43 +public abstract class ClassValue<T> {
1.44 + /**
1.45 + * Sole constructor. (For invocation by subclass constructors, typically
1.46 + * implicit.)
1.47 + */
1.48 + protected ClassValue() {
1.49 + }
1.50 +
1.51 + /**
1.52 + * Computes the given class's derived value for this {@code ClassValue}.
1.53 + * <p>
1.54 + * This method will be invoked within the first thread that accesses
1.55 + * the value with the {@link #get get} method.
1.56 + * <p>
1.57 + * Normally, this method is invoked at most once per class,
1.58 + * but it may be invoked again if there has been a call to
1.59 + * {@link #remove remove}.
1.60 + * <p>
1.61 + * If this method throws an exception, the corresponding call to {@code get}
1.62 + * will terminate abnormally with that exception, and no class value will be recorded.
1.63 + *
1.64 + * @param type the type whose class value must be computed
1.65 + * @return the newly computed value associated with this {@code ClassValue}, for the given class or interface
1.66 + * @see #get
1.67 + * @see #remove
1.68 + */
1.69 + protected abstract T computeValue(Class<?> type);
1.70 +
1.71 + /**
1.72 + * Returns the value for the given class.
1.73 + * If no value has yet been computed, it is obtained by
1.74 + * an invocation of the {@link #computeValue computeValue} method.
1.75 + * <p>
1.76 + * The actual installation of the value on the class
1.77 + * is performed atomically.
1.78 + * At that point, if several racing threads have
1.79 + * computed values, one is chosen, and returned to
1.80 + * all the racing threads.
1.81 + * <p>
1.82 + * The {@code type} parameter is typically a class, but it may be any type,
1.83 + * such as an interface, a primitive type (like {@code int.class}), or {@code void.class}.
1.84 + * <p>
1.85 + * In the absence of {@code remove} calls, a class value has a simple
1.86 + * state diagram: uninitialized and initialized.
1.87 + * When {@code remove} calls are made,
1.88 + * the rules for value observation are more complex.
1.89 + * See the documentation for {@link #remove remove} for more information.
1.90 + *
1.91 + * @param type the type whose class value must be computed or retrieved
1.92 + * @return the current value associated with this {@code ClassValue}, for the given class or interface
1.93 + * @throws NullPointerException if the argument is null
1.94 + * @see #remove
1.95 + * @see #computeValue
1.96 + */
1.97 + public T get(Class<?> type) {
1.98 + T value = access(type, id, false, null);
1.99 + if (value == undefined()) {
1.100 + value = access(type, id, true, computeValue(type));
1.101 + }
1.102 + return value;
1.103 + }
1.104 +
1.105 + /**
1.106 + * Removes the associated value for the given class.
1.107 + * If this value is subsequently {@linkplain #get read} for the same class,
1.108 + * its value will be reinitialized by invoking its {@link #computeValue computeValue} method.
1.109 + * This may result in an additional invocation of the
1.110 + * {@code computeValue} method for the given class.
1.111 + * <p>
1.112 + * In order to explain the interaction between {@code get} and {@code remove} calls,
1.113 + * we must model the state transitions of a class value to take into account
1.114 + * the alternation between uninitialized and initialized states.
1.115 + * To do this, number these states sequentially from zero, and note that
1.116 + * uninitialized (or removed) states are numbered with even numbers,
1.117 + * while initialized (or re-initialized) states have odd numbers.
1.118 + * <p>
1.119 + * When a thread {@code T} removes a class value in state {@code 2N},
1.120 + * nothing happens, since the class value is already uninitialized.
1.121 + * Otherwise, the state is advanced atomically to {@code 2N+1}.
1.122 + * <p>
1.123 + * When a thread {@code T} queries a class value in state {@code 2N},
1.124 + * the thread first attempts to initialize the class value to state {@code 2N+1}
1.125 + * by invoking {@code computeValue} and installing the resulting value.
1.126 + * <p>
1.127 + * When {@code T} attempts to install the newly computed value,
1.128 + * if the state is still at {@code 2N}, the class value will be initialized
1.129 + * with the computed value, advancing it to state {@code 2N+1}.
1.130 + * <p>
1.131 + * Otherwise, whether the new state is even or odd,
1.132 + * {@code T} will discard the newly computed value
1.133 + * and retry the {@code get} operation.
1.134 + * <p>
1.135 + * Discarding and retrying is an important proviso,
1.136 + * since otherwise {@code T} could potentially install
1.137 + * a disastrously stale value. For example:
1.138 + * <ul>
1.139 + * <li>{@code T} calls {@code CV.get(C)} and sees state {@code 2N}
1.140 + * <li>{@code T} quickly computes a time-dependent value {@code V0} and gets ready to install it
1.141 + * <li>{@code T} is hit by an unlucky paging or scheduling event, and goes to sleep for a long time
1.142 + * <li>...meanwhile, {@code T2} also calls {@code CV.get(C)} and sees state {@code 2N}
1.143 + * <li>{@code T2} quickly computes a similar time-dependent value {@code V1} and installs it on {@code CV.get(C)}
1.144 + * <li>{@code T2} (or a third thread) then calls {@code CV.remove(C)}, undoing {@code T2}'s work
1.145 + * <li> the previous actions of {@code T2} are repeated several times
1.146 + * <li> also, the relevant computed values change over time: {@code V1}, {@code V2}, ...
1.147 + * <li>...meanwhile, {@code T} wakes up and attempts to install {@code V0}; <em>this must fail</em>
1.148 + * </ul>
1.149 + * We can assume in the above scenario that {@code CV.computeValue} uses locks to properly
1.150 + * observe the time-dependent states as it computes {@code V1}, etc.
1.151 + * This does not remove the threat of a stale value, since there is a window of time
1.152 + * between the return of {@code computeValue} in {@code T} and the installation
1.153 + * of the the new value. No user synchronization is possible during this time.
1.154 + *
1.155 + * @param type the type whose class value must be removed
1.156 + * @throws NullPointerException if the argument is null
1.157 + */
1.158 + public void remove(Class<?> type) {
1.159 + access(type, id, true, undefined());
1.160 + }
1.161 +
1.162 + /// Implementation...
1.163 +
1.164 + private static int COUNTER = 0;
1.165 + private final int id = COUNTER++;
1.166 +
1.167 + @JavaScriptBody(args = {}, body = "return undefined;")
1.168 + private static native Object undefined();
1.169 +
1.170 + @JavaScriptBody(args = { "where", "index", "set", "newValue" }, body =
1.171 + "var data = where['values'];\n" +
1.172 + "if (!data) {\n" +
1.173 + " data = where['values'] = [];\n" +
1.174 + "}\n" +
1.175 + "if (set) {\n" +
1.176 + " data[index] = newValue;\n" +
1.177 + "}\n" +
1.178 + "return data[index];\n" +
1.179 + ""
1.180 + )
1.181 + private static native <T> T access(Class<?> where, int index, boolean set, T newValue);
1.182 +}
2.1 --- a/rt/emul/compacttest/src/test/java/org/apidesign/bck2brwsr/tck/ReflectionClassValueTest.java Tue Jan 17 06:16:06 2017 +0100
2.2 +++ b/rt/emul/compacttest/src/test/java/org/apidesign/bck2brwsr/tck/ReflectionClassValueTest.java Tue Jan 17 07:04:06 2017 +0100
2.3 @@ -17,6 +17,8 @@
2.4 */
2.5 package org.apidesign.bck2brwsr.tck;
2.6
2.7 +import java.io.Serializable;
2.8 +import java.lang.ClassValue;
2.9 import org.apidesign.bck2brwsr.vmtest.Compare;
2.10 import org.apidesign.bck2brwsr.vmtest.VMTest;
2.11 import org.testng.annotations.Factory;
2.12 @@ -56,13 +58,6 @@
2.13 return one == two;
2.14 }
2.15
2.16 - @Compare public boolean valueCanBeCleared() {
2.17 - String one = LOWER.get(Runnable.class);
2.18 - LOWER.remove(Runnable.class);
2.19 - String two = LOWER.get(Runnable.class);
2.20 - return one != two;
2.21 - }
2.22 -
2.23 @Compare public String upperObject() {
2.24 return UPPER.get(Object.class);
2.25 }
2.26 @@ -79,6 +74,47 @@
2.27 return LOWER.get(CharSequence.class) + UPPER.get(CharSequence.class);
2.28 }
2.29
2.30 + private static final class CountingNull extends ClassValue<Object> {
2.31 + int cnt;
2.32 +
2.33 + @Override
2.34 + protected Object computeValue(Class<?> type) {
2.35 + cnt++;
2.36 + return null;
2.37 + }
2.38 + }
2.39 +
2.40 + @Compare public int getNullThreeTimes() {
2.41 + CountingNull counter = new CountingNull();
2.42 + Object o1 = counter.get(Serializable.class);
2.43 + Object o2 = counter.get(Serializable.class);
2.44 + Object o3 = counter.get(Serializable.class);
2.45 + assert o1 == null;
2.46 + assert o2 == null;
2.47 + assert o3 == null;
2.48 + return counter.cnt;
2.49 + }
2.50 +
2.51 + private static final class NewObj extends ClassValue<Integer> {
2.52 + int cnt;
2.53 +
2.54 + @Override
2.55 + protected Integer computeValue(Class<?> type) {
2.56 + cnt++;
2.57 + return new Integer(cnt);
2.58 + }
2.59 + }
2.60 +
2.61 + @Compare public boolean valueCanBeCleared() {
2.62 + NewObj cache = new NewObj();
2.63 + Integer one = cache.get(Runnable.class);
2.64 + Integer two = cache.get(Runnable.class);
2.65 + assert one == two;
2.66 + cache.remove(Runnable.class);
2.67 + Integer three = cache.get(Runnable.class);
2.68 + return one != three;
2.69 + }
2.70 +
2.71 @Factory
2.72 public static Object[] create() {
2.73 return VMTest.create(ReflectionClassValueTest.class);
3.1 --- a/rt/emul/mini/src/main/java/java/lang/ClassValue.java Tue Jan 17 06:16:06 2017 +0100
3.2 +++ /dev/null Thu Jan 01 00:00:00 1970 +0000
3.3 @@ -1,239 +0,0 @@
3.4 -/*
3.5 - * Copyright (c) 2010, 2011, Oracle and/or its affiliates. All rights reserved.
3.6 - * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
3.7 - *
3.8 - * This code is free software; you can redistribute it and/or modify it
3.9 - * under the terms of the GNU General Public License version 2 only, as
3.10 - * published by the Free Software Foundation. Oracle designates this
3.11 - * particular file as subject to the "Classpath" exception as provided
3.12 - * by Oracle in the LICENSE file that accompanied this code.
3.13 - *
3.14 - * This code is distributed in the hope that it will be useful, but WITHOUT
3.15 - * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
3.16 - * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
3.17 - * version 2 for more details (a copy is included in the LICENSE file that
3.18 - * accompanied this code).
3.19 - *
3.20 - * You should have received a copy of the GNU General Public License version
3.21 - * 2 along with this work; if not, write to the Free Software Foundation,
3.22 - * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
3.23 - *
3.24 - * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
3.25 - * or visit www.oracle.com if you need additional information or have any
3.26 - * questions.
3.27 - */
3.28 -
3.29 -package java.lang;
3.30 -
3.31 -import java.util.WeakHashMap;
3.32 -import java.util.concurrent.atomic.AtomicInteger;
3.33 -
3.34 -/**
3.35 - * Lazily associate a computed value with (potentially) every type.
3.36 - * For example, if a dynamic language needs to construct a message dispatch
3.37 - * table for each class encountered at a message send call site,
3.38 - * it can use a {@code ClassValue} to cache information needed to
3.39 - * perform the message send quickly, for each class encountered.
3.40 - * @author John Rose, JSR 292 EG
3.41 - * @since 1.7
3.42 - */
3.43 -public abstract class ClassValue<T> {
3.44 - /**
3.45 - * Sole constructor. (For invocation by subclass constructors, typically
3.46 - * implicit.)
3.47 - */
3.48 - protected ClassValue() {
3.49 - }
3.50 -
3.51 - /**
3.52 - * Computes the given class's derived value for this {@code ClassValue}.
3.53 - * <p>
3.54 - * This method will be invoked within the first thread that accesses
3.55 - * the value with the {@link #get get} method.
3.56 - * <p>
3.57 - * Normally, this method is invoked at most once per class,
3.58 - * but it may be invoked again if there has been a call to
3.59 - * {@link #remove remove}.
3.60 - * <p>
3.61 - * If this method throws an exception, the corresponding call to {@code get}
3.62 - * will terminate abnormally with that exception, and no class value will be recorded.
3.63 - *
3.64 - * @param type the type whose class value must be computed
3.65 - * @return the newly computed value associated with this {@code ClassValue}, for the given class or interface
3.66 - * @see #get
3.67 - * @see #remove
3.68 - */
3.69 - protected abstract T computeValue(Class<?> type);
3.70 -
3.71 - /**
3.72 - * Returns the value for the given class.
3.73 - * If no value has yet been computed, it is obtained by
3.74 - * an invocation of the {@link #computeValue computeValue} method.
3.75 - * <p>
3.76 - * The actual installation of the value on the class
3.77 - * is performed atomically.
3.78 - * At that point, if several racing threads have
3.79 - * computed values, one is chosen, and returned to
3.80 - * all the racing threads.
3.81 - * <p>
3.82 - * The {@code type} parameter is typically a class, but it may be any type,
3.83 - * such as an interface, a primitive type (like {@code int.class}), or {@code void.class}.
3.84 - * <p>
3.85 - * In the absence of {@code remove} calls, a class value has a simple
3.86 - * state diagram: uninitialized and initialized.
3.87 - * When {@code remove} calls are made,
3.88 - * the rules for value observation are more complex.
3.89 - * See the documentation for {@link #remove remove} for more information.
3.90 - *
3.91 - * @param type the type whose class value must be computed or retrieved
3.92 - * @return the current value associated with this {@code ClassValue}, for the given class or interface
3.93 - * @throws NullPointerException if the argument is null
3.94 - * @see #remove
3.95 - * @see #computeValue
3.96 - */
3.97 - public T get(Class<?> type) {
3.98 - ClassValueMap map = getMap(type);
3.99 - if (map != null) {
3.100 - Object x = map.get(this);
3.101 - if (x != null) {
3.102 - return (T) map.unmaskNull(x);
3.103 - }
3.104 - }
3.105 - return setComputedValue(type);
3.106 - }
3.107 -
3.108 - /**
3.109 - * Removes the associated value for the given class.
3.110 - * If this value is subsequently {@linkplain #get read} for the same class,
3.111 - * its value will be reinitialized by invoking its {@link #computeValue computeValue} method.
3.112 - * This may result in an additional invocation of the
3.113 - * {@code computeValue} method for the given class.
3.114 - * <p>
3.115 - * In order to explain the interaction between {@code get} and {@code remove} calls,
3.116 - * we must model the state transitions of a class value to take into account
3.117 - * the alternation between uninitialized and initialized states.
3.118 - * To do this, number these states sequentially from zero, and note that
3.119 - * uninitialized (or removed) states are numbered with even numbers,
3.120 - * while initialized (or re-initialized) states have odd numbers.
3.121 - * <p>
3.122 - * When a thread {@code T} removes a class value in state {@code 2N},
3.123 - * nothing happens, since the class value is already uninitialized.
3.124 - * Otherwise, the state is advanced atomically to {@code 2N+1}.
3.125 - * <p>
3.126 - * When a thread {@code T} queries a class value in state {@code 2N},
3.127 - * the thread first attempts to initialize the class value to state {@code 2N+1}
3.128 - * by invoking {@code computeValue} and installing the resulting value.
3.129 - * <p>
3.130 - * When {@code T} attempts to install the newly computed value,
3.131 - * if the state is still at {@code 2N}, the class value will be initialized
3.132 - * with the computed value, advancing it to state {@code 2N+1}.
3.133 - * <p>
3.134 - * Otherwise, whether the new state is even or odd,
3.135 - * {@code T} will discard the newly computed value
3.136 - * and retry the {@code get} operation.
3.137 - * <p>
3.138 - * Discarding and retrying is an important proviso,
3.139 - * since otherwise {@code T} could potentially install
3.140 - * a disastrously stale value. For example:
3.141 - * <ul>
3.142 - * <li>{@code T} calls {@code CV.get(C)} and sees state {@code 2N}
3.143 - * <li>{@code T} quickly computes a time-dependent value {@code V0} and gets ready to install it
3.144 - * <li>{@code T} is hit by an unlucky paging or scheduling event, and goes to sleep for a long time
3.145 - * <li>...meanwhile, {@code T2} also calls {@code CV.get(C)} and sees state {@code 2N}
3.146 - * <li>{@code T2} quickly computes a similar time-dependent value {@code V1} and installs it on {@code CV.get(C)}
3.147 - * <li>{@code T2} (or a third thread) then calls {@code CV.remove(C)}, undoing {@code T2}'s work
3.148 - * <li> the previous actions of {@code T2} are repeated several times
3.149 - * <li> also, the relevant computed values change over time: {@code V1}, {@code V2}, ...
3.150 - * <li>...meanwhile, {@code T} wakes up and attempts to install {@code V0}; <em>this must fail</em>
3.151 - * </ul>
3.152 - * We can assume in the above scenario that {@code CV.computeValue} uses locks to properly
3.153 - * observe the time-dependent states as it computes {@code V1}, etc.
3.154 - * This does not remove the threat of a stale value, since there is a window of time
3.155 - * between the return of {@code computeValue} in {@code T} and the installation
3.156 - * of the the new value. No user synchronization is possible during this time.
3.157 - *
3.158 - * @param type the type whose class value must be removed
3.159 - * @throws NullPointerException if the argument is null
3.160 - */
3.161 - public void remove(Class<?> type) {
3.162 - ClassValueMap map = getMap(type);
3.163 - if (map != null) {
3.164 - synchronized (map) {
3.165 - map.remove(this);
3.166 - }
3.167 - }
3.168 - }
3.169 -
3.170 - /// Implementation...
3.171 - // FIXME: Use a data structure here similar that of ThreadLocal (7030453).
3.172 -
3.173 - private static final AtomicInteger STORE_BARRIER = new AtomicInteger();
3.174 -
3.175 - /** Slow path for {@link #get}. */
3.176 - private T setComputedValue(Class<?> type) {
3.177 - ClassValueMap map = getMap(type);
3.178 - if (map == null) {
3.179 - map = initializeMap(type);
3.180 - }
3.181 - T value = computeValue(type);
3.182 - STORE_BARRIER.lazySet(0);
3.183 - // All stores pending from computeValue are completed.
3.184 - synchronized (map) {
3.185 - // Warm up the table with a null entry.
3.186 - map.preInitializeEntry(this);
3.187 - }
3.188 - STORE_BARRIER.lazySet(0);
3.189 - // All stores pending from table expansion are completed.
3.190 - synchronized (map) {
3.191 - value = (T) map.initializeEntry(this, value);
3.192 - // One might fear a possible race condition here
3.193 - // if the code for map.put has flushed the write
3.194 - // to map.table[*] before the writes to the Map.Entry
3.195 - // are done. This is not possible, since we have
3.196 - // warmed up the table with an empty entry.
3.197 - }
3.198 - return value;
3.199 - }
3.200 -
3.201 - // Replace this map by a per-class slot.
3.202 - private static final WeakHashMap<Class<?>, ClassValueMap> ROOT
3.203 - = new WeakHashMap<Class<?>, ClassValueMap>();
3.204 -
3.205 - private static ClassValueMap getMap(Class<?> type) {
3.206 - type.getClass(); // test for null
3.207 - return ROOT.get(type);
3.208 - }
3.209 -
3.210 - private static ClassValueMap initializeMap(Class<?> type) {
3.211 - synchronized (ClassValue.class) {
3.212 - ClassValueMap map = ROOT.get(type);
3.213 - if (map == null)
3.214 - ROOT.put(type, map = new ClassValueMap());
3.215 - return map;
3.216 - }
3.217 - }
3.218 -
3.219 - static class ClassValueMap extends WeakHashMap<ClassValue, Object> {
3.220 - /** Make sure this table contains an Entry for the given key, even if it is empty. */
3.221 - void preInitializeEntry(ClassValue key) {
3.222 - if (!this.containsKey(key))
3.223 - this.put(key, null);
3.224 - }
3.225 - /** Make sure this table contains a non-empty Entry for the given key. */
3.226 - Object initializeEntry(ClassValue key, Object value) {
3.227 - Object prior = this.get(key);
3.228 - if (prior != null) {
3.229 - return unmaskNull(prior);
3.230 - }
3.231 - this.put(key, maskNull(value));
3.232 - return value;
3.233 - }
3.234 -
3.235 - Object maskNull(Object x) {
3.236 - return x == null ? this : x;
3.237 - }
3.238 - Object unmaskNull(Object x) {
3.239 - return x == this ? null : x;
3.240 - }
3.241 - }
3.242 -}