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authorRoel Spilker <r.spilker@gmail.com>2014-03-17 21:56:49 +0100
committerRoel Spilker <r.spilker@gmail.com>2014-03-17 21:56:49 +0100
commit17972d59fa7e2eec6b73ba5da8234f5fa7ac2536 (patch)
treefbcc5c272480e5915b60ac0992639c083d2507d8 /src/utils/lombok/core/ReferenceFieldAugment.java
parent362000933f46ad1d509a659e39279298440a97ec (diff)
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[#590][refactor] Fix for deadlock in WeakHashMap. Refactored all code that used a
WeakHashMap to fake a field.
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+/*
+ * Copyright (C) 2014 The Project Lombok Authors.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package lombok.core;
+
+import java.lang.ref.WeakReference;
+import java.util.Map;
+import java.util.WeakHashMap;
+
+public abstract class ReferenceFieldAugment<T, F> {
+
+ /**
+ * Augments a instance of a type with a reference field.
+ * <p>
+ * If the type already declares an instance field with the given name and field type, that field might be used. Otherwise the field will be augmented.
+ * <p>
+ * This code assumes that for any combination of {@code type} and {@code name} this method is only called once.
+ * Otherwise, whether state is shared is undefined.
+ *
+ * @param type to augment
+ * @param fieldType type of the field
+ * @param name of the field
+ * @throws NullPointerException if {@code type}, {@code fieldType} or {@code name} is {@code null}
+ */
+ public static <T, F> ReferenceFieldAugment<T, F> augment(Class<T> type, Class<? super F> fieldType, String name) {
+ return new MapFieldAugment<T, F>();
+ }
+
+ /**
+ * Augments a instance of a type with a weak reference field.
+ * <p>
+ * If the type already declares an instance field with the given name and field type, that field might be used. Otherwise the field will be augmented.
+ * <p>
+ * This code assumes that for any combination of {@code type} and {@code name} this method is only called once.
+ * Otherwise, whether state is shared is undefined.
+ *
+ * @param type to augment
+ * @param fieldType type of the field
+ * @param name of the field
+ * @throws NullPointerException if {@code type}, {@code fieldType} or {@code name} is {@code null}
+ */
+ public static <T, F> ReferenceFieldAugment<T, F> augmentWeakField(Class<T> type, Class<? super F> fieldType, String name) {
+ return new MapWeakFieldAugment<T, F>();
+ }
+
+ private ReferenceFieldAugment() {
+ // prevent external instantiation
+ }
+
+ /**
+ * @throws NullPointerException if {@code object} is {@code null}
+ */
+ public abstract F get(T object);
+
+ /**
+ * @throws NullPointerException if {@code object} or {@code expected} is {@code null}
+ */
+ public final void set(T object, F value) {
+ getAndSet(object, value);
+ }
+
+ /**
+ * @return the value of the field <strong>before</strong> the operation.
+ * @throws NullPointerException if {@code object} or {@code expected} is {@code null}
+ */
+ public abstract F getAndSet(T object, F value);
+
+ /**
+ * @return the value of the field <strong>before</strong> the operation.
+ * @throws NullPointerException if {@code object} is {@code null}
+ */
+ public abstract F clear(T object);
+
+ /**
+ * @return the value of the field <strong>after</strong> the operation. If the value was equal to {@code expected} or already cleared {@code null}, otherwise the current value.
+ * @throws NullPointerException if {@code object} or {@code expected} is {@code null}
+ */
+ public abstract F compareAndClear(T object, F expected);
+
+ /**
+ * @return the value of the field <strong>after</strong> the operation.
+ * @throws NullPointerException if {@code object} or {@code value} is {@code null}
+ */
+ public abstract F setIfAbsent(T object, F value);
+
+ /**
+ * @return the value of the field <strong>after</strong> the operation.
+ * @throws NullPointerException if {@code object}, {@code expected} or {@code value} is {@code null}
+ */
+ public abstract F compareAndSet(T object, F expected, F value);
+
+ private static class MapFieldAugment<T, F> extends ReferenceFieldAugment<T, F> {
+ final Map<T, Object> values = new WeakHashMap<T, Object>();
+
+ @Override
+ public F get(T object) {
+ checkNotNull(object, "object");
+ synchronized (values) {
+ return read(object);
+ }
+ }
+
+ @Override
+ public F getAndSet(T object, F value) {
+ checkNotNull(object, "object");
+ checkNotNull(value, "value");
+ synchronized (values) {
+ F result = read(object);
+ write(object, value);
+ return result;
+ }
+ }
+
+ @Override
+ public F clear(T object) {
+ checkNotNull(object, "object");
+ synchronized (values) {
+ F result = read(object);
+ values.remove(object);
+ return result;
+ }
+ }
+
+ @Override
+ public F compareAndClear(T object, F expected) {
+ checkNotNull(object, "object");
+ checkNotNull(expected, "expected");
+ synchronized (values) {
+ F result = read(object);
+ if (result == null) {
+ return null;
+ }
+ if (!expected.equals(result)) {
+ return result;
+ }
+ values.remove(object);
+ return null;
+ }
+ }
+
+ @Override
+ public F setIfAbsent(T object, F value) {
+ checkNotNull(object, "object");
+ checkNotNull(value, "value");
+ synchronized (values) {
+ F result = read(object);
+ if (result != null) {
+ return result;
+ }
+ write(object, value);
+ return value;
+ }
+ }
+
+ @Override
+ public F compareAndSet(T object, F expected, F value) {
+ checkNotNull(object, "object");
+ checkNotNull(expected, "expected");
+ checkNotNull(value, "value");
+ synchronized (values) {
+ F result = read(object);
+ if (!expected.equals(result)) {
+ return result;
+ }
+ write(object, value);
+ return value;
+ }
+ }
+
+ @SuppressWarnings("unchecked")
+ F read(T object) {
+ return (F)values.get(object);
+ }
+
+ void write(T object, F value) {
+ values.put(object, value);
+ }
+ }
+
+ static class MapWeakFieldAugment<T, F> extends MapFieldAugment<T, F> {
+
+ @SuppressWarnings("unchecked")
+ F read(T object) {
+ WeakReference<F> read = (WeakReference<F>)values.get(object);
+ if (read == null) return null;
+ F result = read.get();
+ if (result == null) values.remove(object);
+ return result;
+ }
+
+ void write(T object, F value) {
+ values.put(object, new WeakReference<F>(value));
+ }
+ }
+
+ private static <T> T checkNotNull(T object, String name) {
+ if (object == null) throw new NullPointerException(name);
+ return object;
+ }
+}