10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.lang.ref;
27
28 import java.util.Objects;
29 import java.util.concurrent.ThreadFactory;
30
31 import jdk.internal.ref.CleanerImpl;
32
33 /**
34 * {@code Cleaner} manages a set of object references and corresponding cleaning actions.
35 * <p>
36 * Cleaning actions are {@link #register(Object object, Runnable action) registered}
37 * to run after the cleaner is notified that the object has become
38 * phantom reachable.
39 * The cleaner uses {@link PhantomReference} and {@link ReferenceQueue} to be
40 * notified when the <a href="package-summary.html#reachability">reachability</a>
41 * changes.
42 * <p>
43 * Each cleaner operates independently, managing the pending cleaning actions
44 * and handling threading and termination when the cleaner is no longer in use.
45 * Registering an object reference and corresponding cleaning action returns
46 * a {@link Cleanable Cleanable}. The most efficient use is to explicitly invoke
47 * the {@link Cleanable#clean clean} method when the object is closed or
48 * no longer needed.
49 * The cleaning action is a {@link Runnable} to be invoked at most once when
118 * Using a static nested class, as above, will avoid accidentally retaining the
119 * object reference.
120 * <p>
121 * <a name="compatible-cleaners"></a>
122 * Cleaning actions should be prepared to be invoked concurrently with
123 * other cleaning actions.
124 * Typically the cleaning actions should be very quick to execute
125 * and not block. If the cleaning action blocks, it may delay processing
126 * other cleaning actions registered to the same cleaner.
127 * All cleaning actions registered to a cleaner should be mutually compatible.
128 * @since 9
129 */
130 public final class Cleaner {
131
132 /**
133 * The Cleaner implementation.
134 */
135 final CleanerImpl impl;
136
137 static {
138 CleanerImpl.setCleanerImplAccess((Cleaner c) -> c.impl);
139 }
140
141 /**
142 * Construct a Cleaner implementation and start it.
143 */
144 private Cleaner() {
145 impl = new CleanerImpl();
146 }
147
148 /**
149 * Returns a new {@code Cleaner}.
150 * <p>
151 * The cleaner creates a {@link Thread#setDaemon(boolean) daemon thread}
152 * to process the phantom reachable objects and to invoke cleaning actions.
153 * The {@linkplain java.lang.Thread#getContextClassLoader context class loader}
154 * of the thread is set to the
155 * {@link ClassLoader#getSystemClassLoader() system class loader}.
156 * The thread has no permissions, enforced only if a
157 * {@link java.lang.System#setSecurityManager(SecurityManager) SecurityManager is set}.
158 * <p>
|
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.lang.ref;
27
28 import java.util.Objects;
29 import java.util.concurrent.ThreadFactory;
30 import java.util.function.Function;
31
32 import jdk.internal.ref.CleanerImpl;
33
34 /**
35 * {@code Cleaner} manages a set of object references and corresponding cleaning actions.
36 * <p>
37 * Cleaning actions are {@link #register(Object object, Runnable action) registered}
38 * to run after the cleaner is notified that the object has become
39 * phantom reachable.
40 * The cleaner uses {@link PhantomReference} and {@link ReferenceQueue} to be
41 * notified when the <a href="package-summary.html#reachability">reachability</a>
42 * changes.
43 * <p>
44 * Each cleaner operates independently, managing the pending cleaning actions
45 * and handling threading and termination when the cleaner is no longer in use.
46 * Registering an object reference and corresponding cleaning action returns
47 * a {@link Cleanable Cleanable}. The most efficient use is to explicitly invoke
48 * the {@link Cleanable#clean clean} method when the object is closed or
49 * no longer needed.
50 * The cleaning action is a {@link Runnable} to be invoked at most once when
119 * Using a static nested class, as above, will avoid accidentally retaining the
120 * object reference.
121 * <p>
122 * <a name="compatible-cleaners"></a>
123 * Cleaning actions should be prepared to be invoked concurrently with
124 * other cleaning actions.
125 * Typically the cleaning actions should be very quick to execute
126 * and not block. If the cleaning action blocks, it may delay processing
127 * other cleaning actions registered to the same cleaner.
128 * All cleaning actions registered to a cleaner should be mutually compatible.
129 * @since 9
130 */
131 public final class Cleaner {
132
133 /**
134 * The Cleaner implementation.
135 */
136 final CleanerImpl impl;
137
138 static {
139 CleanerImpl.setCleanerImplAccess(new Function<Cleaner, CleanerImpl>() {
140 @Override
141 public CleanerImpl apply(Cleaner cleaner) {
142 return cleaner.impl;
143 }
144 });
145 }
146
147 /**
148 * Construct a Cleaner implementation and start it.
149 */
150 private Cleaner() {
151 impl = new CleanerImpl();
152 }
153
154 /**
155 * Returns a new {@code Cleaner}.
156 * <p>
157 * The cleaner creates a {@link Thread#setDaemon(boolean) daemon thread}
158 * to process the phantom reachable objects and to invoke cleaning actions.
159 * The {@linkplain java.lang.Thread#getContextClassLoader context class loader}
160 * of the thread is set to the
161 * {@link ClassLoader#getSystemClassLoader() system class loader}.
162 * The thread has no permissions, enforced only if a
163 * {@link java.lang.System#setSecurityManager(SecurityManager) SecurityManager is set}.
164 * <p>
|