diff -r 476d8d615222 -r 467b7b9caa2b jdk/src/java.base/share/classes/sun/misc/GC.java --- a/jdk/src/java.base/share/classes/sun/misc/GC.java Sun Apr 10 08:41:00 2016 -0700 +++ /dev/null Thu Jan 01 00:00:00 1970 +0000 @@ -1,283 +0,0 @@ -/* - * Copyright (c) 1998, 2008, Oracle and/or its affiliates. All rights reserved. - * 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. - */ - -package sun.misc; - -import java.security.AccessController; -import java.security.PrivilegedAction; -import java.util.SortedSet; -import java.util.TreeSet; - - -/** - * Support for garbage-collection latency requests. - * - * @author Mark Reinhold - * @since 1.2 - */ - -public class GC { - - private GC() { } /* To prevent instantiation */ - - - /* Latency-target value indicating that there's no active target - */ - private static final long NO_TARGET = Long.MAX_VALUE; - - /* The current latency target, or NO_TARGET if there is no target - */ - private static long latencyTarget = NO_TARGET; - - /* The daemon thread that implements the latency-target mechanism, - * or null if there is presently no daemon thread - */ - private static Thread daemon = null; - - /* The lock object for the latencyTarget and daemon fields. The daemon - * thread, if it exists, waits on this lock for notification that the - * latency target has changed. - */ - private static class LatencyLock extends Object { }; - private static Object lock = new LatencyLock(); - - - /** - * Returns the maximum object-inspection age, which is the number - * of real-time milliseconds that have elapsed since the - * least-recently-inspected heap object was last inspected by the garbage - * collector. - * - *
For simple stop-the-world collectors this value is just the time - * since the most recent collection. For generational collectors it is the - * time since the oldest generation was most recently collected. Other - * collectors are free to return a pessimistic estimate of the elapsed - * time, or simply the time since the last full collection was performed. - * - *
Note that in the presence of reference objects, a given object that
- * is no longer strongly reachable may have to be inspected multiple times
- * before it can be reclaimed.
- */
- public static native long maxObjectInspectionAge();
-
- private static class Daemon extends Thread {
-
- public void run() {
- for (;;) {
- long l;
- synchronized (lock) {
-
- l = latencyTarget;
- if (l == NO_TARGET) {
- /* No latency target, so exit */
- GC.daemon = null;
- return;
- }
-
- long d = maxObjectInspectionAge();
- if (d >= l) {
- /* Do a full collection. There is a remote possibility
- * that a full collection will occurr between the time
- * we sample the inspection age and the time the GC
- * actually starts, but this is sufficiently unlikely
- * that it doesn't seem worth the more expensive JVM
- * interface that would be required.
- */
- System.gc();
- d = 0;
- }
-
- /* Wait for the latency period to expire,
- * or for notification that the period has changed
- */
- try {
- lock.wait(l - d);
- } catch (InterruptedException x) {
- continue;
- }
- }
- }
- }
-
- private Daemon(ThreadGroup tg) {
- super(tg, null, "GC Daemon", 0L, false);
- }
-
- /* Create a new daemon thread in the root thread group */
- public static void create() {
- PrivilegedAction{@link #requestLatency}
- * method. Given a request, the only interesting operation is that of
- * cancellation.
- */
- public static class LatencyRequest
- implements Comparablelatency
is non-positive
- */
- public static LatencyRequest requestLatency(long latency) {
- return new LatencyRequest(latency);
- }
-
-
- /**
- * Returns the current smallest garbage-collection latency request, or zero
- * if there are no active requests.
- */
- public static long currentLatencyTarget() {
- long t = latencyTarget;
- return (t == NO_TARGET) ? 0 : t;
- }
-
-}