--- a/jdk/src/java.base/share/classes/sun/misc/GC.java Tue Apr 05 18:23:10 2016 +0300
+++ /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 <em>object-inspection age</em>, 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.
- *
- * <p> 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.
- *
- * <p> 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<Void> pa = new PrivilegedAction<Void>() {
- public Void run() {
- ThreadGroup tg = Thread.currentThread().getThreadGroup();
- for (ThreadGroup tgn = tg;
- tgn != null;
- tg = tgn, tgn = tg.getParent());
- Daemon d = new Daemon(tg);
- d.setDaemon(true);
- d.setPriority(Thread.MIN_PRIORITY + 1);
- d.start();
- GC.daemon = d;
- return null;
- }};
- AccessController.doPrivileged(pa);
- }
-
- }
-
-
- /* Sets the latency target to the given value.
- * Must be invoked while holding the lock.
- */
- private static void setLatencyTarget(long ms) {
- latencyTarget = ms;
- if (daemon == null) {
- /* Create a new daemon thread */
- Daemon.create();
- } else {
- /* Notify the existing daemon thread
- * that the lateency target has changed
- */
- lock.notify();
- }
- }
-
-
- /**
- * Represents an active garbage-collection latency request. Instances of
- * this class are created by the <code>{@link #requestLatency}</code>
- * method. Given a request, the only interesting operation is that of
- * cancellation.
- */
- public static class LatencyRequest
- implements Comparable<LatencyRequest> {
-
- /* Instance counter, used to generate unique identifers */
- private static long counter = 0;
-
- /* Sorted set of active latency requests */
- private static SortedSet<LatencyRequest> requests = null;
-
- /* Examine the request set and reset the latency target if necessary.
- * Must be invoked while holding the lock.
- */
- private static void adjustLatencyIfNeeded() {
- if ((requests == null) || requests.isEmpty()) {
- if (latencyTarget != NO_TARGET) {
- setLatencyTarget(NO_TARGET);
- }
- } else {
- LatencyRequest r = requests.first();
- if (r.latency != latencyTarget) {
- setLatencyTarget(r.latency);
- }
- }
- }
-
- /* The requested latency, or NO_TARGET
- * if this request has been cancelled
- */
- private long latency;
-
- /* Unique identifier for this request */
- private long id;
-
- private LatencyRequest(long ms) {
- if (ms <= 0) {
- throw new IllegalArgumentException("Non-positive latency: "
- + ms);
- }
- this.latency = ms;
- synchronized (lock) {
- this.id = ++counter;
- if (requests == null) {
- requests = new TreeSet<LatencyRequest>();
- }
- requests.add(this);
- adjustLatencyIfNeeded();
- }
- }
-
- /**
- * Cancels this latency request.
- *
- * @throws IllegalStateException
- * If this request has already been cancelled
- */
- public void cancel() {
- synchronized (lock) {
- if (this.latency == NO_TARGET) {
- throw new IllegalStateException("Request already"
- + " cancelled");
- }
- if (!requests.remove(this)) {
- throw new InternalError("Latency request "
- + this + " not found");
- }
- if (requests.isEmpty()) requests = null;
- this.latency = NO_TARGET;
- adjustLatencyIfNeeded();
- }
- }
-
- public int compareTo(LatencyRequest r) {
- long d = this.latency - r.latency;
- if (d == 0) d = this.id - r.id;
- return (d < 0) ? -1 : ((d > 0) ? +1 : 0);
- }
-
- public String toString() {
- return (LatencyRequest.class.getName()
- + "[" + latency + "," + id + "]");
- }
-
- }
-
-
- /**
- * Makes a new request for a garbage-collection latency of the given
- * number of real-time milliseconds. A low-priority daemon thread makes a
- * best effort to ensure that the maximum object-inspection age never
- * exceeds the smallest of the currently active requests.
- *
- * @param latency
- * The requested latency
- *
- * @throws IllegalArgumentException
- * If the given <code>latency</code> 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;
- }
-
-}