| /* |
| * Copyright (c) 2003, 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). |
| * |
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| |
| package java.lang.management; |
| |
| /** |
| * The management interface for a memory pool. A memory pool |
| * represents the memory resource managed by the Java virtual machine |
| * and is managed by one or more {@link MemoryManagerMXBean memory managers}. |
| * |
| * <p> A Java virtual machine has one or more instances of the |
| * implementation class of this interface. An instance |
| * implementing this interface is |
| * an <a href="ManagementFactory.html#MXBean">MXBean</a> |
| * that can be obtained by calling |
| * the {@link ManagementFactory#getMemoryPoolMXBeans} method or |
| * from the {@link ManagementFactory#getPlatformMBeanServer |
| * platform <tt>MBeanServer</tt>} method. |
| * |
| * <p>The <tt>ObjectName</tt> for uniquely identifying the MXBean for |
| * a memory pool within an <tt>MBeanServer</tt> is: |
| * <blockquote> |
| * {@link ManagementFactory#MEMORY_POOL_MXBEAN_DOMAIN_TYPE |
| * <tt>java.lang:type=MemoryPool</tt>}<tt>,name=</tt><i>pool's name</i> |
| * </blockquote> |
| * |
| * It can be obtained by calling the |
| * {@link PlatformManagedObject#getObjectName} method. |
| * |
| * <h4>Memory Type</h4> |
| * <p>The Java virtual machine has a heap for object allocation and also |
| * maintains non-heap memory for the method area and the Java virtual |
| * machine execution. The Java virtual machine can have one or more |
| * memory pools. Each memory pool represents a memory area |
| * of one of the following types: |
| * <ul> |
| * <li>{@link MemoryType#HEAP heap}</li> |
| * <li>{@link MemoryType#NON_HEAP non-heap}</li> |
| * </ul> |
| * |
| * <h4>Memory Usage Monitoring</h4> |
| * |
| * A memory pool has the following attributes: |
| * <ul> |
| * <li><a href="#Usage">Memory usage</a></li> |
| * <li><a href="#PeakUsage">Peak memory usage</a></li> |
| * <li><a href="#UsageThreshold">Usage Threshold</a></li> |
| * <li><a href="#CollectionThreshold">Collection Usage Threshold</a> |
| * (only supported by some <em>garbage-collected</em> memory pools)</li> |
| * </ul> |
| * |
| * <h4><a name="Usage">1. Memory Usage</a></h4> |
| * |
| * The {@link #getUsage} method provides an estimate |
| * of the current usage of a memory pool. |
| * For a garbage-collected memory pool, the amount of used memory |
| * includes the memory occupied by all objects in the pool |
| * including both <em>reachable</em> and <em>unreachable</em> objects. |
| * |
| * <p>In general, this method is a lightweight operation for getting |
| * an approximate memory usage. For some memory pools, for example, |
| * when objects are not packed contiguously, this method may be |
| * an expensive operation that requires some computation to determine |
| * the current memory usage. An implementation should document when |
| * this is the case. |
| * |
| * <h4><a name="PeakUsage">2. Peak Memory Usage</a></h4> |
| * |
| * The Java virtual machine maintains the peak memory usage of a memory |
| * pool since the virtual machine was started or the peak was reset. |
| * The peak memory usage is returned by the {@link #getPeakUsage} method |
| * and reset by calling the {@link #resetPeakUsage} method. |
| * |
| * <h4><a name="UsageThreshold">3. Usage Threshold</a></h4> |
| * |
| * Each memory pool has a manageable attribute |
| * called the <i>usage threshold</i> which has a default value supplied |
| * by the Java virtual machine. The default value is platform-dependent. |
| * The usage threshold can be set via the |
| * {@link #setUsageThreshold setUsageThreshold} method. |
| * If the threshold is set to a positive value, the usage threshold crossing |
| * checking is enabled in this memory pool. |
| * If the usage threshold is set to zero, usage |
| * threshold crossing checking on this memory pool is disabled. |
| * The {@link MemoryPoolMXBean#isUsageThresholdSupported} method can |
| * be used to determine if this functionality is supported. |
| * <p> |
| * A Java virtual machine performs usage threshold crossing checking on a |
| * memory pool basis at its best appropriate time, typically, |
| * at garbage collection time. |
| * Each memory pool maintains a {@link #getUsageThresholdCount |
| * usage threshold count} that will get incremented |
| * every time when the Java virtual machine |
| * detects that the memory pool usage is crossing the threshold. |
| * <p> |
| * This manageable usage threshold attribute is designed for monitoring the |
| * increasing trend of memory usage with low overhead. |
| * Usage threshold may not be appropriate for some memory pools. |
| * For example, a generational garbage collector, a common garbage collection |
| * algorithm used in many Java virtual machine implementations, |
| * manages two or more generations segregating objects by age. |
| * Most of the objects are allocated in |
| * the <em>youngest generation</em> (say a nursery memory pool). |
| * The nursery memory pool is designed to be filled up and |
| * collecting the nursery memory pool will free most of its memory space |
| * since it is expected to contain mostly short-lived objects |
| * and mostly are unreachable at garbage collection time. |
| * In this case, it is more appropriate for the nursery memory pool |
| * not to support a usage threshold. In addition, |
| * if the cost of an object allocation |
| * in one memory pool is very low (for example, just atomic pointer exchange), |
| * the Java virtual machine would probably not support the usage threshold |
| * for that memory pool since the overhead in comparing the usage with |
| * the threshold is higher than the cost of object allocation. |
| * |
| * <p> |
| * The memory usage of the system can be monitored using |
| * <a href="#Polling">polling</a> or |
| * <a href="#ThresholdNotification">threshold notification</a> mechanisms. |
| * |
| * <ol type="a"> |
| * <li><a name="Polling"><b>Polling</b></a> |
| * <p> |
| * An application can continuously monitor its memory usage |
| * by calling either the {@link #getUsage} method for all |
| * memory pools or the {@link #isUsageThresholdExceeded} method |
| * for those memory pools that support a usage threshold. |
| * Below is example code that has a thread delicated for |
| * task distribution and processing. At every interval, |
| * it will determine if it should receive and process new tasks based |
| * on its memory usage. If the memory usage exceeds its usage threshold, |
| * it will redistribute all outstanding tasks to other VMs and |
| * stop receiving new tasks until the memory usage returns |
| * below its usage threshold. |
| * |
| * <pre> |
| * // Assume the usage threshold is supported for this pool. |
| * // Set the threshold to myThreshold above which no new tasks |
| * // should be taken. |
| * pool.setUsageThreshold(myThreshold); |
| * .... |
| * |
| * boolean lowMemory = false; |
| * while (true) { |
| * if (pool.isUsageThresholdExceeded()) { |
| * // potential low memory, so redistribute tasks to other VMs |
| * lowMemory = true; |
| * redistributeTasks(); |
| * // stop receiving new tasks |
| * stopReceivingTasks(); |
| * } else { |
| * if (lowMemory) { |
| * // resume receiving tasks |
| * lowMemory = false; |
| * resumeReceivingTasks(); |
| * } |
| * // processing outstanding task |
| * ... |
| * } |
| * // sleep for sometime |
| * try { |
| * Thread.sleep(sometime); |
| * } catch (InterruptedException e) { |
| * ... |
| * } |
| * } |
| * </pre> |
| * |
| * <hr> |
| * The above example does not differentiate the case where |
| * the memory usage has temporarily dropped below the usage threshold |
| * from the case where the memory usage remains above the threshould |
| * between two iterations. The usage threshold count returned by |
| * the {@link #getUsageThresholdCount} method |
| * can be used to determine |
| * if the memory usage has returned below the threshold |
| * between two polls. |
| * <p> |
| * Below shows another example that takes some action if a |
| * memory pool is under low memory and ignores the memory usage |
| * changes during the action processing time. |
| * |
| * <pre> |
| * // Assume the usage threshold is supported for this pool. |
| * // Set the threshold to myThreshold which determines if |
| * // the application will take some action under low memory condition. |
| * pool.setUsageThreshold(myThreshold); |
| * |
| * int prevCrossingCount = 0; |
| * while (true) { |
| * // A busy loop to detect when the memory usage |
| * // has exceeded the threshold. |
| * while (!pool.isUsageThresholdExceeded() || |
| * pool.getUsageThresholdCount() == prevCrossingCount) { |
| * try { |
| * Thread.sleep(sometime) |
| * } catch (InterruptException e) { |
| * .... |
| * } |
| * } |
| * |
| * // Do some processing such as check for memory usage |
| * // and issue a warning |
| * .... |
| * |
| * // Gets the current threshold count. The busy loop will then |
| * // ignore any crossing of threshold happens during the processing. |
| * prevCrossingCount = pool.getUsageThresholdCount(); |
| * } |
| * </pre><hr> |
| * </li> |
| * <li><a name="ThresholdNotification"><b>Usage Threshold Notifications</b></a> |
| * <p> |
| * Usage threshold notification will be emitted by {@link MemoryMXBean}. |
| * When the Java virtual machine detects that the memory usage of |
| * a memory pool has reached or exceeded the usage threshold |
| * the virtual machine will trigger the <tt>MemoryMXBean</tt> to emit an |
| * {@link MemoryNotificationInfo#MEMORY_THRESHOLD_EXCEEDED |
| * usage threshold exceeded notification}. |
| * Another usage threshold exceeded notification will not be |
| * generated until the usage has fallen below the threshold and |
| * then exceeded it again. |
| * <p> |
| * Below is an example code implementing the same logic as the |
| * first example above but using the usage threshold notification |
| * mechanism to detect low memory conditions instead of polling. |
| * In this example code, upon receiving notification, the notification |
| * listener notifies another thread to perform the actual action |
| * such as to redistribute outstanding tasks, stop receiving tasks, |
| * or resume receiving tasks. |
| * The <tt>handleNotification</tt> method should be designed to |
| * do a very minimal amount of work and return without delay to avoid |
| * causing delay in delivering subsequent notifications. Time-consuming |
| * actions should be performed by a separate thread. |
| * The notification listener may be invoked by multiple threads |
| * concurrently; so the tasks performed by the listener |
| * should be properly synchronized. |
| * |
| * <pre> |
| * class MyListener implements javax.management.NotificationListener { |
| * public void handleNotification(Notification notification, Object handback) { |
| * String notifType = notification.getType(); |
| * if (notifType.equals(MemoryNotificationInfo.MEMORY_THRESHOLD_EXCEEDED)) { |
| * // potential low memory, notify another thread |
| * // to redistribute outstanding tasks to other VMs |
| * // and stop receiving new tasks. |
| * lowMemory = true; |
| * notifyAnotherThread(lowMemory); |
| * } |
| * } |
| * } |
| * |
| * // Register MyListener with MemoryMXBean |
| * MemoryMXBean mbean = ManagementFactory.getMemoryMXBean(); |
| * NotificationEmitter emitter = (NotificationEmitter) mbean; |
| * MyListener listener = new MyListener(); |
| * emitter.addNotificationListener(listener, null, null); |
| * |
| * // Assume this pool supports a usage threshold. |
| * // Set the threshold to myThreshold above which no new tasks |
| * // should be taken. |
| * pool.setUsageThreshold(myThreshold); |
| * |
| * // Usage threshold detection is enabled and notification will be |
| * // handled by MyListener. Continue for other processing. |
| * .... |
| * |
| * </pre> |
| * <hr> |
| * <p> |
| * There is no guarantee about when the <tt>MemoryMXBean</tt> will emit |
| * a threshold notification and when the notification will be delivered. |
| * When a notification listener is invoked, the memory usage of |
| * the memory pool may have crossed the usage threshold more |
| * than once. |
| * The {@link MemoryNotificationInfo#getCount} method returns the number |
| * of times that the memory usage has crossed the usage threshold |
| * at the point in time when the notification was constructed. |
| * It can be compared with the current usage threshold count returned |
| * by the {@link #getUsageThresholdCount} method to determine if |
| * such situation has occurred. |
| * </li> |
| * </ol> |
| * |
| * <h4><a name="CollectionThreshold">4. Collection Usage Threshold</a></h4> |
| * |
| * Collection usage threshold is a manageable attribute only applicable |
| * to some garbage-collected memory pools. |
| * After a Java virtual machine has expended effort in reclaiming memory |
| * space by recycling unused objects in a memory pool at garbage collection |
| * time, some number of bytes in the memory pools that are garbaged |
| * collected will still be in use. The collection usage threshold |
| * allows a value to be set for this number of bytes such |
| * that if the threshold is exceeded, |
| * a {@link MemoryNotificationInfo#MEMORY_THRESHOLD_EXCEEDED |
| * collection usage threshold exceeded notification} |
| * will be emitted by the {@link MemoryMXBean}. |
| * In addition, the {@link #getCollectionUsageThresholdCount |
| * collection usage threshold count} will then be incremented. |
| * |
| * <p> |
| * The {@link MemoryPoolMXBean#isCollectionUsageThresholdSupported} method can |
| * be used to determine if this functionality is supported. |
| * |
| * <p> |
| * A Java virtual machine performs collection usage threshold checking |
| * on a memory pool basis. This checking is enabled if the collection |
| * usage threshold is set to a positive value. |
| * If the collection usage threshold is set to zero, this checking |
| * is disabled on this memory pool. Default value is zero. |
| * The Java virtual machine performs the collection usage threshold |
| * checking at garbage collection time. |
| * |
| * <p> |
| * Some garbage-collected memory pools may |
| * choose not to support the collection usage threshold. For example, |
| * a memory pool is only managed by a continuous concurrent garbage |
| * collector. Objects can be allocated in this memory pool by some thread |
| * while the unused objects are reclaimed by the concurrent garbage |
| * collector simultaneously. Unless there is a well-defined |
| * garbage collection time which is the best appropriate time |
| * to check the memory usage, the collection usage threshold should not |
| * be supported. |
| * |
| * <p> |
| * The collection usage threshold is designed for monitoring the memory usage |
| * after the Java virtual machine has expended effort in reclaiming |
| * memory space. The collection usage could also be monitored |
| * by the polling and threshold notification mechanism |
| * described above for the <a href="#UsageThreshold">usage threshold</a> |
| * in a similar fashion. |
| * |
| * @see ManagementFactory#getPlatformMXBeans(Class) |
| * @see <a href="../../../javax/management/package-summary.html"> |
| * JMX Specification.</a> |
| * @see <a href="package-summary.html#examples"> |
| * Ways to Access MXBeans</a> |
| * |
| * @author Mandy Chung |
| * @since 1.5 |
| */ |
| public interface MemoryPoolMXBean extends PlatformManagedObject { |
| /** |
| * Returns the name representing this memory pool. |
| * |
| * @return the name of this memory pool. |
| */ |
| public String getName(); |
| |
| /** |
| * Returns the type of this memory pool. |
| * |
| * <p> |
| * <b>MBeanServer access</b>:<br> |
| * The mapped type of <tt>MemoryType</tt> is <tt>String</tt> |
| * and the value is the name of the <tt>MemoryType</tt>. |
| * |
| * @return the type of this memory pool. |
| */ |
| public MemoryType getType(); |
| |
| /** |
| * Returns an estimate of the memory usage of this memory pool. |
| * This method returns <tt>null</tt> |
| * if this memory pool is not valid (i.e. no longer exists). |
| * |
| * <p> |
| * This method requests the Java virtual machine to make |
| * a best-effort estimate of the current memory usage of this |
| * memory pool. For some memory pools, this method may be an |
| * expensive operation that requires some computation to determine |
| * the estimate. An implementation should document when |
| * this is the case. |
| * |
| * <p>This method is designed for use in monitoring system |
| * memory usage and detecting low memory condition. |
| * |
| * <p> |
| * <b>MBeanServer access</b>:<br> |
| * The mapped type of <tt>MemoryUsage</tt> is |
| * <tt>CompositeData</tt> with attributes as specified in |
| * {@link MemoryUsage#from MemoryUsage}. |
| * |
| * @return a {@link MemoryUsage} object; or <tt>null</tt> if |
| * this pool not valid. |
| */ |
| public MemoryUsage getUsage(); |
| |
| /** |
| * Returns the peak memory usage of this memory pool since the |
| * Java virtual machine was started or since the peak was reset. |
| * This method returns <tt>null</tt> |
| * if this memory pool is not valid (i.e. no longer exists). |
| * |
| * <p> |
| * <b>MBeanServer access</b>:<br> |
| * The mapped type of <tt>MemoryUsage</tt> is |
| * <tt>CompositeData</tt> with attributes as specified in |
| * {@link MemoryUsage#from MemoryUsage}. |
| * |
| * @return a {@link MemoryUsage} object representing the peak |
| * memory usage; or <tt>null</tt> if this pool is not valid. |
| * |
| */ |
| public MemoryUsage getPeakUsage(); |
| |
| /** |
| * Resets the peak memory usage statistic of this memory pool |
| * to the current memory usage. |
| * |
| * @throws java.lang.SecurityException if a security manager |
| * exists and the caller does not have |
| * ManagementPermission("control"). |
| */ |
| public void resetPeakUsage(); |
| |
| /** |
| * Tests if this memory pool is valid in the Java virtual |
| * machine. A memory pool becomes invalid once the Java virtual |
| * machine removes it from the memory system. |
| * |
| * @return <tt>true</tt> if the memory pool is valid in the running |
| * Java virtual machine; |
| * <tt>false</tt> otherwise. |
| */ |
| public boolean isValid(); |
| |
| /** |
| * Returns the name of memory managers that manages this memory pool. |
| * Each memory pool will be managed by at least one memory manager. |
| * |
| * @return an array of <tt>String</tt> objects, each is the name of |
| * a memory manager managing this memory pool. |
| */ |
| public String[] getMemoryManagerNames(); |
| |
| /** |
| * Returns the usage threshold value of this memory pool in bytes. |
| * Each memory pool has a platform-dependent default threshold value. |
| * The current usage threshold can be changed via the |
| * {@link #setUsageThreshold setUsageThreshold} method. |
| * |
| * @return the usage threshold value of this memory pool in bytes. |
| * |
| * @throws UnsupportedOperationException if this memory pool |
| * does not support a usage threshold. |
| * |
| * @see #isUsageThresholdSupported |
| */ |
| public long getUsageThreshold(); |
| |
| /** |
| * Sets the threshold of this memory pool to the given <tt>threshold</tt> |
| * value if this memory pool supports the usage threshold. |
| * The usage threshold crossing checking is enabled in this memory pool |
| * if the threshold is set to a positive value. |
| * The usage threshold crossing checking is disabled |
| * if it is set to zero. |
| * |
| * @param threshold the new threshold value in bytes. Must be non-negative. |
| * |
| * @throws IllegalArgumentException if <tt>threshold</tt> is negative |
| * or greater than the maximum amount of memory for |
| * this memory pool if defined. |
| * |
| * @throws UnsupportedOperationException if this memory pool |
| * does not support a usage threshold. |
| * |
| * @throws java.lang.SecurityException if a security manager |
| * exists and the caller does not have |
| * ManagementPermission("control"). |
| * |
| * @see #isUsageThresholdSupported |
| * @see <a href="#UsageThreshold">Usage threshold</a> |
| */ |
| public void setUsageThreshold(long threshold); |
| |
| /** |
| * Tests if the memory usage of this memory pool |
| * reaches or exceeds its usage threshold value. |
| * |
| * @return <tt>true</tt> if the memory usage of |
| * this memory pool reaches or exceeds the threshold value; |
| * <tt>false</tt> otherwise. |
| * |
| * @throws UnsupportedOperationException if this memory pool |
| * does not support a usage threshold. |
| */ |
| public boolean isUsageThresholdExceeded(); |
| |
| /** |
| * Returns the number of times that the memory usage has crossed |
| * the usage threshold. |
| * |
| * @return the number of times that the memory usage |
| * has crossed its usage threshold value. |
| * |
| * @throws UnsupportedOperationException if this memory pool |
| * does not support a usage threshold. |
| */ |
| public long getUsageThresholdCount(); |
| |
| /** |
| * Tests if this memory pool supports usage threshold. |
| * |
| * @return <tt>true</tt> if this memory pool supports usage threshold; |
| * <tt>false</tt> otherwise. |
| */ |
| public boolean isUsageThresholdSupported(); |
| |
| /** |
| * Returns the collection usage threshold value of this memory pool |
| * in bytes. The default value is zero. The collection usage |
| * threshold can be changed via the |
| * {@link #setCollectionUsageThreshold setCollectionUsageThreshold} method. |
| * |
| * @return the collection usage threshold of this memory pool in bytes. |
| * |
| * @throws UnsupportedOperationException if this memory pool |
| * does not support a collection usage threshold. |
| * |
| * @see #isCollectionUsageThresholdSupported |
| */ |
| public long getCollectionUsageThreshold(); |
| |
| /** |
| * Sets the collection usage threshold of this memory pool to |
| * the given <tt>threshold</tt> value. |
| * When this threshold is set to positive, the Java virtual machine |
| * will check the memory usage at its best appropriate time after it has |
| * expended effort in recycling unused objects in this memory pool. |
| * <p> |
| * The collection usage threshold crossing checking is enabled |
| * in this memory pool if the threshold is set to a positive value. |
| * The collection usage threshold crossing checking is disabled |
| * if it is set to zero. |
| * |
| * @param threshold the new collection usage threshold value in bytes. |
| * Must be non-negative. |
| * |
| * @throws IllegalArgumentException if <tt>threshold</tt> is negative |
| * or greater than the maximum amount of memory for |
| * this memory pool if defined. |
| * |
| * @throws UnsupportedOperationException if this memory pool |
| * does not support a collection usage threshold. |
| * |
| * @throws java.lang.SecurityException if a security manager |
| * exists and the caller does not have |
| * ManagementPermission("control"). |
| * |
| * @see #isCollectionUsageThresholdSupported |
| * @see <a href="#CollectionThreshold">Collection usage threshold</a> |
| */ |
| public void setCollectionUsageThreshold(long threshold); |
| |
| /** |
| * Tests if the memory usage of this memory pool after |
| * the most recent collection on which the Java virtual |
| * machine has expended effort has reached or |
| * exceeded its collection usage threshold. |
| * This method does not request the Java virtual |
| * machine to perform any garbage collection other than its normal |
| * automatic memory management. |
| * |
| * @return <tt>true</tt> if the memory usage of this memory pool |
| * reaches or exceeds the collection usage threshold value |
| * in the most recent collection; |
| * <tt>false</tt> otherwise. |
| * |
| * @throws UnsupportedOperationException if this memory pool |
| * does not support a usage threshold. |
| */ |
| public boolean isCollectionUsageThresholdExceeded(); |
| |
| /** |
| * Returns the number of times that the Java virtual machine |
| * has detected that the memory usage has reached or |
| * exceeded the collection usage threshold. |
| * |
| * @return the number of times that the memory |
| * usage has reached or exceeded the collection usage threshold. |
| * |
| * @throws UnsupportedOperationException if this memory pool |
| * does not support a collection usage threshold. |
| * |
| * @see #isCollectionUsageThresholdSupported |
| */ |
| public long getCollectionUsageThresholdCount(); |
| |
| /** |
| * Returns the memory usage after the Java virtual machine |
| * most recently expended effort in recycling unused objects |
| * in this memory pool. |
| * This method does not request the Java virtual |
| * machine to perform any garbage collection other than its normal |
| * automatic memory management. |
| * This method returns <tt>null</tt> if the Java virtual |
| * machine does not support this method. |
| * |
| * <p> |
| * <b>MBeanServer access</b>:<br> |
| * The mapped type of <tt>MemoryUsage</tt> is |
| * <tt>CompositeData</tt> with attributes as specified in |
| * {@link MemoryUsage#from MemoryUsage}. |
| * |
| * @return a {@link MemoryUsage} representing the memory usage of |
| * this memory pool after the Java virtual machine most recently |
| * expended effort in recycling unused objects; |
| * <tt>null</tt> if this method is not supported. |
| */ |
| public MemoryUsage getCollectionUsage(); |
| |
| /** |
| * Tests if this memory pool supports a collection usage threshold. |
| * |
| * @return <tt>true</tt> if this memory pool supports the |
| * collection usage threshold; <tt>false</tt> otherwise. |
| */ |
| public boolean isCollectionUsageThresholdSupported(); |
| } |
