mirror of git://gcc.gnu.org/git/gcc.git
319 lines
12 KiB
Java
319 lines
12 KiB
Java
/* MemoryPoolMXBean.java - Interface for a memory pool bean
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Copyright (C) 2006 Free Software Foundation
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package java.lang.management;
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/**
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* <p>
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* Provides access to information about one of the memory
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* resources or pools used by the virtual machine. Instances
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* of this bean are obtained by calling
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* {@link ManagementFactory#getMemoryPoolMXBeans()}. One
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* bean is returned for each memory pool provided.
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* </p>
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* <p>
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* The memory pool bean allows the usage of the pool to be
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* monitored. The bean can provide statistics on the current
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* and peak usage of the pool, and on the threshold levels the
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* pool uses.
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* </p>
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* <p>
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* {@link getUsage()} returns an approximation of the current
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* usage of the pool. Calls to this method are expected to be
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* generally quick to perform; if the call is expensive, the
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* documentation of the bean should specify so. For memory
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* pool beans that represent the memory used by garbage
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* collectors, the usage level includes both referenced and
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* unreferenced objects.
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* </p>
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* <p>
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* {@link getPeakUsage()} and {@link resetPeakUsage()} enable
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* the retrieval of the peak usage level and setting it to the
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* current usage level, respectively. Initially, the peak usage
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* level is relative to the start of the virtual machine.
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* </p>
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* <p>
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* Memory pools may also include optional support for usage thresholds.
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* The usage threshold is a particular level of memory usage. When this
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* value is crossed (the current memory usage becomes equal to or greater
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* than this threshold level), the usage threshold count is increased.
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* This feature is designed for monitoring the trend in memory usage.
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* Support for a collection usage threshold is also provided, for
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* particular garbage collectors. This is used to monitor the amount
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* of memory left uncollected after a garbage collection cycle. There
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* is no need to make special garbage collection runs to support this;
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* the level following collection just needs to be monitored.
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* </p>
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*
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* @author Andrew John Hughes (gnu_andrew@member.fsf.org)
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* @since 1.5
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*/
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public interface MemoryPoolMXBean
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{
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/**
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* Returns memory usage statistics after a best-effort attempt
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* has been made to remove unused objects from the pool. This
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* method is designed for use by the pools of garbage collectors,
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* in order to monitor the amount of memory used after collections.
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* It will return <code>null</code> if such functionality is
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* unsupported by the memory pool represented by this bean.
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*
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* @return the memory usage of the memory pool after the most
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* recent garbage collection cycle, or <code>null</code>
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* if this operation is not supported.
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*/
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MemoryUsage getCollectionUsage();
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/**
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* Returns the collection usage threshold level in bytes. This
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* value is initially zero.
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*
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* @return the collection usage threshold in bytes.
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* @throws UnsupportedOperationException if the collection usage
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* threshold is not supported.
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* @see #getCollectionUsageThresholdCount()
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* @see #isCollectionUsageThresholdExceeded()
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* @see #isCollectionUsageThresholdSupported()
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* @see #setCollectionUsageThreshold(long)
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*/
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long getCollectionUsageThreshold();
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/**
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* Returns the number of times the usage level has matched or
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* exceeded the collection usage threshold.
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*
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* @return the number of times the usage level has matched
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* or exceeded the collection usage threshold.
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* @throws UnsupportedOperationException if the collection usage
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* threshold is not supported.
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* @see #getCollectionUsageThreshold()
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* @see #isCollectionUsageThresholdExceeded()
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* @see #isCollectionUsageThresholdSupported()
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* @see #setCollectionUsageThreshold(long)
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*/
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long getCollectionUsageThresholdCount();
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/**
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* Returns the names of the memory managers associated with this
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* pool. Each pool has at least one memory manager.
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*
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* @return an array containing the name of each memory manager
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* responsible for this pool.
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*/
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String[] getMemoryManagerNames();
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/**
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* Returns the name of the memory pool.
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*
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* @return the memory pool name.
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*/
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String getName();
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/**
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* Returns memory usage statistics for the peak memory usage
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* of the pool. The peak is the maximum memory usage occurring
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* since the virtual machine was started or since the peak
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* was reset by {@link #resetPeakUsage()}. The return value
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* may be <code>null</code> if this pool is no longer valid.
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*
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* @return the memory usage of the memory pool at its peak,
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* or <code>null</code> if this pool is no longer valid.
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*/
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MemoryUsage getPeakUsage();
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/**
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* Returns the type of memory used by this pool. This can be
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* either heap or non-heap memory.
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*
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* @return the type of this pool.
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*/
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MemoryType getType();
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/**
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* Returns memory usage statistics for the current memory usage
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* of the pool. The return value may be <code>null</code> if
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* this pool is no longer valid. Obtaining these values is
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* expected to be a relatively quick operation; if this will
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* instead be an expensive operation to perform, the documentation
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* of the implementating bean should specify that this is the
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* case. The values are intended to be an estimate for monitoring
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* purposes.
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*
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* @return the memory usage of the memory pool at present,
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* or <code>null</code> if this pool is no longer valid.
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*/
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MemoryUsage getUsage();
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/**
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* Returns the usage threshold level in bytes. This
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* value is initially defined by the virtual machine.
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*
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* @return the usage threshold in bytes.
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* @throws UnsupportedOperationException if the usage threshold
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* is not supported.
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* @see #getUsageThresholdCount()
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* @see #isUsageThresholdExceeded()
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* @see #isUsageThresholdSupported()
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* @see #setUsageThreshold(long)
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*/
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long getUsageThreshold();
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/**
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* Returns the number of times the usage level has matched or
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* exceeded the usage threshold.
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*
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* @return the number of times the usage level has matched
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* or exceeded the usage threshold.
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* @throws UnsupportedOperationException if the usage threshold
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* is not supported.
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* @see #getUsageThreshold()
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* @see #isUsageThresholdExceeded()
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* @see #isUsageThresholdSupported()
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* @see #setUsageThreshold(long)
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*/
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long getUsageThresholdCount();
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/**
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* Returns true if the collection usage level is equal to
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* or greater than the collection usage threshold.
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*
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* @return true if the collection usage threshold has been
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* matched or exceeded.
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* @throws UnsupportedOperationException if the collection usage
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* threshold is not supported.
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* @see #getCollectionUsageThreshold()
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* @see #getCollectionUsageThresholdCount()
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* @see #isCollectionUsageThresholdSupported()
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* @see #setCollectionUsageThreshold(long)
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*/
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boolean isCollectionUsageThresholdExceeded();
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/**
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* Returns true if this memory pool supports a collection usage
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* level threshold.
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*
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* @return true if a collection usage level threshold is supported.
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* @see #getCollectionUsageThreshold()
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* @see #getCollectionUsageThresholdCount()
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* @see #isCollectionUsageThresholdExceeded()
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* @see #setCollectionUsageThreshold(long)
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*/
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boolean isCollectionUsageThresholdSupported();
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/**
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* Returns true if the usage level is equal to
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* or greater than the usage threshold.
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*
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* @return true if the usage threshold has been
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* matched or exceeded.
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* @throws UnsupportedOperationException if the usage threshold
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* is not supported.
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* @see #getUsageThreshold()
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* @see #getUsageThresholdCount()
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* @see #isUsageThresholdSupported()
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* @see #setUsageThreshold(long)
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*/
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boolean isUsageThresholdExceeded();
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/**
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* Returns true if this memory pool supports a usage level threshold.
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*
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* @return true if a usage level threshold is supported.
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* @see #getUsageThreshold()
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* @see #getUsageThresholdCount()
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* @see #isUsageThresholdExceeded()
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* @see #setUsageThreshold(long)
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*/
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boolean isUsageThresholdSupported();
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/**
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* Returns true if this memory pool is still valid. A memory pool
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* becomes invalid when it is removed by the virtual machine and
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* no longer used.
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*
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* @return true if this memory pool is valid.
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*/
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boolean isValid();
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/**
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* Resets the peak memory usage level to the current memory usage
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* level.
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*
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* @throws SecurityException if a security manager exists and
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* denies ManagementPermission("control").
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*/
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void resetPeakUsage();
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/**
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* Sets the collection threshold usage level to the given value.
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* A value of zero disables the collection threshold.
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*
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* @param threshold the new threshold level.
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* @throws IllegalArgumentException if the threshold hold level
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* is negative.
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* @throws UnsupportedOperationException if the collection usage
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* threshold is not supported.
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* @throws SecurityException if a security manager exists and
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* denies ManagementPermission("control").
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* @see #getCollectionUsageThreshold()
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* @see #getCollectionUsageThresholdCount()
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* @see #isCollectionUsageThresholdExceeded()
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* @see #isCollectionUsageThresholdSupported()
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*/
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void setCollectionUsageThreshold(long threshold);
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/**
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* Sets the threshold usage level to the given value. A value of
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* zero disables the threshold.
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*
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* @param threshold the new threshold level.
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* @throws IllegalArgumentException if the threshold hold level
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* is negative.
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* @throws UnsupportedOperationException if the usage threshold
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* is not supported.
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* @throws SecurityException if a security manager exists and
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* denies ManagementPermission("control").
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* @see #getUsageThreshold()
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* @see #getUsageThresholdCount()
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* @see #isUsageThresholdExceeded()
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* @see #isUsageThresholdSupported()
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*/
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void setUsageThreshold(long threshold);
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}
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