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265 lines
9.4 KiB
Java
265 lines
9.4 KiB
Java
/* MemoryUsage.java - Information on the usage of a memory pool.
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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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import javax.management.openmbean.CompositeData;
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import javax.management.openmbean.CompositeType;
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import javax.management.openmbean.SimpleType;
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/**
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* <p>
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* Retains information on the usage of a particular memory
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* pool, or heap/non-heap memory as a whole. Memory usage
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* is represented by four values (all in bytes):
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* </p>
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* <ul>
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* <li><strong>Initial Level</strong>: This is the initial
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* amount of memory allocated for the pool by the operating
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* system. This value may be undefined.</li>
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* <li><strong>Used Level</strong>: This is the amount of
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* memory currently in use.</li>
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* <li><strong>Committed Level</strong>: This is the current
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* amount of memory allocated for the pool by the operating
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* system. This value will always be equal to or greater than
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* the current amount of memory in use. It may drop below
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* the initial amount, if the virtual machine judges this to
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* be practical.</li>
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* <li><strong>Maximum Level</strong>: This is the maximum
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* amount of memory that may be allocated for the pool by
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* the operating system. Like the initial amount, it may
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* be undefined. If it is defined, it will be greater than
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* or equal to the used and committed amounts and may change
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* over time. It is not guaranteed that the maximum amount
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* of memory may actually be allocated to the pool. For
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* example, a request for an amount of memory greater than
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* the current committed level, but less than the maximum,
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* may still fail due to resources at the operating system
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* level not being sufficient to fulfill the demand.</li>
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* </ul>
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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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* @see MemoryMXBean
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* @see MemoryPoolMXBean
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*/
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public class MemoryUsage
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{
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/**
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* The initial amount of memory allocated.
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*/
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private long init;
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/**
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* The amount of memory used.
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*/
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private long used;
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/**
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* The amount of memory committed for use.
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*/
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private long committed;
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/**
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* The maximum amount of memory available.
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*/
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private long maximum;
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/**
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* Constructs a new {@link MemoryUsage} object with
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* the specified allocation levels.
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*
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* @param init the initial amount of memory allocated,
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* or -1 if this value is undefined. Must
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* be >= -1.
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* @param used the amount of memory used. Must be >= 0,
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* and <= committed.
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* @param committed the amount of memory committed for use
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* at present. Must be >= 0 and <=
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* maximum (if defined).
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* @param maximum the maximum amount of memory that may be
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* used, or -1 if this value is undefined.
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* Must be >= -1.
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* @throws IllegalArgumentException if the values break any
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* of the limits specified
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* above.
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*/
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public MemoryUsage(long init, long used, long committed,
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long maximum)
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{
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if (init < -1)
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throw new IllegalArgumentException("Initial value of "
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+ init + " is too small.");
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if (used < 0)
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throw new IllegalArgumentException("Used value of "
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+ used + " is too small.");
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if (committed < 0)
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throw new IllegalArgumentException("Committed value of "
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+ committed + " is too small.");
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if (committed < used)
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throw new IllegalArgumentException("Committed value of "
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+ committed + " is below "
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+ used + ", the amount used.");
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if (maximum < -1)
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throw new IllegalArgumentException("Maximum value of "
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+ maximum + " is too small.");
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if (maximum != -1 && maximum < committed)
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throw new IllegalArgumentException("Maximum value of "
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+ maximum + " is below "
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+ committed + ", the amount "
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+ "committed.");
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this.init = init;
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this.used = used;
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this.committed = committed;
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this.maximum = maximum;
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}
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/**
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* <p>
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* Returns a {@link MemoryUsage} instance using the values
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* given in the supplied
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* {@link javax.management.openmbean.CompositeData} object.
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* The composite data instance should contain the following
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* attributes:
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* </p>
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* <ul>
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* <li>init</li>
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* <li>used</li>
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* <li>committed</li>
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* <li>max</li>
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* </ul>
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* <p>
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* All should have the type, <code>java.lang.Long</code>.
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* </p>
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*
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* @param data the composite data structure to take values from.
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* @return a new instance containing the values from the
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* composite data structure, or <code>null</code>
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* if the data structure was also <code>null</code>.
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* @throws IllegalArgumentException if the composite data structure
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* does not match the structure
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* outlined above, or the values
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* are invalid.
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*/
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public static MemoryUsage from(CompositeData data)
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{
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if (data == null)
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return null;
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CompositeType type = data.getCompositeType();
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ThreadInfo.checkAttribute(type, "Init", SimpleType.LONG);
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ThreadInfo.checkAttribute(type, "Used", SimpleType.LONG);
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ThreadInfo.checkAttribute(type, "Committed", SimpleType.LONG);
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ThreadInfo.checkAttribute(type, "Max", SimpleType.LONG);
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return new MemoryUsage(((Long) data.get("Init")).longValue(),
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((Long) data.get("Used")).longValue(),
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((Long) data.get("Committed")).longValue(),
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((Long) data.get("Max")).longValue());
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}
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/**
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* Returns the amount of memory committed for use by this
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* memory pool (in bytes). This amount is guaranteed to
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* be available, unlike the maximum.
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*
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* @return the committed amount of memory.
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*/
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public long getCommitted()
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{
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return committed;
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}
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/**
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* Returns the initial amount of memory allocated to the
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* pool (in bytes). This method may return -1, if the
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* value is undefined.
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*
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* @return the initial amount of memory allocated, or -1
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* if this value is undefined.
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*/
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public long getInit()
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{
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return init;
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}
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/**
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* Returns the maximum amount of memory available for this
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* pool (in bytes). This amount is not guaranteed to
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* actually be usable. This method may return -1, if the
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* value is undefined.
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*
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* @return the maximum amount of memory available, or -1
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* if this value is undefined.
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*/
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public long getMax()
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{
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return maximum;
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}
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/**
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* Returns the amount of memory used (in bytes).
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*
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* @return the amount of used memory.
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*/
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public long getUsed()
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{
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return used;
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}
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/**
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* Returns a {@link java.lang.String} representation of
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* this {@link MemoryUsage} object. This takes the form
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* <code>java.lang.management.MemoryUsage[init=i, used=u,
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* committed=c, maximum=m]</code>, where <code>i</code>
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* is the initial level, <code>u</code> is the used level,
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* <code>c</code> is the committed level and <code>m</code>
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* is the maximum level.
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*
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* @return the string specified above.
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*/
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public String toString()
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{
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int megabyte = 1024 * 1024;
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return getClass().getName() +
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"[init=" + init + " bytes (~" + (init / megabyte) +
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"MB), used=" + used + " bytes (~" + (used / megabyte) +
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"MB), committed=" + committed + " bytes (~" + (committed / megabyte) +
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"MB), maximum=" + maximum + " bytes (~" + (maximum / megabyte) +
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"MB)]";
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}
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}
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