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author | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
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committer | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
commit | 554fd8c5195424bdbcabf5de30fdc183aba391bd (patch) | |
tree | 976dc5ab7fddf506dadce60ae936f43f58787092 /libjava/classpath/java/lang/management/MemoryMXBean.java | |
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Diffstat (limited to 'libjava/classpath/java/lang/management/MemoryMXBean.java')
-rw-r--r-- | libjava/classpath/java/lang/management/MemoryMXBean.java | 172 |
1 files changed, 172 insertions, 0 deletions
diff --git a/libjava/classpath/java/lang/management/MemoryMXBean.java b/libjava/classpath/java/lang/management/MemoryMXBean.java new file mode 100644 index 000000000..acf0e6795 --- /dev/null +++ b/libjava/classpath/java/lang/management/MemoryMXBean.java @@ -0,0 +1,172 @@ +/* MemoryMXBean.java - Interface for a memory bean + Copyright (C) 2006 Free Software Foundation + +This file is part of GNU Classpath. + +GNU Classpath is free software; you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation; either version 2, or (at your option) +any later version. + +GNU Classpath 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 for more details. + +You should have received a copy of the GNU General Public License +along with GNU Classpath; see the file COPYING. If not, write to the +Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA +02110-1301 USA. + +Linking this library statically or dynamically with other modules is +making a combined work based on this library. Thus, the terms and +conditions of the GNU General Public License cover the whole +combination. + +As a special exception, the copyright holders of this library give you +permission to link this library with independent modules to produce an +executable, regardless of the license terms of these independent +modules, and to copy and distribute the resulting executable under +terms of your choice, provided that you also meet, for each linked +independent module, the terms and conditions of the license of that +module. An independent module is a module which is not derived from +or based on this library. If you modify this library, you may extend +this exception to your version of the library, but you are not +obligated to do so. If you do not wish to do so, delete this +exception statement from your version. */ + +package java.lang.management; + +/** + * <p> + * Provides access to information about the memory used + * by the virtual machine. An instance of this bean is + * obtained by calling + * {@link ManagementFactory#getMemoryMXBean()}. + * </p> + * <p> + * The Java virtual machine uses two types of memory: + * heap memory and non-heap memory. The heap is the + * storage location for class and array instances, and is + * thus the main source of memory associated with running + * Java programs. The heap is created when the virtual + * machine is started, and is periodically scanned by the + * garbage collector(s), in order to reclaim memory which + * is no longer used (e.g. because an object reference has + * gone out of scope). + * </p> + * <p> + * Non-heap memory is used by the virtual machine in order to + * perform its duties. Thus, it mainly acts as the storage + * location for structures created as a result of parsing Java + * bytecode, such as the constant pool and constructor/method + * declarations. When a Just-In-Time (JIT) compiler is in + * operation, this will use non-heap memory to store compiled + * bytecode. + * </p> + * <p> + * Both types of memory may be non-contiguous. During the + * lifetime of the virtual machine, the size of both may + * either change (either expanding or contracting) or stay + * the same. + * </p> + * <h2>Notifications</h2> + * <p> + * Implementations of this interface also conform to the + * {@link javax.management.NotificationEmitter} interface, + * and supply two notifications reflecting memory usage. + * These notifications occur when a usage threshold is + * exceeded; for more details of these, see the documentation + * of {@link MemoryPoolMXBean}. If threshold monitoring + * is supported, then a notification will be emitted each time + * the threshold is crossed. Another notification will not + * be emitted unless the usage level has dropped below the + * threshold again in the meantime. + * </p> + * <p> + * The emitted notifications are instances of + * {@link javax.management.Notification}, with a type of + * either + * {@link java.lang.management.MemoryNotificationInfo#MEMORY_THRESHOLD_EXCEEDED} + * or + * {@link java.lang.management.MemoryNotificationInfo#MEMORY_COLLECTION_THRESHOLD_EXCEEDED} + * (depending on whether the notification refers to the general + * usage threshold or the garbage collection threshold) and an instance + * of {@link java.lang.management.MemoryNotificationInfo} contained + * in the user data section. This is wrapped inside an instance + * of {@link javax.management.openmbean.CompositeData}, as explained + * in the documentation for + * {@link java.lang.management.MemoryNotificationInfo}. + * </p> + * + * @author Andrew John Hughes (gnu_andrew@member.fsf.org) + * @since 1.5 + */ +public interface MemoryMXBean +{ + + /** + * Instigates a garbage collection cycle. The virtual + * machine's garbage collector should make the best + * attempt it can at reclaiming unused memory. This + * is equivalent to invoking {@link java.lang.System.gc()}. + * + * @see java.lang.System#gc() + */ + void gc(); + + /** + * Returns a {@link MemoryUsage} object representing the + * current state of the heap. This incorporates various + * statistics on both the initial and current memory + * allocations used by the heap. + * + * @return a {@link MemoryUsage} object for the heap. + */ + MemoryUsage getHeapMemoryUsage(); + + /** + * Returns a {@link MemoryUsage} object representing the + * current state of non-heap memory. This incorporates + * various statistics on both the initial and current + * memory allocations used by non-heap memory.. + * + * @return a {@link MemoryUsage} object for non-heap + * memory. + */ + MemoryUsage getNonHeapMemoryUsage(); + + /** + * Returns the number of objects which are waiting to + * be garbage collected (finalized). An object is + * finalized when the garbage collector determines that + * there are no more references to that object are in + * use. + * + * @return the number of objects awaiting finalization. + */ + int getObjectPendingFinalizationCount(); + + /** + * Returns true if the virtual machine will emit additional + * information when memory is allocated and deallocated. The + * format of the output is left up to the virtual machine. + * + * @return true if verbose memory output is on. + */ + boolean isVerbose(); + + /** + * Turns on or off the emission of additional information + * when memory is allocated and deallocated. The format of the + * output is left up to the virtual machine. This method + * may be called by multiple threads concurrently, but there + * is only one global setting of verbosity that is affected. + * + * @param verbose the new setting for verbose memory output. + * @throws SecurityException if a security manager exists and + * denies ManagementPermission("control"). + */ + void setVerbose(boolean verbose); + +} |