sk.baka.webvm.misc
Class MgmtUtils

java.lang.Object
  sk.baka.webvm.misc.MgmtUtils

public final class MgmtUtils
extends Object

Provides utilities for the java.util.management package.

Author:

Martin Vysny

Method Summary

static MemoryUsage	add(MemoryUsage u1, MemoryUsage u2) Sums two memory usages together.
static String	getFreePerc(MemoryUsage mu) Returns amount of free memory in the following format: xx%
static MemoryUsage	getHeapFromRuntime() Computes and returns the memory usage object, using information only from Runtime.
static MemoryUsage	getInMB(MemoryUsage mu) Returns a new object with all values divided by 1024*1024 (converted from bytes to mebibytes).
static SortedMap<String,MemoryPoolMXBean>	getMemoryPools() Returns all known memory pools which are garbage-collectable and provide meaningful usage information.
static MemoryUsage	getNonHeapSummary() Sums up all non-heap pools and return their memory usage.
static String	getUsagePerc(MemoryUsage mu) Returns memory usage in the following format: xx%
static boolean	isNonHeapPool() Checks if there is a non-heap pool in the memory pool list.
static String	toString(MemoryUsage mu, boolean inMegs) Formats a memory usage instance to a compact string.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

getNonHeapSummary

public static MemoryUsage getNonHeapSummary()

Sums up all non-heap pools and return their memory usage.

Returns:

memory usage, null if no pool collects non-heap space.

isNonHeapPool

public static boolean isNonHeapPool()

Checks if there is a non-heap pool in the memory pool list.

Returns:

true if there is pool managing non-heap memory, false otherwise.

getHeapFromRuntime

public static MemoryUsage getHeapFromRuntime()

Computes and returns the memory usage object, using information only from Runtime.

Returns:

non-null usage object.

add

public static MemoryUsage add(MemoryUsage u1,
                              MemoryUsage u2)

Sums two memory usages together. Does not allow null values.

Parameters:

u1 - first usage, must not be null

u2 - second usage, must not be null

Returns:

a summed usage, never null

getInMB

public static MemoryUsage getInMB(MemoryUsage mu)

Returns a new object with all values divided by 1024*1024 (converted from bytes to mebibytes).

Parameters:

mu - the memory usage to convert

Returns:

new memory object with values in mebibytes. Returns null if null was supplied.

toString

public static String toString(MemoryUsage mu,
                              boolean inMegs)

Formats a memory usage instance to a compact string. Uses the following format: [used (committed) / max].

Parameters:

mu - the memory usage object.

inMegs - if true then given memory usage values are already megabytes. If false then the values are in bytes.

Returns:

[used (committed) / max], or [not available] if null was given

getUsagePerc

public static String getUsagePerc(MemoryUsage mu)

Returns memory usage in the following format: xx%

Parameters:

mu - the memory usage object, may be null

Returns:

formatted percent value; "not available" if the object is null or max is -1; "none" if max is zero

getFreePerc

public static String getFreePerc(MemoryUsage mu)

Returns amount of free memory in the following format: xx%

Parameters:

mu - the memory usage object, may be null

Returns:

formatted percent value; "?" if the object is null or max is -1; "none" if max is zero

getMemoryPools

public static SortedMap<String,MemoryPoolMXBean> getMemoryPools()

Returns all known memory pools which are garbage-collectable and provide meaningful usage information.

Returns:

map of memory pools, never null, may be empty.