uk.org.ogsadai.common
Class MemoryUtilities

java.lang.Object
  |
  +--uk.org.ogsadai.common.MemoryUtilities

public class MemoryUtilities

extends java.lang.Object

Utilities for managing, checking and logging memory usage.

Author:

The OGSA-DAI Project Team.

Field Summary

private static java.lang.String	COPYRIGHT_NOTICE
private static DAILogger	LOG
private static long	MAX_MEMORY
private static java.lang.Runtime	RUNTIME
static double	THRESHOLD Threshold ratio for how full the JVM memory must be before an exception is thrown (to avoid a java.lang.OutOfMemoryError).

Constructor Summary

MemoryUtilities()

Method Summary

static void	checkMemory(byte[] bytes, DAILogger log) Check that the copying of a byte array within the JVM will not go over the threshold memory ratio set for this system.
static void	checkMemory(java.io.ByteArrayOutputStream stream, DAILogger log) Check that the convertion of a ByteArrayOutputStream to a byte array within the JVM will not go over the threshold memory ratio set for this system.
static void	checkMemory(int numberOfBytesToAdd, DAILogger log) Check that the allocation of an extra number of bytes within the JVM will not go over the threshold ratio set for this system.
static void	checkMemory(java.lang.StringBuffer buffer, DAILogger log) Check that the conversion of a StringBuffer to a String within the JVM will not go over the threshold memory ratio set for this system.
static void	checkMemory(java.lang.String stringToCopy, DAILogger log) Check that the copying of a String within the JVM will not go over the threshold memory ratio set for this system.
private static long	getCurrentlyUsedMemory() Get current memory in use.
private static double	getCurrentRatio(int numberOfBytesToAdd) Get ratio of current memory in use + number of requested bytes to total memory.
static void	logMemoryUsage(DAILogger log) Logs the current state of the JVM memory at DEBUG level to this object's own log and in the logger provided.

Methods inherited from class java.lang.Object

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

Field Detail

COPYRIGHT_NOTICE

private static final java.lang.String COPYRIGHT_NOTICE

See Also:

Constant Field Values

LOG

private static final DAILogger LOG

RUNTIME

private static final java.lang.Runtime RUNTIME

MAX_MEMORY

private static final long MAX_MEMORY

THRESHOLD

public static final double THRESHOLD

Threshold ratio for how full the JVM memory must be before an exception is thrown (to avoid a java.lang.OutOfMemoryError).

See Also:

Constant Field Values

Constructor Detail

MemoryUtilities

public MemoryUtilities()

Method Detail

checkMemory

public static void checkMemory(java.lang.String stringToCopy,
                               DAILogger log)
                        throws OutOfMemoryException

Check that the copying of a String within the JVM will not go over the threshold memory ratio set for this system.

Parameters:

stringToCopy - The string to be copied.

log - Destination of memory usage info.

Throws:

OutOfMemoryException - if the ratio of used memory would be exceeded by allocating the number of bytes specified.

checkMemory

public static void checkMemory(byte[] bytes,
                               DAILogger log)
                        throws OutOfMemoryException

Check that the copying of a byte array within the JVM will not go over the threshold memory ratio set for this system.

Parameters:

bytes - The byte array to be copied.

log - Destination of memory usage info.

Throws:

OutOfMemoryException - if the ratio of used memory would be exceeded by allocating the number of bytes specified.

checkMemory

public static void checkMemory(java.lang.StringBuffer buffer,
                               DAILogger log)
                        throws OutOfMemoryException

Check that the conversion of a StringBuffer to a String within the JVM will not go over the threshold memory ratio set for this system.

Parameters:

buffer - The java.lang.StringBuffer to be converted.

log - Destination of memory usage info.

Throws:

OutOfMemoryException - if the ratio of used memory would be exceeded by allocating the number of bytes specified.

checkMemory

public static void checkMemory(java.io.ByteArrayOutputStream stream,
                               DAILogger log)
                        throws OutOfMemoryException

Check that the convertion of a ByteArrayOutputStream to a byte array within the JVM will not go over the threshold memory ratio set for this system.

Parameters:

stream - The java.io.ByteArrayOutputStream to be converted.

log - Destination of memory usage info.

Throws:

OutOfMemoryException - if the ratio of used memory would be exceeded by allocating the number of bytes specified.

checkMemory

public static void checkMemory(int numberOfBytesToAdd,
                               DAILogger log)
                        throws OutOfMemoryException

Check that the allocation of an extra number of bytes within the JVM will not go over the threshold ratio set for this system.

Parameters:

numberOfBytesToAdd - Number of bytes of memory to be tested prior to allocation

log - Destination of memory usage info.

Throws:

OutOfMemoryException - if the ratio of used memory would be exceeded by allocating the number of bytes specified.

getCurrentRatio

private static double getCurrentRatio(int numberOfBytesToAdd)

Get ratio of current memory in use + number of requested bytes to total memory.

Parameters:

numberOfBytesToAdd - Requested number of bytes.

Returns:

ratio.

getCurrentlyUsedMemory

private static long getCurrentlyUsedMemory()

Get current memory in use.

Returns:

current memory in use.

logMemoryUsage

public static void logMemoryUsage(DAILogger log)

Logs the current state of the JVM memory at DEBUG level to this object's own log and in the logger provided.

For analysis purposes, the format of the log message is as follows: [NUMBER] of [NUMBER] bytes in use. [NUMBER]%

Parameters:

log - Destination for log messages.