PIOT-GDA-02-006: Create module - SystemMemUtilTask

[labbenchstudios]

Description

• Create the SystemMemUtilTask module and implement the functionality to retrieve JVM memory utilization.

Review the README

• Please see README.md for further information on, and use of, this content.
• License for embedded documentation and source codes: PIOT-DOC-LIC

Estimated effort may vary greatly

• The estimated level of effort for this exercise shown in the 'Estimate' section below is a very rough approximation. The actual level of effort may vary greatly depending on your development and test environment, experience with the requisite technologies, and many other factors.

Actions

NOTE: The implementation examples depicted here are only one way to implement the requirements listed. Your own implementation may vary of course.

• Within the programmingtheiot.gda.system package, create a new Java class named SystemMemUtilTask. This should be derived from BaseSystemUtilTask.
• Import statements should include the following (you may choose to include the Logger for debugging):

import java.lang.management.ManagementFactory;
import java.lang.management.MemoryUsage;

import java.util.logging.Logger;

import programmingtheiot.common.ConfigConst;

• Add in an override for the inherited template method getTelemetryValue(). It will retrieve JVM memory utilization and return the value as a float. Use the @Override annotation and be sure to remove the abstract keyword if you're copying / pasting from the base class. You'll have to perform a simple calculation to derive this, as follows:

MemoryUsage memUsage = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();
double memUtil = ((double) memUsage.getUsed() / (double) memUsage.getMax()) * 100.0d;

• Log the value, then return it as a float (once the value is calculated, for our purposes, it's OK to cast from double to float)
• Here's one way to implement these requirements (your own implementation may vary from this). Also note that this may not work with all OSes:

public SystemMemUtilTask()
{
	super(ConfigConst.NOT_SET, ConfigConst.DEFAULT_TYPE_ID);
}

@Override
public float getTelemetryValue()
{
	MemoryUsage memUsage = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();
	double memUsed = (double) memUsage.getUsed();
	double memMax  = (double) memUsage.getMax();
	
	_Logger.fine("Mem used: " + memUsed + "; Mem Max: " + memMax);
	
	double memUtil = (memUsed / memMax) * 100.0d;
	
	return (float) memUtil;
}

Estimate

• Small

Tests

• Unit tests (in ./src/test/java/programmingtheiot/part01/unit)
  • Run ./system/SystemMemUtilTaskTest. The testGetTelemetryValue() unit test should pass while logging values between 0.0% and 100.0%.