refactor: Refactor VerticalVmRamScalingExample

- Update docs - Introduce new constant - Format resource allocation message Signed-off-by: Manoel Campos <manoelcampos@gmail.com>

Author: manoelcampos

src/main/java/org/cloudsimplus/examples/autoscaling/VerticalVmRamScalingExample.java

@@ -114,6 +114,14 @@ public class VerticalVmRamScalingExample {
  private static final int VM_RAM = 1000;
  private static final int VM_PES = 5;
  private static final int VM_MIPS = 1000;
+
+ /**
+ * The percentage (in scale from 0 to 1) to scale VM RAM capacity up/down
+ * when it becomes under/overloaded.
+ * @see #createVerticalRamScalingForVm(Vm)
+ */
+ private static final double VM_RAM_SCALING_FACTOR = 0.1;
+
  private final CloudSimPlus simulation;
  private final DatacenterBroker broker0;
  private final List<Host> hostList;
@@ -172,7 +180,7 @@ private void onClockTickListener(final EventInfo event) {
  event.getTime(), vm.getId(), vm.getRam().getPercentUtilization() * 100.0,
  vm.getRam().getAllocatedResource(), vm.getRam().getCapacity());
 
- System.out.printf(" | Host Ram Allocation: %6.2f%% (%5d of %5d MB). Running Cloudlets: %d",
+ System.out.printf(" | Host Ram Allocation: %6.2f%% (%5d of %5d MB). Running Cloudlets: %d%n",
  vm.getHost().getRam().getPercentUtilization() * 100,
  vm.getHost().getRam().getAllocatedResource(),
  vm.getHost().getRam().getCapacity(), vm.getCloudletScheduler().getCloudletExecList().size());
@@ -241,14 +249,16 @@ private Vm createVm() {
  * @see #createListOfScalableVms(int)
  */
  private void createVerticalRamScalingForVm(final Vm vm) {
- final var verticalRamScaling = new VerticalVmScalingSimple(Ram.class, 0.1);
+ final var verticalRamScaling = new VerticalVmScalingSimple(Ram.class, VM_RAM_SCALING_FACTOR);
+
  /* By uncommenting the line below, you will see that, instead of gradually
  * increasing or decreasing the RAM when the scaling object detects
  * the RAM usage is up or down the defined thresholds,
  * it will automatically calculate the amount of RAM to add/remove to
  * move the VM from the over or under-load condition.
  */
  //verticalRamScaling.setResourceScaling(new ResourceScalingInstantaneous());
+
  verticalRamScaling.setLowerThresholdFunction(this::lowerRamUtilizationThreshold)
  .setUpperThresholdFunction(this::upperRamUtilizationThreshold);
  vm.setRamVerticalScaling(verticalRamScaling);
@@ -287,13 +297,16 @@ private double upperRamUtilizationThreshold(final Vm vm) {
  private void createCloudletList() {
  final int initialRamUtilization1 = 100; //MB
 
+ // A constant RAM utilization model
  final var ramModel1 = new UtilizationModelDynamic(Unit.ABSOLUTE, initialRamUtilization1);
  for (long length: CLOUDLET_LENGTHS) {
  cloudletList.add(createCloudlet(ramModel1, length));
  }
 
  final int initialRamUtilization2 = 10; //MB
  final int maxRamUtilization = 500; //MB
+
+ // An increasing RAM utilization model
  final var ramModel2 = new UtilizationModelDynamic(Unit.ABSOLUTE, initialRamUtilization2);
  ramModel2
  .setMaxResourceUtilization(maxRamUtilization)