Fixes #34: Add Error Prone, NullAway and JSpecify

.mvn/jvm.config

@@ -0,0 +1,10 @@
+--add-exports jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.file=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.main=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.model=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.parser=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.processing=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.tree=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED
+--add-opens jdk.compiler/com.sun.tools.javac.code=ALL-UNNAMED
+--add-opens jdk.compiler/com.sun.tools.javac.comp=ALL-UNNAMED

pom.xml

@@ -49,6 +49,11 @@
     </issueManagement>
 
     <properties>
+        <errorprone.version>2.50.0</errorprone.version>
+        <nullaway.version>0.14.2</nullaway.version>
+        <jspecify.version>1.0.0</jspecify.version>
+        <!-- Error Prone arguments (see maven-compiler-plugin). -->
+        <errorprone.args>-XepDisableWarningsInGeneratedCode -XepExcludedPaths:.*/target/generated-sources/.* -Xep:StringConcatToTextBlock:OFF</errorprone.args>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <license-maven-plugin.version>5.0.0</license-maven-plugin.version>
         <!-- License file to be used by the com.mycila.license-maven-plugin -->
@@ -63,6 +68,42 @@
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-compiler-plugin</artifactId>
                 <version>3.14.0</version>
+                <configuration>
+                    <annotationProcessorPaths>
+                        <path>
+                            <!--
+                            Error Prone: Google's static analyzer that runs as a javac plugin,
+                            finding common mistakes at compile time.
+                            It is also the base to run NullAway.
+                            StringConcatToTextBlock is disabled because it crashes on some string concatenations.
+                            Requires the options in .mvn/jvm.config to work on JDK 16+.
+                            https://errorprone.info
+                            -->
+                            <groupId>com.google.errorprone</groupId>
+                            <artifactId>error_prone_core</artifactId>
+                            <version>${errorprone.version}</version>
+                        </path>
+                        <path>
+                            <!--
+                            NullAway: Error Prone check that fails the build when a value
+                            that may be null is used without a check, avoiding NullPointerException.
+                            Just packages annotated with JSpecify @NullMarked (see package-info.java files) are checked.
+                            Inside them, everything is considered non-null by default, unless annotated with @Nullable.
+                            This way, classes from dependencies (such as CloudSim Plus) are considered unannotated.
+                            https://github.com/uber/NullAway
+                            -->
+                            <groupId>com.uber.nullaway</groupId>
+                            <artifactId>nullaway</artifactId>
+                            <version>${nullaway.version}</version>
+                        </path>
+                    </annotationProcessorPaths>
+                    <compilerArgs>
+                        <!-- Error Prone and NullAway settings (see the comments in annotationProcessorPaths above). -->
+                        <arg>-XDcompilePolicy=simple</arg>
+                        <arg>--should-stop=ifError=FLOW</arg>
+                        <arg>-Xplugin:ErrorProne ${errorprone.args} -Xep:NullAway:ERROR -XepOpt:NullAway:OnlyNullMarked=true</arg>
+                    </compilerArgs>
+                </configuration>
             </plugin>
 
 			<plugin>
@@ -152,5 +193,15 @@
             <artifactId>logback-classic</artifactId>
             <version>${logback.version}</version>
         </dependency>
+        <dependency>
+            <!--
+            JSpecify annotations (such as @Nullable) to indicate values that may be null.
+            They are checked by NullAway at compile time.
+            https://jspecify.dev
+            -->
+            <groupId>org.jspecify</groupId>
+            <artifactId>jspecify</artifactId>
+            <version>${jspecify.version}</version>
+        </dependency>
     </dependencies>
 </project>

src/main/java/org/cloudbus/cloudsim/examples/network/applications/NetworkVmExampleAbstract.java

@@ -230,7 +230,7 @@ protected void createNetwork(final NetworkDatacenter datacenter) {
      * @return the index of the switch to connect the host
      */
     public static int getSwitchIndex(final NetworkHost host, final int switchPorts) {
-        return Math.round(host.getId() % Integer.MAX_VALUE) / switchPorts;
+        return (int) (host.getId() % Integer.MAX_VALUE) / switchPorts;
     }
 
     /**

src/main/java/org/cloudbus/cloudsim/examples/network/applications/package-info.java

@@ -0,0 +1,4 @@
+@NullMarked
+package org.cloudbus.cloudsim.examples.network.applications;
+
+import org.jspecify.annotations.NullMarked;

src/main/java/org/cloudbus/cloudsim/examples/network/package-info.java

@@ -0,0 +1,12 @@
+/*
+ * Title:        CloudSim Toolkit
+ * Description:  CloudSim (Cloud Simulation) Toolkit for Modeling and Simulation
+ *               of Clouds
+ * Licence:      GPL - http://www.gnu.org/copyleft/gpl.html
+ *
+ * Copyright (c) 2009, The University of Melbourne, Australia
+ */
+@NullMarked
+package org.cloudbus.cloudsim.examples.network;
+
+import org.jspecify.annotations.NullMarked;

src/main/java/org/cloudsimplus/examples/HostFaultInjectionExample1.java

@@ -95,7 +95,7 @@ public final class HostFaultInjectionExample1 {
     /** @see HostFaultInjection#setMaxTimeToFailInHours(double) */
     private static final double MAX_TIME_TO_FAIL_IN_HOURS = TimeUtil.daysToHours(30);
 
-    private List<Host> hostList;
+    private final List<Host> hostList = new ArrayList<>();
 
     private static final int VMS_BY_BROKER = 2;
     private static final int VM_PES = 2; //number of cpus
@@ -220,7 +220,6 @@ public void createAndSubmitCloudlets(final DatacenterBroker broker) {
     }
 
     private Datacenter createDatacenter() {
-        hostList = new ArrayList<>();
         for (int id = 1; id <= HOSTS; id++) {
             hostList.add(createHost(id));
         }
@@ -327,8 +326,8 @@ private List<Cloudlet> cloneCloudlets(final Vm sourceVm) {
             final var clonedCloudlet = cloneCloudlet(sourceCloudlet);
             clonedCloudletList.add(clonedCloudlet);
             System.out.printf(
-                "# %s: Cloning %s as Cloudlet %d%n",
-                sourceVm.getBroker(), sourceCloudlet, clonedCloudlet.getId(), sourceVm);
+                "# %s: Cloning %s from %s as Cloudlet %d%n",
+                sourceVm.getBroker(), sourceCloudlet, sourceVm, clonedCloudlet.getId());
         }
 
         return clonedCloudletList;

src/main/java/org/cloudsimplus/examples/ParallelSimulationsExample.java

@@ -73,6 +73,8 @@
 public class ParallelSimulationsExample implements Runnable {
     private final String title;
     private final CloudSimPlus simulation;
+    /** Created when the simulation is started inside {@link #run()}. */
+    @SuppressWarnings("NullAway.Init")
     private DatacenterBroker broker;
     private List<Cloudlet> cloudletList;
     private List<Vm> vmList;

src/main/java/org/cloudsimplus/examples/autoscaling/package-info.java

@@ -5,4 +5,7 @@
  *
  * @author Manoel Campos da Silva Filho
  */
+@NullMarked
 package org.cloudsimplus.examples.autoscaling;
+
+import org.jspecify.annotations.NullMarked;

src/main/java/org/cloudsimplus/examples/brokers/package-info.java

@@ -14,4 +14,7 @@
  *
  * @author Manoel Campos da Silva Filho
  */
+@NullMarked
 package org.cloudsimplus.examples.brokers;
+
+import org.jspecify.annotations.NullMarked;

src/main/java/org/cloudsimplus/examples/costs/package-info.java

@@ -0,0 +1,27 @@
+/*
+ * CloudSim Plus: A modern, highly-extensible and easier-to-use Framework for
+ * Modeling and Simulation of Cloud Computing Infrastructures and Services.
+ * http://cloudsimplus.org
+ *
+ *     Copyright (C) 2015-2021 Universidade da Beira Interior (UBI, Portugal) and
+ *     the Instituto Federal de Educação Ciência e Tecnologia do Tocantins (IFTO, Brazil).
+ *
+ *     This file is part of CloudSim Plus.
+ *
+ *     CloudSim Plus 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 3 of the License, or
+ *     (at your option) any later version.
+ *
+ *     CloudSim Plus 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 CloudSim Plus. If not, see <http://www.gnu.org/licenses/>.
+ */
+@NullMarked
+package org.cloudsimplus.examples.costs;
+
+import org.jspecify.annotations.NullMarked;

src/main/java/org/cloudsimplus/examples/dynamic/DynamicVmAllocationPolicyBestFitExample.java

@@ -133,7 +133,7 @@ public final class DynamicVmAllocationPolicyBestFitExample {
     private final List<Vm> vmList = new ArrayList<>();
 
     private CloudSimPlus simulation;
-    private List<Host> hostList;
+    private final List<Host> hostList = new ArrayList<>();
 
     public static void main(String[] args) {
         new DynamicVmAllocationPolicyBestFitExample();
@@ -234,7 +234,6 @@ public Vm createVm(int pes) {
      * @return
      */
     private Datacenter createDatacenter() {
-        this.hostList = new ArrayList<>();
         for(int i = 0; i < HOSTS; i++){
             final int pes = HOST_INITIAL_PES + i;
             final var host = createHost(pes, HOST_MIPS);

src/main/java/org/cloudsimplus/examples/dynamic/package-info.java

@@ -5,4 +5,7 @@
  *
  * @author Manoel Campos da Silva Filho
  */
+@NullMarked
 package org.cloudsimplus.examples.dynamic;
+
+import org.jspecify.annotations.NullMarked;

src/main/java/org/cloudsimplus/examples/listeners/package-info.java

@@ -7,4 +7,7 @@
  *
  * @author Manoel Campos da Silva Filho
  */
+@NullMarked
 package org.cloudsimplus.examples.listeners;
+
+import org.jspecify.annotations.NullMarked;

src/main/java/org/cloudsimplus/examples/migration/ManualMigrationExample1.java

@@ -135,7 +135,7 @@ public final class ManualMigrationExample1 {
     private final Datacenter datacenter0;
 
     private CloudSimPlus simulation;
-    private List<Host> hostList;
+    private final List<Host> hostList = new ArrayList<>();
     private boolean migrationRequested;
     private int migrationsNumber;
 
@@ -280,7 +280,6 @@ public Vm createVm(int pes) {
      * @return
      */
     private Datacenter createDatacenter() {
-        this.hostList = new ArrayList<>();
         for(int i = 0; i < HOSTS; i++){
             final int pes = HOST_INITIAL_PES + i;
             hostList.add(createHost(pes, HOST_MIPS));

src/main/java/org/cloudsimplus/examples/migration/MigrationExample1.java

@@ -202,8 +202,8 @@ public final class MigrationExample1 {
     private final DatacenterBrokerSimple broker;
 
     private final CloudSimPlus simulation;
-    private VmAllocationPolicyMigrationStaticThreshold allocationPolicy;
-    private List<Host> hostList;
+    private final VmAllocationPolicyMigrationStaticThreshold allocationPolicy;
+    private final List<Host> hostList;
     private int migrationsNumber = 0;
 
     public static void main(String[] args) {
@@ -220,6 +220,8 @@ private MigrationExample1(){
         System.out.println("Starting " + getClass().getSimpleName());
         simulation = new CloudSimPlus();
 
+        this.hostList = createHosts();
+        this.allocationPolicy = createAllocationPolicy();
         @SuppressWarnings("unused")
         final var datacenter0 = createDatacenter();
         broker = new DatacenterBrokerSimple(simulation);
@@ -424,25 +426,7 @@ private double getCpuUsageIncrement(final UtilizationModelDynamic um){
      * @return
      */
     private Datacenter createDatacenter() {
-        this.hostList = createHosts();
         System.out.println();
-
-        /**
-         * Sets an upper utilization threshold higher than the
-         * {@link #HOST_OVER_UTILIZATION_THRESHOLD_FOR_VM_MIGRATION}
-         * to enable placing VMs which will use more CPU than
-         * defined by the value in the mentioned constant.
-         * After VMs are all submitted to Hosts, the threshold is changed
-         * to the value of the constant.
-         * This is used to  place VMs into a Host which will
-         * become overloaded in order to trigger the migration.
-         */
-        this.allocationPolicy =
-            new VmAllocationPolicyMigrationBestFitStaticThreshold(
-                new VmSelectionPolicyMinimumUtilization(),
-                HOST_OVER_UTILIZATION_THRESHOLD_FOR_VM_MIGRATION + 0.2);
-        this.allocationPolicy.setUnderUtilizationThreshold(HOST_UNDER_UTILIZATION_THRESHOLD_FOR_VM_MIGRATION);
-
         final var dc = new DatacenterSimple(simulation, hostList, allocationPolicy);
         for (Host host : hostList) {
             System.out.printf(
@@ -454,6 +438,26 @@ private Datacenter createDatacenter() {
         return dc;
     }
 
+    /**
+     * Creates a VmAllocationPolicy that
+     * sets an upper utilization threshold higher than the
+     * {@link #HOST_OVER_UTILIZATION_THRESHOLD_FOR_VM_MIGRATION}
+     * to enable placing VMs which will use more CPU than
+     * defined by the value in the mentioned constant.
+     * After VMs are all submitted to Hosts, the threshold is changed
+     * to the value of the constant.
+     * This is used to  place VMs into a Host which will
+     * become overloaded in order to trigger the migration.
+     */
+    private VmAllocationPolicyMigrationStaticThreshold createAllocationPolicy() {
+        final var policy =
+            new VmAllocationPolicyMigrationBestFitStaticThreshold(
+                new VmSelectionPolicyMinimumUtilization(),
+                HOST_OVER_UTILIZATION_THRESHOLD_FOR_VM_MIGRATION + 0.2);
+        policy.setUnderUtilizationThreshold(HOST_UNDER_UTILIZATION_THRESHOLD_FOR_VM_MIGRATION);
+        return policy;
+    }
+
     private List<Host> createHosts() {
         final var hostList = new ArrayList<Host>(HOST_PES.length);
         for (int i = 0; i < HOST_PES.length; i++) {

src/main/java/org/cloudsimplus/examples/migration/package-info.java

@@ -5,4 +5,7 @@
  *
  * @author Manoel Campos da Silva Filho
  */
+@NullMarked
 package org.cloudsimplus.examples.migration;
+
+import org.jspecify.annotations.NullMarked;

src/main/java/org/cloudsimplus/examples/package-info.java

@@ -0,0 +1,27 @@
+/*
+ * CloudSim Plus: A modern, highly-extensible and easier-to-use Framework for
+ * Modeling and Simulation of Cloud Computing Infrastructures and Services.
+ * http://cloudsimplus.org
+ *
+ *     Copyright (C) 2015-2021 Universidade da Beira Interior (UBI, Portugal) and
+ *     the Instituto Federal de Educação Ciência e Tecnologia do Tocantins (IFTO, Brazil).
+ *
+ *     This file is part of CloudSim Plus.
+ *
+ *     CloudSim Plus 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 3 of the License, or
+ *     (at your option) any later version.
+ *
+ *     CloudSim Plus 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 CloudSim Plus. If not, see <http://www.gnu.org/licenses/>.
+ */
+@NullMarked
+package org.cloudsimplus.examples;
+
+import org.jspecify.annotations.NullMarked;

src/main/java/org/cloudsimplus/examples/performance/UtilizationModelStochasticPerformance.java

@@ -43,6 +43,7 @@
 import org.cloudsimplus.utilizationmodels.UtilizationModelStochastic;
 import org.cloudsimplus.vms.Vm;
 import org.cloudsimplus.vms.VmSimple;
+import org.jspecify.annotations.Nullable;
 
 import java.lang.management.ManagementFactory;
 import java.lang.management.MemoryPoolMXBean;
@@ -127,7 +128,12 @@ public class UtilizationModelStochasticPerformance {
     private List<Vm> vmList;
     private List<Cloudlet> cloudletList;
     private Datacenter datacenter0;
-    private UtilizationModelStochastic um;
+    /**
+     * The utilization model shared by all Cloudlets
+     * (when {@link #MULTIPLE_UTILIZATION_MODELS} is false).
+     * It's null until the first Cloudlet is created.
+     */
+    private @Nullable UtilizationModelStochastic um;
 
     public static void main(String[] args) {
         new UtilizationModelStochasticPerformance();

src/main/java/org/cloudsimplus/examples/performance/package-info.java

@@ -0,0 +1,27 @@
+/*
+ * CloudSim Plus: A modern, highly-extensible and easier-to-use Framework for
+ * Modeling and Simulation of Cloud Computing Infrastructures and Services.
+ * http://cloudsimplus.org
+ *
+ *     Copyright (C) 2015-2021 Universidade da Beira Interior (UBI, Portugal) and
+ *     the Instituto Federal de Educação Ciência e Tecnologia do Tocantins (IFTO, Brazil).
+ *
+ *     This file is part of CloudSim Plus.
+ *
+ *     CloudSim Plus 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 3 of the License, or
+ *     (at your option) any later version.
+ *
+ *     CloudSim Plus 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 CloudSim Plus. If not, see <http://www.gnu.org/licenses/>.
+ */
+@NullMarked
+package org.cloudsimplus.examples.performance;
+
+import org.jspecify.annotations.NullMarked;