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Added lookupSingleton convenience method to ConfigurationManager (#21)
* Added lookupSingleton convenience method to ConfigurationManager for getting a mandated single instance of a class from a configuration * Fixed typo in comment * Fixed copyright date since I modified ConfigurationManager
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‎olcut-core/src/main/java/com/oracle/labs/mlrg/olcut/config/ConfigurationManager.java

Lines changed: 62 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,5 @@
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/*
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* Copyright (c) 2004-2020, Oracle and/or its affiliates.
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* Copyright (c) 2004-2021, Oracle and/or its affiliates.
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*
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* Licensed under the 2-clause BSD license.
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*
@@ -83,6 +83,7 @@
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import java.util.logging.Logger;
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import java.util.regex.Matcher;
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import java.util.regex.Pattern;
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import java.util.stream.Collectors;
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import static com.oracle.labs.mlrg.olcut.config.PropertySheet.StoredFieldType;
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@@ -1474,6 +1475,66 @@ public <T extends Configurable> List<T> lookupAll(Class<T> c, ComponentListener<
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return lookupAll(c);
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}
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/**
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* Looks for a single instance of a specified Configurable in the configuration. If there is
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* no such instance, this method returns null. If there is more than one instance, an
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* exception is thrown. lookupSingleton can optionally include any class that may be
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* assignable (a subclass or implementation) to the provided type. Note that this
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* could potentially allow a user to load their own class. If the security of the
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* class you're looking up is important, declare it final to prevent code insertion.
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*
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* @param c The Class of component to lookup.
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* @param allowAssignable allow types that are assignable to the given class to match
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* @param <T> The type of the component.
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* @return the one instance of the desired class this configuration manager knows about or null if
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* no such instance is present
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* @throws PropertyException if there is more than one instance
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*/
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@SuppressWarnings("unchecked") // Casts to T are implicitly checked as we use Class<T> to find the names.
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public <T extends Configurable> T lookupSingleton(Class<T> c, boolean allowAssignable) throws PropertyException {
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List<String> instanceNames = new ArrayList<>();
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for(Map.Entry<String, ConfigurationData> e : configurationDataMap.entrySet()) {
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ConfigurationData rpd = e.getValue();
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try {
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Class pclass = Class.forName(rpd.getClassName());
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if (!rpd.isImportable() &&
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((allowAssignable && c.isAssignableFrom(pclass)) ||
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(!allowAssignable && rpd.getClassName().equals(c.getName())))) {
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instanceNames.add(e.getKey());
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}
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} catch(ClassNotFoundException ex) {
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logger.warning(String.format("No class %s found in ConfigurationManager",
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rpd.getClassName()));
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}
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}
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//
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// Check that we got only one instance and that it is not an interface.
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if (instanceNames.isEmpty()) {
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return null;
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}
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if (instanceNames.size() > 1) {
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String names = instanceNames.stream().collect(Collectors.joining(", "));
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throw new PropertyException("", "Multiple instances of " + c.getName() + " found in configuration: " + names);
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}
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String matchedName = instanceNames.get(0);
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ConfigurationData cd = configurationDataMap.get(matchedName);
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try {
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Class matchedClass = Class.forName(cd.getClassName());
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if (!matchedClass.isInterface()) {
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return (T)lookup(matchedName);
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} else {
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throw new PropertyException("matchedName", "Cannot instantiate component with type "
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+ matchedClass + " since it is an interface");
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}
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} catch (ClassNotFoundException e) {
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throw new PropertyException(e,matchedName,"Class not found for component " + matchedName);
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}
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}
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/**
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* Gets a list of all of the component names of the components that have
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* a given type. This will not instantiate the components.

‎olcut-core/src/test/java/com/oracle/labs/mlrg/olcut/config/ConfigurationManagerTest.java

Lines changed: 52 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -28,19 +28,69 @@
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package com.oracle.labs.mlrg.olcut.config;
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import com.oracle.labs.mlrg.olcut.config.test.Ape;
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import com.oracle.labs.mlrg.olcut.config.test.Barbary;
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import com.oracle.labs.mlrg.olcut.config.test.Chimp;
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import com.oracle.labs.mlrg.olcut.config.test.Gorilla;
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import com.oracle.labs.mlrg.olcut.config.test.Monkey;
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import com.oracle.labs.mlrg.olcut.config.test.Orangutan;
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import org.junit.jupiter.api.BeforeAll;
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import org.junit.jupiter.api.Test;
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import java.util.ArrayList;
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import java.util.List;
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import static org.junit.jupiter.api.Assertions.assertEquals;
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import static org.junit.jupiter.api.Assertions.assertNotNull;
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import static org.junit.jupiter.api.Assertions.*;
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/**
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*
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*/
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public class ConfigurationManagerTest {
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private static ConfigurationManager singletonCM;
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@BeforeAll
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public static void setup() {
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singletonCM = new ConfigurationManager("/com/oracle/labs/mlrg/olcut/config/singletonConfig.xml");
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}
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@Test
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public void testSingletonTrue() {
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Chimp c = singletonCM.lookupSingleton(Chimp.class, false);
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assertNotNull(c, "Failed to find actual singleton");
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c = singletonCM.lookupSingleton(Chimp.class, true);
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assertNotNull(c, "Failed to find actual singleton");
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}
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@Test
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public void testSingletonTrueSubclass() {
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Orangutan o = singletonCM.lookupSingleton(Orangutan.class, true);
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assertNotNull(o, "Failed to find Bornean as subclass");
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o = singletonCM.lookupSingleton(Orangutan.class, false);
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assertNull(o, "Should not have found an Orangutan ");
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}
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@Test
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public void testSingletonMultipleClasses() {
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assertThrows(PropertyException.class, () -> {singletonCM.lookupSingleton(Gorilla.class, false);},
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"Config has multiple Gorillas but no exception was thrown");
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assertThrows(PropertyException.class, () -> {singletonCM.lookupSingleton(Gorilla.class, true);},
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"Config has multiple Gorillas but no exception was thrown");
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}
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@Test
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public void testSingletonMultipleInterfaces() {
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assertThrows(PropertyException.class, () -> {singletonCM.lookupSingleton(Monkey.class, true);},
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"Config has multiple Gorillas but no exception was thrown");
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Monkey m = singletonCM.lookupSingleton(Monkey.class, false);
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assertNull(m, "Looked up interface without allowAssignable but didn't get null");
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}
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@Test
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public void testSingletonNoImport() {
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assertNull(singletonCM.lookupSingleton(Barbary.class, false), "Should ignore imports");
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assertNull(singletonCM.lookupSingleton(Barbary.class, true), "Should ignore imports");
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}
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@Test
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public void testMultipleLoading() {

‎olcut-core/src/test/java/com/oracle/labs/mlrg/olcut/config/test/Bornean.java

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@@ -0,0 +1,9 @@
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package com.oracle.labs.mlrg.olcut.config.test;
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public class Bornean extends Orangutan {
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@Override
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public String getMonkeyName() {
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return "Bornean Orangutan";
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}
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}

‎olcut-core/src/test/resources/com/oracle/labs/mlrg/olcut/config/singletonConfig.xml

Lines changed: 24 additions & 0 deletions
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@@ -0,0 +1,24 @@
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<?xml version="1.0" encoding="US-ASCII"?>
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<config>
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<component name="chimp" type="com.oracle.labs.mlrg.olcut.config.test.Chimp">
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</component>
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<component name="kingKong" type="com.oracle.labs.mlrg.olcut.config.test.Gorilla">
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</component>
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<component name="grodd" type="com.oracle.labs.mlrg.olcut.config.test.Gorilla">
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</component>
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<component name="harlow" type="com.oracle.labs.mlrg.olcut.config.test.Rhesus">
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</component>
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<component name="bornie" type="com.oracle.labs.mlrg.olcut.config.test.Bornean">
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</component>
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<component name="barbie" type="com.oracle.labs.mlrg.olcut.config.test.Barbary" import="true">
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</component>
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</config>

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