/*******************************************************************************
* Copyright (c) 2000, 2015 IBM Corporation and others.
*
* This program and the accompanying materials
* are made available under the terms of the Eclipse Public License 2.0
* which accompanies this distribution, and is available at
* https://www.eclipse.org/legal/epl-2.0/
*
* SPDX-License-Identifier: EPL-2.0
*
* Contributors:
* IBM Corporation - initial API and implementation
* David Green - fix factories with non-standard class loading (bug 200068)
* Filip Hrbek - fix thread safety problem described in bug 305863
* Sergey Prigogin (Google) - use parameterized types (bug 442021)
*******************************************************************************/
package org.eclipse.core.internal.runtime;
import java.util.*;
import org.eclipse.core.runtime.*;
/**
* This class is the standard implementation of <code>IAdapterManager</code>. It provides
* fast lookup of property values with the following semantics:
* <ul>
* <li>At most one factory will be invoked per property lookup
* <li>If multiple installed factories provide the same adapter, only the first found in
* the search order will be invoked.
* <li>The search order from a class with the definition <br>
* <code>class X extends Y implements A, B</code><br> is as follows: <il>
* <li>the target's class: X
* <li>X's superclasses in order to <code>Object</code>
* <li>a breadth-first traversal of each class's interfaces in the
* order returned by <code>getInterfaces</code> (in the example, X's
* superinterfaces then Y's superinterfaces) </li>
* </ul>
*
* @see IAdapterFactory
* @see IAdapterManager
*/
public final class AdapterManager implements IAdapterManager {
/**
* Cache of adapters for a given adaptable class. Maps String -> Map
* (adaptable class name -> (adapter class name -> factory instance))
* Thread safety note: The outer map is synchronized using a synchronized
* map wrapper class. The inner map is not synchronized, but it is immutable
* so synchronization is not necessary.
*/
private Map<String, Map<String, IAdapterFactory>> adapterLookup;
/**
* Cache of classes for a given type name. Avoids too many loadClass calls.
* (factory -> (type name -> Class)).
* Thread safety note: Since this structure is a nested hash map, and both
* the inner and outer maps are mutable, access to this entire structure is
* controlled by the classLookupLock field. Note the field can still be
* nulled concurrently without holding the lock.
*/
private Map<IAdapterFactory, Map<String, Class<?>>> classLookup;
/**
* The lock object controlling access to the classLookup data structure.
*/
private final Object classLookupLock = new Object();
/**
* Cache of class lookup order (Class -> Class[]). This avoids having to compute often, and
* provides clients with quick lookup for instanceOf checks based on type name.
* Thread safety note: The map is synchronized using a synchronized
* map wrapper class. The arrays within the map are immutable.
*/
private Map<Class<?>, Class<?>[]> classSearchOrderLookup;
/**
* Map of factories, keyed by <code>String</code>, fully qualified class name of
* the adaptable class that the factory provides adapters for. Value is a <code>List</code>
* of <code>IAdapterFactory</code>.
*/
private final HashMap<String, List<IAdapterFactory>> factories;
private final ArrayList<IAdapterManagerProvider> lazyFactoryProviders;
private static final AdapterManager singleton = new AdapterManager();
public static AdapterManager getDefault() {
return singleton;
}
/**
* Private constructor to block instance creation.
*/
private AdapterManager() {
factories = new HashMap<>(5);
lazyFactoryProviders = new ArrayList<>(1);
}
/**
* Given a type name, add all of the factories that respond to those types into
* the given table. Each entry will be keyed by the adapter class name (supplied in
* IAdapterFactory.getAdapterList).
*/
private void addFactoriesFor(String typeName, Map<String, IAdapterFactory> table) {
List<IAdapterFactory> factoryList = getFactories().get(typeName);
if (factoryList == null)
return;
for (int i = 0, imax = factoryList.size(); i < imax; i++) {
IAdapterFactory factory = factoryList.get(i);
if (factory instanceof IAdapterFactoryExt) {
String[] adapters = ((IAdapterFactoryExt) factory).getAdapterNames();
for (int j = 0; j < adapters.length; j++) {
if (table.get(adapters[j]) == null)
table.put(adapters[j], factory);
}
} else {
Class<?>[] adapters = factory.getAdapterList();
for (int j = 0; j < adapters.length; j++) {
String adapterName = adapters[j].getName();
if (table.get(adapterName) == null)
table.put(adapterName, factory);
}
}
}
}
private void cacheClassLookup(IAdapterFactory factory, Class<?> clazz) {
synchronized (classLookupLock) {
//cache reference to lookup to protect against concurrent flush
Map<IAdapterFactory, Map<String, Class<?>>> lookup = classLookup;
if (lookup == null)
classLookup = lookup = new HashMap<>(4);
Map<String, Class<?>> classes = lookup.get(factory);
if (classes == null) {
classes = new HashMap<>(4);
lookup.put(factory, classes);
}
classes.put(clazz.getName(), clazz);
}
}
private Class<?> cachedClassForName(IAdapterFactory factory, String typeName) {
synchronized (classLookupLock) {
Class<?> clazz = null;
//cache reference to lookup to protect against concurrent flush
Map<IAdapterFactory, Map<String, Class<?>>> lookup = classLookup;
if (lookup != null) {
Map<String, Class<?>> classes = lookup.get(factory);
if (classes != null) {
clazz = classes.get(typeName);
}
}
return clazz;
}
}
/**
* Returns the class with the given fully qualified name, or null
* if that class does not exist or belongs to a plug-in that has not
* yet been loaded.
*/
private Class<?> classForName(IAdapterFactory factory, String typeName) {
Class<?> clazz = cachedClassForName(factory, typeName);
if (clazz == null) {
if (factory instanceof IAdapterFactoryExt)
factory = ((IAdapterFactoryExt) factory).loadFactory(false);
if (factory != null) {
try {
clazz = factory.getClass().getClassLoader().loadClass(typeName);
} catch (ClassNotFoundException e) {
// it is possible that the default bundle classloader is unaware of this class
// but the adaptor factory can load it in some other way. See bug 200068.
if (typeName == null)
return null;
Class<?>[] adapterList = factory.getAdapterList();
clazz = null;
for (int i = 0; i < adapterList.length; i++) {
if (typeName.equals(adapterList[i].getName())) {
clazz = adapterList[i];
break;
}
}
if (clazz == null)
return null; // class not yet loaded
}
cacheClassLookup(factory, clazz);
}
}
return clazz;
}
@Override
public String[] computeAdapterTypes(Class<? extends Object> adaptable) {
Set<String> types = getFactories(adaptable).keySet();
return types.toArray(new String[types.size()]);
}
/**
* Computes the adapters that the provided class can adapt to, along
* with the factory object that can perform that transformation. Returns
* a table of adapter class name to factory object.
*/
private Map<String, IAdapterFactory> getFactories(Class<? extends Object> adaptable) {
//cache reference to lookup to protect against concurrent flush
Map<String, Map<String, IAdapterFactory>> lookup = adapterLookup;
if (lookup == null)
adapterLookup = lookup = Collections.synchronizedMap(new HashMap<String, Map<String, IAdapterFactory>>(30));
Map<String, IAdapterFactory> table = lookup.get(adaptable.getName());
if (table == null) {
// calculate adapters for the class
table = new HashMap<>(4);
Class<?>[] classes = computeClassOrder(adaptable);
for (int i = 0; i < classes.length; i++)
addFactoriesFor(classes[i].getName(), table);
// cache the table
lookup.put(adaptable.getName(), table);
}
return table;
}
/**
* Returns the super-type search order starting with <code>adaptable</code>.
* The search order is defined in this class' comment.
*/
@Override
@SuppressWarnings("unchecked")
public <T> Class<? super T>[] computeClassOrder(Class<T> adaptable) {
Class<?>[] classes = null;
//cache reference to lookup to protect against concurrent flush
Map<Class<?>, Class<?>[]> lookup = classSearchOrderLookup;
if (lookup == null)
classSearchOrderLookup = lookup = Collections.synchronizedMap(new HashMap<Class<?>, Class<?>[]>());
else
classes = lookup.get(adaptable);
// compute class order only if it hasn't been cached before
if (classes == null) {
classes = doComputeClassOrder(adaptable);
lookup.put(adaptable, classes);
}
return (Class<? super T>[]) classes;
}
/**
* Computes the super-type search order starting with <code>adaptable</code>.
* The search order is defined in this class' comment.
*/
private Class<?>[] doComputeClassOrder(Class<?> adaptable) {
List<Class<?>> classes = new ArrayList<>();
Class<?> clazz = adaptable;
Set<Class<?>> seen = new HashSet<>(4);
//first traverse class hierarchy
while (clazz != null) {
classes.add(clazz);
clazz = clazz.getSuperclass();
}
//now traverse interface hierarchy for each class
Class<?>[] classHierarchy = classes.toArray(new Class[classes.size()]);
for (int i = 0; i < classHierarchy.length; i++)
computeInterfaceOrder(classHierarchy[i].getInterfaces(), classes, seen);
return classes.toArray(new Class[classes.size()]);
}
private void computeInterfaceOrder(Class<?>[] interfaces, Collection<Class<?>> classes, Set<Class<?>> seen) {
List<Class<?>> newInterfaces = new ArrayList<>(interfaces.length);
for (int i = 0; i < interfaces.length; i++) {
Class<?> interfac = interfaces[i];
if (seen.add(interfac)) {
//note we cannot recurse here without changing the resulting interface order
classes.add(interfac);
newInterfaces.add(interfac);
}
}
for (Class<?> clazz : newInterfaces)
computeInterfaceOrder(clazz.getInterfaces(), classes, seen);
}
/**
* Flushes the cache of adapter search paths. This is generally required whenever an
* adapter is added or removed.
* <p>
* It is likely easier to just toss the whole cache rather than trying to be smart
* and remove only those entries affected.
* </p>
*/
public synchronized void flushLookup() {
adapterLookup = null;
classLookup = null;
classSearchOrderLookup = null;
}
@Override
@SuppressWarnings("unchecked")
public <T> T getAdapter(Object adaptable, Class<T> adapterType) {
Assert.isNotNull(adaptable);
Assert.isNotNull(adapterType);
String adapterTypeName = adapterType.getName();
IAdapterFactory factory = getFactories(adaptable.getClass()).get(adapterTypeName);
T result = null;
if (factory != null) {
result = factory.getAdapter(adaptable, adapterType);
}
if (result == null && adapterType.isInstance(adaptable)) {
return (T) adaptable;
}
if (result == null || adapterType.isInstance(result)) {
return result;
}
// Here we have a result which does not match the expected type.
// Throwing an exception here allows us to identify the violating factory.
// If we don't do this, clients will just see CCE without any idea who
// supplied the wrong adapter
throw new AssertionFailedException("Adapter factory " //$NON-NLS-1$
+ factory + " returned " + result.getClass().getName() //$NON-NLS-1$
+ " that is not an instance of " + adapterTypeName); //$NON-NLS-1$
}
@Override
public Object getAdapter(Object adaptable, String adapterType) {
Assert.isNotNull(adaptable);
Assert.isNotNull(adapterType);
return getAdapter(adaptable, adapterType, false);
}
/**
* Returns an adapter of the given type for the provided adapter.
* @param adaptable the object to adapt
* @param adapterType the type to adapt the object to
* @param force <code>true</code> if the plug-in providing the
* factory should be activated if necessary. <code>false</code>
* if no plugin activations are desired.
*/
private Object getAdapter(Object adaptable, String adapterType, boolean force) {
IAdapterFactory factory = getFactories(adaptable.getClass()).get(adapterType);
if (force && factory instanceof IAdapterFactoryExt)
factory = ((IAdapterFactoryExt) factory).loadFactory(true);
Object result = null;
if (factory != null) {
Class<?> clazz = classForName(factory, adapterType);
if (clazz != null)
result = factory.getAdapter(adaptable, clazz);
}
if (result == null && adaptable.getClass().getName().equals(adapterType))
return adaptable;
return result;
}
@Override
public boolean hasAdapter(Object adaptable, String adapterTypeName) {
return getFactories(adaptable.getClass()).get(adapterTypeName) != null;
}
@Override
public int queryAdapter(Object adaptable, String adapterTypeName) {
IAdapterFactory factory = getFactories(adaptable.getClass()).get(adapterTypeName);
if (factory == null)
return NONE;
if (factory instanceof IAdapterFactoryExt) {
factory = ((IAdapterFactoryExt) factory).loadFactory(false); // don't force loading
if (factory == null)
return NOT_LOADED;
}
return LOADED;
}
@Override
public Object loadAdapter(Object adaptable, String adapterTypeName) {
return getAdapter(adaptable, adapterTypeName, true);
}
/*
* @see IAdapterManager#registerAdapters
*/
@Override
public synchronized void registerAdapters(IAdapterFactory factory, Class<?> adaptable) {
registerFactory(factory, adaptable.getName());
flushLookup();
}
/*
* @see IAdapterManager#registerAdapters
*/
public void registerFactory(IAdapterFactory factory, String adaptableType) {
List<IAdapterFactory> list = factories.get(adaptableType);
if (list == null) {
list = new ArrayList<>(5);
factories.put(adaptableType, list);
}
list.add(factory);
}
/*
* @see IAdapterManager#unregisterAdapters
*/
@Override
public synchronized void unregisterAdapters(IAdapterFactory factory) {
for (List<IAdapterFactory> list : factories.values())
list.remove(factory);
flushLookup();
}
/*
* @see IAdapterManager#unregisterAdapters
*/
@Override
public synchronized void unregisterAdapters(IAdapterFactory factory, Class<?> adaptable) {
List<IAdapterFactory> factoryList = factories.get(adaptable.getName());
if (factoryList == null)
return;
factoryList.remove(factory);
flushLookup();
}
/*
* Shuts down the adapter manager by removing all factories
* and removing the registry change listener. Should only be
* invoked during platform shutdown.
*/
public synchronized void unregisterAllAdapters() {
factories.clear();
flushLookup();
}
public void registerLazyFactoryProvider(IAdapterManagerProvider factoryProvider) {
synchronized (lazyFactoryProviders) {
lazyFactoryProviders.add(factoryProvider);
}
}
public boolean unregisterLazyFactoryProvider(IAdapterManagerProvider factoryProvider) {
synchronized (lazyFactoryProviders) {
return lazyFactoryProviders.remove(factoryProvider);
}
}
public HashMap<String, List<IAdapterFactory>> getFactories() {
synchronized (lazyFactoryProviders) {
while (lazyFactoryProviders.size() > 0) {
IAdapterManagerProvider provider = lazyFactoryProviders.remove(0);
if (provider.addFactories(this))
flushLookup();
}
}
return factories;
}
}
