/*
* The MIT License
*
* Copyright (c) 2004-2010, Sun Microsystems, Inc., InfraDNA, Inc., CloudBees, Inc.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* THE SOFTWARE.
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package hudson;
import com.google.common.collect.Iterables;
import com.google.common.collect.Lists;
import com.google.common.collect.Maps;
import com.google.inject.AbstractModule;
import com.google.inject.Binding;
import com.google.inject.Guice;
import com.google.inject.Injector;
import com.google.inject.Key;
import com.google.inject.Module;
import com.google.inject.Provider;
import com.google.inject.Scope;
import com.google.inject.Scopes;
import com.google.inject.name.Names;
import com.google.common.collect.ImmutableList;
import hudson.init.InitMilestone;
import hudson.model.Descriptor;
import hudson.model.Hudson;
import jenkins.ExtensionComponentSet;
import jenkins.ExtensionFilter;
import jenkins.ExtensionRefreshException;
import jenkins.ProxyInjector;
import jenkins.model.Jenkins;
import net.java.sezpoz.Index;
import net.java.sezpoz.IndexItem;
import org.kohsuke.accmod.Restricted;
import org.kohsuke.accmod.restrictions.NoExternalUse;
import java.lang.annotation.Annotation;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.logging.Logger;
import java.util.logging.Level;
import java.util.List;
import java.util.ArrayList;
import java.util.Collection;
import java.lang.reflect.AnnotatedElement;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
/**
* Discovers the implementations of an extension point.
*
* <p>
* This extension point allows you to write your implementations of {@link ExtensionPoint}s
* in arbitrary DI containers, and have Hudson discover them.
*
* <p>
* {@link ExtensionFinder} itself is an extension point, but to avoid infinite recursion,
* Jenkins discovers {@link ExtensionFinder}s through {@link Sezpoz} and that alone.
*
* @author Kohsuke Kawaguchi
* @since 1.286
* @see ExtensionFilter
*/
public abstract class ExtensionFinder implements ExtensionPoint {
/**
* @deprecated as of 1.356
* Use and implement {@link #find(Class,Hudson)} that allows us to put some metadata.
*/
@Restricted(NoExternalUse.class)
@Deprecated
public <T> Collection<T> findExtensions(Class<T> type, Hudson hudson) {
return Collections.emptyList();
}
/**
* Returns true if this extension finder supports the {@link #refresh()} operation.
*/
public boolean isRefreshable() {
try {
return getClass().getMethod("refresh").getDeclaringClass()!=ExtensionFinder.class;
} catch (NoSuchMethodException e) {
return false;
}
}
/**
* Rebuilds the internal index, if any, so that future {@link #find(Class, Hudson)} calls
* will discover components newly added to {@link PluginManager#uberClassLoader}.
*
* <p>
* The point of the refresh operation is not to disrupt instances of already loaded {@link ExtensionComponent}s,
* and only instantiate those that are new. Otherwise this will break the singleton semantics of various
* objects, such as {@link Descriptor}s.
*
* <p>
* The behaviour is undefined if {@link #isRefreshable()} is returning false.
*
* @since 1.442
* @see #isRefreshable()
* @return never null
*/
public abstract ExtensionComponentSet refresh() throws ExtensionRefreshException;
/**
* Discover extensions of the given type.
*
* <p>
* This method is called only once per the given type after all the plugins are loaded,
* so implementations need not worry about caching.
*
* <p>
* This method should return all the known components at the time of the call, including
* those that are discovered later via {@link #refresh()}, even though those components
* are separately returned in {@link ExtensionComponentSet}.
*
* @param <T>
* The type of the extension points. This is not bound to {@link ExtensionPoint} because
* of {@link Descriptor}, which by itself doesn't implement {@link ExtensionPoint} for
* a historical reason.
* @param jenkins
* Jenkins whose behalf this extension finder is performing lookup.
* @return
* Can be empty but never null.
* @since 1.356
* Older implementations provide {@link #findExtensions(Class,Hudson)}
*/
public abstract <T> Collection<ExtensionComponent<T>> find(Class<T> type, Hudson jenkins);
@Deprecated
public <T> Collection<ExtensionComponent<T>> _find(Class<T> type, Hudson hudson) {
return find(type, hudson);
}
/**
* Performs class initializations without creating instances.
*
* If two threads try to initialize classes in the opposite order, a dead lock will ensue,
* and we can get into a similar situation with {@link ExtensionFinder}s.
*
* <p>
* That is, one thread can try to list extensions, which results in {@link ExtensionFinder}
* loading and initializing classes. This happens inside a context of a lock, so that
* another thread that tries to list the same extensions don't end up creating different
* extension instances. So this activity locks extension list first, then class initialization next.
*
* <p>
* In the mean time, another thread can load and initialize a class, and that initialization
* can eventually results in listing up extensions, for example through static initializer.
* Such activity locks class initialization first, then locks extension list.
*
* <p>
* This inconsistent locking order results in a dead lock, you see.
*
* <p>
* So to reduce the likelihood, this method is called in prior to {@link #find(Class,Hudson)} invocation,
* but from outside the lock. The implementation is expected to perform all the class initialization activities
* from here.
*
* <p>
* See https://bugs.openjdk.java.net/browse/JDK-4993813 for how to force a class initialization.
* Also see http://kohsuke.org/2010/09/01/deadlock-that-you-cant-avoid/ for how class initialization
* can results in a dead lock.
*/
public void scout(Class extensionType, Hudson hudson) {
}
@Extension
public static final class DefaultGuiceExtensionAnnotation extends GuiceExtensionAnnotation<Extension> {
public DefaultGuiceExtensionAnnotation() {
super(Extension.class);
}
@Override
protected boolean isOptional(Extension annotation) {
return annotation.optional();
}
@Override
protected double getOrdinal(Extension annotation) {
return annotation.ordinal();
}
@Override
protected boolean isActive(AnnotatedElement e) {
return true;
}
}
/**
* Captures information about the annotation that we use to mark Guice-instantiated components.
*/
public static abstract class GuiceExtensionAnnotation<T extends Annotation> {
public final Class<T> annotationType;
protected GuiceExtensionAnnotation(Class<T> annotationType) {
this.annotationType = annotationType;
}
protected abstract double getOrdinal(T annotation);
/**
* Hook to enable subtypes to control which ones to pick up and which ones to ignore.
*/
protected abstract boolean isActive(AnnotatedElement e);
protected abstract boolean isOptional(T annotation);
}
/**
* Discovers components via sezpoz but instantiates them by using Guice.
*/
@Extension
public static class GuiceFinder extends ExtensionFinder {
/**
* Injector that we find components from.
* <p>
* To support refresh when Guice doesn't let us alter the bindings, we'll create
* a child container to house newly discovered components. This field points to the
* youngest such container.
*/
private volatile Injector container;
/**
* Sezpoz index we are currently using in {@link #container} (and its ancestors.)
* Needed to compute delta.
*/
private List<IndexItem<?,Object>> sezpozIndex;
private final Map<Key,Annotation> annotations = new HashMap<>();
private final Sezpoz moduleFinder = new Sezpoz();
/**
* Map from {@link GuiceExtensionAnnotation#annotationType} to {@link GuiceExtensionAnnotation}
*/
private Map<Class<? extends Annotation>,GuiceExtensionAnnotation<?>> extensionAnnotations = Maps.newHashMap();
public GuiceFinder() {
for (ExtensionComponent<GuiceExtensionAnnotation> ec : moduleFinder.find(GuiceExtensionAnnotation.class, Hudson.getInstance())) {
GuiceExtensionAnnotation gea = ec.getInstance();
extensionAnnotations.put(gea.annotationType,gea);
}
sezpozIndex = loadSezpozIndices(Jenkins.getInstance().getPluginManager().uberClassLoader);
List<Module> modules = new ArrayList<>();
modules.add(new AbstractModule() {
@Override
protected void configure() {
Jenkins j = Jenkins.getInstance();
bind(Jenkins.class).toInstance(j);
bind(PluginManager.class).toInstance(j.getPluginManager());
}
});
modules.add(new SezpozModule(sezpozIndex));
for (ExtensionComponent<Module> ec : moduleFinder.find(Module.class, Hudson.getInstance())) {
modules.add(ec.getInstance());
}
try {
container = Guice.createInjector(modules);
} catch (Throwable e) {
LOGGER.log(Level.SEVERE, "Failed to create Guice container from all the plugins",e);
// failing to load all bindings are disastrous, so recover by creating minimum that works
// by just including the core
container = Guice.createInjector(new SezpozModule(loadSezpozIndices(Jenkins.class.getClassLoader())));
}
// expose Injector via lookup mechanism for interop with non-Guice clients
Jenkins.getInstance().lookup.set(Injector.class,new ProxyInjector() {
protected Injector resolve() {
return getContainer();
}
});
}
private ImmutableList<IndexItem<?, Object>> loadSezpozIndices(ClassLoader classLoader) {
List<IndexItem<?,Object>> indices = Lists.newArrayList();
for (GuiceExtensionAnnotation<?> gea : extensionAnnotations.values()) {
Iterables.addAll(indices, Index.load(gea.annotationType, Object.class, classLoader));
}
return ImmutableList.copyOf(indices);
}
public Injector getContainer() {
return container;
}
/**
* The basic idea is:
*
* <ul>
* <li>List up delta as a series of modules
* <li>
* </ul>
*/
@Override
public synchronized ExtensionComponentSet refresh() throws ExtensionRefreshException {
// figure out newly discovered sezpoz components
List<IndexItem<?, Object>> delta = Lists.newArrayList();
for (Class<? extends Annotation> annotationType : extensionAnnotations.keySet()) {
delta.addAll(Sezpoz.listDelta(annotationType,sezpozIndex));
}
List<IndexItem<?, Object>> l = Lists.newArrayList(sezpozIndex);
l.addAll(delta);
sezpozIndex = l;
List<Module> modules = new ArrayList<>();
modules.add(new SezpozModule(delta));
for (ExtensionComponent<Module> ec : moduleFinder.refresh().find(Module.class)) {
modules.add(ec.getInstance());
}
try {
final Injector child = container.createChildInjector(modules);
container = child;
return new ExtensionComponentSet() {
@Override
public <T> Collection<ExtensionComponent<T>> find(Class<T> type) {
List<ExtensionComponent<T>> result = new ArrayList<>();
_find(type, result, child);
return result;
}
};
} catch (Throwable e) {
LOGGER.log(Level.SEVERE, "Failed to create Guice container from newly added plugins",e);
throw new ExtensionRefreshException(e);
}
}
private Object instantiate(IndexItem<?,Object> item) {
try {
return item.instance();
} catch (LinkageError | Exception e) {
// sometimes the instantiation fails in an indirect classloading failure,
// which results in a LinkageError
LOGGER.log(isOptional(item.annotation()) ? Level.FINE : Level.WARNING,
"Failed to load "+item.className(), e);
}
return null;
}
private boolean isOptional(Annotation annotation) {
GuiceExtensionAnnotation gea = extensionAnnotations.get(annotation.annotationType());
return gea.isOptional(annotation);
}
private boolean isActive(Annotation annotation, AnnotatedElement e) {
GuiceExtensionAnnotation gea = extensionAnnotations.get(annotation.annotationType());
return gea.isActive(e);
}
public <U> Collection<ExtensionComponent<U>> find(Class<U> type, Hudson jenkins) {
// the find method contract requires us to traverse all known components
List<ExtensionComponent<U>> result = new ArrayList<>();
for (Injector i=container; i!=null; i=i.getParent()) {
_find(type, result, i);
}
return result;
}
private <U> void _find(Class<U> type, List<ExtensionComponent<U>> result, Injector container) {
for (Entry<Key<?>, Binding<?>> e : container.getBindings().entrySet()) {
if (type.isAssignableFrom(e.getKey().getTypeLiteral().getRawType())) {
Annotation a = annotations.get(e.getKey());
Object o = e.getValue().getProvider().get();
if (o!=null) {
GuiceExtensionAnnotation gea = a!=null ? extensionAnnotations.get(a.annotationType()) : null;
result.add(new ExtensionComponent<>(type.cast(o), gea != null ? gea.getOrdinal(a) : 0));
}
}
}
}
/**
* TODO: need to learn more about concurrent access to {@link Injector} and how it interacts
* with classloading.
*/
@Override
public void scout(Class extensionType, Hudson hudson) {
}
/**
* {@link Scope} that allows a failure to create a component,
* and change the value to null.
*
* <p>
* This is necessary as a failure to load one plugin shouldn't fail the startup of the entire Jenkins.
* Instead, we should just drop the failing plugins.
*/
public static final Scope FAULT_TOLERANT_SCOPE = new FaultTolerantScope(true);
private static final Scope QUIET_FAULT_TOLERANT_SCOPE = new FaultTolerantScope(false);
private static final class FaultTolerantScope implements Scope {
private final boolean verbose;
FaultTolerantScope(boolean verbose) {
this.verbose = verbose;
}
public <T> Provider<T> scope(final Key<T> key, final Provider<T> unscoped) {
final Provider<T> base = Scopes.SINGLETON.scope(key,unscoped);
return new Provider<T>() {
public T get() {
try {
return base.get();
} catch (Exception | LinkageError e) {
error(key, e);
return null;
}
}
void error(Key<T> key, Throwable x) {
if (verbose) {
LOGGER.log(Level.WARNING, "Failed to instantiate " + key + "; skipping this component", x);
} else {
LOGGER.log(Level.INFO, "Failed to instantiate optional component {0}; skipping", key.getTypeLiteral());
LOGGER.log(Level.FINE, key.toString(), x);
}
}
};
}
}
private static final Logger LOGGER = Logger.getLogger(GuiceFinder.class.getName());
/**
* {@link Module} that finds components via sezpoz index.
* Instead of using SezPoz to instantiate, we'll instantiate them by using Guice,
* so that we can take advantage of dependency injection.
*/
private class SezpozModule extends AbstractModule {
private final List<IndexItem<?,Object>> index;
public SezpozModule(List<IndexItem<?,Object>> index) {
this.index = index;
}
/**
* Guice performs various reflection operations on the class to figure out the dependency graph,
* and that process can cause additional classloading problems, which will fail the injector creation,
* which in turn has disastrous effect on the startup.
*
* <p>
* Ultimately I'd like to isolate problems to plugins and selectively disable them, allowing
* Jenkins to start with plugins that work, but I haven't figured out how.
*
* So this is an attempt to detect subset of problems eagerly, by invoking various reflection
* operations and try to find non-existent classes early.
*/
private void resolve(Class c) {
try {
c.getGenericSuperclass();
c.getGenericInterfaces();
ClassLoader ecl = c.getClassLoader();
Method m = ClassLoader.class.getDeclaredMethod("resolveClass", Class.class);
m.setAccessible(true);
m.invoke(ecl, c);
c.getConstructors();
c.getMethods();
for (Field f : c.getFields()) {
if (f.getAnnotation(javax.inject.Inject.class) != null || f.getAnnotation(com.google.inject.Inject.class) != null) {
resolve(f.getType());
}
}
LOGGER.log(Level.FINER, "{0} looks OK", c);
while (c != Object.class) {
c.getGenericSuperclass();
c = c.getSuperclass();
}
} catch (Exception x) {
throw (LinkageError)new LinkageError("Failed to resolve "+c).initCause(x);
}
}
@SuppressWarnings({"unchecked", "ChainOfInstanceofChecks"})
@Override
protected void configure() {
for (final IndexItem<?,Object> item : index) {
boolean optional = isOptional(item.annotation());
try {
AnnotatedElement e = item.element();
Annotation a = item.annotation();
if (!isActive(a,e)) continue;
Scope scope = optional ? QUIET_FAULT_TOLERANT_SCOPE : FAULT_TOLERANT_SCOPE;
if (e instanceof Class) {
Key key = Key.get((Class)e);
resolve((Class)e);
annotations.put(key,a);
bind(key).in(scope);
} else {
Class extType;
if (e instanceof Field) {
extType = ((Field)e).getType();
} else
if (e instanceof Method) {
extType = ((Method)e).getReturnType();
} else
throw new AssertionError();
resolve(extType);
// make unique key, because Guice wants that.
Key key = Key.get(extType, Names.named(item.className() + "." + item.memberName()));
annotations.put(key,a);
bind(key).toProvider(new Provider() {
public Object get() {
return instantiate(item);
}
}).in(scope);
}
} catch (Exception|LinkageError e) {
// sometimes the instantiation fails in an indirect classloading failure,
// which results in a LinkageError
LOGGER.log(optional ? Level.FINE : Level.WARNING,
"Failed to load "+item.className(), e);
}
}
}
}
}
/**
* The bootstrap implementation that looks for the {@link Extension} marker.
*
* <p>
* Uses Sezpoz as the underlying mechanism.
*/
public static final class Sezpoz extends ExtensionFinder {
private volatile List<IndexItem<Extension,Object>> indices;
/**
* Loads indices (ideally once but as few times as possible), then reuse them later.
* {@link ExtensionList#ensureLoaded()} guarantees that this method won't be called until
* {@link InitMilestone#PLUGINS_PREPARED} is attained, so this method is guaranteed to
* see all the classes and indices.
*/
private List<IndexItem<Extension,Object>> getIndices() {
// this method cannot be synchronized because of a dead lock possibility in the following order of events:
// 1. thread X can start listing indices, locking this object 'SZ'
// 2. thread Y starts loading a class, locking a classloader 'CL'
// 3. thread X needs to load a class, now blocked on CL
// 4. thread Y decides to load extensions, now blocked on SZ.
// 5. dead lock
if (indices==null) {
ClassLoader cl = Jenkins.getInstance().getPluginManager().uberClassLoader;
indices = ImmutableList.copyOf(Index.load(Extension.class, Object.class, cl));
}
return indices;
}
/**
* {@inheritDoc}
*
* <p>
* SezPoz implements value-equality of {@link IndexItem}, so
*/
@Override
public synchronized ExtensionComponentSet refresh() {
final List<IndexItem<Extension,Object>> old = indices;
if (old==null) return ExtensionComponentSet.EMPTY; // we haven't loaded anything
final List<IndexItem<Extension, Object>> delta = listDelta(Extension.class,old);
List<IndexItem<Extension,Object>> r = Lists.newArrayList(old);
r.addAll(delta);
indices = ImmutableList.copyOf(r);
return new ExtensionComponentSet() {
@Override
public <T> Collection<ExtensionComponent<T>> find(Class<T> type) {
return _find(type,delta);
}
};
}
static <T extends Annotation> List<IndexItem<T,Object>> listDelta(Class<T> annotationType, List<? extends IndexItem<?,Object>> old) {
// list up newly discovered components
final List<IndexItem<T,Object>> delta = Lists.newArrayList();
ClassLoader cl = Jenkins.getInstance().getPluginManager().uberClassLoader;
for (IndexItem<T,Object> ii : Index.load(annotationType, Object.class, cl)) {
if (!old.contains(ii)) {
delta.add(ii);
}
}
return delta;
}
public <T> Collection<ExtensionComponent<T>> find(Class<T> type, Hudson jenkins) {
return _find(type,getIndices());
}
/**
* Finds all the matching {@link IndexItem}s that match the given type and instantiate them.
*/
private <T> Collection<ExtensionComponent<T>> _find(Class<T> type, List<IndexItem<Extension,Object>> indices) {
List<ExtensionComponent<T>> result = new ArrayList<>();
for (IndexItem<Extension,Object> item : indices) {
try {
AnnotatedElement e = item.element();
Class<?> extType;
if (e instanceof Class) {
extType = (Class) e;
} else
if (e instanceof Field) {
extType = ((Field)e).getType();
} else
if (e instanceof Method) {
extType = ((Method)e).getReturnType();
} else
throw new AssertionError();
if(type.isAssignableFrom(extType)) {
Object instance = item.instance();
if(instance!=null)
result.add(new ExtensionComponent<>(type.cast(instance),item.annotation()));
}
} catch (LinkageError|Exception e) {
// sometimes the instantiation fails in an indirect classloading failure,
// which results in a LinkageError
LOGGER.log(logLevel(item), "Failed to load "+item.className(), e);
}
}
return result;
}
@Override
public void scout(Class extensionType, Hudson hudson) {
for (IndexItem<Extension,Object> item : getIndices()) {
try {
// we might end up having multiple threads concurrently calling into element(),
// but we can't synchronize this --- if we do, the one thread that's supposed to load a class
// can block while other threads wait for the entry into the element call().
// looking at the sezpoz code, it should be safe to do so
AnnotatedElement e = item.element();
Class<?> extType;
if (e instanceof Class) {
extType = (Class) e;
} else
if (e instanceof Field) {
extType = ((Field)e).getType();
} else
if (e instanceof Method) {
extType = ((Method)e).getReturnType();
} else
throw new AssertionError();
// according to JDK-4993813 this is the only way to force class initialization
Class.forName(extType.getName(),true,extType.getClassLoader());
} catch (Exception | LinkageError e) {
LOGGER.log(logLevel(item), "Failed to scout "+item.className(), e);
}
}
}
private Level logLevel(IndexItem<Extension, Object> item) {
return item.annotation().optional() ? Level.FINE : Level.WARNING;
}
}
private static final Logger LOGGER = Logger.getLogger(ExtensionFinder.class.getName());
}