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[JENKINS-27421] Categories also seem to provide a far simpler way to …
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…work around unserializable iterators, map entries, etc.
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@jglick
jglick committed May 11, 2017
1 parent ab9a154 commit ee84510
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Showing 3 changed files with 69 additions and 77 deletions.
3 changes: 2 additions & 1 deletion src/main/java/org/jenkinsci/plugins/workflow/cps/CpsThread.java
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Expand Up @@ -53,6 +53,7 @@
import org.codehaus.groovy.runtime.DefaultGroovyMethods;
import org.codehaus.groovy.runtime.GroovyCategorySupport;
import org.codehaus.groovy.runtime.InvokerHelper;
import org.jenkinsci.plugins.workflow.cps.persistence.IteratorHack;
import static org.jenkinsci.plugins.workflow.cps.persistence.PersistenceContext.*;
import org.jenkinsci.plugins.workflow.support.concurrent.Futures;
import org.jenkinsci.plugins.workflow.support.concurrent.Timeout;
Expand Down Expand Up @@ -196,7 +197,7 @@ private CpsDefaultGroovyMethodsExt() {}
LOGGER.log(FINE, "runNextChunk on {0}", resumeValue);
final Outcome o = resumeValue;
resumeValue = null;
outcome = GroovyCategorySupport.use(Arrays.<Class>asList(CpsDefaultGroovyMethods.class, CpsDefaultGroovyMethodsExt.class), new Closure<Outcome>(null) {
outcome = GroovyCategorySupport.use(Arrays.<Class>asList(CpsDefaultGroovyMethods.class, CpsDefaultGroovyMethodsExt.class, IteratorHack.class), new Closure<Outcome>(null) {
@Override public Outcome call() {
return program.run0(o);
}
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139 changes: 67 additions & 72 deletions src/main/java/org/jenkinsci/plugins/workflow/cps/persistence/IteratorHack.java
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Expand Up @@ -24,91 +24,86 @@

package org.jenkinsci.plugins.workflow.cps.persistence;

import com.google.common.collect.ImmutableSet;
import com.google.common.util.concurrent.Futures;
import com.google.common.util.concurrent.ListenableFuture;
import com.thoughtworks.xstream.converters.reflection.ReflectionProvider;
import hudson.Extension;
import java.lang.reflect.Field;
import com.cloudbees.groovy.cps.impl.Caller;
import java.io.Serializable;
import java.util.AbstractList;
import java.util.HashMap;
import java.util.AbstractMap;
import java.util.ArrayList;
import java.util.Collection;
import java.util.ConcurrentModificationException;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.logging.Level;
import java.util.logging.Logger;
import jenkins.model.Jenkins;
import org.jenkinsci.plugins.workflow.pickles.Pickle;
import org.jenkinsci.plugins.workflow.pickles.PickleFactory;
import java.util.NoSuchElementException;

/**
* Makes Java iterators effectively serializable.
*/
@Extension public class IteratorHack extends PickleFactory {
public class IteratorHack {

private static final Logger LOGGER = Logger.getLogger(IteratorHack.class.getName());
private static final Set<String> ACCEPTED_TYPES = ImmutableSet.of("java.util.ArrayList$Itr");

@Override public Pickle writeReplace(Object object) {
if (ACCEPTED_TYPES.contains(object.getClass().getName())) {
return new Replacement(object);
} else {
return null;
/**
* Similar to the inner class of {@link AbstractList} except it is serializable.
* Since {@link AbstractList#modCount} is {@code transient} we cannot rely on it and thus cannot throw {@link ConcurrentModificationException}.
*/
private static final class Itr<E> implements Iterator<E>, Serializable {
private static final long serialVersionUID = 1;
private final List<E> list;
private int cursor = 0;
private int lastRet = -1;
Itr(List<E> list) {
this.list = list;
}
}

@SuppressWarnings("rawtypes")
private static class Replacement extends Pickle {

private final Class type;
private final Map<Class,Map<String,Object>> fields;

Replacement(Object o) {
type = o.getClass();
fields = new HashMap<>();
ReflectionProvider rp = Jenkins.XSTREAM2.getReflectionProvider();
rp.visitSerializableFields(o, new ReflectionProvider.Visitor() {
@Override public void visit(String name, Class type, Class definedIn, Object value) {
if (name.equals("expectedModCount")) {
LOGGER.log(Level.FINER, "ignoring expectedModCount={0}", value);
return;
}
Map<String,Object> fieldsByClass = fields.get(definedIn);
if (fieldsByClass == null) {
fieldsByClass = new HashMap<>();
fields.put(definedIn, fieldsByClass);
}
fieldsByClass.put(name, value);
}
});
LOGGER.log(Level.FINE, "replacing {0} with {1}", new Object[] {o, fields});
@Override public boolean hasNext() {
return cursor != list.size();
}

@Override public ListenableFuture<?> rehydrate() {
ReflectionProvider rp = Jenkins.XSTREAM2.getReflectionProvider();
Object o = rp.newInstance(type);
for (Map.Entry<Class,Map<String,Object>> entry : fields.entrySet()) {
Class definedIn = entry.getKey();
for (Map.Entry<String,Object> entry2 : entry.getValue().entrySet()) {
String fieldName = entry2.getKey();
Object value = entry2.getValue();
rp.writeField(o, fieldName, value, definedIn);
if (fieldName.equals("this$0")) {
try {
Field f = AbstractList.class.getDeclaredField("modCount"); // TODO if not handling only ArrayList.Itr, search in superclasses
f.setAccessible(true);
int modCount = f.getInt(value);
LOGGER.log(Level.FINER, "found a modCount={0}", modCount);
rp.writeField(o, "expectedModCount", modCount, type); // TODO search in superclasses
} catch (Exception x) {
return Futures.immediateFailedFuture(x);
}
}
@Override public E next() {
try {
int i = cursor;
E next = list.get(i);
lastRet = i;
cursor = i + 1;
return next;
} catch (IndexOutOfBoundsException e) {
throw new NoSuchElementException();
}
}
@Override public void remove() {
if (lastRet < 0) {
throw new IllegalStateException();
}
try {
list.remove(lastRet);
if (lastRet < cursor) {
cursor--;
}
lastRet = -1;
} catch (IndexOutOfBoundsException e) {
throw new ConcurrentModificationException();
}
LOGGER.log(Level.FINE, "reconstructed {0}", o);
return Futures.immediateFuture(o);
}
}

/** Serializable replacement for {@link List#iterator}. */
public static <E> Iterator<E> iterator(List<E> list) {
// TODO !Caller.isAsynchronous(list, "iterator") && !Caller.isAsynchronous(IteratorHack.class, "iterator", list) when used from a Java 5-style for-loop, so not sure how to sidestep this when running in @NonCPS
return new Itr<>(list);
}

/** Serializable replacement for {@link Map#entrySet}. */
public static <K, V> Collection<Map.Entry<K, V>> entrySet(Map<K, V> map) {
if (!Caller.isAsynchronous(map, "entrySet") && !Caller.isAsynchronous(IteratorHack.class, "entrySet", map)) {
// In @NonCPS so no need to bother processing this.
return map.entrySet();
}
// TODO return an actual Set
List<Map.Entry<K, V>> entries = new ArrayList<>();
for (Map.Entry<K, V> entry : map.entrySet()) {
// TODO return an object holding references to the map and the key and delegating all calls accordingly
entries.add(new AbstractMap.SimpleImmutableEntry<>(entry));
}
return entries;
}

private IteratorHack() {}

}
4 changes: 0 additions & 4 deletions src/test/java/org/jenkinsci/plugins/workflow/SerializationTest.java
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Expand Up @@ -219,12 +219,8 @@ public void stop(Throwable cause) throws Exception {
SemaphoreStep.success("new-one/1", null);
SemaphoreStep.success("new-two/1", null);
story.j.waitForCompletion(b);
/* TODO desired behavior:
story.j.assertBuildStatusSuccess(b);
story.j.assertLogContains("running new-style loop on two -> 2", b);
*/
story.j.assertBuildStatus(Result.FAILURE, b);
story.j.assertLogContains("java.io.NotSerializableException: java.util.LinkedHashMap$Entry", b);
}
});
}
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