org.h2.util.SynchronizedVerifier Maven / Gradle / Ivy
/*
* Copyright 2004-2014 H2 Group. Multiple-Licensed under the MPL 2.0,
* and the EPL 1.0 (http://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.h2.util;
import java.util.Collections;
import java.util.HashMap;
import java.util.IdentityHashMap;
import java.util.Map;
import java.util.concurrent.atomic.AtomicBoolean;
/**
* A utility class that allows to verify access to a resource is synchronized.
*/
public class SynchronizedVerifier {
private static volatile boolean enabled;
private static final Map, AtomicBoolean> DETECT =
Collections.synchronizedMap(new HashMap, AtomicBoolean>());
private static final Map CURRENT =
Collections.synchronizedMap(new IdentityHashMap());
/**
* Enable or disable detection for a given class.
*
* @param clazz the class
* @param value the new value (true means detection is enabled)
*/
public static void setDetect(Class clazz, boolean value) {
if (value) {
DETECT.put(clazz, new AtomicBoolean());
} else {
AtomicBoolean b = DETECT.remove(clazz);
if (b == null) {
throw new AssertionError("Detection was not enabled");
} else if (!b.get()) {
throw new AssertionError("No object of this class was tested");
}
}
enabled = DETECT.size() > 0;
}
/**
* Verify the object is not accessed concurrently.
*
* @param o the object
*/
public static void check(Object o) {
if (enabled) {
detectConcurrentAccess(o);
}
}
private static void detectConcurrentAccess(Object o) {
AtomicBoolean value = DETECT.get(o.getClass());
if (value != null) {
value.set(true);
if (CURRENT.remove(o) != null) {
throw new AssertionError("Concurrent access");
}
CURRENT.put(o, o);
try {
Thread.sleep(1);
} catch (InterruptedException e) {
// ignore
}
Object old = CURRENT.remove(o);
if (old == null) {
throw new AssertionError("Concurrent access");
}
}
}
}