com.google.gwt.emul.java.util.ConcurrentModificationDetector Maven / Gradle / Ivy
/*
* Copyright 2014 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
package java.util;
/**
* A helper to detect concurrent modifications to collections. This is implemented as a helper
* utility so that we could remove the checks easily by a flag.
*/
class ConcurrentModificationDetector {
public static void structureChanged(Object map) {
// Ensure that modCount is initialized if it is not already.
int modCount = getModCount(map) | 0;
setModCount(map, modCount + 1);
}
public static void recordLastKnownStructure(Object host, Iterator iterator) {
setModCount(iterator, getModCount(host));
}
public static void checkStructuralChange(Object host, Iterator iterator) {
if (getModCount(iterator) != getModCount(host)) {
throw new ConcurrentModificationException();
}
}
private static native void setModCount(Object o, int modCount) /*-{
o._gwt_modCount = modCount;
}-*/;
private static native int getModCount(Object o) /*-{
return o._gwt_modCount;
}-*/;
}