/*Copy right 2020 Jacky Zong . All rights reserved.*/
package org.apache.ibatis.cache;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;
import java.util.StringJoiner;
import org.apache.ibatis.reflection.ArrayUtil;
public class CacheKey implements Cloneable, Serializable {
private static final long serialVersionUID = 1146682552656046210L;
public static final CacheKey NULL_CACHE_KEY = new CacheKey() {
@Override
public void update(Object object) {
throw new CacheException("Not allowed to update a null cache key instance.");
}
@Override
public void updateAll(Object[] objects) {
throw new CacheException("Not allowed to update a null cache key instance.");
}
};
private static final int DEFAULT_MULTIPLIER = 37;
private static final int DEFAULT_HASHCODE = 17;
private final int multiplier;
private int hashcode;
private long checksum;
private int count;
private List<Object> updateList;
public CacheKey() {
this.hashcode = DEFAULT_HASHCODE;
this.multiplier = DEFAULT_MULTIPLIER;
this.count = 0;
this.updateList = new ArrayList<>();
}
public CacheKey(Object[] objects) {
this();
updateAll(objects);
}
public int getUpdateCount() {
return updateList.size();
}
public void update(Object object) {
int baseHashCode = object == null ? 1 : ArrayUtil.hashCode(object);
count++;
checksum += baseHashCode;
baseHashCode *= count;
hashcode = multiplier * hashcode + baseHashCode;
updateList.add(object);
}
public void updateAll(Object[] objects) {
for (Object o : objects) {
update(o);
}
}
@Override
public boolean equals(Object object) {
if (this == object) {
return true;
}
if (!(object instanceof CacheKey)) {
return false;
}
final CacheKey cacheKey = (CacheKey) object;
if (hashcode != cacheKey.hashcode) {
return false;
}
if (checksum != cacheKey.checksum) {
return false;
}
if (count != cacheKey.count) {
return false;
}
for (int i = 0; i < updateList.size(); i++) {
Object thisObject = updateList.get(i);
Object thatObject = cacheKey.updateList.get(i);
if (!ArrayUtil.equals(thisObject, thatObject)) {
return false;
}
}
return true;
}
@Override
public int hashCode() {
return hashcode;
}
@Override
public String toString() {
StringJoiner returnValue = new StringJoiner(":");
returnValue.add(String.valueOf(hashcode));
returnValue.add(String.valueOf(checksum));
updateList.stream().map(ArrayUtil::toString).forEach(returnValue::add);
return returnValue.toString();
}
@Override
public CacheKey clone() throws CloneNotSupportedException {
CacheKey clonedCacheKey = (CacheKey) super.clone();
clonedCacheKey.updateList = new ArrayList<>(updateList);
return clonedCacheKey;
}
}