cn.hutool.core.map.SafeConcurrentHashMap Maven / Gradle / Ivy
package cn.hutool.core.map;
import cn.hutool.core.util.JdkUtil;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.function.Function;
/**
* 安全的ConcurrentHashMap实现
* 此类用于解决在JDK8中调用{@link ConcurrentHashMap#computeIfAbsent(Object, Function)}可能造成的死循环问题。
* 方法来自Dubbo，见：issues#2349
*
* 相关bug见：@see https://bugs.openjdk.java.net/browse/JDK-8161372
*
* @param 键类型
* @param 值类型
*/
public class SafeConcurrentHashMap extends ConcurrentHashMap {
private static final long serialVersionUID = 1L;
// region == 构造 ==
/**
* 构造，默认初始大小（16）
*/
public SafeConcurrentHashMap() {
super();
}
/**
* 构造
*
* @param initialCapacity 预估初始大小
*/
public SafeConcurrentHashMap(int initialCapacity) {
super(initialCapacity);
}
/**
* 构造
*
* @param m 初始键值对
*/
public SafeConcurrentHashMap(Map m) {
super(m);
}
/**
* 构造
*
* @param initialCapacity 初始容量
* @param loadFactor 增长系数
*/
public SafeConcurrentHashMap(int initialCapacity, float loadFactor) {
super(initialCapacity, loadFactor);
}
/**
* 构造
*
* @param initialCapacity 初始容量
* @param loadFactor 增长系数
* @param concurrencyLevel 并发级别，即Segment的个数
*/
public SafeConcurrentHashMap(int initialCapacity,
float loadFactor, int concurrencyLevel) {
super(initialCapacity, loadFactor, concurrencyLevel);
}
// endregion == 构造 ==
@Override
public V computeIfAbsent(K key, Function mappingFunction) {
if (JdkUtil.IS_JDK8) {
return MapUtil.computeIfAbsentForJdk8(this, key, mappingFunction);
} else {
return super.computeIfAbsent(key, mappingFunction);
}
}
}