com.litongjava.tio.utils.map.SyncWriteMap Maven / Gradle / Ivy

package com.litongjava.tio.utils.map;

import java.util.HashMap;
import java.util.Map;
import java.util.function.BiFunction;
import java.util.function.Function;

/**
 * SyncWriteMap 同步写 HashMap
 * 创建原因是 HashMap扩容时，遇到并发修改可能造成 100% CPU 占用
 * 
 * SyncWriteMap 拥有 HashMap 的性能，但不保障并发访问的线程安全
 * 只用于读多写少且不用保障线程安全的场景
 * 
 * 例如 MethodKit 中用于缓存 MethodInfo 的 cache，被写入的数据
 * 不用保障是单例，读取之后会做 null 值判断
 * 
 * ActionMapping 中的 HashMap 是系统启动时在独立线程内初始化的，
 * 不存在并发写，只存在并发读的情况，所以仍然可以使用 HashMap
 */
public class SyncWriteMap extends HashMap {

  private static final long serialVersionUID = -7287230891751869148L;

  public SyncWriteMap() {
  }

  public SyncWriteMap(int initialCapacity) {
    super(initialCapacity);
  }

  public SyncWriteMap(int initialCapacity, float loadFactor) {
    super(initialCapacity, loadFactor);
  }

  public SyncWriteMap(Map m) {
    super(m);
  }

  @Override
  public V put(K key, V value) {
    synchronized (this) {
      return super.put(key, value);
    }
  }

  @Override
  public V putIfAbsent(K key, V value) {
    synchronized (this) {
      return super.putIfAbsent(key, value);
    }
  }

  @Override
  public void putAll(Map m) {
    synchronized (this) {
      super.putAll(m);
    }
  }

  @Override
  public V remove(Object key) {
    synchronized (this) {
      return super.remove(key);
    }
  }

  @Override
  public void clear() {
    synchronized (this) {
      super.clear();
    }
  }

  @Override
  public V computeIfAbsent(K key, Function mappingFunction) {
    synchronized (this) {
      return super.computeIfAbsent(key, mappingFunction);
    }
  }

  @Override
  public V computeIfPresent(K key, BiFunction remappingFunction) {
    synchronized (this) {
      return super.computeIfPresent(key, remappingFunction);
    }
  }

  @Override
  public V compute(K key, BiFunction remappingFunction) {
    synchronized (this) {
      return super.compute(key, remappingFunction);
    }
  }

  @Override
  public boolean replace(K key, V oldValue, V newValue) {
    synchronized (this) {
      return super.replace(key, oldValue, newValue);
    }
  }

  @Override
  public V replace(K key, V value) {
    synchronized (this) {
      return super.replace(key, value);
    }
  }

  @Override
  public void replaceAll(BiFunction function) {
    synchronized (this) {
      super.replaceAll(function);
    }
  }

  @Override
  public V merge(K key, V value, BiFunction remappingFunction) {
    synchronized (this) {
      return super.merge(key, value, remappingFunction);
    }
  }
}