EnhancedClassInstanceContext.java

package org.skywalking.apm.agent.core.plugin.interceptor;

import org.skywalking.apm.agent.core.plugin.AbstractClassEnhancePluginDefine;
import org.skywalking.apm.agent.core.plugin.interceptor.enhance.ClassEnhancePluginDefine;

import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

/**
 * Enhanced instance field type.
 * <p>
 * Any plugins({@link AbstractClassEnhancePluginDefine}'s subclass) override
 * {@link ClassEnhancePluginDefine#getConstructorsInterceptPoints}
 * or
 * {@link ClassEnhancePluginDefine#getInstanceMethodsInterceptPoints}
 * will add a field with this type.
 *
 * @author wusheng
 */
public class EnhancedClassInstanceContext {
    /**
     * extend field, can store any instance as you want.
     */
    private Map<Object, Object> context = new ConcurrentHashMap<Object, Object>();

    /**
     * store a new instance or override it.
     *
     * @param key
     * @param value
     */
    public void set(Object key, Object value) {
        context.put(key, value);
    }

    /**
     * get an stored instance, if it is existed.
     *
     * @param key
     * @return null or stored instance.
     */
    public Object get(Object key) {
        return context.get(key);
    }

    /**
     * judge whether stores by the key.
     *
     * @param key
     * @return true, if stored a instance by the key.
     */
    public boolean isContain(Object key) {
        return context.containsKey(key);
    }

    /**
     * get an stored instance, if it is existed.
     *
     * @param key
     * @param type
     * @param <T>  expected stored instance's type
     * @return null or stored instance.
     */
    public <T> T get(Object key, Class<T> type) {
        return (T) this.get(key);
    }
}