package com.dc.util.shadow.shadow;
/** * 影子对象接口 * @author Daemon* @param <Entity> 影子的实体*/
public interface IShadow<Entity> {/*** 影子有效*/void valid();/*** 影子失效*/void invalid();/*** 影子是否失效* * @return 影子是否失效*/boolean isvalid();/*** 获得影子的实体* * @return 影子的实体*/Entity getEntity();
}

package com.dc.util.shadow.shadow.nomal;
import com.dc.util.shadow.shadow.IShadow;/** * 影子（通过将isvalid声明为volatile确保其可见性） * @author Daemon* @param <Entity> 影子的实体*/
public class Shadow<Entity> implements IShadow<Entity> {/*** 影子是否有效*/protected volatile boolean isvalid;/*** 影子的实体*/protected final Entity entity;public Shadow(Entity entity) {this.entity = entity;isvalid = true;}public Shadow(Entity entity, boolean isvalid) {this.entity = entity;this.isvalid = isvalid;}public void valid() {isvalid = true;}public void invalid() {isvalid = false;}public boolean isvalid() {return isvalid;}public Entity getEntity() {return entity;}}

package com.dc.util.shadow.shadow.week;
import com.dc.util.shadow.shadow.IShadow;/** * 弱可见性的影子（属性isvalid可见性无保证） * @author Daemon* @param <Entity> 影子的实体*/
public class WeekShadow<Entity> implements IShadow<Entity> {/*** 影子是否有效*/protected boolean isvalid;/*** 影子的实体*/protected final Entity entity;public WeekShadow(Entity entity) {this.entity = entity;isvalid = true;}public WeekShadow(Entity entity, boolean isvalid) {this.entity = entity;this.isvalid = isvalid;}public void valid() {isvalid = true;}public void invalid() {isvalid = false;}public boolean isvalid() {return isvalid;}public Entity getEntity() {return entity;}}

package com.dc.util.shadow;import com.dc.util.array.ArraySnapshot;
import com.dc.util.array.SynSimpleArray;
import com.dc.util.hash.HashSegmentTools;
import com.dc.util.shadow.shadow.IShadow;
import com.dc.util.shadow.shadow.nomal.Shadow;/*** 房间测试类 * @author Daemon*/
public class RoomTest {public static void main(String[] args) {//创建房间Room room = new Room();//创建测试用户：daemon, dcUser user1 = new User("daemon");User user2 = new User("dc");//添加用户daemon, dc的影子到房间中Shadow<User> daemonShadow = new Shadow<User>(user1);room.addUser(daemonShadow);Shadow<User> dcShadow = new Shadow<User>(user2);room.addUser(dcShadow);//推送消息1room.pushMsg("test1 test1 test1");//用户daemon退出房间System.out.println("\n~~~~~~~daemonShadow\n");daemonShadow.invalid();//推送消息2room.pushMsg("test2 test2 test2");//清理无效的用户影子room.clearInValidShadow();System.out.println("\n~~~~~~~clearInValidShadow\n");//推送消息3room.pushMsg("test3 test3 test3");}
}

/*** 用户 * @author Daemon*/
class User {
String userName;User(String userName) {this.userName = userName;}
}

/*** 房间 * @author Daemon*/
class Room {/*** 用户影子容器*/ShadowContext<User> userContext = new ShadowContext<User>(4);/*** 用户加入房间 * @param userShadow 用户影子*/void addUser(IShadow<User> userShadow) {userContext.add(userShadow);}/*** 推送消息给房间内的所有用户 * @param msg 推送的消息*/@SuppressWarnings("unchecked")void pushMsg(String msg) {System.out.println("----pushMsg:" + msg);//循环容器内的所有对象for( ShadowArray<User> shadowArray : userContext.shadowArrays ) {//获得当前用户队列的一个快照ArraySnapshot arraySnapshot = shadowArray.getArraySnapshot();int size = arraySnapshot.size;Object[] elementData = arraySnapshot.elementData;//          System.out.println(size + " " + elementData.length);//发送给每个有效的用户for( int i=0; i<size; i++ ) {IShadow<User> userShadow = (IShadow<User>) elementData[i];if( userShadow.isvalid() ) {send(userShadow.getEntity(), msg);} else {//失效的影子不予处理，打印信息方便测试System.out.println( "*****invalid user:'" + userShadow.getEntity().userName + "'" );}}}System.out.println("----pushMsg over\n");}/*** 推送消息给有用户 * @param user 用户* @param msg 推送的消息*/void send(User user, String msg) {System.out.println( ">>>>>send to user:'" + user.userName );}/*** 清除掉失效的影子*/void clearInValidShadow() { userContext.clearInValidShadow();}
}

/*** 用户影子容器 * @author Daemon* @param <EntityType> 用户*/
class ShadowContext<EntityType> extends HashSegmentTools {/*** 将用户存放在不同的桶内，降低添加时候的锁竞争*/final ShadowArray<EntityType>[] shadowArrays;@SuppressWarnings("unchecked")ShadowContext(int concurrencyLevel) {super(concurrencyLevel);int ssize = segmentMask + 1;shadowArrays = new ShadowArray[ssize];for( int i=0; i<ssize; i++ ) {shadowArrays[i] = new ShadowArray<EntityType>();}}/*** 添加用户 * @param shadow 用户影子*/void add(IShadow<EntityType> shadow) {shadowArrays[getSegmentIndex(shadow)].add(shadow);}/*** 清除掉失效的影子*/void clearInValidShadow() {for( ShadowArray<EntityType> array : shadowArrays ) {array.clearInValidShadow();}}
}

/*** 用户数组封装类，对外提供线程安全的方法 * @author Daemon* @param <EntityType> 用户*/
class ShadowArray<EntityType> extends SynSimpleArray<IShadow<EntityType>> {ShadowArray() {super(0);}/*** 清除掉失效的影子*/@SuppressWarnings("unchecked")synchronized void clearInValidShadow() {int size = this.size;Object[] array = this.elementData;//循环所有的元素，查找是否有存在失效的影子IShadow<EntityType> shadow;for( int i=0; i<size; i++ ) {shadow = (IShadow<EntityType>) array[i];if( ! shadow.isvalid() ) {//发现有失效的影子，更新队列信息并返回int newSize = 0;Object[] newArray = new Object[size+6];for( int j=0; j<i; j++ ) {newArray[newSize++] = (IShadow<EntityType>) array[j];}for( int j=i+1; j<size; j++ ) {shadow = (IShadow<EntityType>) array[j];if( shadow.isvalid() )newArray[newSize++] = shadow;}this.size = newSize;this.elementData = newArray;return;}}//没有发现失效的影子}
}

----pushMsg:test1 test1 test1
>>>>>send to user:'daemon
>>>>>send to user:'dc
----pushMsg over~~~~~~~daemonShadow----pushMsg:test2 test2 test2
*****invalid user:'daemon'
>>>>>send to user:'dc
----pushMsg over~~~~~~~clearInValidShadow----pushMsg:test3 test3 test3
>>>>>send to user:'dc
----pushMsg over