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基于memcached的SNA实现

memcachedBeanCacheAcegiLinux 
阅读更多

系统要集群，使用SNA方案。
一、 缓存的处理
缓存要使用统一的缓存服务器，集中式缓存。
原先的实现采用ehcache。
在spring里的配置，以资源缓存为例：

Xml代码
  1. <!-- EhCache Manager -->   
  2.     < bean   id = "cacheManager"   class = "org.springframework.cache.ehcache.EhCacheManagerFactoryBean" >   
  3.         < property   name = "configLocation" >   
  4.             < value > classpath:ehcache.xml </ value >   
  5.         </ property >   
  6. </ bean >   
  7.   
  8. < bean   id = "resourceCacheBackend"   
  9.           class = "org.springframework.cache.ehcache.EhCacheFactoryBean" >   
  10.         < property   name = "cacheManager"   ref = "cacheManager" />   
  11.         < property   name = "cacheName"   value = "resourceCache" />   
  12.     </ bean >   
  13.   
  14.     < bean   id = "resourceCache"   
  15.           class = "com.framework.extcomponent.security.authentication.services.acegi.cache.EhCacheBasedResourceCache"   
  16.           autowire = "byName" >   
  17.         < property   name = "cache"   ref = "resourceCacheBackend" />   
  18.     </ bean >    
<!-- EhCache Manager -->
    <bean id="cacheManager" class="org.springframework.cache.ehcache.EhCacheManagerFactoryBean">
        <property name="configLocation">
            <value>classpath:ehcache.xml</value>
        </property>
</bean>

<bean id="resourceCacheBackend"
          class="org.springframework.cache.ehcache.EhCacheFactoryBean">
        <property name="cacheManager" ref="cacheManager"/>
        <property name="cacheName" value="resourceCache"/>
    </bean>

    <bean id="resourceCache"
          class="com.framework.extcomponent.security.authentication.services.acegi.cache.EhCacheBasedResourceCache"
          autowire="byName">
        <property name="cache" ref="resourceCacheBackend"/>
    </bean>

 

cacheManager负责对ehcache进行管理，初始化、启动、停止。
resourceCacheBackend负责实际执行缓存操作，put 、get、remove。
resourceCache实现具有业务语义的业务应用层面的缓存操作，内部调用resourceCacheBackend操作。

现在采用memcached。
关于客户端，采用文初封装的客户端，地址在http://code.google.com/p/memcache-client-forjava/ 。
使用spring的FactoryBean进行二次封装。同理：
memcachedManager负责对memcached进行管理，初始化、启动、停止。
代码：

Java代码
  1. /**  
  2. * User: ronghao  
  3. * Date: 2008-10-14  
  4. * Time: 10:36:30  
  5. * 管理Memcached 的CacheManager  
  6. */   
  7. public   class  MemcachedCacheManagerFactoryBean  implements  FactoryBean, InitializingBean, DisposableBean {  
  8.   
  9.     protected   final  Log logger = LogFactory.getLog(getClass());  
  10.   
  11.     private  ICacheManager<IMemcachedCache> cacheManager;  
  12.   
  13.     public  Object getObject()  throws  Exception {  
  14.         return  cacheManager;  
  15.     }  
  16.   
  17.     public  Class getObjectType() {  
  18.         return   this .cacheManager.getClass();  
  19.     }  
  20.   
  21.     public   boolean  isSingleton() {  
  22.         return   true ;  
  23.     }  
  24.   
  25.     public   void  afterPropertiesSet()  throws  Exception {  
  26.         logger.info("Initializing Memcached CacheManager" );  
  27.         cacheManager = CacheUtil.getCacheManager(IMemcachedCache.class ,  
  28.                 MemcachedCacheManager.class .getName());  
  29.         cacheManager.start();  
  30.     }  
  31.   
  32.     public   void  destroy()  throws  Exception {  
  33.         logger.info("Shutting down Memcached CacheManager" );  
  34.         cacheManager.stop();  
  35.     }  
  36. }   
/**
* User: ronghao
* Date: 2008-10-14
* Time: 10:36:30
* 管理Memcached 的CacheManager
*/
public class MemcachedCacheManagerFactoryBean implements FactoryBean, InitializingBean, DisposableBean {

    protected final Log logger = LogFactory.getLog(getClass());

    private ICacheManager<IMemcachedCache> cacheManager;

    public Object getObject() throws Exception {
        return cacheManager;
    }

    public Class getObjectType() {
        return this.cacheManager.getClass();
    }

    public boolean isSingleton() {
        return true;
    }

    public void afterPropertiesSet() throws Exception {
        logger.info("Initializing Memcached CacheManager");
        cacheManager = CacheUtil.getCacheManager(IMemcachedCache.class,
                MemcachedCacheManager.class.getName());
        cacheManager.start();
    }

    public void destroy() throws Exception {
        logger.info("Shutting down Memcached CacheManager");
        cacheManager.stop();
    }
}
 


配置：

Xml代码
  1. < bean   id = "memcachedManager"   
  2.           class = "com.framework.extcomponent.cache.MemcachedCacheManagerFactoryBean" />    
<bean id="memcachedManager"
          class="com.framework.extcomponent.cache.MemcachedCacheManagerFactoryBean"/>
 


resourceCacheBackend负责实际执行缓存操作，put 、get、remove。
代码：

Java代码
  1. /**  
  2. * User: ronghao  
  3. * Date: 2008-10-14  
  4. * Time: 10:37:16  
  5. * 返回  MemcachedCache  
  6. */   
  7. public   class  MemcachedCacheFactoryBean  implements  FactoryBean, BeanNameAware, InitializingBean {  
  8.   
  9.     protected   final  Log logger = LogFactory.getLog(getClass());  
  10.   
  11.     private  ICacheManager<IMemcachedCache> cacheManager;  
  12.     private  String cacheName;  
  13.     private  String beanName;  
  14.     private  IMemcachedCache cache;  
  15.   
  16.     public   void  setCacheManager(ICacheManager<IMemcachedCache> cacheManager) {  
  17.         this .cacheManager = cacheManager;  
  18.     }  
  19.   
  20.     public   void  setCacheName(String cacheName) {  
  21.         this .cacheName = cacheName;  
  22.     }  
  23.   
  24.     public  Object getObject()  throws  Exception {  
  25.         return  cache;  
  26.     }  
  27.   
  28.     public  Class getObjectType() {  
  29.         return   this .cache.getClass();  
  30.     }  
  31.   
  32.     public   boolean  isSingleton() {  
  33.         return   true ;   
  34.     }  
  35.   
  36.     public   void  setBeanName(String name) {  
  37.         this .beanName=name;  
  38.     }  
  39.   
  40.     public   void  afterPropertiesSet()  throws  Exception {  
  41.         // If no cache name given, use bean name as cache name.   
  42.        if  ( this .cacheName ==  null ) {  
  43.         this .cacheName =  this .beanName;  
  44.     }  
  45.         cache = cacheManager.getCache(cacheName);  
  46.     }  
  47. }   
/**
* User: ronghao
* Date: 2008-10-14
* Time: 10:37:16
* 返回  MemcachedCache
*/
public class MemcachedCacheFactoryBean implements FactoryBean, BeanNameAware, InitializingBean {

    protected final Log logger = LogFactory.getLog(getClass());

    private ICacheManager<IMemcachedCache> cacheManager;
    private String cacheName;
    private String beanName;
    private IMemcachedCache cache;

    public void setCacheManager(ICacheManager<IMemcachedCache> cacheManager) {
        this.cacheManager = cacheManager;
    }

    public void setCacheName(String cacheName) {
        this.cacheName = cacheName;
    }

    public Object getObject() throws Exception {
        return cache;
    }

    public Class getObjectType() {
        return this.cache.getClass();
    }

    public boolean isSingleton() {
        return true; 
    }

    public void setBeanName(String name) {
        this.beanName=name;
    }

    public void afterPropertiesSet() throws Exception {
        // If no cache name given, use bean name as cache name.
       if (this.cacheName == null) {
		this.cacheName = this.beanName;
	}
        cache = cacheManager.getCache(cacheName);
    }
}
 


配置：

Xml代码
  1. < bean   id = "resourceCacheBackend"   
  2.           class = "com.framework.extcomponent.cache.MemcachedCacheFactoryBean" >   
  3.         < property   name = "cacheManager"   ref = "memcachedManager" />   
  4.         < property   name = "cacheName"   value = "memcache" />   
  5.     </ bean >    
<bean id="resourceCacheBackend"
          class="com.framework.extcomponent.cache.MemcachedCacheFactoryBean">
        <property name="cacheManager" ref="memcachedManager"/>
        <property name="cacheName" value="memcache"/>
    </bean>
 


resourceCache同上，替换新的实现类MemcachedBasedResourceCache即可。

二、 Session失效的处理
采用memcached作为httpsession的存储，并不直接保存httpsession对象，自定义SessionMap，SessionMap直接继承HashMap，保存SessionMap。

会话胶粘：未失败转发的情况下没必要在memcached保存的SessionMap和httpsession之间复制来复制去，眉来眼去。

利用memcached计数器保存在线人数。

系统权限采用了acegi，在acegi的拦截器链里配置snaFilter

Xml代码
  1. < bean   id = "filterChainProxy"   
  2.           class = "org.acegisecurity.util.FilterChainProxy" >   
  3.         < property   name = "filterInvocationDefinitionSource" >   
  4.             < value >   
  5.                 CONVERT_URL_TO_LOWERCASE_BEFORE_COMPARISON  
  6.                 PATTERN_TYPE_APACHE_ANT  
  7.                 /**=snaFilter,httpSessionContextIntegrationFilter,logoutFilter,authenticationProcessingFilter,basicProcessingFilter,securityContextHolderAwareRequestFilter,exceptionTranslationFilter,filterInvocationInterceptor  
  8.             </ value >   
  9.         </ property >   
  10. </ bean >    
<bean id="filterChainProxy"
          class="org.acegisecurity.util.FilterChainProxy">
        <property name="filterInvocationDefinitionSource">
            <value>
                CONVERT_URL_TO_LOWERCASE_BEFORE_COMPARISON
                PATTERN_TYPE_APACHE_ANT
                /**=snaFilter,httpSessionContextIntegrationFilter,logoutFilter,authenticationProcessingFilter,basicProcessingFilter,securityContextHolderAwareRequestFilter,exceptionTranslationFilter,filterInvocationInterceptor
            </value>
        </property>
</bean>
 


注意需要配置在第一个。
snaFilter的职责：
1、 没有HttpSession时，创建HttpSession;
2、 创建Cookie保存HttpSession id;
3、 如果Cookie保存的HttpSession id与当前HttpSession id一致，说明是正常请求；
4、 如果Cookie保存的HttpSession id与当前HttpSession id不一致，说明是失败转发；失败转发的处理：
     4.1、根据Cookie保存的HttpSession id从memcached获取SessionMap；
     4.2、SessionMap属性复制到当前HttpSession；
     4.3、memcached删除SessionMap。
5、 判断当前请求url是否是登出url，是则删除SessionMap，在线人数减1.

代码：

Java代码
  1. public   void  doFilter(ServletRequest servletRequest, ServletResponse servletResponse,  
  2.                          FilterChain filterChain) throws  IOException, ServletException {  
  3.         final  HttpServletRequest hrequest = (HttpServletRequest) servletRequest;  
  4.         final  HttpServletResponse hresponse = (HttpServletResponse) servletResponse;  
  5.         String uri = hrequest.getRequestURI();  
  6.         logger.debug("开始SNA拦截-----------------"  + uri);  
  7.         HttpSession httpSession = hrequest.getSession();  
  8.         String sessionId = httpSession.getId();  
  9.         //如果是登出,则直接干掉sessionMap   
  10.         if  (uri.equals(logoutUrl)) {  
  11.             logger.debug("remove sessionmap:"  + sessionId);  
  12.             //在线人数减1   
  13.             getCache().addOrDecr("userCount" , 1 );  
  14.             getCache().remove(sessionId);  
  15.         } else  {  
  16.             String cookiesessionid = getSessionIdFromCookie(hrequest, hresponse);  
  17.             if  (!sessionId.equals(cookiesessionid)) {  
  18.                 createCookie(sessionId, hresponse);  
  19.                 SessionMap sessionMap = getSessionMap(cookiesessionid);  
  20.                 if  (sessionMap !=  null ) {  
  21.                     logger.debug("fail over--------sessionid:"  + sessionId +  "cookiesessionid:"  + cookiesessionid);  
  22.                     initialHttpSession(sessionMap, httpSession);  
  23.                     cache.remove(cookiesessionid);  
  24.                 }  
  25.             }  
  26.         }  
  27.         filterChain.doFilter(hrequest, hresponse);  
  28. }   
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse,
                         FilterChain filterChain) throws IOException, ServletException {
        final HttpServletRequest hrequest = (HttpServletRequest) servletRequest;
        final HttpServletResponse hresponse = (HttpServletResponse) servletResponse;
        String uri = hrequest.getRequestURI();
        logger.debug("开始SNA拦截-----------------" + uri);
        HttpSession httpSession = hrequest.getSession();
        String sessionId = httpSession.getId();
        //如果是登出,则直接干掉sessionMap
        if (uri.equals(logoutUrl)) {
            logger.debug("remove sessionmap:" + sessionId);
            //在线人数减1
            getCache().addOrDecr("userCount",1);
            getCache().remove(sessionId);
        } else {
            String cookiesessionid = getSessionIdFromCookie(hrequest, hresponse);
            if (!sessionId.equals(cookiesessionid)) {
                createCookie(sessionId, hresponse);
                SessionMap sessionMap = getSessionMap(cookiesessionid);
                if (sessionMap != null) {
                    logger.debug("fail over--------sessionid:" + sessionId + "cookiesessionid:" + cookiesessionid);
                    initialHttpSession(sessionMap, httpSession);
                    cache.remove(cookiesessionid);
                }
            }
        }
        filterChain.doFilter(hrequest, hresponse);
}
 



利用HttpSessionAttributeListener监听httpsession的属性变化,同步到memecached中的sessionmap。

Java代码
  1. public   void  attributeAdded(HttpSessionBindingEvent event) {  
  2.         HttpSession httpSession = event.getSession();  
  3.         String attrName = event.getName();  
  4.         Object attrValue = event.getValue();  
  5.         String sessionId = httpSession.getId();  
  6.         logger.debug("attributeAdded sessionId:"  + sessionId +  "name:"  + attrName +  ",value:"  + attrValue);  
  7.         SessionMap sessionMap = getSessionMap(sessionId);  
  8.         if  (sessionMap ==  null ){  
  9.             //在线人数加1   
  10.             getCache().addOrIncr("userCount" , 1 );  
  11.             sessionMap = new  SessionMap();  
  12.         }  
  13.         logger.debug("name:"  + attrName +  ",value:"  + attrValue);  
  14.         sessionMap.put(attrName, attrValue);  
  15.         getCache().put(sessionId, sessionMap);  
  16.     }  
  17.   
  18.     public   void  attributeRemoved(HttpSessionBindingEvent event) {  
  19.         HttpSession httpSession = event.getSession();  
  20.         String attrName = event.getName();  
  21.         String sessionId = httpSession.getId();  
  22.         logger.debug("attributeRemoved sessionId:"  + sessionId +  "name:"  + attrName);  
  23.         SessionMap sessionMap = getSessionMap(sessionId);  
  24.         if  (sessionMap !=  null ) {  
  25.             logger.debug("remove:"  + attrName);  
  26.             sessionMap.remove(attrName);  
  27.             getCache().put(sessionId, sessionMap);  
  28.         }  
  29.     }  
  30.   
  31.     public   void  attributeReplaced(HttpSessionBindingEvent event) {  
  32.         attributeAdded(event);  
  33.     }   
public void attributeAdded(HttpSessionBindingEvent event) {
        HttpSession httpSession = event.getSession();
        String attrName = event.getName();
        Object attrValue = event.getValue();
        String sessionId = httpSession.getId();
        logger.debug("attributeAdded sessionId:" + sessionId + "name:" + attrName + ",value:" + attrValue);
        SessionMap sessionMap = getSessionMap(sessionId);
        if (sessionMap == null){
            //在线人数加1
            getCache().addOrIncr("userCount",1);
            sessionMap = new SessionMap();
        }
        logger.debug("name:" + attrName + ",value:" + attrValue);
        sessionMap.put(attrName, attrValue);
        getCache().put(sessionId, sessionMap);
    }

    public void attributeRemoved(HttpSessionBindingEvent event) {
        HttpSession httpSession = event.getSession();
        String attrName = event.getName();
        String sessionId = httpSession.getId();
        logger.debug("attributeRemoved sessionId:" + sessionId + "name:" + attrName);
        SessionMap sessionMap = getSessionMap(sessionId);
        if (sessionMap != null) {
            logger.debug("remove:" + attrName);
            sessionMap.remove(attrName);
            getCache().put(sessionId, sessionMap);
        }
    }

    public void attributeReplaced(HttpSessionBindingEvent event) {
        attributeAdded(event);
    }
 



利用HttpSessionListener，sessionDestroyed事件时根据sessionid删除memcached里的sessionMap（如果存在）。不再担心httpsession的过期问题。

Java代码
  1. public   void  sessionDestroyed(HttpSessionEvent event) {  
  2.         HttpSession httpSession = event.getSession();  
  3.         String sessionId = httpSession.getId();  
  4.         logger.debug("session Removed sessionId:"  + sessionId);  
  5.         SessionMap sessionMap = getSessionMap(sessionId);  
  6.         if  (sessionMap !=  null ) {  
  7.             logger.debug("remove sessionmap:"  + sessionId);  
  8.             //在线人数减1   
  9.             getCache().addOrDecr("userCount" , 1 );  
  10.             getCache().remove(sessionId);  
  11.         }  
  12.     }   
public void sessionDestroyed(HttpSessionEvent event) {
        HttpSession httpSession = event.getSession();
        String sessionId = httpSession.getId();
        logger.debug("session Removed sessionId:" + sessionId);
        SessionMap sessionMap = getSessionMap(sessionId);
        if (sessionMap != null) {
            logger.debug("remove sessionmap:" + sessionId);
            //在线人数减1
            getCache().addOrDecr("userCount",1);
            getCache().remove(sessionId);
        }
    }
 



三、 文件保存的处理
和缓存类似，采用集中式的文件服务。对于linux，采用nfs。参考文档http://linux.vbird.org/linux_server/0330nfs.php#What_NFS_perm 。关键在于对权限的分配。
应用程序本身不用修改。

 

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