java - 内存缓存+ Spring 缓存

Question

我正在尝试使用 Memcached 设置 Spring 3.1 缓存解决方案。我已经成功地合并了 ehcache(Spring 内置了对此的支持)。但是，我遇到了 memcached 的问题。我提前为长度道歉(它主要是样板代码)...

我使用的是 Java 配置，所以我注释了我的 Controller 配置以启用缓存，如下所示。

@Configuration  @EnableWebMvc  @EnableCaching 
@ComponentScan("com.ehcache.reference.web")
public class ControllerConfig extends WebMvcConfigurerAdapter {
   //Bean to create ViewResolver and add the Resource handler
}

这设置了三个 Controller ，允许对 Stock 元素执行基本的 CRUD 操作。业务对象如下所示:

public class Stock implements Serializable {
  private String name;
  private double cost; //This isn't a real app, don't care about correctness of value
  //Getters, Setters contructors, etc... left out just a standard POJO

我正在使用 MyBatis，所以我为 Stock 对象创建了一个 Mapper。然后将映射器注入(inject)到我的 DAO 中，然后将 DAO 注入(inject)到服务中。工作缓存(在两种实现中)出现在“服务”层中。下面是利用注入(inject)的 DAO 的服务层:

public class TradingServiceImpl implements TradingService {

  @Autowired
  private final StockDao stockDao;

  public TradingServiceImpl(final StockDao stockDao) {
    this.stockDao = stockDao;
  }

  @Override
  public void addNewStock(final Stock stock) {
    stockDao.save(stock);
  }

  @Override
  @Cacheable(value = "stockCache")
  public Stock getStock(final String stockName) {
    return stockDao.findByName(stockName);
  }

  @Override
  public List<Stock> getAll() {
    return stockDao.findAll();
  }

  @Override
  @CacheEvict(value = "stockCache", key = "#stock.name")
  public void removeStock(final Stock stock) {
    stockDao.delete(stock);
  }

  @Override
  @CacheEvict(value = "stockCache", key = "#stock.name")
  public void updateStock(final Stock stock) {
    stockDao.update(stock);
  }
}

这是示例 Controller ，它应该缓存显示所有股票的结果(当从数据库中添加、更新或删除股票时，此缓存将被完全驱逐):

@Controller
public class ListAllStocksController {

  @Autowired
  private TradingService tradingService;

  @Cacheable("viewCache")
  @RequestMapping(value = "listStocks.html", method = RequestMethod.GET)
  public ModelAndView displayAllStocks() {
    //The SerializableModelAndView extends Spring's ModelAndView and implements Serializable due to spymemcached not being able to add a non-serializable object to the cache
    final ModelAndView mav = new SerializableModelAndView("listStocks");
    mav.addObject("stocks", tradingService.getAll());
    return mav;
  }

  @CacheEvict(value = "viewCache", allEntries = true)
  @RequestMapping(value = "editStock.html", method = RequestMethod.POST, params = "submit=Edit")
  public ModelAndView editStock(final Stock stock, final BindingResult result) {
    final ModelAndView mav = new ModelAndView("redirect:listStocks.html");
    tradingService.updateStock(stock);
    return mav;
  }

  @CacheEvict(value = "viewCache", allEntries = true)
  @RequestMapping(value = "listStocks.html", method = RequestMethod.POST, params = "submit=Delete")
  public ModelAndView deleteStockAction(@RequestParam("name") final String name) {
    final ModelAndView mav = new ModelAndView("redirect:listStocks.html");
    tradingService.removeStock(stock);
    return mav;
  }

}

这是我的小缓存管理器:

public class MemCacheManager extends AbstractCacheManager {
  private final Collection<MemCache> internalCaches;

  public MemCacheManager(final Collection<MemCache> internalCaches) {
    this.internalCaches = internalCaches;
  }

  @Override
  protected Collection<? extends Cache> loadCaches() {
    Assert.notNull(internalCaches, "A collection caches is required and cannot be empty");
    return internalCaches;
  }
}

这是我的 MemCache 类的样子:

public class MemCache implements Cache {

  private MemcachedClient cache;
  private final String name;
  private static final Logger LOGGER = Logger.getLogger(MemCache.class);

  public MemCache(final String name, final int port) throws URISyntaxException {
    this.name = name;
    try {
      cache = new MemcachedClient(AddrUtil.getAddresses("localhost:" + port));
      final SerializingTranscoder stc = (SerializingTranscoder) cache.getTranscoder();
      stc.setCompressionThreshold(600000);
    } catch (final IOException e) { //Let it attempt to reconnect }
  }

  @Override
  public String getName() {
    return name;
  }

  @Override
  public Object getNativeCache() {
    return cache;
  }

  @Override
  public ValueWrapper get(final Object key) {
    Object value = null;
    try {
      value = cache.get(key.toString());
    } catch (final Exception e) {
      LOGGER.warn(e);
    }
    if (value == null) {
      return null;
    }
    return new SimpleValueWrapper(value);
  }

  @Override
  public void put(final Object key, final Object value) {
    cache.set(key.toString(), 7 * 24 * 3600, value);
    Assert.assertNotNull(get(key)); //This fails on the viewCache
  }

  @Override
  public void evict(final Object key) {
    this.cache.delete(key.toString());
  }

  @Override
  public void clear() {
    cache.flush();
  }
}

我在 CouchBase 和常规 memcached 上都试过了。下面的设置显示了 memcached 仅自行启动。

@Configuration @EnableCaching @Profile("memcached")
public class MemCacheConfiguration implements CachingConfigurer {

  @Override @Bean
  public CacheManager cacheManager() {
    CacheManager cacheManager;
    try {
      cacheManager = new MemCacheManager(internalCaches());
      return cacheManager;
    } catch (final URISyntaxException e) {
      throw new RuntimeException(e);
    }
  }

  @Bean
  public Collection<MemCache> internalCaches() throws URISyntaxException {
    final Collection<MemCache> caches = new ArrayList<MemCache>();
    // caches.add(new MemCache("stockCache", 11212));
    caches.add(new MemCache("viewCache", 11211));
    return caches;
  }

  @Override
  public KeyGenerator keyGenerator() {
    return new DefaultKeyGenerator();
  }

}

在上面的例子中，我们将简单地使用 memcached。这是我第一次启动应用程序并点击列表 Controller 时看到的日志记录:

58513 [qtp1656205248-16] TRACE org.springframework.cache.interceptor.CacheInterceptor  - Computed cache key 0 for operation CacheableOperation[public org.springframework.web.servlet.ModelAndView com.ehcache.reference.web.ListAllStocksController.displayAllStocks()] caches=[viewCache] | condition='' | key='0'
58519 [qtp1656205248-16] WARN  com.memcache.MemCache  - Retrieved: null from the cache 'viewCache' at <0> key of type <java.lang.Integer>
58519 [qtp1656205248-16] ERROR com.memcache.MemCache  - Returning null
58520 [qtp1656205248-16] DEBUG org.mybatis.spring.SqlSessionUtils  - Creating a new SqlSession
58520 [qtp1656205248-16] DEBUG org.mybatis.spring.SqlSessionUtils  - SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@640f434f] was not registered for synchronization because synchronization is not active
58520 [qtp1656205248-16] DEBUG org.mybatis.spring.transaction.SpringManagedTransaction  - JDBC Connection [org.hsqldb.jdbc.JDBCConnection@260c2adb] will not be managed by Spring
58521 [qtp1656205248-16] DEBUG com.ehcache.reference.dao.StockMapper.findAll  - ooo Using Connection [org.hsqldb.jdbc.JDBCConnection@260c2adb]
58521 [qtp1656205248-16] DEBUG com.ehcache.reference.dao.StockMapper.findAll  - ==>  Preparing: SELECT * from STOCK
58521 [qtp1656205248-16] DEBUG com.ehcache.reference.dao.StockMapper.findAll  - ==> Parameters:
58521 [qtp1656205248-16] DEBUG org.mybatis.spring.SqlSessionUtils  - Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@640f434f]
58521 [qtp1656205248-16] WARN  com.memcache.MemCache  - Setting: ModelAndView: reference to view with name 'listStocks'; model is {stocks=[]} into the cache 'viewCache' at <0> key of type <java.lang.Integer>
58527 [qtp1656205248-16] WARN  com.memcache.MemCache  - Retrieved: ModelAndView: materialized View is [null]; model is null from the cache 'viewCache' at <0> key of type <java.lang.Integer>

这一切看起来都是正确的，这是一个全新的启动，缓存中应该没有任何内容。我现在将股票添加到缓存中:

263036 [qtp1656205248-14] DEBUG org.mybatis.spring.SqlSessionUtils  - Creating a new SqlSession
263036 [qtp1656205248-14] DEBUG org.mybatis.spring.SqlSessionUtils  - SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@3d20b8d5] was not registered for synchronization because synchronization is not active
263038 [qtp1656205248-14] DEBUG org.mybatis.spring.transaction.SpringManagedTransaction  - JDBC Connection [org.hsqldb.jdbc.JDBCConnection@40b5f9bb] will not be managed by Spring
263038 [qtp1656205248-14] DEBUG com.ehcache.reference.dao.StockMapper.save  - ooo Using Connection [org.hsqldb.jdbc.JDBCConnection@40b5f9bb]
263038 [qtp1656205248-14] DEBUG com.ehcache.reference.dao.StockMapper.save  - ==>  Preparing: INSERT INTO STOCK (name, cost) VALUES (?, ?)
263039 [qtp1656205248-14] DEBUG com.ehcache.reference.dao.StockMapper.save  - ==> Parameters: A(String), 1.0(Double)
263039 [qtp1656205248-14] DEBUG org.mybatis.spring.SqlSessionUtils  - Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@3d20b8d5]
263039 [qtp1656205248-14] TRACE org.springframework.cache.interceptor.CacheInterceptor  - Invalidating cache key 0 for operation CacheEvictOperation[public org.springframework.web.servlet.ModelAndView com.ehcache.reference.web.AddStockController.addNewStock(com.ehcache.reference.business.Stock,org.springframework.validation.BindingResult)] caches=[viewCache] | condition='' | key='0',false,false on method public org.springframework.web.servlet.ModelAndView com.ehcache.reference.web.AddStockController.addNewStock(com.ehcache.reference.business.Stock,org.springframework.validation.BindingResult)
263039 [qtp1656205248-14] WARN  com.memcache.MemCache  - Evicting value at <0> in cache 'viewCache'
263049 [qtp1656205248-18] TRACE org.springframework.cache.interceptor.CacheInterceptor  - Computed cache key 0 for operation CacheableOperation[public org.springframework.web.servlet.ModelAndView com.ehcache.reference.web.ListAllStocksController.displayAllStocks()] caches=[viewCache] | condition='' | key='0'
263051 [qtp1656205248-18] WARN  com.memcache.MemCache  - Retrieved: null from the cache 'viewCache' at <0> key of type <java.lang.Integer>
263051 [qtp1656205248-18] ERROR com.memcache.MemCache  - Returning null
263051 [qtp1656205248-18] DEBUG org.mybatis.spring.SqlSessionUtils  - Creating a new SqlSession
263051 [qtp1656205248-18] DEBUG org.mybatis.spring.SqlSessionUtils  - SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@7050d0a7] was not registered for synchronization because synchronization is not active
263051 [qtp1656205248-18] DEBUG org.mybatis.spring.transaction.SpringManagedTransaction  - JDBC Connection [org.hsqldb.jdbc.JDBCConnection@49b2bd8c] will not be managed by Spring
263051 [qtp1656205248-18] DEBUG com.ehcache.reference.dao.StockMapper.findAll  - ooo Using Connection [org.hsqldb.jdbc.JDBCConnection@49b2bd8c]
263051 [qtp1656205248-18] DEBUG com.ehcache.reference.dao.StockMapper.findAll  - ==>  Preparing: SELECT * from STOCK
263052 [qtp1656205248-18] DEBUG com.ehcache.reference.dao.StockMapper.findAll  - ==> Parameters:
263053 [qtp1656205248-18] DEBUG org.mybatis.spring.SqlSessionUtils  - Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@7050d0a7]
263053 [qtp1656205248-18] WARN  com.memcache.MemCache  - Setting: ModelAndView: reference to view with name 'listStocks'; model is {stocks=[Stock Name: <A>      Current Cost <1.0>]} into the cache 'viewCache' at <0> key of type <java.lang.Integer>
263055 [qtp1656205248-18] WARN  com.memcache.MemCache  - Retrieved: ModelAndView: materialized View is [null]; model is null from the cache 'viewCache' at <0> key of type <java.lang.Integer>

减去最后一行，一切看起来都是正确的。这是我从 memcached --vv 的输出:

<156 get 0               ##Initial listing of all
>156 END                 
<156 set 0 1 604800 79   ##Cache initial result on startup
>156 STORED
<156 get 0
>156 sending key 0
>156 END
<156 delete 0            ##Invalidation when stock added
>156 DELETED
<156 get 0               ##Add redirects to the get page
>156 END
<156 set 0 1 604800 79   ##Store the new value
>156 STORED
<156 get 0
>156 sending key 0       ##Refresh the page
>156 END

这里不好玩的一点是，当我向系统添加股票时，我被重定向到 displayAllStocks 方法。它最初正确地执行此操作，但是如果我刷新页面，我会收到原始版本(显示没有库存的版本)。我被困在这里，不确定此时可能导致此问题的原因。如果我以任何方式使缓存无效，重定向将正常工作。在随后的刷新中，我检索到似乎是第一个输入的值(已删除)

这是配置问题吗？ memcache 或 spymemcached 中的限制/错误，或者只是我的 MemCache 代码中的错误？

Answer 1

在 TradingServiceImpl 中，getStock 方法总是从缓存中返回相同的对象，而与股票名称无关。您应该将其更改为:

  @Override
  @Cacheable(value = "stockCache", key="#stockName")
  public Stock getStock(final String stockName) {
    return stockDao.findByName(stockName);
  }

你在哪里驱逐viewCache？我在你的代码中没有看到它。

如果你想在 Spring 3.1 缓存抽象上使用 memcached，你可以选择 Simple-Spring-Memcached(当前快照版本 - 你需要从源代码构建它)。 Here您可以找到如何使用 SSM 将 memcached 与 Spring Cache 集成的示例配置。
示例项目:spring-cache-integration-test在 SSM svn 中可以使用此集成。

更新:Simple Spring Memcached 3.0.0 与 Spring Cache 集成已经可用。