/**
    * Copyright By Grandsoft Company Limited.  
    * 2012-6-5 上午09:52:32
    */
   package gboat2.base.cache;
   
   import gboat2.base.bridge.GboatAppContext;
   
   import java.io.FileInputStream;
  import java.io.IOException;
  import java.io.InputStream;
  import java.util.Properties;
  
  import org.apache.commons.io.IOUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import com.opensymphony.oscache.base.CacheEntry;
  import com.opensymphony.oscache.base.NeedsRefreshException;
  import com.opensymphony.oscache.general.GeneralCacheAdministrator;
  
  /**
   * 
   * gboat2 平台中缓存对象基类，目前封装的方法不包含集群功能。包含：添加、删除和读取。请不要在程序中手动调用 {@link #destroy()}
   * 方法，因为该方法是为 oscache bundle 停止时预留的<br>
   * 注意：缓存中目前放的对象是永远不过期的，往缓存中放的时候要注意，用过之后，记得清掉，不然会造成内存泄露，如果是长久不变参数，可以长久驻留内存.
   * 
   * @author zhangxj-a
   * @since 1.0
   * @date 2012-6-5
   */
  public class BaseCache {
  
      private static Logger logger = LoggerFactory.getLogger(BaseCache.class);
  
      /** 获得 webapproot */
      public final static String WEB_APP_ROOT = GboatAppContext.getWebRootPath();
  
      /** OSCache 配置文件相对路径 GBOAT2_OSCHACHE_LOCATION */
      public final static String GBOAT2_OSCHACHE_LOCATION = "WEB-INF/config/oscache.properties";
  
      public final static String LOCAL_OSCHACHE_LOCATION = "properties/oscache.properties";
  
      public static final String DEFAULT_KEY_PREFIX = "Gboat2";
      
      private GeneralCacheAdministrator generalCacheAdministrator;
  
      private int refreshPeriod;
  
      private String keyPrefix;
      
      protected BaseCache() {
          this(CacheEntry.INDEFINITE_EXPIRY);
      }
      
      protected BaseCache(int refreshPeriod) {
          this(refreshPeriod, DEFAULT_KEY_PREFIX);
      }
      
      /**
       * 构造方法
       * 
       * @param refreshPeriod
       * @param keyPrefix
       */
      protected BaseCache(int refreshPeriod, String keyPrefix) {
          this.refreshPeriod = refreshPeriod;
          this.keyPrefix = keyPrefix;
          Properties oscache = this.loadProperties(getCachePropertiesPath());
          generalCacheAdministrator = new GeneralCacheAdministrator(oscache);
      }
  
      /**
       * 添加被缓存的对象
       * 
       * @param catalog
       * @param key
       * @param value
       */
      public void put(String catalog, String key, Object value) {
          this.generalCacheAdministrator.putInCache(this.keyPrefix + "_" + catalog + "_" + key, value);
      }
  
      /**
       * 删除被缓存对象
       * 
       * @param catalog
       * @param key
       */
      public void remove(String catalog, String key) {
          this.generalCacheAdministrator.removeEntry(this.keyPrefix + "_" + catalog + "_" + key);
      }
  
      /**
       * 获得被缓存的对象
       * 
       * @param catalog
       * @param key
       * @return
      * @throws RuntimeException 如果在缓存中不再此key，则抛出一个运行时异常提醒用户
      */
     public Object get(String catalog, String key) {
         try {
             return this.generalCacheAdministrator.getFromCache(this.keyPrefix + "_" + catalog + "_" + key, refreshPeriod);
         } catch (NeedsRefreshException e) {
             this.generalCacheAdministrator.cancelUpdate(this.keyPrefix + "_" + catalog + "_" + key);
             // logger.error("key为："+key+"的对象不存在，请检查",e);
             return null;
         }
     }
 
     /**
      * Shuts down the cache administrator.
      */
     public void destroy() {
         this.generalCacheAdministrator.destroy();
     }
 
     private String getCachePropertiesPath() {
         return WEB_APP_ROOT + GBOAT2_OSCHACHE_LOCATION;
     }
 
     /**
      * 采取两步策略：<br>
      * 首先去 WEB-INF/config/ 目录下查找 oscache.properties 文件，<br>
      * 如果不存在，尝试加载 bundle 内部的 oscache.properties 属性文件
      * 
      * @param path 路径
      * @return 读取文件内容
      * @throws IOException io异常
      */
     private Properties loadProperties(String path) {
         Properties props = new Properties();
         InputStream logStream = null;
         try {
             logStream = new FileInputStream(path);
             props.load(logStream);
       
             logger.info("OSCache: Gboat2 uses Global oscache. properties file is {}", path);
         } catch (IOException e) {
             try {
                 logStream = this.getClass().getClassLoader().getResourceAsStream(LOCAL_OSCHACHE_LOCATION);
                 props.load(logStream);
                 logger.info("OSCache: Gboat2 uses Part oscache.properties file in the directory of properties/ in Gboa2.cache bundle as OSCache default config");
             } catch (IOException e2) {
                 logger.warn(" Gboat2 OSCache: No properties file found in the classpath by filename : oscache.properties."
                         + " Gboat2 will use OSCache default properties, to change this, please add oscache.properties file in the directory of WEB-INF/config/");
             }
         } finally {
             IOUtils.closeQuietly(logStream);
         }
         return props;
     }
 
 }