Package org.infinispan.commands.read

Source Code of org.infinispan.commands.read.GetKeyValueCommand

/*
* JBoss, Home of Professional Open Source
* Copyright 2008, Red Hat Middleware LLC, and individual contributors
* by the @authors tag. See the copyright.txt in the distribution for a
* full listing of individual contributors.
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
package org.infinispan.commands.read;

import org.infinispan.commands.Visitor;
import org.infinispan.container.entries.CacheEntry;
import org.infinispan.context.InvocationContext;
import org.infinispan.marshall.Ids;
import org.infinispan.marshall.Marshallable;
import org.infinispan.marshall.exts.ReplicableCommandExternalizer;
import org.infinispan.notifications.cachelistener.CacheNotifier;
import org.infinispan.util.logging.Log;
import org.infinispan.util.logging.LogFactory;

/**
* Implements functionality defined by {@link org.infinispan.Cache#get(Object)} and
* {@link org.infinispan.Cache#containsKey(Object)} operations
*
* @author Manik Surtani (<a href="mailto:manik@jboss.org">manik@jboss.org</a>)
* @since 4.0
*/
@Marshallable(externalizer = ReplicableCommandExternalizer.class, id = Ids.GET_KEY_VALUE_COMMAND)
public class GetKeyValueCommand extends AbstractDataCommand {
   public static final byte COMMAND_ID = 4;
   private static final Log log = LogFactory.getLog(GetKeyValueCommand.class);
   private static final boolean trace = log.isTraceEnabled();
   private CacheNotifier notifier;
   private boolean returnCacheEntry;

   public GetKeyValueCommand(Object key, CacheNotifier notifier) {
      this.key = key;
      this.notifier = notifier;
   }

   public GetKeyValueCommand() {
   }

   @Override
   public Object acceptVisitor(InvocationContext ctx, Visitor visitor) throws Throwable {
      return visitor.visitGetKeyValueCommand(ctx, this);
   }

   /**
    * Will make this method to return an {@link CacheEntry} instead of the corresponding value associated with the key.
    */
   public void setReturnCacheEntry(boolean returnCacheEntry) {
      this.returnCacheEntry = returnCacheEntry;
   }

   @Override
   public Object perform(InvocationContext ctx) throws Throwable {
      CacheEntry entry = ctx.lookupEntry(key);
      if (entry == null || entry.isNull()) {
         if (trace) {
            log.trace("Entry not found");
         }
         return null;
      }
      if (entry.isRemoved()) {
         if (trace) {
            log.trace("Entry has been deleted and is of type " + entry.getClass().getSimpleName());
         }
         return null;
      }
      final Object value = entry.getValue();
      // FIXME: There's no point in notifying twice.
      notifier.notifyCacheEntryVisited(key, value, true, ctx);
      final Object result = returnCacheEntry ? entry : value;
      if (trace) {
         log.trace("Found value " + result);
      }
      notifier.notifyCacheEntryVisited(key, value, false, ctx);
      return result;
   }

   @Override
   public byte getCommandId() {
      return COMMAND_ID;
   }
}
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