package org.apache.commons.jcs.auxiliary.remote;
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.apache.commons.jcs.auxiliary.AbstractAuxiliaryCache;
import org.apache.commons.jcs.auxiliary.remote.behavior.IRemoteCacheAttributes;
import org.apache.commons.jcs.engine.CacheStatus;
import org.apache.commons.jcs.engine.behavior.ICache;
import org.apache.commons.jcs.engine.behavior.ICacheElement;
import org.apache.commons.jcs.engine.behavior.ICompositeCacheManager;
import org.apache.commons.jcs.engine.behavior.IElementSerializer;
import org.apache.commons.jcs.engine.logging.behavior.ICacheEventLogger;
import org.apache.commons.jcs.engine.stats.StatElement;
import org.apache.commons.jcs.engine.stats.Stats;
import org.apache.commons.jcs.engine.stats.behavior.IStatElement;
import org.apache.commons.jcs.engine.stats.behavior.IStats;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
/** An abstract base for the No Wait Facade. Different implementations will failover differently. */
public abstract class AbstractRemoteCacheNoWaitFacade<K, V>
extends AbstractAuxiliaryCache<K, V>
{
/** log instance */
private static final Log log = LogFactory.getLog( AbstractRemoteCacheNoWaitFacade.class );
/** The connection to a remote server, or a zombie. */
protected List<RemoteCacheNoWait<K, V>> noWaits;
/** holds failover and cluster information */
private IRemoteCacheAttributes remoteCacheAttributes;
/**
* Constructs with the given remote cache, and fires events to any listeners.
* <p>
* @param noWaits
* @param rca
* @param cacheMgr
* @param cacheEventLogger
* @param elementSerializer
*/
public AbstractRemoteCacheNoWaitFacade( List<ICache<K, V>> noWaits, RemoteCacheAttributes rca,
ICompositeCacheManager cacheMgr, ICacheEventLogger cacheEventLogger,
IElementSerializer elementSerializer )
{
if ( log.isDebugEnabled() )
{
log.debug( "CONSTRUCTING NO WAIT FACADE" );
}
this.noWaits = new ArrayList<RemoteCacheNoWait<K,V>>();
for (ICache<K, V> nw : noWaits)
{
RemoteCacheNoWait<K,V> rcnw = (RemoteCacheNoWait<K,V>) nw;
this.noWaits.add(rcnw);
}
this.remoteCacheAttributes = rca;
setCacheEventLogger( cacheEventLogger );
setElementSerializer( elementSerializer );
}
/**
* Put an element in the cache.
* <p>
* @param ce
* @throws IOException
*/
@Override
public void update( ICacheElement<K, V> ce )
throws IOException
{
if ( log.isDebugEnabled() )
{
log.debug( "updating through cache facade, noWaits.length = " + noWaits.size() );
}
for (RemoteCacheNoWait<K, V> nw : noWaits)
{
try
{
nw.update( ce );
// an initial move into a zombie will lock this to primary
// recovery. will not discover other servers until primary
// reconnect
// and subsequent error
}
catch ( IOException ex )
{
String message = "Problem updating no wait. Will initiate failover if the noWait is in error.";
log.error( message, ex );
if ( getCacheEventLogger() != null )
{
getCacheEventLogger().logError( "RemoteCacheNoWaitFacade",
ICacheEventLogger.UPDATE_EVENT,
message + ":" + ex.getMessage() + " REGION: " + ce.getCacheName()
+ " ELEMENT: " + ce );
}
// can handle failover here? Is it safe to try the others?
// check to see it the noWait is now a zombie
// if it is a zombie, then move to the next in the failover list
// will need to keep them in order or a count
failover( nw );
// should start a failover thread
// should probably only failover if there is only one in the noWait
// list
// Should start a background thread to restore the original primary if we are in failover state.
}
}
}
/**
* Synchronously reads from the remote cache.
* <p>
* @param key
* @return Either an ICacheElement<K, V> or null if it is not found.
*/
@Override
public ICacheElement<K, V> get( K key )
{
for (RemoteCacheNoWait<K, V> nw : noWaits)
{
try
{
ICacheElement<K, V> obj = nw.get( key );
if ( obj != null )
{
return obj;
}
}
catch ( IOException ex )
{
log.debug( "Failed to get." );
return null;
}
}
return null;
}
/**
* Synchronously read from the remote cache.
* <p>
* @param pattern
* @return map
* @throws IOException
*/
@Override
public Map<K, ICacheElement<K, V>> getMatching( String pattern )
throws IOException
{
for (RemoteCacheNoWait<K, V> nw : noWaits)
{
try
{
return nw.getMatching( pattern );
}
catch ( IOException ex )
{
log.debug( "Failed to getMatching." );
}
}
return Collections.emptyMap();
}
/**
* Gets multiple items from the cache based on the given set of keys.
* <p>
* @param keys
* @return a map of K key to ICacheElement<K, V> element, or an empty map if there is no
* data in cache for any of these keys
*/
@Override
public Map<K, ICacheElement<K, V>> getMultiple( Set<K> keys )
{
if ( keys != null && !keys.isEmpty() )
{
for (RemoteCacheNoWait<K, V> nw : noWaits)
{
try
{
return nw.getMultiple( keys );
}
catch ( IOException ex )
{
log.debug( "Failed to get." );
}
}
}
return Collections.emptyMap();
}
/**
* Return the keys in this cache.
* <p>
* @see org.apache.commons.jcs.auxiliary.AuxiliaryCache#getKeySet()
*/
@Override
public Set<K> getKeySet() throws IOException
{
HashSet<K> allKeys = new HashSet<K>();
for (RemoteCacheNoWait<K, V> nw : noWaits)
{
if ( nw != null )
{
Set<K> keys = nw.getKeySet();
if(keys != null)
{
allKeys.addAll( keys );
}
}
}
return allKeys;
}
/**
* Adds a remove request to the remote cache.
* <p>
* @param key
* @return whether or not it was removed, right now it return false.
*/
@Override
public boolean remove( K key )
{
try
{
for (RemoteCacheNoWait<K, V> nw : noWaits)
{
nw.remove( key );
}
}
catch ( IOException ex )
{
log.error( ex );
}
return false;
}
/**
* Adds a removeAll request to the remote cache.
*/
@Override
public void removeAll()
{
try
{
for (RemoteCacheNoWait<K, V> nw : noWaits)
{
nw.removeAll();
}
}
catch ( IOException ex )
{
log.error( ex );
}
}
/** Adds a dispose request to the remote cache. */
@Override
public void dispose()
{
for (RemoteCacheNoWait<K, V> nw : noWaits)
{
nw.dispose();
}
}
/**
* No remote invocation.
* <p>
* @return The size value
*/
@Override
public int getSize()
{
return 0;
// cache.getSize();
}
/**
* Gets the cacheType attribute of the RemoteCacheNoWaitFacade object.
* <p>
* @return The cacheType value
*/
@Override
public CacheType getCacheType()
{
return CacheType.REMOTE_CACHE;
}
/**
* Gets the cacheName attribute of the RemoteCacheNoWaitFacade object.
* <p>
* @return The cacheName value
*/
@Override
public String getCacheName()
{
return remoteCacheAttributes.getCacheName();
}
/**
* Gets the status attribute of the RemoteCacheNoWaitFacade object
* <p>
* Return ALIVE if any are alive.
* <p>
* @return The status value
*/
@Override
public CacheStatus getStatus()
{
for (RemoteCacheNoWait<K, V> nw : noWaits)
{
if ( nw.getStatus() == CacheStatus.ALIVE )
{
return CacheStatus.ALIVE;
}
}
return CacheStatus.DISPOSED;
}
/**
* String form of some of the configuration information for the remote cache.
* <p>
* @return Some info for logging.
*/
@Override
public String toString()
{
return "RemoteCacheNoWaitFacade: " + remoteCacheAttributes.getCacheName() + ", rca = " + remoteCacheAttributes;
}
/**
* Begin the failover process if this is a local cache. Clustered remote caches do not failover.
* <p>
* @param rcnw The no wait in error.
*/
protected abstract void failover( RemoteCacheNoWait<K, V> rcnw );
/**
* Get the primary server from the list of failovers
*
* @return a no wait
*/
public RemoteCacheNoWait<K, V> getPrimaryServer()
{
return noWaits.get(0);
}
/**
* restore the primary server in the list of failovers
*
*/
public void restorePrimaryServer(RemoteCacheNoWait<K, V> rcnw)
{
noWaits.clear();
noWaits.add(rcnw);
}
/**
* @return Returns the AuxiliaryCacheAttributes.
*/
@Override
public IRemoteCacheAttributes getAuxiliaryCacheAttributes()
{
return this.remoteCacheAttributes;
}
/**
* getStats
* @return String
*/
@Override
public String getStats()
{
return getStatistics().toString();
}
/**
* @return statistics about the cache region
*/
@Override
public IStats getStatistics()
{
IStats stats = new Stats();
stats.setTypeName( "Remote Cache No Wait Facade" );
ArrayList<IStatElement<?>> elems = new ArrayList<IStatElement<?>>();
if ( noWaits != null )
{
elems.add(new StatElement<Integer>( "Number of No Waits", Integer.valueOf(noWaits.size()) ) );
for ( RemoteCacheNoWait<K, V> rcnw : noWaits )
{
// get the stats from the super too
IStats sStats = rcnw.getStatistics();
elems.addAll(sStats.getStatElements());
}
}
stats.setStatElements( elems );
return stats;
}
/**
* This typically returns end point info .
* <p>
* @return the name
*/
@Override
public String getEventLoggingExtraInfo()
{
return "Remote Cache No Wait Facade";
}
}