package org.jboss.cache.commands.remote;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.jboss.cache.DataContainer;
import org.jboss.cache.InvocationContext;
import org.jboss.cache.commands.DataCommand;
import org.jboss.cache.commands.ReplicableCommand;
import org.jboss.cache.commands.read.ExistsCommand;
import org.jboss.cache.commands.read.GetChildrenNamesCommand;
import org.jboss.cache.commands.read.GetDataMapCommand;
import org.jboss.cache.interceptors.InterceptorChain;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
/**
* Issues a clustered get call, for use primarily by the {@link org.jboss.cache.loader.ClusteredCacheLoader}. This is
* not a {@link org.jboss.cache.commands.VisitableCommand} and hence
* not passed up the {@link org.jboss.cache.interceptors.base.CommandInterceptor} chain.
* <p/>
*
* @author Mircea.Markus@jboss.com
* @since 2.2.0
*/
public class ClusteredGetCommand implements ReplicableCommand
{
public static final int METHOD_ID = 22;
private DataCommand dataCommand;
private boolean searchBackupSubtrees;
private DataContainer dataContainer;
private InterceptorChain interceptorChain;
private static final Log log = LogFactory.getLog(ClusteredGetCommand.class);
private static boolean trace = log.isTraceEnabled();
public ClusteredGetCommand(boolean searchBackupSubtrees, DataCommand dataCommand)
{
this.searchBackupSubtrees = searchBackupSubtrees;
this.dataCommand = dataCommand;
}
public ClusteredGetCommand()
{
}
public void initialize(DataContainer dataContainer, InterceptorChain interceptorChain)
{
this.dataContainer = dataContainer;
this.interceptorChain = interceptorChain;
}
/**
* Invokes a {@link org.jboss.cache.commands.DataCommand} on a remote cache and returns results.
*
* @param context invocation context, ignored.
* @return a List containing 2 elements: a boolean, (true or false) and a value (Object) which is the result of invoking a remote get specified by {@link #getDataCommand()}. If buddy replication is used one further element is added - an Fqn of the backup subtree in which this node may be found.
*/
public Object perform(InvocationContext context) throws Throwable
{
if (trace)
log.trace("Clustered Get called with params: " + dataCommand + ", " + searchBackupSubtrees);
Object callResults = null;
try
{
if (trace) log.trace("Clustered get: invoking call with Fqn " + dataCommand.getFqn());
InvocationContext ctx = interceptorChain.getInvocationContext();
ctx.setOriginLocal(false);
// very hacky to be calling this command directly.
callResults = dataCommand.perform(ctx);
boolean found = validResult(callResults);
if (trace) log.trace("Got result " + callResults + ", found=" + found);
if (found && callResults == null) callResults = createEmptyResults();
}
catch (Exception e)
{
log.warn("Problems processing clusteredGet call", e);
}
List<Object> results = new ArrayList<Object>(2);
if (callResults != null)
{
results.add(true);
results.add(callResults);
}
else
{
results.add(false);
results.add(null);
}
return results;
}
public int getCommandId()
{
return METHOD_ID;
}
/**
* Returns true if the call results returned a valid result.
*/
private boolean validResult(Object callResults)
{
if (dataCommand instanceof GetDataMapCommand || dataCommand instanceof GetChildrenNamesCommand)
{
return callResults != null && dataContainer.exists(dataCommand.getFqn());
}
return dataCommand instanceof ExistsCommand && (Boolean) callResults;
}
/**
* Creates an empty Collection class based on the return type of the method called.
*/
private Object createEmptyResults()
{
if (dataCommand instanceof GetDataMapCommand || dataCommand instanceof GetChildrenNamesCommand)
{
return Collections.emptyMap();
}
return null;
}
public Boolean getSearchBackupSubtrees()
{
return searchBackupSubtrees;
}
public DataCommand getDataCommand()
{
return dataCommand;
}
public Object[] getParameters()
{
return new Object[]{dataCommand, searchBackupSubtrees}; //To change body of implemented methods use File | Settings | File Templates.
}
public void setParameters(int commandId, Object[] args)
{
dataCommand = (DataCommand) args[0];
searchBackupSubtrees = (Boolean) args[1];
}
@Override
public boolean equals(Object o)
{
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
ClusteredGetCommand that = (ClusteredGetCommand) o;
if (dataCommand != null ? !dataCommand.equals(that.dataCommand) : that.dataCommand != null)
return false;
return searchBackupSubtrees == that.searchBackupSubtrees;
}
@Override
public int hashCode()
{
int result;
result = (dataCommand != null ? dataCommand.hashCode() : 0);
result = 31 * result + (searchBackupSubtrees ? 1 : 0);
return result;
}
@Override
public String toString()
{
return "ClusteredGetCommand{" +
"dataCommand=" + dataCommand +
", searchBackupSubtrees=" + searchBackupSubtrees +
'}';
}
}