Package org.apache.directory.ldap.client.api

Source Code of org.apache.directory.ldap.client.api.SearchCursor

/*
*   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.
*
*/

package org.apache.directory.ldap.client.api;


import java.util.concurrent.TimeUnit;

import org.apache.directory.ldap.client.api.exception.LdapException;
import org.apache.directory.ldap.client.api.future.SearchFuture;
import org.apache.directory.ldap.client.api.message.SearchResponse;
import org.apache.directory.ldap.client.api.message.SearchResultDone;
import org.apache.directory.shared.ldap.cursor.AbstractCursor;
import org.apache.directory.shared.ldap.cursor.InvalidCursorPositionException;


/**
* An implementation of Cursor based on the underlying SearchFuture instance.
*
* Note: This is a forward only cursor hence the only valid operations are next(), get() and close()
*
* @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
* @version $Rev$, $Date$
*/
public class SearchCursor extends AbstractCursor
{

    /** the search future */
    private SearchFuture future;

    /** wait time while polling for a SearchResponse */
    private long timeout;

    /** time units of timeout value */
    private TimeUnit timeUnit;

    /** a reference to hold the retrieved SearchResponse object from SearchFuture */
    private SearchResponse response;

    private boolean done;

    public SearchCursor( SearchFuture future, long timeout, TimeUnit timeUnit )
    {
        this.future = future;
        this.timeout = timeout;
        this.timeUnit = timeUnit;
    }


    public boolean next() throws Exception
    {
        try
        {
            if( future.isCancelled() )
            {
                response = null;
                done = true;
                return false;
            }
           
            response = future.get( timeout, timeUnit );
        }
        catch ( Exception e )
        {
            LdapException ldapException = new LdapException( LdapConnection.NO_RESPONSE_ERROR );
            ldapException.initCause( e );

            // Send an abandon request
            if ( !future.isCancelled() )
            {
                future.cancel( true );
            }

            // close the cursor
            close( ldapException );
           
            throw ldapException;
        }

        if ( response == null )
        {
            future.cancel( true );

            throw new LdapException( LdapConnection.TIME_OUT_ERROR );
        }

        done = ( response instanceof SearchResultDone );

        if ( done )
        {
            response = null;
        }

        return !done;
    }


    public SearchResponse get() throws Exception
    {
        if ( !available() )
        {
            throw new InvalidCursorPositionException();
        }

        return response;
    }


    public boolean isElementReused()
    {
        return true;
    }


    public boolean available()
    {
        return response != null;
    }


    @Override
    public void close() throws Exception
    {
        close( null );
    }


    @Override
    public void close( Exception cause ) throws Exception
    {
        if( done )
        {
            super.close();
            return;
        }
       
        if ( !future.isCancelled() )
        {
            future.cancel( true );
        }

        if ( cause != null )
        {
            super.close( cause );
        }
        else
        {
            super.close();
        }
    }


    // rest of all operations will throw UnsupportedOperationException
    public void after( Object element ) throws Exception
    {
        throw new UnsupportedOperationException();
    }


    public void afterLast() throws Exception
    {
        throw new UnsupportedOperationException();
    }


    public void before( Object element ) throws Exception
    {
        throw new UnsupportedOperationException();
    }


    public void beforeFirst() throws Exception
    {
        throw new UnsupportedOperationException();
    }


    public boolean first() throws Exception
    {
        throw new UnsupportedOperationException();
    }


    public boolean last() throws Exception
    {
        throw new UnsupportedOperationException();
    }


    public boolean previous() throws Exception
    {
        throw new UnsupportedOperationException();
    }

}
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