001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    package org.apache.servicemix.executors;
018    
019    /**
020     * The Executor interface is a simple interface
021     * on top of a thread pool.
022     * 
023     * @author <a href="mailto:gnodet [at] gmail.com">Guillaume Nodet</a>
024     */
025    public interface Executor {
026    
027        /**
028         * Execute a command.
029         * 
030         * @param command the command to execute
031         */
032        void execute(Runnable command);
033        
034        /**
035         * Shutdown this executor.
036         * This must be called to kill all threads.
037         */
038        void shutdown();
039    
040        /**
041         * The capacity of the underlying queue (if any)
042         * @return
043         */
044        int capacity();
045        
046        /**
047         * The current size of the underlying queue (if any)
048         * @return
049         */
050        int size();
051        
052    }