/*
 * 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.servicemix.executors;

/**
 * The Executor interface is a simple interface
 * on top of a thread pool.
 * 
 * @author <a href="mailto:gnodet [at] gmail.com">Guillaume Nodet</a>
 */
public interface Executor {

    /**
     * Execute a command.
     * 
     * @param command the command to execute
     */
    void execute(Runnable command);
    
    /**
     * Shutdown this executor.
     * This must be called to kill all threads.
     */
    void shutdown();

    /**
     * The capacity of the underlying queue (if any)
     * @return
     */
    int capacity();
    
    /**
     * The current size of the underlying queue (if any)
     * @return
     */
    int size();
    
}
