// $Id$
// 
// 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.
// 
using System;

namespace Org.Apache.Etch.Bindings.Csharp.Util
{
    /// <summary>
    /// Generic implementation of Startable
    /// </summary>
    abstract public class AbstractStartable : Startable
    {
        public void Start()
        {
            lock (this)
            {
                if (IsStarted())
                    throw new Exception("is already started");
                SetStarted();
            }

            try
            {
                Start0();
            }
            catch (Exception)
            {
                Stop();
                throw;
            }
        }

        public void Stop()
        {
            lock (this)
            {
                CheckIsStarted();
                SetStopped();
            }

            Stop0();
        }

        private bool started;

        private void SetStarted()
        {
            started = true;
        }

        protected void SetStopped()
        {
            started = false;
        }

        public bool IsStarted()
        {
            return started;
        }

        /// <summary>
        /// Check that the startable is started
        /// Exception:
        ///     ThreadInterruptedException if not started
        /// </summary>
        /// 
        public void CheckIsStarted()
        {
            if (!IsStarted())
                throw new Exception("is not started");
        }

        /// <summary>
        /// 
        /// </summary>
        /// Exception:
        ///     throws Exception
        abstract protected void Start0();

        /// <summary>
        /// 
        /// </summary>
        /// Exception:
        ///     throws Exception
        abstract protected void Stop0();

    }
}