namespace Chernobyl.Threading.Pools
{
    /// <summary>
    /// A pool that just holds a list of completed and
    /// uncompleted jobs. Each time take is called, a 
    /// job is pulled off the uncompleted list and passed
    /// back. When the job is given back, that job is placed
    /// onto the completed jobs. 
    /// </summary>
    public class AsynchronizedPool : ThreadPool
    {
        /// <summary>
        /// Takes a job from the pool. If the pool has 
        /// no more jobs to give or it does not want to 
        /// give a job out then null will be returned.
        /// </summary>
        /// <param name="objectToTake">The job to fill with
        /// the taken job.</param>
        /// <returns>True if there was a job that could be 
        /// taken from the pool and that job was assigned to 
        /// <paramref name="objectToTake"/>, false if otherwise.</returns>
        public override bool Take(out Job objectToTake)
        {
            // are their any jobs left?
            lock(UncompletedJobs)
            {
                if (UncompletedJobs.First != null)
                {
                    objectToTake = UncompletedJobs.First.Value;
                    return true;
                }

                // refresh our job pool
                lock(CompletedJobs)
                {
                    UncompletedJobs = CompletedJobs;
                    CompletedJobs.Clear();
                    objectToTake = UncompletedJobs.First.Value;
                    return true;
                }
            }
        }
    }
}