source: branches/GeneralizedQAP/HeuristicLab.Optimization/3.3/Algorithms/BasicAlgorithm.cs @ 15603

#region License Information
/* HeuristicLab
 * Copyright (C) 2002-2016 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
 *
 * This file is part of HeuristicLab.
 *
 * HeuristicLab is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * HeuristicLab is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
 */
#endregion

using System;
using System.Threading;
using HeuristicLab.Common;
using HeuristicLab.Core;
using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;

namespace HeuristicLab.Optimization {
  [StorableClass]
  public abstract class BasicAlgorithm : Algorithm, IStorableContent {

    private bool pausePending;
    private bool executionTimeActive;

    public string Filename { get; set; }

    public abstract bool SupportsPause { get; }

    [Storable]
    private bool initialized;
    [Storable]
    private readonly ResultCollection results;
    public override ResultCollection Results {
      get { return results; }
    }

    private CancellationTokenSource cancellationTokenSource;
    protected CancellationTokenSource CancellationTokenSource {
      get { return cancellationTokenSource; }
      private set { cancellationTokenSource = value; }
    }

    [Storable]
    private TimeSpan executionTime;
    private DateTime startDate;
    public override TimeSpan ExecutionTime {
      get { return executionTime + (executionTimeActive ? DateTime.UtcNow - startDate : TimeSpan.Zero); }
    }

    [StorableConstructor]
    protected BasicAlgorithm(bool deserializing) : base(deserializing) { }
    protected BasicAlgorithm(BasicAlgorithm original, Cloner cloner)
      : base(original, cloner) {
      results = cloner.Clone(original.Results);
      initialized = original.initialized;
      executionTime = original.executionTime;
    }
    protected BasicAlgorithm()
      : base() {
      results = new ResultCollection();
      executionTime = TimeSpan.Zero;
    }

    public override void Prepare() {
      executionTime = TimeSpan.Zero;
      if (Problem == null) return;
      base.Prepare();
      results.Clear();
      initialized = false;
      OnPrepared();
    }

    public override void Start(CancellationToken cancellationToken) {
      startDate = DateTime.UtcNow;
      executionTimeActive = true;
      base.Start(cancellationToken);
      CancellationTokenSource = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);
      pausePending = false;
      OnStarted();

      try {
        Run((object)cancellationTokenSource.Token);
      }
      catch (OperationCanceledException) {
      }
      catch (AggregateException ae) {
        ae.FlattenAndHandle(new[] { typeof(OperationCanceledException) }, e => OnExceptionOccurred(e));
      }
      catch (Exception e) {
        OnExceptionOccurred(e);
      }

      CancellationTokenSource.Dispose();
      CancellationTokenSource = null;
      if (pausePending) OnPaused();
      else OnStopped();
    }

    public override void Pause() {
      // CancellationToken.ThrowIfCancellationRequested() must be called from within the Run method, otherwise pause does nothing
      // alternatively check the IsCancellationRequested property of the cancellation token
      if (!SupportsPause)
        throw new NotSupportedException("Pause is not supported by this algorithm.");

      base.Pause();
      pausePending = true;
      CancellationTokenSource.Cancel();
    }

    public override void Stop() {
      // CancellationToken.ThrowIfCancellationRequested() must be called from within the Run method, otherwise stop does nothing
      // alternatively check the IsCancellationRequested property of the cancellation token
      base.Stop();
      if (ExecutionState == ExecutionState.Paused) OnStopped();
      else CancellationTokenSource.Cancel();
    }

    private void Run(object state) {
      CancellationToken cancellationToken = (CancellationToken)state;
      if (!initialized)
        Initialize(cancellationToken);
      initialized = true;
      Run(cancellationToken);
    }

    protected virtual void Initialize(CancellationToken cancellationToken) { }
    protected abstract void Run(CancellationToken cancellationToken);

    protected override void OnPaused() {
      executionTime += DateTime.UtcNow - startDate;
      executionTimeActive = false;
      base.OnPaused();
    }

    protected override void OnStopped() {
      if (executionTimeActive) { // don't do if going from pause to stop
        executionTime += DateTime.UtcNow - startDate;
        executionTimeActive = false;
      }
      base.OnStopped();
    }
  }
}