Package com.hexaly.optimizer

Class HexalyOptimizer

java.lang.Object
com.hexaly.optimizer.HexalyOptimizer
All Implemented Interfaces:
AutoCloseable
public class HexalyOptimizer extends Object implements AutoCloseable
Hexaly Optimizer environment. Main class of Hexaly Optimizer library. Here are described the basic steps for using Hexaly Optimizer:
  1. Build your model (HxModel) by creating some expressions (HxExpression).
  2. If desired, parameterize and add phases to the optimizer (HxParam, HxPhase).
  3. Run the optimizer (HexalyOptimizer).
  4. Retrieve the best solution found by the optimizer (HxSolution).
  5. Consult the statistics of the resolution (HxStatistics).

Note that this API is not thread safe. If multiple threads access and modify a same Hexaly Optimizer environment, it must be synchronized. The only methods that can be used without synchronization are getState() and stop(). Please consult HxVersion for copyright and version info.

  • Constructor Details

    • HexalyOptimizer

      public HexalyOptimizer()
      Constructs a complete Hexaly Optimizer environment and takes a token license. If no token is available or if the token server is not accessible, an exception is thrown. The token license is released when the destructor of this Hexaly Optimizer environment is called.

  • Method Details

    • delete

      public void delete()
      Deletes the Hexaly Optimizer objects and release the license token. Calling this method releases the native memory used by Hexaly Optimizer and makes the Hexaly Optimizer license available for another Hexaly Optimizer model.

    • close

      public void close()
      Deletes the Hexaly objects and release the license token. Calling this method releases the native memory used by Hexaly Optimizer and makes the Hexaly license available for another Hexaly model.
      Specified by:
      close in interface AutoCloseable

    • getState

      public HxState getState()
      Gets the state of this Hexaly Optimizer environment. This method can be called in any state. In particular, this method can be called in state HxState.Running.
      Returns:
      State of Hexaly Optimizer.

    • getModel

      public HxModel getModel()
      Gets the model associated to this Hexaly Optimizer environment. Once the model is created and closed, the optimizer can be launched with solve().
      Returns:
      Model.

    • getParam

      public HxParam getParam()
      Gets the parameters of this Hexaly Optimizer environment.
      Returns:
      Parameters.

    • solve

      public void solve()
      Solves the model. This method returns only when the time limit, the iteration limit, the objective bounds are reached or when the method stop() is called. The model must be closed to launch the resolution.

    • computeInconsistency

      public HxInconsistency computeInconsistency()
      Computes an inconsistency core for this model. Only allowed in state HxState.Stopped.
      Returns:
      The inconsistency core.

    • stop

      public void stop()
      Aborts the resolution previously launched using solve(). If no resolution was launched, this method does nothing. Called from another thread or callback, this method enables users to stop the resolution properly. Solution and statistics remain valid. This method can be called in any state, notably in state HxState.Running. Note that the effect of this method is not immediate. In particular when called within a callback, the resolution will not be stopped before the end of the callback.
      See Also:

    • createPhase

      public HxPhase createPhase()
      Adds a new phase to this Hexaly Optimizer environment. Only allowed in states HxState.Modeling or HxState.Stopped.
      Returns:
      Created phase.

    • getPhase

      public HxPhase getPhase(int phaseIndex)
      Gets the phase with the given index.
      Parameters:
      phaseIndex - Index of the phase.
      Returns:
      Phase.

    • getNbPhases

      public int getNbPhases()
      Gets the number of phases.
      Returns:
      Number of phases.

    • getSolution

      public HxSolution getSolution()
      Gets the best solution found by the optimizer. If the optimizer has not been started at least once, all the decision variables of the solution are set to 0, or to their closest bound if 0 is not part of their domain (such a solution may be infeasible).. Only allowed in states HxState.Paused or HxState.Stopped.
      Returns:
      Best solution.

    • getStatistics

      public HxStatistics getStatistics()
      Gets the statistics of this Hexaly Optimizer environment. Statistics are reset to zero before each resolution. Only allowed in states HxState.Paused or HxState.Stopped. Note that for performance reasons, this function always returns the same object.
      Returns:
      Statistics.
      See Also:

    • toString

      public String toString()
      Returns a String representation of this Hexaly Optimizer environment. This representation provides useful info related to the model, the parameters, and the phases (if any). Useful for debugging or logging purposes.
      Overrides:
      toString in class Object
      Returns:
      String representation of this Hexaly Optimizer.

    • saveEnvironment

      public void saveEnvironment(String filename)
      Export a complete environment or a model to a file. Currently, this function supports 2 file formats:
      • HXB: with this format, the complete environment (model, parameters, solution, etc.) is exported. This format is useful to debug or replay a model in the same conditions. Since the produced file is binary, it offers good performance and space efficiency. This format was also known as LSB which corresponds to its former file extension (.lsb). It is still supported by this method but it is deprecated.
      • HXM: with this format, only the model is exported in the Hexaly modeling language. This format is useful to have a quick view of the optimization model or to perform some modifications. However, the file may be heavy for big models and the exact reproductibility is not guaranteed since the parameters from one execution to another may differ.
      The chosen file format is determined by the file suffix. An exception is thrown if the provided file suffix is not supported. The suffix may optionally be followed by .gz. In that case, this function produces a compressed result (using deflate algorithm).
      Parameters:
      filename - Name of the file.
      Since:
      3.0
      See Also:

    • loadEnvironment

      public void loadEnvironment(String filename)
      Import a complete environment or a model from a file. Only allowed in state HxState.Modeling. The current model must be empty.

      The only format supported is LSB.

      The chosen file format is determined by the file suffix. An exception is thrown if the provided file suffix is not supported. The suffix may optionally be followed by .gz. In that case, this function uncompress the stream before reading.

      Parameters:
      filename - Name of the file.
      Since:
      3.0
      See Also:

    • addCallback

      public void addCallback(HxCallbackType type, HxCallback callback)
      Adds a new callback for a specific event type. The callback will be called time the given event occurs.

      The same callback can be used for different events. Only allowed in states HxState.Stopped or HxState.Modeling.

      Note: When a callback is called, the optimizer is paused. In that state, you can call all the methods marked as "allowed in state HxState.Paused". Calling any other method will throw an error. For example, you can stop the resolution from a callback, retrieve the current solution or retrieve the statistics of the optimizer but you can't remove a constraint.

      Parameters:
      type - Event to watch.
      callback - Callback. Cannot be null.
      Since:
      4.0
      See Also:

    • removeCallback

      public boolean removeCallback(HxCallbackType type, HxCallback callback)
      Removes the callback for the given event type.
      Parameters:
      type - Event.
      callback - User callback to delete.
      Returns:
      false if the callback was not added for the given event, true otherwise.
      Since:
      4.0
      See Also:

    • hashCode

      public int hashCode()
      Overrides:
      hashCode in class Object

    • equals

      public boolean equals(Object obj)
      Overrides:
      equals in class Object