Package localsolver

Class LocalSolver

  • All Implemented Interfaces:
    java.lang.AutoCloseable
    public class LocalSolver
extends java.lang.Object
implements java.lang.AutoCloseable
    LocalSolver environment. Main class of LocalSolver library. Here are described the basic steps for using LocalSolver:
    1. Build your model (LSModel) by creating some expressions (LSExpression).
    2. If desired, parameterize and add phases to the solver (LSParam, LSPhase).
    3. Run the solver (LocalSolver).
    4. Retrieve the best solution found by the solver (LSSolution).
    5. Consult the statistics of the resolution (LSStatistics).

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

    • Constructor Detail

      • LocalSolver

        public LocalSolver()
        Constructs a complete LocalSolver 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 LocalSolver environment is called.

    • Method Detail

      • delete

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

      • close

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

      • getState

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

      • getModel

        public LSModel getModel()
        Gets the model associated to this LocalSolver environment. Once the model is created and closed, the solver can be launched with solve().
        Returns:
        Model.

      • getParam

        public LSParam getParam()
        Gets the parameters of this LocalSolver 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 LSInconsistency computeInconsistency()
        Computes an inconsistency core for this model. Only allowed in state LSState.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 LSState.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:
        solve(), addCallback(localsolver.LSCallbackType, localsolver.LSCallback)

      • getPhase

        public LSPhase 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 LSSolution getSolution()
        Gets the best solution found by the solver. If the solver 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 LSState.Paused or LSState.Stopped.
        Returns:
        Best solution.

      • getStatistics

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

      • toString

        public java.lang.String toString()
        Returns a String representation of this LocalSolver 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 java.lang.Object
        Returns:
        String representation of this LocalSolver.

      • saveEnvironment

        public void saveEnvironment​(java.lang.String filename)
        Export a complete environment or a model to a file. Currently, this function supports 2 file formats:
        • LSB: 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.
        • LSP: with this format, only the model is exported in the LSP 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(java.lang.String)

      • loadEnvironment

        public void loadEnvironment​(java.lang.String filename)
        Import a complete environment or a model from a file. Only allowed in state LSState.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:
        saveEnvironment(java.lang.String)

      • addCallback

        public void addCallback​(LSCallbackType type,
                        LSCallback 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 LSState.Stopped or LSState.Modeling.

        Note: When a callback is called, the solver is paused. In that state, you can call all the methods marked as "allowed in state LSState.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 solver but you can't remove a constraint.

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

      • hashCode

        public int hashCode()
        Overrides:
        hashCode in class java.lang.Object

      • equals

        public boolean equals​(java.lang.Object obj)
        Overrides:
        equals in class java.lang.Object