ILOG CPLEX C++ API 9.0 Reference Manual

IloCplex::CallbackI
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When cplex.use(cb) is called for a callback object cb that is already used by
another instance of IloCplex, a copy of the implementation object of cb is
created by calling duplicateCallback and used in its place. The method use
will return a handle to that copy.
When a parallel optimizer is used, IloCplex creates copies of every callback that
it uses by calling duplicateCallback. One copy of a callback is created for
each additional thread being used in the parallel optimizer. During the optimization,
each thread will invoke the copy corresponding to the thread number. The methods
provided by the callback APIs are guaranteed to be threadsafe. However, when
accessing parameters passed to callbacks or members stored in a callback, it is up to
the user to make sure of thread safety by synchronizing access or creating distinct
copies of the data in the implementation of duplicateCallback.
protected IloEnv getEnv()
This method returns the environment belonging to the IloCplex object that invoked
the method main.
protected IloModel getModel()
This method returns the model currently extracted for the instance of IloCplex where
the invoking callback executed.
protected IloInt getNcols()
This method returns the number of columns in the model currently being optimizated.
protected IloInt getNQCs()
This method returns the number of quadratic constraints in the model currently being
optimized.
protected IloInt getNrows()
This method returns the number of rows in the model currently being optimized.
protected virtual void main()
This virtual method is to be implemented by the user in a derived callback class to define
the functionality of the callback. When an instance of IloCplex uses a callback (an
instance of IloCplex::CallbackI or one of its derived subclasses), IloCplex
calls this virtual method main at the point during the optimization at which the callback
is executed.
ILOG CPLEX C++ API 9.0 REFERENCE M ANUAL 101