Module de.learnlib.filter.cache
Package de.learnlib.filter.cache.sul

Class SULCache<I,O>

java.lang.Object
de.learnlib.filter.cache.sul.SULCache<I,O>
Type Parameters:
I - input symbol type
O - output symbol type
All Implemented Interfaces:
LearningCache<MealyMachine<?,I,?,O>,I,Word<O>>, LearningCache.MealyLearningCache<I,O>, Resumable<de.learnlib.filter.cache.sul.AbstractSULCache.SULCacheState<I,O>>, SUL<I,O>, SupportsGrowingAlphabet<I>
Direct Known Subclasses:
ThreadSafeSULCache
public class SULCache<I,O> extends Object
A cache to be used with a SUL.

Because on a SUL, a query is executed step-by-step, it is impossible to determine in advance whether the cached information is sufficient to answer the complete query. However, in general it is undesired to execute any actions on the underlying SUL as long as the requested information can be provided from the cache.

This class therefore defers any real execution to the point where the cached information is definitely insufficient; if such a point is not reached before a call to SUL.post() is made, the underlying SUL is not queried.

Note: this implementation is not thread-safe. If you require a cache that is usable in a parallel environment. use the ThreadSafeSULCache (or rather the ThreadSafeSULCaches factory) from the learnlib-parallelism artifact.

  • Method Details

    • pre

      public void pre()
      Description copied from interface: SUL
      setup SUL.
      Specified by:
      pre in interface SUL<I,O>

    • post

      public void post()
      Description copied from interface: SUL
      shut down SUL.
      Specified by:
      post in interface SUL<I,O>

    • step

      public O step(I in)
      Description copied from interface: SUL
      make one step on the SUL.
      Specified by:
      step in interface SUL<I,O>
      Parameters:
      in - input to the SUL
      Returns:
      output of SUL

    • canFork

      public boolean canFork()
      Description copied from interface: SUL
      Returns whether this SUL is capable of forking.
      Specified by:
      canFork in interface SUL<I,O>
      Returns:
      true if this SUL can be forked, false otherwise
      See Also:

    • fork

      public SUL<I,O> fork()
      Description copied from interface: SUL
      Forks this SUL, if possible. The fork of a SUL is a copy which behaves exactly the same as this SUL. This method should always return a reset SUL, regardless of whether this call is made between a call to SUL.pre() and SUL.post().

      If SUL.canFork() returns true, this method must return a non-null object, which should behave exactly like this SUL (in particular, it must be forkable as well). Otherwise, a UnsupportedOperationException must be thrown.

      Implementation note: if resetting a SUL changes the internal state of this object in a non-trivial way (e.g., incrementing a counter to ensure independent sessions), care must be taken that forks of this SUL manipulate the same internal state.

      Specified by:
      fork in interface SUL<I,O>
      Returns:
      a fork of this SUL.

    • createCacheConsistencyTest

      public EquivalenceOracle.MealyEquivalenceOracle<I,O> createCacheConsistencyTest()
      Description copied from interface: LearningCache
      Creates a cache consistency test. A cache consistency test is an equivalence oracle which checks a given hypothesis against the current contents of the cache. Hence, no queries are posed to the underlying system.

      The created cache consistency test is backed by the cache contents. This method does not need to be invoked repeatedly when the cache contents change.

      Specified by:
      createCacheConsistencyTest in interface LearningCache<I,O,C extends de.learnlib.filter.cache.sul.AbstractSULCache.SULCacheState<I,O>>
      Returns:
      a cache consistency test for the contents of this cache

    • addAlphabetSymbol

      public void addAlphabetSymbol(I symbol)
      Specified by:
      addAlphabetSymbol in interface SupportsGrowingAlphabet<I>

    • suspend

      public de.learnlib.filter.cache.sul.AbstractSULCache.SULCacheState<I,O> suspend()
      Description copied from interface: Resumable
      Expose the state object.
      Specified by:
      suspend in interface Resumable<I>
      Returns:
      The state.

    • resume

      public void resume(de.learnlib.filter.cache.sul.AbstractSULCache.SULCacheState<I,O> state)
      Description copied from interface: Resumable
      Resume the data structure from a previously suspended point in time.
      Specified by:
      resume in interface Resumable<I>
      Parameters:
      state - The learner state.