/**
* Implementation of {@link #getServiceProviders(Class, Filter, Hints)} without the filtering
* applied by the {@link #isAcceptable(Object, Class, Hints, Filter)} method. If this filtering is
* not already presents in the filter given to this method, then it must be applied on the
* elements returned by the iterator. The later is preferrable when:
*
* <p>
*
* <ul>
* <li>There is some cheaper tests to perform before {@code isAcceptable}.
* <li>We don't want a restrictive filter in order to avoid trigging a classpath scan if this
* method doesn't found any element to iterate.
* </ul>
*
* <p><b>Note:</b> {@link #synchronizeIteratorProviders} should also be invoked once before this
* method.
*
* @todo Use Hints to match Constructor.
*/
final <T> Iterator<T> getUnfilteredProviders(final Class<T> category) {
/*
* If the map is not empty, then this mean that a scanning is under progress, i.e.
* 'scanForPlugins' is currently being executed. This is okay as long as the user
* is not asking for one of the categories under scanning. Otherwise, the answer
* returned by 'getServiceProviders' would be incomplete because not all plugins
* have been found yet. This can lead to some bugs hard to spot because this methoud
* could complete normally but return the wrong plugin. It is safer to thrown an
* exception so the user is advised that something is wrong.
*/
if (scanningCategories.contains(category)) {
throw new RecursiveSearchException(category);
}
scanForPluginsIfNeeded(category);
return getServiceProviders(category, true);
}
/**
* Returns the providers in the registry for the specified category, filter and hints. Providers
* that are not {@linkplain OptionalFactory#isAvailable available} will be ignored. This method
* will {@linkplain #scanForPlugins() scan for plugins} the first time it is invoked for the given
* category.
*
* @param <T> The class represented by the {@code category} argument.
* @param category The category to look for. Usually an interface class (not the actual
* implementation class).
* @param filter The optional filter, or {@code null}.
* @param hints The optional user requirements, or {@code null}.
* @return Factories ready to use for the specified category, filter and hints.
* @since 2.3
*/
public synchronized <T> Iterator<T> getServiceProviders(
final Class<T> category, final Filter filter, final Hints hints) {
/*
* The implementation of this method is very similar to the 'getUnfilteredProviders'
* one except for filter handling. See the comments in 'getUnfilteredProviders' for
* more implementation details.
*/
if (scanningCategories.contains(category)) {
// Please note you will get errors here if you accidentally allow
// more than one thread to use your FactoryRegistry at a time.
throw new RecursiveSearchException(category);
}
final Filter hintsFilter =
new Filter() {
public boolean filter(final Object provider) {
return isAcceptable(category.cast(provider), category, hints, filter);
}
};
synchronizeIteratorProviders();
scanForPluginsIfNeeded(category);
return getServiceProviders(category, hintsFilter, true);
}
