DataTypeService.java
/*
* Portions of this software was developed by employees of the National Institute
* of Standards and Technology (NIST), an agency of the Federal Government and is
* being made available as a public service. Pursuant to title 17 United States
* Code Section 105, works of NIST employees are not subject to copyright
* protection in the United States. This software may be subject to foreign
* copyright. Permission in the United States and in foreign countries, to the
* extent that NIST may hold copyright, to use, copy, modify, create derivative
* works, and distribute this software and its documentation without fee is hereby
* granted on a non-exclusive basis, provided that this notice and disclaimer
* of warranty appears in all copies.
*
* THE SOFTWARE IS PROVIDED 'AS IS' WITHOUT ANY WARRANTY OF ANY KIND, EITHER
* EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, ANY WARRANTY
* THAT THE SOFTWARE WILL CONFORM TO SPECIFICATIONS, ANY IMPLIED WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND FREEDOM FROM
* INFRINGEMENT, AND ANY WARRANTY THAT THE DOCUMENTATION WILL CONFORM TO THE
* SOFTWARE, OR ANY WARRANTY THAT THE SOFTWARE WILL BE ERROR FREE. IN NO EVENT
* SHALL NIST BE LIABLE FOR ANY DAMAGES, INCLUDING, BUT NOT LIMITED TO, DIRECT,
* INDIRECT, SPECIAL OR CONSEQUENTIAL DAMAGES, ARISING OUT OF, RESULTING FROM,
* OR IN ANY WAY CONNECTED WITH THIS SOFTWARE, WHETHER OR NOT BASED UPON WARRANTY,
* CONTRACT, TORT, OR OTHERWISE, WHETHER OR NOT INJURY WAS SUSTAINED BY PERSONS OR
* PROPERTY OR OTHERWISE, AND WHETHER OR NOT LOSS WAS SUSTAINED FROM, OR AROSE OUT
* OF THE RESULTS OF, OR USE OF, THE SOFTWARE OR SERVICES PROVIDED HEREUNDER.
*/
package gov.nist.secauto.metaschema.core.datatype;
import gov.nist.secauto.metaschema.core.util.CustomCollectors;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import java.util.List;
import java.util.Map;
import java.util.ServiceLoader;
import java.util.ServiceLoader.Provider;
import java.util.concurrent.ConcurrentHashMap;
import java.util.function.Function;
import java.util.stream.Collectors;
import edu.umd.cs.findbugs.annotations.NonNull;
import edu.umd.cs.findbugs.annotations.Nullable;
import nl.talsmasoftware.lazy4j.Lazy;
/**
* This class provides a singleton service to allow data types to be discovered
* within the system based on an SPI provided by {@link IDataTypeProvider}.
*/
public final class DataTypeService {
private static final Logger LOGGER = LogManager.getLogger(DataTypeService.class);
private static final Lazy<DataTypeService> INSTANCE = Lazy.lazy(() -> new DataTypeService());
private Map<String, IDataTypeAdapter<?>> libraryByName;
private Map<Class<? extends IDataTypeAdapter<?>>, IDataTypeAdapter<?>> libraryByClass;
/**
* Get the singleton service instance, which will be lazy constructed on first
* access.
*
* @return the service instance
*/
@SuppressWarnings("null")
@NonNull
public static DataTypeService getInstance() {
return INSTANCE.get();
}
private DataTypeService() {
load();
}
/**
* Lookup a specific {@link IDataTypeAdapter} instance by its name.
*
* @param name
* the data type name of data type adapter to get the instance for
* @return the instance or {@code null} if the instance is unknown to the type
* system
*/
@Nullable
public IDataTypeAdapter<?> getJavaTypeAdapterByName(@NonNull String name) {
return libraryByName.get(name);
}
/**
* Lookup a specific {@link IDataTypeAdapter} instance by its class.
*
* @param clazz
* the adapter class to get the instance for
* @param <TYPE>
* the type of the requested adapter
* @return the instance or {@code null} if the instance is unknown to the type
* system
*/
@SuppressWarnings("unchecked")
@Nullable
public <TYPE extends IDataTypeAdapter<?>> TYPE getJavaTypeAdapterByClass(@NonNull Class<TYPE> clazz) {
return (TYPE) libraryByClass.get(clazz);
}
/**
* Load available data types registered with the {@link IDataTypeProvider} SPI.
*
* @throws IllegalStateException
* if there are two adapters with the same name
*/
private void load() {
ServiceLoader<IDataTypeProvider> loader = ServiceLoader.load(IDataTypeProvider.class);
List<IDataTypeAdapter<?>> dataTypes = loader.stream()
.map(Provider<IDataTypeProvider>::get)
.flatMap(provider -> provider.getJavaTypeAdapters().stream())
.collect(Collectors.toList());
Map<String, IDataTypeAdapter<?>> libraryByName = dataTypes.stream()
.flatMap(dataType -> dataType.getNames().stream()
.map(name -> Map.entry(name, dataType)))
.collect(CustomCollectors.toMap(
Map.Entry::getKey,
(entry) -> entry.getValue(),
(key, v1, v2) -> {
if (LOGGER.isWarnEnabled()) {
LOGGER.warn("Data types '{}' and '{}' have duplicate name '{}'. Using the first.",
v1.getClass().getName(),
v2.getClass().getName(),
key);
}
return v1;
},
ConcurrentHashMap::new));
@SuppressWarnings({ "unchecked", "null" }) Map<Class<? extends IDataTypeAdapter<?>>,
IDataTypeAdapter<?>> libraryByClass = dataTypes.stream()
.collect(CustomCollectors.toMap(
dataType -> (Class<? extends IDataTypeAdapter<?>>) dataType.getClass(),
Function.identity(),
(key, v1, v2) -> {
if (LOGGER.isWarnEnabled()) {
LOGGER.warn("Duplicate data type class '{}'. Using the first.",
key.getClass().getName());
}
return v1;
},
ConcurrentHashMap::new));
synchronized (this) {
this.libraryByName = libraryByName;
this.libraryByClass = libraryByClass;
}
}
}