[MRESOLVER-232] Refactor selector (#138)

Make SimpleNamedLockFactorySelector logic reusable.

maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/synccontext/named/NamedLockFactorySelectorSupport.java

@@ -0,0 +1,109 @@
+package org.eclipse.aether.internal.impl.synccontext.named;
+
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import org.eclipse.aether.named.NamedLockFactory;
+
+import java.util.Map;
+
+/**
+ * Selector implementation support class: by extending this class one may override defaults, or provide completely
+ * alternative way of configuration. This implementation uses Java System properties to select factory and name mapper.
+ *
+ * @since TBD
+ */
+public abstract class NamedLockFactorySelectorSupport
+    implements NamedLockFactorySelector
+{
+    public static final String FACTORY_KEY = "aether.syncContext.named.factory";
+
+    public static final String NAME_MAPPER_KEY = "aether.syncContext.named.nameMapper";
+
+    private final NamedLockFactory namedLockFactory;
+
+    private final NameMapper nameMapper;
+
+    public NamedLockFactorySelectorSupport( final Map<String, NamedLockFactory> factories,
+                                            final String defaultFactoryName,
+                                            final Map<String, NameMapper> nameMappers,
+                                            final String defaultNameMapperName )
+    {
+        this.namedLockFactory = selectNamedLockFactory( factories, getFactoryName( defaultFactoryName ) );
+        this.nameMapper = selectNameMapper( nameMappers, getNameMapperName( defaultNameMapperName ) );
+    }
+
+    /**
+     * Returns the selected {@link NamedLockFactory}, never null.
+     */
+    @Override
+    public NamedLockFactory getSelectedNamedLockFactory()
+    {
+        return namedLockFactory;
+    }
+
+    /**
+     * Returns the selected {@link NameMapper}, never null.
+     */
+    @Override
+    public NameMapper getSelectedNameMapper()
+    {
+        return nameMapper;
+    }
+
+    /**
+     * Returns selected factory name (or passed in default) using System property value of {@link #FACTORY_KEY}.
+     */
+    protected String getFactoryName( final String defaultFactoryName )
+    {
+        return System.getProperty( FACTORY_KEY, defaultFactoryName );
+    }
+
+    /**
+     * Returns selected name mapper name (or passed in default) using System property value of {@link #NAME_MAPPER_KEY}.
+     */
+    protected String getNameMapperName( final String defaultNameMapperName )
+    {
+        return System.getProperty( NAME_MAPPER_KEY, defaultNameMapperName );
+    }
+
+    private NamedLockFactory selectNamedLockFactory( final Map<String, NamedLockFactory> factories,
+                                                     final String factoryName )
+    {
+        NamedLockFactory factory = factories.get( factoryName );
+        if ( factory == null )
+        {
+            throw new IllegalArgumentException( "Unknown NamedLockFactory name: " + factoryName
+                + ", known ones: " + factories.keySet() );
+        }
+        return factory;
+    }
+
+    private NameMapper selectNameMapper( final Map<String, NameMapper> nameMappers,
+                                         final String mapperName )
+    {
+        NameMapper nameMapper = nameMappers.get( mapperName );
+        if ( nameMapper == null )
+        {
+            throw new IllegalArgumentException( "Unknown NameMapper name: " + mapperName
+                + ", known ones: " + nameMappers.keySet() );
+        }
+        return nameMapper;
+    }
+}

maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/synccontext/named/SimpleNamedLockFactorySelector.java

@@ -32,109 +32,52 @@
 import java.util.Map;
 
 /**
- * Simple selector implementation that uses Java system properties and sane default values.
+ * Simple selector implementation that uses {@link LocalReadWriteLockNamedLockFactory} and {@link GAVNameMapper} as
+ * default name lock factory and name mapper.
+ *
+ * @since TBD
  */
 @Singleton
 @Named
 public final class SimpleNamedLockFactorySelector
-    implements NamedLockFactorySelector
+    extends NamedLockFactorySelectorSupport
 {
-    public static final String FACTORY_KEY = "aether.syncContext.named.factory";
-
-    public static final String NAME_MAPPER_KEY = "aether.syncContext.named.nameMapper";
-
-    private final NamedLockFactory namedLockFactory;
-
-    private final NameMapper nameMapper;
-
-    /**
-     * Constructor used with DI, where factories are injected and selected based on key.
-     */
-    @Inject
-    public SimpleNamedLockFactorySelector( final Map<String, NamedLockFactory> factories,
-                                           final Map<String, NameMapper> nameMappers )
-    {
-        this.namedLockFactory = selectNamedLockFactory( factories, getFactoryName() );
-        this.nameMapper = selectNameMapper( nameMappers, getNameMapperName() );
-    }
+    private static final Map<String, NamedLockFactory> FACTORIES;
 
-    /**
-     * Returns selected factory name (or sane default) using System property value of {@link #FACTORY_KEY} and defaults
-     * to {@link LocalReadWriteLockNamedLockFactory#NAME}.
-     */
-    private String getFactoryName()
-    {
-        return System.getProperty( FACTORY_KEY, LocalReadWriteLockNamedLockFactory.NAME );
-    }
+    private static final Map<String, NameMapper> NAME_MAPPERS;
 
-    /**
-     * Returns selected name mapper name (or sane default) using System property value of {@link #NAME_MAPPER_KEY} and
-     * defaults to {@link GAVNameMapper#NAME}.
-     */
-    private String getNameMapperName()
+    static
     {
-        return System.getProperty( NAME_MAPPER_KEY, GAVNameMapper.NAME );
+        FACTORIES = new HashMap<>();
+        FACTORIES.put( NoopNamedLockFactory.NAME, new NoopNamedLockFactory() );
+        FACTORIES.put( LocalReadWriteLockNamedLockFactory.NAME, new LocalReadWriteLockNamedLockFactory() );
+        FACTORIES.put( LocalSemaphoreNamedLockFactory.NAME, new LocalSemaphoreNamedLockFactory() );
+        FACTORIES.put( FileLockNamedLockFactory.NAME, new FileLockNamedLockFactory() );
+
+        NAME_MAPPERS = new HashMap<>();
+        NAME_MAPPERS.put( StaticNameMapper.NAME, new StaticNameMapper() );
+        NAME_MAPPERS.put( GAVNameMapper.NAME, new GAVNameMapper() );
+        NAME_MAPPERS.put( DiscriminatingNameMapper.NAME, new DiscriminatingNameMapper( new GAVNameMapper() ) );
+        NAME_MAPPERS.put( FileGAVNameMapper.NAME, new FileGAVNameMapper() );
     }
 
     /**
      * Default constructor for ServiceLocator.
      */
     public SimpleNamedLockFactorySelector()
     {
-        Map<String, NamedLockFactory> factories = new HashMap<>();
-        factories.put( NoopNamedLockFactory.NAME, new NoopNamedLockFactory() );
-        factories.put( LocalReadWriteLockNamedLockFactory.NAME, new LocalReadWriteLockNamedLockFactory() );
-        factories.put( LocalSemaphoreNamedLockFactory.NAME, new LocalSemaphoreNamedLockFactory() );
-        factories.put( FileLockNamedLockFactory.NAME, new FileLockNamedLockFactory() );
-        this.namedLockFactory = selectNamedLockFactory( factories, getFactoryName() );
-
-        Map<String, NameMapper> nameMappers = new HashMap<>();
-        nameMappers.put( StaticNameMapper.NAME, new StaticNameMapper() );
-        nameMappers.put( GAVNameMapper.NAME, new GAVNameMapper() );
-        nameMappers.put( DiscriminatingNameMapper.NAME, new DiscriminatingNameMapper( new GAVNameMapper() ) );
-        nameMappers.put( FileGAVNameMapper.NAME, new FileGAVNameMapper() );
-        this.nameMapper = selectNameMapper( nameMappers, getNameMapperName() );
+        this( FACTORIES, NAME_MAPPERS );
     }
 
-    /**
-     * Returns the selected {@link NamedLockFactory}, never null.
-     */
-    @Override
-    public NamedLockFactory getSelectedNamedLockFactory()
-    {
-        return namedLockFactory;
-    }
-
-    /**
-     * Returns the selected {@link NameMapper}, never null.
-     */
-    @Override
-    public NameMapper getSelectedNameMapper()
-    {
-        return nameMapper;
-    }
-
-    private NamedLockFactory selectNamedLockFactory( final Map<String, NamedLockFactory> factories,
-                                                     final String factoryName )
-    {
-        NamedLockFactory factory = factories.get( factoryName );
-        if ( factory == null )
-        {
-            throw new IllegalArgumentException( "Unknown NamedLockFactory name: " + factoryName
-                + ", known ones: " + factories.keySet() );
-        }
-        return factory;
-    }
-
-    private NameMapper selectNameMapper( final Map<String, NameMapper> nameMappers,
-                                         final String mapperName )
+    @Inject
+    public SimpleNamedLockFactorySelector( final Map<String, NamedLockFactory> factories,
+                                           final Map<String, NameMapper> nameMappers )
     {
-        NameMapper nameMapper = nameMappers.get( mapperName );
-        if ( nameMapper == null )
-        {
-            throw new IllegalArgumentException( "Unknown NameMapper name: " + mapperName
-                + ", known ones: " + nameMappers.keySet() );
-        }
-        return nameMapper;
+        super(
+            factories,
+            LocalReadWriteLockNamedLockFactory.NAME,
+            nameMappers,
+            GAVNameMapper.NAME
+        );
     }
 }