src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkLateBoundDefault.java - bazel - Git at Google

 // Copyright 2017 The Bazel Authors. All rights reserved.
 //
 // Licensed 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.

 package com.google.devtools.build.lib.analysis.skylark;

 import com.google.common.base.Preconditions;
 import com.google.common.cache.CacheBuilder;
 import com.google.common.cache.CacheLoader;
 import com.google.common.cache.LoadingCache;
 import com.google.common.collect.ImmutableMap;
 import com.google.devtools.build.lib.analysis.skylark.annotations.SkylarkConfigurationField;
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.packages.Attribute.AbstractLabelLateBoundDefault;
 import com.google.devtools.build.lib.packages.Attribute.LateBoundDefault;
 import com.google.devtools.build.lib.packages.AttributeMap;
 import com.google.devtools.build.lib.packages.Rule;
 import com.google.devtools.build.lib.skyframe.serialization.autocodec.AutoCodec;
 import com.google.devtools.build.lib.skylarkbuildapi.LateBoundDefaultApi;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkInterfaceUtils;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
 import com.google.devtools.build.lib.syntax.Printer;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.util.Map;
 import java.util.concurrent.ExecutionException;
 import javax.annotation.concurrent.Immutable;

 /**
  * An implementation of {@link LateBoundDefault} which obtains a late-bound attribute value (of type
  * 'label') specifically by skylark configuration fragment name and field name, as registered by
  * {@link SkylarkConfigurationField}.
  *
  * <p>For example, a SkylarkLateBoundDefault on "java" and "toolchain" would require a valid
  * configuration fragment named "java" with a method annotated with {@link
  * SkylarkConfigurationField} of name "toolchain". This {@link LateBoundDefault} would provide a
  * late-bound dependency (defined by the label returned by that configuration field) in the current
  * target configuration.
  */
 @Immutable
 @AutoCodec
 public class SkylarkLateBoundDefault<FragmentT> extends AbstractLabelLateBoundDefault<FragmentT>
     implements LateBoundDefaultApi {

   private final Method method;
   private final String fragmentName;
   private final String fragmentFieldName;

   @Override
   public Label resolve(Rule rule, AttributeMap attributes, FragmentT config) {
     try {
       Object result = method.invoke(config);
       return (Label) result;
     } catch (IllegalAccessException | InvocationTargetException e) {
       // Configuration field methods should not throw either of these exceptions.
       throw new AssertionError("Method invocation failed: " + e);
     }
   }

   /**
    * Returns the {@link SkylarkConfigurationField} annotation corresponding to this method.
    */
   private static Label getDefaultLabel(
       SkylarkConfigurationField annotation, String toolsRepository) {
     if (annotation.defaultLabel().isEmpty()) {
       return null;
     }
     Label defaultLabel = annotation.defaultInToolRepository()
         ? Label.parseAbsoluteUnchecked(toolsRepository + annotation.defaultLabel())
         : Label.parseAbsoluteUnchecked(annotation.defaultLabel());
     return defaultLabel;
   }

   private SkylarkLateBoundDefault(SkylarkConfigurationField annotation,
       Class<FragmentT> fragmentClass, String fragmentName, Method method, String toolsRepository) {
     this(
         getDefaultLabel(annotation, toolsRepository),
         fragmentClass,
         method,
         fragmentName,
         annotation.name());
   }

   @AutoCodec.VisibleForSerialization
   @AutoCodec.Instantiator
   SkylarkLateBoundDefault(
       Label defaultVal,
       Class<FragmentT> fragmentClass,
       Method method,
       String fragmentName,
       String fragmentFieldName) {
     super(/*useHostConfiguration=*/ false, fragmentClass, defaultVal);
     this.method = method;
     this.fragmentName = fragmentName;
     this.fragmentFieldName = fragmentFieldName;
   }

   /**
    * Returns the skylark name of the configuration fragment that this late bound default requires.
    */
   public String getFragmentName() {
     return fragmentName;
   }

   /**
    * Returns the skylark name of the configuration field name, as registered by
    * {@link SkylarkConfigurationField} annotation on the configuration fragment.
    */
   public String getFragmentFieldName() {
     return fragmentFieldName;
   }

   @Override
   public void repr(Printer printer) {
     printer.format("<late-bound default>");
   }

   /** For use by @AutoCodec since the {@link #defaultValue} field is hard for it to process. */
   @AutoCodec.VisibleForSerialization
   Label getDefaultVal() {
     return getDefault();
   }

   /**
    * An exception thrown if a user specifies an invalid configuration field identifier.
    *
    * @see SkylarkConfigurationField
    **/
   public static class InvalidConfigurationFieldException extends Exception {
     public InvalidConfigurationFieldException(String message) {
       super(message);
     }
   }


   private static class CacheKey {
     private final Class<?> fragmentClass;
     private final String toolsRepository;

     private CacheKey(Class<?> fragmentClass,
         String toolsRepository) {
       this.fragmentClass = fragmentClass;
       this.toolsRepository = toolsRepository;
     }

     @Override
     public boolean equals(Object object) {
       if (object == this) {
         return true;
       } else if (!(object instanceof CacheKey)) {
         return false;
       } else {
         CacheKey cacheKey = (CacheKey) object;
         return fragmentClass.equals(cacheKey.fragmentClass)
             && toolsRepository.equals(cacheKey.toolsRepository);
       }
     }

     @Override
     public int hashCode() {
       int result = fragmentClass.hashCode();
       result = 31 * result + toolsRepository.hashCode();
       return result;
     }
   }

   /**
    * A cache for efficient {@link SkylarkLateBoundDefault} loading by configuration fragment. Each
    * configuration fragment class key is mapped to a {@link Map} where keys are configuration field
    * skylark names, and values are the {@link SkylarkLateBoundDefault}s. Methods must be annotated
    * with {@link SkylarkConfigurationField} to be considered.
    */
   private static final LoadingCache<CacheKey, Map<String, SkylarkLateBoundDefault<?>>> fieldCache =
       CacheBuilder.newBuilder()
           .initialCapacity(10)
           .maximumSize(100)
           .build(
               new CacheLoader<CacheKey, Map<String, SkylarkLateBoundDefault<?>>>() {
                 @Override
                 public Map<String, SkylarkLateBoundDefault<?>> load(CacheKey key) throws Exception {
                   ImmutableMap.Builder<String, SkylarkLateBoundDefault<?>> lateBoundDefaultMap =
                       new ImmutableMap.Builder<>();
                   Class<?> fragmentClass = key.fragmentClass;
                   SkylarkModule fragmentModule =
                       SkylarkInterfaceUtils.getSkylarkModule(fragmentClass);

                   if (fragmentModule != null) {
                     for (Method method : fragmentClass.getMethods()) {
                       if (method.isAnnotationPresent(SkylarkConfigurationField.class)) {
                         // TODO(b/68817606): Use annotation processors to verify these constraints.
                         Preconditions.checkArgument(
                             method.getReturnType() == Label.class,
                             String.format("Method %s must have return type 'Label'", method));
                         Preconditions.checkArgument(
                             method.getParameterTypes().length == 0,
                             String.format("Method %s must not accept arguments", method));

                         SkylarkConfigurationField configField =
                             method.getAnnotation(SkylarkConfigurationField.class);
                         lateBoundDefaultMap.put(
                             configField.name(),
                             new SkylarkLateBoundDefault<>(
                                 configField,
                                 fragmentClass,
                                 fragmentModule.name(),
                                 method,
                                 key.toolsRepository));
                       }
                     }
                   }
                   return lateBoundDefaultMap.build();
                 }
               });

   /**
    * Returns a {@link LateBoundDefault} which obtains a late-bound attribute value (of type 'label')
    * specifically by skylark configuration fragment name and field name, as registered by {@link
    * SkylarkConfigurationField}.
    *
    * @param fragmentClass the configuration fragment class, which must have a valid skylark name
    * @param fragmentFieldName the configuration field name, as registered by {@link
    *     SkylarkConfigurationField} annotation
    * @param toolsRepository the Bazel tools repository path fragment
    * @throws InvalidConfigurationFieldException if there is no valid configuration field with the
    *     given fragment class and field name
    */
   @SuppressWarnings("unchecked")
   public static <FragmentT> SkylarkLateBoundDefault<FragmentT> forConfigurationField(
       Class<FragmentT> fragmentClass, String fragmentFieldName, String toolsRepository)
       throws InvalidConfigurationFieldException {
     try {
       CacheKey cacheKey = new CacheKey(fragmentClass, toolsRepository);
       SkylarkLateBoundDefault<?> resolver = fieldCache.get(cacheKey).get(fragmentFieldName);
       if (resolver == null) {
         SkylarkModule moduleAnnotation = SkylarkInterfaceUtils.getSkylarkModule(fragmentClass);
         if (moduleAnnotation == null) {
           throw new AssertionError("fragment class must have a valid Starlark name");
         }
         throw new InvalidConfigurationFieldException(
             String.format("invalid configuration field name '%s' on fragment '%s'",
                 fragmentFieldName, moduleAnnotation.name()));
       }
       return (SkylarkLateBoundDefault<FragmentT>) resolver; // unchecked cast
     } catch (ExecutionException e) {
       throw new IllegalStateException("method invocation failed: " + e);
     }
   }

 }
	// Copyright 2017 The Bazel Authors. All rights reserved.
	//
	// Licensed 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.

	package com.google.devtools.build.lib.analysis.skylark;

	import com.google.common.base.Preconditions;
	import com.google.common.cache.CacheBuilder;
	import com.google.common.cache.CacheLoader;
	import com.google.common.cache.LoadingCache;
	import com.google.common.collect.ImmutableMap;
	import com.google.devtools.build.lib.analysis.skylark.annotations.SkylarkConfigurationField;
	import com.google.devtools.build.lib.cmdline.Label;
	import com.google.devtools.build.lib.packages.Attribute.AbstractLabelLateBoundDefault;
	import com.google.devtools.build.lib.packages.Attribute.LateBoundDefault;
	import com.google.devtools.build.lib.packages.AttributeMap;
	import com.google.devtools.build.lib.packages.Rule;
	import com.google.devtools.build.lib.skyframe.serialization.autocodec.AutoCodec;
	import com.google.devtools.build.lib.skylarkbuildapi.LateBoundDefaultApi;
	import com.google.devtools.build.lib.skylarkinterface.SkylarkInterfaceUtils;
	import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
	import com.google.devtools.build.lib.syntax.Printer;
	import java.lang.reflect.InvocationTargetException;
	import java.lang.reflect.Method;
	import java.util.Map;
	import java.util.concurrent.ExecutionException;
	import javax.annotation.concurrent.Immutable;

	/**
	* An implementation of {@link LateBoundDefault} which obtains a late-bound attribute value (of type
	* 'label') specifically by skylark configuration fragment name and field name, as registered by
	* {@link SkylarkConfigurationField}.
	*
	* <p>For example, a SkylarkLateBoundDefault on "java" and "toolchain" would require a valid
	* configuration fragment named "java" with a method annotated with {@link
	* SkylarkConfigurationField} of name "toolchain". This {@link LateBoundDefault} would provide a
	* late-bound dependency (defined by the label returned by that configuration field) in the current
	* target configuration.
	*/
	@Immutable
	@AutoCodec
	public class SkylarkLateBoundDefault<FragmentT> extends AbstractLabelLateBoundDefault<FragmentT>
	implements LateBoundDefaultApi {

	private final Method method;
	private final String fragmentName;
	private final String fragmentFieldName;

	@Override
	public Label resolve(Rule rule, AttributeMap attributes, FragmentT config) {
	try {
	Object result = method.invoke(config);
	return (Label) result;
	} catch (IllegalAccessException \| InvocationTargetException e) {
	// Configuration field methods should not throw either of these exceptions.
	throw new AssertionError("Method invocation failed: " + e);
	}
	}

	/**
	* Returns the {@link SkylarkConfigurationField} annotation corresponding to this method.
	*/
	private static Label getDefaultLabel(
	SkylarkConfigurationField annotation, String toolsRepository) {
	if (annotation.defaultLabel().isEmpty()) {
	return null;
	}
	Label defaultLabel = annotation.defaultInToolRepository()
	? Label.parseAbsoluteUnchecked(toolsRepository + annotation.defaultLabel())
	: Label.parseAbsoluteUnchecked(annotation.defaultLabel());
	return defaultLabel;
	}

	private SkylarkLateBoundDefault(SkylarkConfigurationField annotation,
	Class<FragmentT> fragmentClass, String fragmentName, Method method, String toolsRepository) {
	this(
	getDefaultLabel(annotation, toolsRepository),
	fragmentClass,
	method,
	fragmentName,
	annotation.name());
	}

	@AutoCodec.VisibleForSerialization
	@AutoCodec.Instantiator
	SkylarkLateBoundDefault(
	Label defaultVal,
	Class<FragmentT> fragmentClass,
	Method method,
	String fragmentName,
	String fragmentFieldName) {
	super(/useHostConfiguration=/ false, fragmentClass, defaultVal);
	this.method = method;
	this.fragmentName = fragmentName;
	this.fragmentFieldName = fragmentFieldName;
	}

	/**
	* Returns the skylark name of the configuration fragment that this late bound default requires.
	*/
	public String getFragmentName() {
	return fragmentName;
	}

	/**
	* Returns the skylark name of the configuration field name, as registered by
	* {@link SkylarkConfigurationField} annotation on the configuration fragment.
	*/
	public String getFragmentFieldName() {
	return fragmentFieldName;
	}

	@Override
	public void repr(Printer printer) {
	printer.format("<late-bound default>");
	}

	/** For use by @AutoCodec since the {@link #defaultValue} field is hard for it to process. */
	@AutoCodec.VisibleForSerialization
	Label getDefaultVal() {
	return getDefault();
	}

	/**
	* An exception thrown if a user specifies an invalid configuration field identifier.
	*
	* @see SkylarkConfigurationField
	**/
	public static class InvalidConfigurationFieldException extends Exception {
	public InvalidConfigurationFieldException(String message) {
	super(message);
	}
	}


	private static class CacheKey {
	private final Class<?> fragmentClass;
	private final String toolsRepository;

	private CacheKey(Class<?> fragmentClass,
	String toolsRepository) {
	this.fragmentClass = fragmentClass;
	this.toolsRepository = toolsRepository;
	}

	@Override
	public boolean equals(Object object) {
	if (object == this) {
	return true;
	} else if (!(object instanceof CacheKey)) {
	return false;
	} else {
	CacheKey cacheKey = (CacheKey) object;
	return fragmentClass.equals(cacheKey.fragmentClass)
	&& toolsRepository.equals(cacheKey.toolsRepository);
	}
	}

	@Override
	public int hashCode() {
	int result = fragmentClass.hashCode();
	result = 31 * result + toolsRepository.hashCode();
	return result;
	}
	}

	/**
	* A cache for efficient {@link SkylarkLateBoundDefault} loading by configuration fragment. Each
	* configuration fragment class key is mapped to a {@link Map} where keys are configuration field
	* skylark names, and values are the {@link SkylarkLateBoundDefault}s. Methods must be annotated
	* with {@link SkylarkConfigurationField} to be considered.
	*/
	private static final LoadingCache<CacheKey, Map<String, SkylarkLateBoundDefault<?>>> fieldCache =
	CacheBuilder.newBuilder()
	.initialCapacity(10)
	.maximumSize(100)
	.build(
	new CacheLoader<CacheKey, Map<String, SkylarkLateBoundDefault<?>>>() {
	@Override
	public Map<String, SkylarkLateBoundDefault<?>> load(CacheKey key) throws Exception {
	ImmutableMap.Builder<String, SkylarkLateBoundDefault<?>> lateBoundDefaultMap =
	new ImmutableMap.Builder<>();
	Class<?> fragmentClass = key.fragmentClass;
	SkylarkModule fragmentModule =
	SkylarkInterfaceUtils.getSkylarkModule(fragmentClass);

	if (fragmentModule != null) {
	for (Method method : fragmentClass.getMethods()) {
	if (method.isAnnotationPresent(SkylarkConfigurationField.class)) {
	// TODO(b/68817606): Use annotation processors to verify these constraints.
	Preconditions.checkArgument(
	method.getReturnType() == Label.class,
	String.format("Method %s must have return type 'Label'", method));
	Preconditions.checkArgument(
	method.getParameterTypes().length == 0,
	String.format("Method %s must not accept arguments", method));

	SkylarkConfigurationField configField =
	method.getAnnotation(SkylarkConfigurationField.class);
	lateBoundDefaultMap.put(
	configField.name(),
	new SkylarkLateBoundDefault<>(
	configField,
	fragmentClass,
	fragmentModule.name(),
	method,
	key.toolsRepository));
	}
	}
	}
	return lateBoundDefaultMap.build();
	}
	});

	/**
	* Returns a {@link LateBoundDefault} which obtains a late-bound attribute value (of type 'label')
	* specifically by skylark configuration fragment name and field name, as registered by {@link
	* SkylarkConfigurationField}.
	*
	* @param fragmentClass the configuration fragment class, which must have a valid skylark name
	* @param fragmentFieldName the configuration field name, as registered by {@link
	* SkylarkConfigurationField} annotation
	* @param toolsRepository the Bazel tools repository path fragment
	* @throws InvalidConfigurationFieldException if there is no valid configuration field with the
	* given fragment class and field name
	*/
	@SuppressWarnings("unchecked")
	public static <FragmentT> SkylarkLateBoundDefault<FragmentT> forConfigurationField(
	Class<FragmentT> fragmentClass, String fragmentFieldName, String toolsRepository)
	throws InvalidConfigurationFieldException {
	try {
	CacheKey cacheKey = new CacheKey(fragmentClass, toolsRepository);
	SkylarkLateBoundDefault<?> resolver = fieldCache.get(cacheKey).get(fragmentFieldName);
	if (resolver == null) {
	SkylarkModule moduleAnnotation = SkylarkInterfaceUtils.getSkylarkModule(fragmentClass);
	if (moduleAnnotation == null) {
	throw new AssertionError("fragment class must have a valid Starlark name");
	}
	throw new InvalidConfigurationFieldException(
	String.format("invalid configuration field name '%s' on fragment '%s'",
	fragmentFieldName, moduleAnnotation.name()));
	}
	return (SkylarkLateBoundDefault<FragmentT>) resolver; // unchecked cast
	} catch (ExecutionException e) {
	throw new IllegalStateException("method invocation failed: " + e);
	}
	}

	}