From af52e472b4f0b00b0d00c04b3fa54a79f94b9a49 Mon Sep 17 00:00:00 2001 From: Tavian Barnes Date: Sun, 14 Sep 2014 23:56:51 -0400 Subject: lazy: Implement Lazy, very much like Dagger's. --- .../java/com/tavianator/sangria/lazy/Lazy.java | 81 ++++++ .../com/tavianator/sangria/lazy/LazyBinder.java | 273 +++++++++++++++++++++ .../com/tavianator/sangria/lazy/LazyBinding.java | 34 +++ .../sangria/lazy/LazyBindingVisitor.java | 37 +++ .../com/tavianator/sangria/lazy/package-info.java | 25 ++ 5 files changed, 450 insertions(+) create mode 100644 sangria-lazy/src/main/java/com/tavianator/sangria/lazy/Lazy.java create mode 100644 sangria-lazy/src/main/java/com/tavianator/sangria/lazy/LazyBinder.java create mode 100644 sangria-lazy/src/main/java/com/tavianator/sangria/lazy/LazyBinding.java create mode 100644 sangria-lazy/src/main/java/com/tavianator/sangria/lazy/LazyBindingVisitor.java create mode 100644 sangria-lazy/src/main/java/com/tavianator/sangria/lazy/package-info.java (limited to 'sangria-lazy/src/main') diff --git a/sangria-lazy/src/main/java/com/tavianator/sangria/lazy/Lazy.java b/sangria-lazy/src/main/java/com/tavianator/sangria/lazy/Lazy.java new file mode 100644 index 0000000..adf531c --- /dev/null +++ b/sangria-lazy/src/main/java/com/tavianator/sangria/lazy/Lazy.java @@ -0,0 +1,81 @@ +/**************************************************************************** + * Sangria * + * Copyright (C) 2014 Tavian Barnes * + * * + * 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.tavianator.sangria.lazy; + +import javax.inject.Inject; +import javax.inject.Provider; + +/** + * A lazily-loaded dependency. Like a {@link Provider}, calling {@link #get()} will produce an instance of {@code T}. + * Unlike a {@link Provider}, the same instance will be returned for every future call to {@link #get()}. Different + * {@code Lazy} instances are independent and will return different instances from {@link #get()}. + * + *

+ * {@link Lazy} works automatically for unqualified bindings, as long as just-in-time bindings are enabled. For + * qualified bindings, or if explicit bindings are requred, use {@link LazyBinder}: + *

+ * + * 
+ * // Either separately...
+ * bind(Dependency.class)
+ *         .annotatedWith(Names.named("name"))
+ *         .to(RealDependency.class);
+ *
+ * LazyBinder.create(binder())
+ *         .bind(Dependency.class)
+ *         .annotatedWith(Names.named("name"));
+ *
+ * // ... or in one go
+ * LazyBinder.create(binder())
+ *         .bind(Dependency.class)
+ *         .annotatedWith(Names.named("name"))
+ *         .to(RealDependency.class);
+ *
+ * ...
+ *
+ * {@literal @}Inject {@literal @}Named("name") Lazy<Dependency> lazy;
+ *
+ * + * @author Tavian Barnes (tavianator@tavianator.com) + * @version 1.2 + * @since 1.2 + */ +public final class Lazy { + private final Provider provider; + private volatile T instance = null; + + @Inject + Lazy(Provider provider) { + this.provider = provider; + } + + /** + * @return A lazily-produced value of type {@code T}. + */ + public T get() { + // Double-checked locking + if (instance == null) { + synchronized (this) { + if (instance == null) { + instance = provider.get(); + } + } + } + return instance; + } +} diff --git a/sangria-lazy/src/main/java/com/tavianator/sangria/lazy/LazyBinder.java b/sangria-lazy/src/main/java/com/tavianator/sangria/lazy/LazyBinder.java new file mode 100644 index 0000000..26d3848 --- /dev/null +++ b/sangria-lazy/src/main/java/com/tavianator/sangria/lazy/LazyBinder.java @@ -0,0 +1,273 @@ +/**************************************************************************** + * Sangria * + * Copyright (C) 2014 Tavian Barnes * + * * + * 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.tavianator.sangria.lazy; + +import java.lang.annotation.Annotation; +import java.lang.reflect.Constructor; + +import javax.inject.Provider; + +import com.google.inject.Binder; +import com.google.inject.Key; +import com.google.inject.Scope; +import com.google.inject.TypeLiteral; +import com.google.inject.binder.AnnotatedBindingBuilder; +import com.google.inject.binder.LinkedBindingBuilder; +import com.google.inject.binder.ScopedBindingBuilder; +import com.google.inject.spi.BindingTargetVisitor; +import com.google.inject.spi.ProviderInstanceBinding; +import com.google.inject.spi.ProviderWithExtensionVisitor; +import com.google.inject.util.Types; + +import com.tavianator.sangria.core.PotentialAnnotation; + +/** + * Binder for {@link Lazy} instances. + * + * @author Tavian Barnes (tavianator@tavianator.com) + * @version 1.2 + * @since 1.2 + */ +public class LazyBinder { + private static final Class[] SKIPPED_SOURCES = { + LazyBinder.class, + BindingAnnotator.class, + LazyBindingBuilder.class, + }; + + private final Binder binder; + + private LazyBinder(Binder binder) { + this.binder = binder; + } + + /** + * Create a {@link LazyBinder}. + * + * @param binder The {@link Binder} to use. + * @return A {@link LazyBinder} instance. + */ + public static LazyBinder create(Binder binder) { + return new LazyBinder(binder.skipSources(SKIPPED_SOURCES)); + } + + @SuppressWarnings("unchecked") + private static TypeLiteral> lazyOf(TypeLiteral type) { + return (TypeLiteral>)TypeLiteral.get(Types.newParameterizedType(Lazy.class, type.getType())); + } + + /** + * See the EDSL examples at {@link Lazy}. + */ + public AnnotatedBindingBuilder bind(Class type) { + return bind(TypeLiteral.get(type)); + } + + /** + * See the EDSL examples at {@link Lazy}. + */ + public AnnotatedBindingBuilder bind(TypeLiteral type) { + AnnotatedBindingBuilder> lazyBinding = binder.bind(lazyOf(type)); + return new LazyBindingBuilder<>(binder, type, lazyBinding, PotentialAnnotation.none()); + } + + /** + * Applies an annotation to an {@link AnnotatedBindingBuilder}. + */ + private static class BindingAnnotator implements PotentialAnnotation.Visitor> { + private final AnnotatedBindingBuilder builder; + + BindingAnnotator(AnnotatedBindingBuilder builder) { + this.builder = builder; + } + + @Override + public LinkedBindingBuilder visitNoAnnotation() { + return builder; + } + + @Override + public LinkedBindingBuilder visitAnnotationType(Class annotationType) { + return builder.annotatedWith(annotationType); + } + + @Override + public LinkedBindingBuilder visitAnnotationInstance(Annotation annotation) { + return builder.annotatedWith(annotation); + } + } + + /** + * See the EDSL examples at {@link Lazy}. + */ + public LinkedBindingBuilder bind(Key key) { + TypeLiteral type = key.getTypeLiteral(); + PotentialAnnotation potentialAnnotation = PotentialAnnotation.from(key); + return potentialAnnotation.accept(new BindingAnnotator<>(bind(type))); + } + + /** + * Actual binder implementation. + */ + private static class LazyBindingBuilder implements AnnotatedBindingBuilder { + private final Binder binder; + private final TypeLiteral type; + private final AnnotatedBindingBuilder> lazyBinding; + private final PotentialAnnotation potentialAnnotation; + + LazyBindingBuilder( + Binder binder, + TypeLiteral type, + AnnotatedBindingBuilder> lazyBinding, + PotentialAnnotation potentialAnnotation) { + this.binder = binder; + this.type = type; + this.lazyBinding = lazyBinding; + this.potentialAnnotation = potentialAnnotation; + } + + @Override + public LinkedBindingBuilder annotatedWith(Class annotationType) { + PotentialAnnotation newAnnotation = potentialAnnotation.annotatedWith(annotationType); + Key key = newAnnotation.getKey(type); + + lazyBinding.annotatedWith(annotationType) + .toProvider(new LazyProvider<>(binder.getProvider(key), key)); + + return new LazyBindingBuilder<>(binder, type, null, newAnnotation); + } + + @Override + public LinkedBindingBuilder annotatedWith(Annotation annotation) { + PotentialAnnotation newAnnotation = potentialAnnotation.annotatedWith(annotation); + Key key = newAnnotation.getKey(type); + + lazyBinding.annotatedWith(annotation) + .toProvider(new LazyProvider<>(binder.getProvider(key), key)); + + return new LazyBindingBuilder<>(binder, type, null, newAnnotation); + } + + /** + * @return A binding builder for the underlying binding. + */ + private LinkedBindingBuilder makeBinder() { + return binder.bind(potentialAnnotation.getKey(type)); + } + + @Override + public ScopedBindingBuilder to(Class implementation) { + return makeBinder().to(implementation); + } + + @Override + public ScopedBindingBuilder to(TypeLiteral implementation) { + return makeBinder().to(implementation); + } + + @Override + public ScopedBindingBuilder to(Key targetKey) { + return makeBinder().to(targetKey); + } + + @Override + public void toInstance(T instance) { + makeBinder().toInstance(instance); + } + + @Override + public ScopedBindingBuilder toProvider(com.google.inject.Provider provider) { + return makeBinder().toProvider(provider); + } + + @Override + public ScopedBindingBuilder toProvider(Provider provider) { + return makeBinder().toProvider(provider); + } + + @Override + public ScopedBindingBuilder toProvider(Class> providerType) { + return makeBinder().toProvider(providerType); + } + + @Override + public ScopedBindingBuilder toProvider(TypeLiteral> providerType) { + return makeBinder().toProvider(providerType); + } + + @Override + public ScopedBindingBuilder toProvider(Key> providerKey) { + return makeBinder().toProvider(providerKey); + } + + @Override + public ScopedBindingBuilder toConstructor(Constructor constructor) { + return makeBinder().toConstructor(constructor); + } + + @Override + public ScopedBindingBuilder toConstructor(Constructor constructor, TypeLiteral type) { + return makeBinder().toConstructor(constructor, type); + } + + @Override + public void in(Class scopeAnnotation) { + makeBinder().in(scopeAnnotation); + } + + @Override + public void in(Scope scope) { + makeBinder().in(scope); + } + + @Override + public void asEagerSingleton() { + makeBinder().asEagerSingleton(); + } + } + + private static class LazyProvider implements LazyBinding, ProviderWithExtensionVisitor> { + private final Provider provider; + private final Key key; + + LazyProvider(Provider provider, Key key) { + this.provider = provider; + this.key = key; + } + + @Override + public Lazy get() { + return new Lazy<>(provider); + } + + @Override + public Key getTargetKey() { + return key; + } + + @SuppressWarnings("unchecked") // B must be Lazy + @Override + public V acceptExtensionVisitor(BindingTargetVisitor visitor, ProviderInstanceBinding binding) { + if (visitor instanceof LazyBindingVisitor) { + return ((LazyBindingVisitor)visitor).visit(this); + } else { + return visitor.visit(binding); + } + } + } +} diff --git a/sangria-lazy/src/main/java/com/tavianator/sangria/lazy/LazyBinding.java b/sangria-lazy/src/main/java/com/tavianator/sangria/lazy/LazyBinding.java new file mode 100644 index 0000000..518ae57 --- /dev/null +++ b/sangria-lazy/src/main/java/com/tavianator/sangria/lazy/LazyBinding.java @@ -0,0 +1,34 @@ +/**************************************************************************** + * Sangria * + * Copyright (C) 2014 Tavian Barnes * + * * + * 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.tavianator.sangria.lazy; + +import com.google.inject.Key; + +/** + * SPI for {@link LazyBinder} bindings. + * + * @author Tavian Barnes (tavianator@tavianator.com) + * @version 1.2 + * @since 1.2 + */ +public interface LazyBinding { + /** + * @return The key wrapped by the {@link Lazy Lazy<T>} binding. + */ + Key getTargetKey(); +} diff --git a/sangria-lazy/src/main/java/com/tavianator/sangria/lazy/LazyBindingVisitor.java b/sangria-lazy/src/main/java/com/tavianator/sangria/lazy/LazyBindingVisitor.java new file mode 100644 index 0000000..ef95a0c --- /dev/null +++ b/sangria-lazy/src/main/java/com/tavianator/sangria/lazy/LazyBindingVisitor.java @@ -0,0 +1,37 @@ +/**************************************************************************** + * Sangria * + * Copyright (C) 2014 Tavian Barnes * + * * + * 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.tavianator.sangria.lazy; + +import com.google.inject.spi.BindingTargetVisitor; + +/** + * Visitor interface for the lazy binding SPI. + * + * @author Tavian Barnes (tavianator@tavianator.com) + * @version 1.2 + * @since 1.2 + */ +public interface LazyBindingVisitor extends BindingTargetVisitor { + /** + * Visit a {@link LazyBinding}. + * + * @param binding The binding to visit. + * @return A value of type {@code V}. + */ + V visit(LazyBinding binding); +} diff --git a/sangria-lazy/src/main/java/com/tavianator/sangria/lazy/package-info.java b/sangria-lazy/src/main/java/com/tavianator/sangria/lazy/package-info.java new file mode 100644 index 0000000..15b5b1a --- /dev/null +++ b/sangria-lazy/src/main/java/com/tavianator/sangria/lazy/package-info.java @@ -0,0 +1,25 @@ +/**************************************************************************** + * Sangria * + * Copyright (C) 2014 Tavian Barnes * + * * + * 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. * + ****************************************************************************/ + +/** + * Lazy loading. + * + * @author Tavian Barnes (tavianator@tavianator.com) + * @version 1.2 + * @since 1.2 + */ +package com.tavianator.sangria.lazy; 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