/*
* Copyright (C) 2008 Google Inc.
*
* 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.inject.assistedinject;
import static com.google.common.base.Preconditions.checkState;
import static com.google.common.collect.Iterables.getOnlyElement;
import com.google.common.base.MoreObjects;
import com.google.common.base.Objects;
import com.google.common.collect.HashMultimap;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Iterables;
import com.google.common.collect.Lists;
import com.google.common.collect.Multimap;
import com.google.common.collect.Sets;
import com.google.inject.AbstractModule;
import com.google.inject.Binder;
import com.google.inject.Binding;
import com.google.inject.ConfigurationException;
import com.google.inject.Inject;
import com.google.inject.Injector;
import com.google.inject.Key;
import com.google.inject.Module;
import com.google.inject.Provider;
import com.google.inject.ProvisionException;
import com.google.inject.Scopes;
import com.google.inject.TypeLiteral;
import com.google.inject.internal.Annotations;
import com.google.inject.internal.BytecodeGen;
import com.google.inject.internal.Errors;
import com.google.inject.internal.ErrorsException;
import com.google.inject.internal.UniqueAnnotations;
import com.google.inject.internal.util.Classes;
import com.google.inject.spi.BindingTargetVisitor;
import com.google.inject.spi.Dependency;
import com.google.inject.spi.HasDependencies;
import com.google.inject.spi.InjectionPoint;
import com.google.inject.spi.Message;
import com.google.inject.spi.ProviderInstanceBinding;
import com.google.inject.spi.ProviderWithExtensionVisitor;
import com.google.inject.spi.Toolable;
import com.google.inject.util.Providers;
import java.lang.annotation.Annotation;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.lang.reflect.Proxy;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
* The newer implementation of factory provider. This implementation uses a child injector to create
* values.
*
* @author jessewilson@google.com (Jesse Wilson)
* @author dtm@google.com (Daniel Martin)
* @author schmitt@google.com (Peter Schmitt)
* @author sameb@google.com (Sam Berlin)
*/
final class FactoryProvider2<F>
implements InvocationHandler,
ProviderWithExtensionVisitor<F>,
HasDependencies,
AssistedInjectBinding<F> {
/** A constant annotation to denote the return value, instead of creating a new one each time. */
static final Annotation RETURN_ANNOTATION = UniqueAnnotations.create();
// use the logger under a well-known name, not FactoryProvider2
static final Logger logger = Logger.getLogger(AssistedInject.class.getName());
/** if a factory method parameter isn't annotated, it gets this annotation. */
static final Assisted DEFAULT_ANNOTATION =
new Assisted() {
@Override
public String value() {
return "";
}
@Override
public Class<? extends Annotation> annotationType() {
return Assisted.class;
}
@Override
public boolean equals(Object o) {
return o instanceof Assisted && ((Assisted) o).value().isEmpty();
}
@Override
public int hashCode() {
return 127 * "value".hashCode() ^ "".hashCode();
}
@Override
public String toString() {
return "@" + Assisted.class.getName() + "(value=)";
}
};
/** All the data necessary to perform an assisted inject. */
private static class AssistData implements AssistedMethod {
/** the constructor the implementation is constructed with. */
final Constructor<?> constructor;
/** the return type in the factory method that the constructor is bound to. */
final Key<?> returnType;
/** the parameters in the factory method associated with this data. */
final ImmutableList<Key<?>> paramTypes;
/** the type of the implementation constructed */
final TypeLiteral<?> implementationType;
/** All non-assisted dependencies required by this method. */
final Set<Dependency<?>> dependencies;
/** The factory method associated with this data */
final Method factoryMethod;
/** true if {@link #isValidForOptimizedAssistedInject} returned true. */
final boolean optimized;
/** the list of optimized providers, empty if not optimized. */
final List<ThreadLocalProvider> providers;
/** used to perform optimized factory creations. */
volatile Binding<?> cachedBinding; // TODO: volatile necessary?
AssistData(
Constructor<?> constructor,
Key<?> returnType,
ImmutableList<Key<?>> paramTypes,
TypeLiteral<?> implementationType,
Method factoryMethod,
Set<Dependency<?>> dependencies,
boolean optimized,
List<ThreadLocalProvider> providers) {
this.constructor = constructor;
this.returnType = returnType;
this.paramTypes = paramTypes;
this.implementationType = implementationType;
this.factoryMethod = factoryMethod;
this.dependencies = dependencies;
this.optimized = optimized;
this.providers = providers;
}
@Override
public String toString() {
return MoreObjects.toStringHelper(getClass())
.add("ctor", constructor)
.add("return type", returnType)
.add("param type", paramTypes)
.add("implementation type", implementationType)
.add("dependencies", dependencies)
.add("factory method", factoryMethod)
.add("optimized", optimized)
.add("providers", providers)
.add("cached binding", cachedBinding)
.toString();
}
@Override
public Set<Dependency<?>> getDependencies() {
return dependencies;
}
@Override
public Method getFactoryMethod() {
return factoryMethod;
}
@Override
public Constructor<?> getImplementationConstructor() {
return constructor;
}
@Override
public TypeLiteral<?> getImplementationType() {
return implementationType;
}
}
/** Mapping from method to the data about how the method will be assisted. */
private final ImmutableMap<Method, AssistData> assistDataByMethod;
/** Mapping from method to method handle, for generated default methods. */
private final ImmutableMap<Method, MethodHandleWrapper> methodHandleByMethod;
/** the hosting injector, or null if we haven't been initialized yet */
private Injector injector;
/** the factory interface, implemented and provided */
private final F factory;
/** The key that this is bound to. */
private final Key<F> factoryKey;
/** The binding collector, for equality/hashing purposes. */
private final BindingCollector collector;
/**
* @param factoryKey a key for a Java interface that defines one or more create methods.
* @param collector binding configuration that maps method return types to implementation types.
*/
FactoryProvider2(Key<F> factoryKey, BindingCollector collector) {
this.factoryKey = factoryKey;
this.collector = collector;
TypeLiteral<F> factoryType = factoryKey.getTypeLiteral();
Errors errors = new Errors();
@SuppressWarnings("unchecked") // we imprecisely treat the class literal of T as a Class<T>
Class<F> factoryRawType = (Class<F>) (Class<?>) factoryType.getRawType();
try {
if (!factoryRawType.isInterface()) {
throw errors.addMessage("%s must be an interface.", factoryRawType).toException();
}
Multimap<String, Method> defaultMethods = HashMultimap.create();
Multimap<String, Method> otherMethods = HashMultimap.create();
ImmutableMap.Builder<Method, AssistData> assistDataBuilder = ImmutableMap.builder();
// TODO: also grab methods from superinterfaces
for (Method method : factoryRawType.getMethods()) {
// Skip static methods
if (Modifier.isStatic(method.getModifiers())) {
continue;
}
// Skip default methods that java8 may have created.
if (isDefault(method) && (method.isBridge() || method.isSynthetic())) {
// Even synthetic default methods need the return type validation...
// unavoidable consequence of javac8. :-(
validateFactoryReturnType(errors, method.getReturnType(), factoryRawType);
defaultMethods.put(method.getName(), method);
continue;
}
otherMethods.put(method.getName(), method);
TypeLiteral<?> returnTypeLiteral = factoryType.getReturnType(method);
Key<?> returnType;
try {
returnType =
Annotations.getKey(returnTypeLiteral, method, method.getAnnotations(), errors);
} catch (ConfigurationException ce) {
// If this was an error due to returnTypeLiteral not being specified, rephrase
// it as our factory not being specified, so it makes more sense to users.
if (isTypeNotSpecified(returnTypeLiteral, ce)) {
throw errors.keyNotFullySpecified(TypeLiteral.get(factoryRawType)).toException();
} else {
throw ce;
}
}
validateFactoryReturnType(errors, returnType.getTypeLiteral().getRawType(), factoryRawType);
List<TypeLiteral<?>> params = factoryType.getParameterTypes(method);
Annotation[][] paramAnnotations = method.getParameterAnnotations();
int p = 0;
List<Key<?>> keys = Lists.newArrayList();
for (TypeLiteral<?> param : params) {
Key<?> paramKey = Annotations.getKey(param, method, paramAnnotations[p++], errors);
Class<?> underlylingType = paramKey.getTypeLiteral().getRawType();
if (underlylingType.equals(Provider.class)
|| underlylingType.equals(javax.inject.Provider.class)) {
errors.addMessage(
"A Provider may not be a type in a factory method of an AssistedInject."
+ "\n Offending instance is parameter [%s] with key [%s] on method [%s]",
p, paramKey, method);
}
keys.add(assistKey(method, paramKey, errors));
}
ImmutableList<Key<?>> immutableParamList = ImmutableList.copyOf(keys);
// try to match up the method to the constructor
TypeLiteral<?> implementation = collector.getBindings().get(returnType);
if (implementation == null) {
implementation = returnType.getTypeLiteral();
}
Class<? extends Annotation> scope =
Annotations.findScopeAnnotation(errors, implementation.getRawType());
if (scope != null) {
errors.addMessage(
"Found scope annotation [%s] on implementation class "
+ "[%s] of AssistedInject factory [%s].\nThis is not allowed, please"
+ " remove the scope annotation.",
scope, implementation.getRawType(), factoryType);
}
InjectionPoint ctorInjectionPoint;
try {
ctorInjectionPoint =
findMatchingConstructorInjectionPoint(
method, returnType, implementation, immutableParamList);
} catch (ErrorsException ee) {
errors.merge(ee.getErrors());
continue;
}
Constructor<?> constructor = (Constructor<?>) ctorInjectionPoint.getMember();
List<ThreadLocalProvider> providers = Collections.emptyList();
Set<Dependency<?>> deps = getDependencies(ctorInjectionPoint, implementation);
boolean optimized = false;
// Now go through all dependencies of the implementation and see if it is OK to
// use an optimized form of assistedinject2. The optimized form requires that
// all injections directly inject the object itself (and not a Provider of the object,
// or an Injector), because it caches a single child injector and mutates the Provider
// of the arguments in a ThreadLocal.
if (isValidForOptimizedAssistedInject(deps, implementation.getRawType(), factoryType)) {
ImmutableList.Builder<ThreadLocalProvider> providerListBuilder = ImmutableList.builder();
for (int i = 0; i < params.size(); i++) {
providerListBuilder.add(new ThreadLocalProvider());
}
providers = providerListBuilder.build();
optimized = true;
}
AssistData data =
new AssistData(
constructor,
returnType,
immutableParamList,
implementation,
method,
removeAssistedDeps(deps),
optimized,
providers);
assistDataBuilder.put(method, data);
}
factory =
factoryRawType.cast(
Proxy.newProxyInstance(
BytecodeGen.getClassLoader(factoryRawType),
new Class<?>[] {factoryRawType},
this));
// Now go back through default methods. Try to use MethodHandles to make things
// work. If that doesn't work, fallback to trying to find compatible method
// signatures.
Map<Method, AssistData> dataSoFar = assistDataBuilder.build();
ImmutableMap.Builder<Method, MethodHandleWrapper> methodHandleBuilder =
ImmutableMap.builder();
for (Map.Entry<String, Method> entry : defaultMethods.entries()) {
Method defaultMethod = entry.getValue();
MethodHandleWrapper handle = MethodHandleWrapper.create(defaultMethod, factory);
if (handle != null) {
methodHandleBuilder.put(defaultMethod, handle);
} else {
boolean foundMatch = false;
for (Method otherMethod : otherMethods.get(defaultMethod.getName())) {
if (dataSoFar.containsKey(otherMethod) && isCompatible(defaultMethod, otherMethod)) {
if (foundMatch) {
errors.addMessage(
"Generated default method %s with parameters %s is"
+ " signature-compatible with more than one non-default method."
+ " Unable to create factory. As a workaround, remove the override"
+ " so javac stops generating a default method.",
defaultMethod, Arrays.asList(defaultMethod.getParameterTypes()));
} else {
assistDataBuilder.put(defaultMethod, dataSoFar.get(otherMethod));
foundMatch = true;
}
}
}
if (!foundMatch) {
throw new IllegalStateException("Can't find method compatible with: " + defaultMethod);
}
}
}
// If we generated any errors (from finding matching constructors, for instance), throw an exception.
if (errors.hasErrors()) {
throw errors.toException();
}
assistDataByMethod = assistDataBuilder.build();
methodHandleByMethod = methodHandleBuilder.build();
} catch (ErrorsException e) {
throw new ConfigurationException(e.getErrors().getMessages());
}
}
static boolean isDefault(Method method) {
// Per the javadoc, default methods are non-abstract, public, non-static.
// They're also in interfaces, but we can guarantee that already since we only act
// on interfaces.
return (method.getModifiers() & (Modifier.ABSTRACT | Modifier.PUBLIC | Modifier.STATIC))
== Modifier.PUBLIC;
}
private boolean isCompatible(Method src, Method dst) {
if (!src.getReturnType().isAssignableFrom(dst.getReturnType())) {
return false;
}
Class<?>[] srcParams = src.getParameterTypes();
Class<?>[] dstParams = dst.getParameterTypes();
if (srcParams.length != dstParams.length) {
return false;
}
for (int i = 0; i < srcParams.length; i++) {
if (!srcParams[i].isAssignableFrom(dstParams[i])) {
return false;
}
}
return true;
}
@Override
public F get() {
return factory;
}
@Override
public Set<Dependency<?>> getDependencies() {
Set<Dependency<?>> combinedDeps = new HashSet<Dependency<?>>();
for (AssistData data : assistDataByMethod.values()) {
combinedDeps.addAll(data.dependencies);
}
return ImmutableSet.copyOf(combinedDeps);
}
@Override
public Key<F> getKey() {
return factoryKey;
}
// Safe cast because values are typed to AssistedData, which is an AssistedMethod, and
// the collection is immutable.
@Override
@SuppressWarnings("unchecked")
public Collection<AssistedMethod> getAssistedMethods() {
return (Collection<AssistedMethod>) (Collection<?>) assistDataByMethod.values();
}
@Override
@SuppressWarnings("unchecked")
public <T, V> V acceptExtensionVisitor(
BindingTargetVisitor<T, V> visitor, ProviderInstanceBinding<? extends T> binding) {
if (visitor instanceof AssistedInjectTargetVisitor) {
return ((AssistedInjectTargetVisitor<T, V>) visitor).visit((AssistedInjectBinding<T>) this);
}
return visitor.visit(binding);
}
private void validateFactoryReturnType(Errors errors, Class<?> returnType, Class<?> factoryType) {
if (Modifier.isPublic(factoryType.getModifiers())
&& !Modifier.isPublic(returnType.getModifiers())) {
errors.addMessage(
"%s is public, but has a method that returns a non-public type: %s. "
+ "Due to limitations with java.lang.reflect.Proxy, this is not allowed. "
+ "Please either make the factory non-public or the return type public.",
factoryType, returnType);
}
}
/**
* Returns true if the ConfigurationException is due to an error of TypeLiteral not being fully
* specified.
*/
private boolean isTypeNotSpecified(TypeLiteral<?> typeLiteral, ConfigurationException ce) {
Collection<Message> messages = ce.getErrorMessages();
if (messages.size() == 1) {
Message msg =
Iterables.getOnlyElement(new Errors().keyNotFullySpecified(typeLiteral).getMessages());
return msg.getMessage().equals(Iterables.getOnlyElement(messages).getMessage());
} else {
return false;
}
}
/**
* Finds a constructor suitable for the method. If the implementation contained any constructors
* marked with {@link AssistedInject}, this requires all {@link Assisted} parameters to exactly
* match the parameters (in any order) listed in the method. Otherwise, if no {@link
* AssistedInject} constructors exist, this will default to looking for an {@literal @}{@link
* Inject} constructor.
*/
private <T> InjectionPoint findMatchingConstructorInjectionPoint(
Method method, Key<?> returnType, TypeLiteral<T> implementation, List<Key<?>> paramList)
throws ErrorsException {
Errors errors = new Errors(method);
if (returnType.getTypeLiteral().equals(implementation)) {
errors = errors.withSource(implementation);
} else {
errors = errors.withSource(returnType).withSource(implementation);
}
Class<?> rawType = implementation.getRawType();
if (Modifier.isInterface(rawType.getModifiers())) {
errors.addMessage(
"%s is an interface, not a concrete class. Unable to create AssistedInject factory.",
implementation);
throw errors.toException();
} else if (Modifier.isAbstract(rawType.getModifiers())) {
errors.addMessage(
"%s is abstract, not a concrete class. Unable to create AssistedInject factory.",
implementation);
throw errors.toException();
} else if (Classes.isInnerClass(rawType)) {
errors.cannotInjectInnerClass(rawType);
throw errors.toException();
}
Constructor<?> matchingConstructor = null;
boolean anyAssistedInjectConstructors = false;
// Look for AssistedInject constructors...
for (Constructor<?> constructor : rawType.getDeclaredConstructors()) {
if (constructor.isAnnotationPresent(AssistedInject.class)) {
anyAssistedInjectConstructors = true;
if (constructorHasMatchingParams(implementation, constructor, paramList, errors)) {
if (matchingConstructor != null) {
errors.addMessage(
"%s has more than one constructor annotated with @AssistedInject"
+ " that matches the parameters in method %s. Unable to create "
+ "AssistedInject factory.",
implementation, method);
throw errors.toException();
} else {
matchingConstructor = constructor;
}
}
}
}
if (!anyAssistedInjectConstructors) {
// If none existed, use @Inject.
try {
return InjectionPoint.forConstructorOf(implementation);
} catch (ConfigurationException e) {
errors.merge(e.getErrorMessages());
throw errors.toException();
}
} else {
// Otherwise, use it or fail with a good error message.
if (matchingConstructor != null) {
// safe because we got the constructor from this implementation.
@SuppressWarnings("unchecked")
InjectionPoint ip =
InjectionPoint.forConstructor(
(Constructor<? super T>) matchingConstructor, implementation);
return ip;
} else {
errors.addMessage(
"%s has @AssistedInject constructors, but none of them match the"
+ " parameters in method %s. Unable to create AssistedInject factory.",
implementation, method);
throw errors.toException();
}
}
}
/**
* Matching logic for constructors annotated with AssistedInject. This returns true if and only if
* all @Assisted parameters in the constructor exactly match (in any order) all @Assisted
* parameters the method's parameter.
*/
private boolean constructorHasMatchingParams(
TypeLiteral<?> type, Constructor<?> constructor, List<Key<?>> paramList, Errors errors)
throws ErrorsException {
List<TypeLiteral<?>> params = type.getParameterTypes(constructor);
Annotation[][] paramAnnotations = constructor.getParameterAnnotations();
int p = 0;
List<Key<?>> constructorKeys = Lists.newArrayList();
for (TypeLiteral<?> param : params) {
Key<?> paramKey = Annotations.getKey(param, constructor, paramAnnotations[p++], errors);
constructorKeys.add(paramKey);
}
// Require that every key exist in the constructor to match up exactly.
for (Key<?> key : paramList) {
// If it didn't exist in the constructor set, we can't use it.
if (!constructorKeys.remove(key)) {
return false;
}
}
// If any keys remain and their annotation is Assisted, we can't use it.
for (Key<?> key : constructorKeys) {
if (key.getAnnotationType() == Assisted.class) {
return false;
}
}
// All @Assisted params match up to the method's parameters.
return true;
}
/** Calculates all dependencies required by the implementation and constructor. */
private Set<Dependency<?>> getDependencies(
InjectionPoint ctorPoint, TypeLiteral<?> implementation) {
ImmutableSet.Builder<Dependency<?>> builder = ImmutableSet.builder();
builder.addAll(ctorPoint.getDependencies());
if (!implementation.getRawType().isInterface()) {
for (InjectionPoint ip : InjectionPoint.forInstanceMethodsAndFields(implementation)) {
builder.addAll(ip.getDependencies());
}
}
return builder.build();
}
/** Return all non-assisted dependencies. */
private Set<Dependency<?>> removeAssistedDeps(Set<Dependency<?>> deps) {
ImmutableSet.Builder<Dependency<?>> builder = ImmutableSet.builder();
for (Dependency<?> dep : deps) {
Class<?> annotationType = dep.getKey().getAnnotationType();
if (annotationType == null || !annotationType.equals(Assisted.class)) {
builder.add(dep);
}
}
return builder.build();
}
/**
* Returns true if all dependencies are suitable for the optimized version of AssistedInject. The
* optimized version caches the binding & uses a ThreadLocal Provider, so can only be applied if
* the assisted bindings are immediately provided. This looks for hints that the values may be
* lazily retrieved, by looking for injections of Injector or a Provider for the assisted values.
*/
private boolean isValidForOptimizedAssistedInject(
Set<Dependency<?>> dependencies, Class<?> implementation, TypeLiteral<?> factoryType) {
Set<Dependency<?>> badDeps = null; // optimization: create lazily
for (Dependency<?> dep : dependencies) {
if (isInjectorOrAssistedProvider(dep)) {
if (badDeps == null) {
badDeps = Sets.newHashSet();
}
badDeps.add(dep);
}
}
if (badDeps != null && !badDeps.isEmpty()) {
logger.log(
Level.WARNING,
"AssistedInject factory {0} will be slow "
+ "because {1} has assisted Provider dependencies or injects the Injector. "
+ "Stop injecting @Assisted Provider<T> (instead use @Assisted T) "
+ "or Injector to speed things up. (It will be a ~6500% speed bump!) "
+ "The exact offending deps are: {2}",
new Object[] {factoryType, implementation, badDeps});
return false;
}
return true;
}
/**
* Returns true if the dependency is for {@link Injector} or if the dependency is a {@link
* Provider} for a parameter that is {@literal @}{@link Assisted}.
*/
private boolean isInjectorOrAssistedProvider(Dependency<?> dependency) {
Class<?> annotationType = dependency.getKey().getAnnotationType();
if (annotationType != null && annotationType.equals(Assisted.class)) { // If it's assisted..
if (dependency
.getKey()
.getTypeLiteral()
.getRawType()
.equals(Provider.class)) { // And a Provider...
return true;
}
} else if (dependency
.getKey()
.getTypeLiteral()
.getRawType()
.equals(Injector.class)) { // If it's the Injector...
return true;
}
return false;
}
/**
* Returns a key similar to {@code key}, but with an {@literal @}Assisted binding annotation. This
* fails if another binding annotation is clobbered in the process. If the key already has the
* {@literal @}Assisted annotation, it is returned as-is to preserve any String value.
*/
private <T> Key<T> assistKey(Method method, Key<T> key, Errors errors) throws ErrorsException {
if (key.getAnnotationType() == null) {
return Key.get(key.getTypeLiteral(), DEFAULT_ANNOTATION);
} else if (key.getAnnotationType() == Assisted.class) {
return key;
} else {
errors
.withSource(method)
.addMessage(
"Only @Assisted is allowed for factory parameters, but found @%s",
key.getAnnotationType());
throw errors.toException();
}
}
/**
* At injector-creation time, we initialize the invocation handler. At this time we make sure all
* factory methods will be able to build the target types.
*/
@Inject
@Toolable
void initialize(Injector injector) {
if (this.injector != null) {
throw new ConfigurationException(
ImmutableList.of(
new Message(
FactoryProvider2.class,
"Factories.create() factories may only be used in one Injector!")));
}
this.injector = injector;
for (Map.Entry<Method, AssistData> entry : assistDataByMethod.entrySet()) {
Method method = entry.getKey();
AssistData data = entry.getValue();
Object[] args;
if (!data.optimized) {
args = new Object[method.getParameterTypes().length];
Arrays.fill(args, "dummy object for validating Factories");
} else {
args = null; // won't be used -- instead will bind to data.providers.
}
getBindingFromNewInjector(
method, args, data); // throws if the binding isn't properly configured
}
}
/**
* Creates a child injector that binds the args, and returns the binding for the method's result.
*/
public Binding<?> getBindingFromNewInjector(
final Method method, final Object[] args, final AssistData data) {
checkState(
injector != null,
"Factories.create() factories cannot be used until they're initialized by Guice.");
final Key<?> returnType = data.returnType;
// We ignore any pre-existing binding annotation.
final Key<?> returnKey = Key.get(returnType.getTypeLiteral(), RETURN_ANNOTATION);
Module assistedModule =
new AbstractModule() {
@Override
@SuppressWarnings({
"unchecked",
"rawtypes"
}) // raw keys are necessary for the args array and return value
protected void configure() {
Binder binder = binder().withSource(method);
int p = 0;
if (!data.optimized) {
for (Key<?> paramKey : data.paramTypes) {
// Wrap in a Provider to cover null, and to prevent Guice from injecting the parameter
binder.bind((Key) paramKey).toProvider(Providers.of(args[p++]));
}
} else {
for (Key<?> paramKey : data.paramTypes) {
// Bind to our ThreadLocalProviders.
binder.bind((Key) paramKey).toProvider(data.providers.get(p++));
}
}
Constructor constructor = data.constructor;
// Constructor *should* always be non-null here,
// but if it isn't, we'll end up throwing a fairly good error
// message for the user.
if (constructor != null) {
binder
.bind(returnKey)
.toConstructor(constructor, (TypeLiteral) data.implementationType)
.in(Scopes.NO_SCOPE); // make sure we erase any scope on the implementation type
}
}
};
Injector forCreate = injector.createChildInjector(assistedModule);
Binding<?> binding = forCreate.getBinding(returnKey);
// If we have providers cached in data, cache the binding for future optimizations.
if (data.optimized) {
data.cachedBinding = binding;
}
return binding;
}
/**
* When a factory method is invoked, we create a child injector that binds all parameters, then
* use that to get an instance of the return type.
*/
@Override
public Object invoke(Object proxy, final Method method, final Object[] args) throws Throwable {
// If we setup a method handle earlier for this method, call it.
// This is necessary for default methods that java8 creates, so we
// can call the default method implementation (and not our proxied version of it).
if (methodHandleByMethod.containsKey(method)) {
return methodHandleByMethod.get(method).invokeWithArguments(args);
}
if (method.getDeclaringClass().equals(Object.class)) {
if ("equals".equals(method.getName())) {
return proxy == args[0];
} else if ("hashCode".equals(method.getName())) {
return System.identityHashCode(proxy);
} else {
return method.invoke(this, args);
}
}
AssistData data = assistDataByMethod.get(method);
checkState(data != null, "No data for method: %s", method);
Provider<?> provider;
if (data.cachedBinding != null) { // Try to get optimized form...
provider = data.cachedBinding.getProvider();
} else {
provider = getBindingFromNewInjector(method, args, data).getProvider();
}
try {
int p = 0;
for (ThreadLocalProvider tlp : data.providers) {
tlp.set(args[p++]);
}
return provider.get();
} catch (ProvisionException e) {
// if this is an exception declared by the factory method, throw it as-is
if (e.getErrorMessages().size() == 1) {
Message onlyError = getOnlyElement(e.getErrorMessages());
Throwable cause = onlyError.getCause();
if (cause != null && canRethrow(method, cause)) {
throw cause;
}
}
throw e;
} finally {
for (ThreadLocalProvider tlp : data.providers) {
tlp.remove();
}
}
}
@Override
public String toString() {
return factory.getClass().getInterfaces()[0].getName();
}
@Override
public int hashCode() {
return Objects.hashCode(factoryKey, collector);
}
@Override
public boolean equals(Object obj) {
if (!(obj instanceof FactoryProvider2)) {
return false;
}
FactoryProvider2<?> other = (FactoryProvider2<?>) obj;
return factoryKey.equals(other.factoryKey) && Objects.equal(collector, other.collector);
}
/** Returns true if {@code thrown} can be thrown by {@code invoked} without wrapping. */
static boolean canRethrow(Method invoked, Throwable thrown) {
if (thrown instanceof Error || thrown instanceof RuntimeException) {
return true;
}
for (Class<?> declared : invoked.getExceptionTypes()) {
if (declared.isInstance(thrown)) {
return true;
}
}
return false;
}
// not <T> because we'll never know and this is easier than suppressing warnings.
private static class ThreadLocalProvider extends ThreadLocal<Object> implements Provider<Object> {
@Override
protected Object initialValue() {
throw new IllegalStateException(
"Cannot use optimized @Assisted provider outside the scope of the constructor."
+ " (This should never happen. If it does, please report it.)");
}
}
/** Wrapper around MethodHandles/MethodHandle, so we can compile+run on java6. */
private static class MethodHandleWrapper {
static final int ALL_MODES =
Modifier.PRIVATE | Modifier.STATIC /* package */ | Modifier.PUBLIC | Modifier.PROTECTED;
static final Method unreflectSpecial;
static final Method bindTo;
static final Method invokeWithArguments;
static final Constructor<?> lookupCxtor;
static final boolean valid;
static {
Method unreflectSpecialTmp = null;
Method bindToTmp = null;
Method invokeWithArgumentsTmp = null;
boolean validTmp = false;
Constructor<?> lookupCxtorTmp = null;
try {
Class<?> lookupClass = Class.forName("java.lang.invoke.MethodHandles$Lookup");
unreflectSpecialTmp = lookupClass.getMethod("unreflectSpecial", Method.class, Class.class);
Class<?> methodHandleClass = Class.forName("java.lang.invoke.MethodHandle");
bindToTmp = methodHandleClass.getMethod("bindTo", Object.class);
invokeWithArgumentsTmp = methodHandleClass.getMethod("invokeWithArguments", Object[].class);
lookupCxtorTmp = lookupClass.getDeclaredConstructor(Class.class, int.class);
lookupCxtorTmp.setAccessible(true);
validTmp = true;
} catch (Exception invalid) {
// Ignore the exception, store the values & exit early in create(..) if invalid.
}
// Store refs to later.
valid = validTmp;
unreflectSpecial = unreflectSpecialTmp;
bindTo = bindToTmp;
invokeWithArguments = invokeWithArgumentsTmp;
lookupCxtor = lookupCxtorTmp;
}
static MethodHandleWrapper create(Method method, Object proxy) {
if (!valid) {
return null;
}
try {
Class<?> declaringClass = method.getDeclaringClass();
// Note: this isn't a public API, but we need to use it in order to call default methods.
Object lookup = lookupCxtor.newInstance(declaringClass, ALL_MODES);
method.setAccessible(true);
// These are part of the public API, but we use reflection since we run on java6
// and they were introduced in java7.
lookup = unreflectSpecial.invoke(lookup, method, declaringClass);
Object handle = bindTo.invoke(lookup, proxy);
return new MethodHandleWrapper(handle);
} catch (InvocationTargetException ite) {
return null;
} catch (IllegalAccessException iae) {
return null;
} catch (InstantiationException ie) {
return null;
}
}
final Object handle;
MethodHandleWrapper(Object handle) {
this.handle = handle;
}
Object invokeWithArguments(Object[] args) throws Exception {
// We must cast the args to an object so the Object[] is the first param,
// as opposed to each individual varargs param.
return invokeWithArguments.invoke(handle, (Object) args);
}
@Override
public String toString() {
return handle.toString();
}
}
}