/**
* Copyright (C) 2006 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.internal;
import com.google.inject.Binding;
import com.google.inject.Injector;
import com.google.inject.Key;
import com.google.inject.MembersInjector;
import com.google.inject.Module;
import com.google.inject.Provider;
import com.google.inject.Stage;
import com.google.inject.TypeLiteral;
import com.google.inject.spi.Dependency;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.Set;
/**
* Builds a tree of injectors. This is a primary injector, plus child injectors needed for each
* {@code Binder.newPrivateBinder() private environment}. The primary injector is not necessarily a
* top-level injector.
*
* <p>Injector construction happens in two phases.
* <ol>
* <li>Static building. In this phase, we interpret commands, create bindings, and inspect
* dependencies. During this phase, we hold a lock to ensure consistency with parent injectors.
* No user code is executed in this phase.</li>
* <li>Dynamic injection. In this phase, we call user code. We inject members that requested
* injection. This may require user's objects be created and their providers be called. And we
* create eager singletons. In this phase, user code may have started other threads. This phase
* is not executed for injectors created using {@link Stage#TOOL the tool stage}</li>
* </ol>
*
* @author crazybob@google.com (Bob Lee)
* @author jessewilson@google.com (Jesse Wilson)
*/
public final class InjectorBuilder {
private final Stopwatch stopwatch = new Stopwatch();
private final Errors errors = new Errors();
private Stage stage;
private final Initializer initializer = new Initializer();
private final BindingProcessor bindingProcesor;
private final InjectionRequestProcessor injectionRequestProcessor;
private final InjectorShell.Builder shellBuilder = new InjectorShell.Builder();
private List<InjectorShell> shells;
public InjectorBuilder() {
injectionRequestProcessor = new InjectionRequestProcessor(errors, initializer);
bindingProcesor = new BindingProcessor(errors, initializer);
}
/**
* Sets the stage for the created injector. If the stage is {@link Stage#PRODUCTION}, this class
* will eagerly load singletons.
*/
public InjectorBuilder stage(Stage stage) {
shellBuilder.stage(stage);
this.stage = stage;
return this;
}
/**
* Sets the parent of the injector to-be-constructed. As a side effect, this sets this injector's
* stage to the stage of {@code parent}.
*/
public InjectorBuilder parentInjector(InjectorImpl parent) {
shellBuilder.parent(parent);
return stage(parent.getInstance(Stage.class));
}
public InjectorBuilder addModules(Iterable<? extends Module> modules) {
shellBuilder.addModules(modules);
return this;
}
public Injector build() {
if (shellBuilder == null) {
throw new AssertionError("Already built, builders are not reusable.");
}
// Synchronize while we're building up the bindings and other injector state. This ensures that
// the JIT bindings in the parent injector don't change while we're being built
synchronized (shellBuilder.lock()) {
shells = shellBuilder.build(initializer, bindingProcesor, stopwatch, errors);
stopwatch.resetAndLog("Injector construction");
initializeStatically();
}
// If we're in the tool stage, stop here. Don't eagerly inject or load anything.
if (stage == Stage.TOOL) {
return new ToolStageInjector(primaryInjector());
}
injectDynamically();
return primaryInjector();
}
/** Initialize and validate everything. */
private void initializeStatically() {
bindingProcesor.initializeBindings();
stopwatch.resetAndLog("Binding initialization");
for (InjectorShell shell : shells) {
shell.getInjector().index();
}
stopwatch.resetAndLog("Binding indexing");
injectionRequestProcessor.process(shells);
stopwatch.resetAndLog("Collecting injection requests");
bindingProcesor.runCreationListeners();
stopwatch.resetAndLog("Binding validation");
injectionRequestProcessor.validate();
stopwatch.resetAndLog("Static validation");
initializer.validateOustandingInjections(errors);
stopwatch.resetAndLog("Instance member validation");
new LookupProcessor(errors).process(shells);
for (InjectorShell shell : shells) {
((DeferredLookups) shell.getInjector().lookups).initialize(errors);
}
stopwatch.resetAndLog("Provider verification");
for (InjectorShell shell : shells) {
if (!shell.getElements().isEmpty()) {
throw new AssertionError("Failed to execute " + shell.getElements());
}
}
errors.throwCreationExceptionIfErrorsExist();
}
/**
* Returns the injector being constructed. This is not necessarily the root injector.
*/
private Injector primaryInjector() {
return shells.get(0).getInjector();
}
/**
* Inject everything that can be injected. This method is intentionally not synchronized. If we
* locked while injecting members (ie. running user code), things would deadlock should the user
* code build a just-in-time binding from another thread.
*/
private void injectDynamically() {
injectionRequestProcessor.injectMembers();
stopwatch.resetAndLog("Static member injection");
initializer.injectAll(errors);
stopwatch.resetAndLog("Instance injection");
errors.throwCreationExceptionIfErrorsExist();
for (InjectorShell shell : shells) {
loadEagerSingletons(shell.getInjector(), stage, errors);
}
stopwatch.resetAndLog("Preloading singletons");
errors.throwCreationExceptionIfErrorsExist();
}
/**
* Loads eager singletons, or all singletons if we're in Stage.PRODUCTION. Bindings discovered
* while we're binding these singletons are not be eager.
*/
void loadEagerSingletons(InjectorImpl injector, Stage stage, final Errors errors) {
@SuppressWarnings("unchecked") // casting Collection<Binding> to Collection<BindingImpl> is safe
Set<BindingImpl<?>> candidateBindings = ImmutableSet.copyOf(Iterables.concat(
(Collection) injector.state.getExplicitBindingsThisLevel().values(),
injector.jitBindings.values()));
for (final BindingImpl<?> binding : candidateBindings) {
if (isEagerSingleton(injector, binding, stage)) {
try {
injector.callInContext(new ContextualCallable<Void>() {
Dependency<?> dependency = Dependency.get(binding.getKey());
public Void call(InternalContext context) {
Dependency previous = context.setDependency(dependency);
Errors errorsForBinding = errors.withSource(dependency);
try {
binding.getInternalFactory().get(errorsForBinding, context, dependency);
} catch (ErrorsException e) {
errorsForBinding.merge(e.getErrors());
} finally {
context.setDependency(previous);
}
return null;
}
});
} catch (ErrorsException e) {
throw new AssertionError();
}
}
}
}
private boolean isEagerSingleton(InjectorImpl injector, BindingImpl<?> binding, Stage stage) {
if (binding.getScoping().isEagerSingleton(stage)) {
return true;
}
// handle a corner case where a child injector links to a binding in a parent injector, and
// that binding is singleton. We won't catch this otherwise because we only iterate the child's
// bindings.
if (binding instanceof LinkedBindingImpl) {
Key<?> linkedBinding = ((LinkedBindingImpl<?>) binding).getLinkedKey();
return isEagerSingleton(injector, injector.getBinding(linkedBinding), stage);
}
return false;
}
/** {@link Injector} exposed to users in {@link Stage#TOOL}. */
static class ToolStageInjector implements Injector {
private final Injector delegateInjector;
ToolStageInjector(Injector delegateInjector) {
this.delegateInjector = delegateInjector;
}
public void injectMembers(Object o) {
throw new UnsupportedOperationException(
"Injector.injectMembers(Object) is not supported in Stage.TOOL");
}
public Map<Key<?>, Binding<?>> getBindings() {
return this.delegateInjector.getBindings();
}
public Map<Key<?>, Binding<?>> getAllBindings() {
return this.delegateInjector.getAllBindings();
}
public <T> Binding<T> getBinding(Key<T> key) {
return this.delegateInjector.getBinding(key);
}
public <T> Binding<T> getBinding(Class<T> type) {
return this.delegateInjector.getBinding(type);
}
public <T> List<Binding<T>> findBindingsByType(TypeLiteral<T> type) {
return this.delegateInjector.findBindingsByType(type);
}
public Injector getParent() {
return delegateInjector.getParent();
}
public Injector createChildInjector(Iterable<? extends Module> modules) {
return delegateInjector.createChildInjector(modules);
}
public Injector createChildInjector(Module... modules) {
return delegateInjector.createChildInjector(modules);
}
public <T> Provider<T> getProvider(Key<T> key) {
throw new UnsupportedOperationException(
"Injector.getProvider(Key<T>) is not supported in Stage.TOOL");
}
public <T> Provider<T> getProvider(Class<T> type) {
throw new UnsupportedOperationException(
"Injector.getProvider(Class<T>) is not supported in Stage.TOOL");
}
public <T> MembersInjector<T> getMembersInjector(TypeLiteral<T> typeLiteral) {
throw new UnsupportedOperationException(
"Injector.getMembersInjector(TypeLiteral<T>) is not supported in Stage.TOOL");
}
public <T> MembersInjector<T> getMembersInjector(Class<T> type) {
throw new UnsupportedOperationException(
"Injector.getMembersInjector(Class<T>) is not supported in Stage.TOOL");
}
public <T> T getInstance(Key<T> key) {
throw new UnsupportedOperationException(
"Injector.getInstance(Key<T>) is not supported in Stage.TOOL");
}
public <T> T getInstance(Class<T> type) {
throw new UnsupportedOperationException(
"Injector.getInstance(Class<T>) is not supported in Stage.TOOL");
}
}
}