org.glassfish.jersey.process.internal.RequestScope Maven / Gradle / Ivy
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package org.glassfish.jersey.process.internal;
import java.lang.annotation.Annotation;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.Callable;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.inject.Singleton;
import org.glassfish.jersey.internal.inject.AbstractBinder;
import org.glassfish.jersey.internal.util.ExtendedLogger;
import org.glassfish.jersey.internal.util.LazyUid;
import org.glassfish.jersey.internal.util.Producer;
import org.glassfish.hk2.api.ActiveDescriptor;
import org.glassfish.hk2.api.Context;
import org.glassfish.hk2.api.ServiceHandle;
import com.google.common.base.Objects;
import static com.google.common.base.Preconditions.checkState;
/**
* Scopes a single request/response processing execution on a single thread.
*
* To execute a code inside of the request scope use one of the {@code runInScope(...)}
* methods and supply the task encapsulating the code that should be executed in the scope.
*
*
* Example:
*
*
* @Inject
* RequestScope requestScope;
*
* ...
*
* requestScope.runInScope(new Runnable() {
* @Override
* public void run() {
* System.out.println("This is execute in the request scope...");
* }
* });
*
*
* An instance of the request scope can be suspended and retrieved via a call to
* {@link RequestScope#suspendCurrent} method. This instance can be later
* used to resume the same request scope and run another task in the same scope:
*
*
* Instance requestScopeInstance =
* requestScope.runInScope(new Callable<Instance>() {
* @Override
* public Instance call() {
* // This is execute in the new request scope.
*
* // The following call will cause that the
* // RequestScope.Instance will not be released
* // automatically and we will have to release
* // it explicitly at the end.
* return requestScope.suspendCurrent();
* }
* });
*
* requestScope.runInScope(requestScopeInstance, new Runnable() {
*
* @Override
* public void run() {
* // This is execute in the same request scope as code above.
* }
* });
*
* // we must release the scope instance explicitly
* requestScopeInstance.release();
*
*
* In the previous example the {@link RequestScope.Instance request scope instance}
* was suspended and retrieved which also informs {@code requestScope} that it
* should not automatically release the instance once the running task is finished.
* The {@code requestScopeInstance} is then used to initialize the next
* request-scoped execution. The second task will run in the same request scope as the
* first task. At the end the suspended {@code requestScopeInstance} must be
* manually {@link RequestScope.Instance#release released}. Not releasing the instance
* could cause memory leaks. Please note that calling {@link RequestScope#suspendCurrent}
* does not retrieve an immutable snapshot of the current request scope but
* a live reference to the internal {@link RequestScope.Instance request scope instance}
* which may change it's state during each request-scoped task execution for
* which this scope instance is used.
*
*
* @author Marek Potociar (marek.potociar at oracle.com)
* @author Miroslav Fuksa (miroslav.fuksa at oracle.com)
*/
@Singleton
public class RequestScope implements Context {
private static final ExtendedLogger logger = new ExtendedLogger(Logger.getLogger(RequestScope.class.getName()), Level.FINEST);
/**
* A thread local copy of the current scope instance.
*/
private ThreadLocal currentScopeInstance = new ThreadLocal();
@Override
public Class getScope() {
return RequestScoped.class;
}
@Override
public U findOrCreate(ActiveDescriptor activeDescriptor, ServiceHandle root) {
final Instance instance = current();
U retVal = instance.get(activeDescriptor);
if (retVal == null) {
retVal = activeDescriptor.create(root);
instance.put(activeDescriptor, retVal);
}
return retVal;
}
@Override
public boolean containsKey(ActiveDescriptor descriptor) {
Instance instance = current();
return instance.contains(descriptor);
}
@Override
public boolean supportsNullCreation() {
return true;
}
@Override
public boolean isActive() {
return true;
}
@Override
public void destroyOne(ActiveDescriptor descriptor) {
final Instance instance = current();
instance.remove(descriptor);
}
@Override
public void shutdown() {
currentScopeInstance = null;
}
/**
* Request scope injection binder.
*/
public static class Binder extends AbstractBinder {
@Override
protected void configure() {
bind(new RequestScope()).to(RequestScope.class);
}
}
/**
* Get a new reference for to currently running request scope instance. This call
* prevents automatic {@link RequestScope.Instance#release() release} of the scope
* instance once the task that runs in the scope has finished.
*
* The returned scope instance may be used to run additional task(s) in the
* same request scope using one of the {@code #runInScope(Instance, ...)} methods.
*
*
* Note that the returned instance must be {@link RequestScope.Instance#release()
* released} manually once not needed anymore to prevent memory leaks.
*
*
* @return currently active {@link RequestScope.Instance request scope instance}.
* @throws IllegalStateException in case there is no active request scope associated
* with the current thread.
* @see #suspendCurrent()
*/
public Instance referenceCurrent() throws IllegalStateException {
return current().getReference();
}
private Instance current() {
Instance scopeInstance = currentScopeInstance.get();
checkState(scopeInstance != null, "Not inside a request scope.");
return scopeInstance;
}
/**
* Get the current {@link RequestScope.Instance request scope instance}
* and mark it as suspended. This call prevents automatic
* {@link RequestScope.Instance#release() release} of the scope instance
* once the task that runs in the scope has finished.
*
* The returned scope instance may be used to run additional task(s) in the
* same request scope using one of the {@code #runInScope(Instance, ...)} methods.
*
*
* Note that the returned instance must be {@link RequestScope.Instance#release()
* released} manually once not needed anymore to prevent memory leaks.
*
*
* @return currently active {@link RequestScope.Instance request scope instance}
* that was suspended or {@code null} if the thread is not currently running
* in an active request scope.
* @see #referenceCurrent()
*/
public Instance suspendCurrent() {
final Instance scopeInstance = currentScopeInstance.get();
if (scopeInstance == null) {
return null;
}
try {
return scopeInstance.getReference();
} finally {
logger.debugLog("Returned a new reference of the request scope instance {0}", scopeInstance);
}
}
/**
* Creates a new instance of the {@link RequestScope.Instance request scope instance}.
* This instance can be then used to run task in the request scope. Returned instance
* is suspended by default and must therefore be closed explicitly as it is shown in
* the following example:
*
* Instance instance = requestScope.createInstance();
* requestScope.runInScope(instance, someRunnableTask);
* instance.release();
*
*
* @return New suspended request scope instance.
*/
public Instance createInstance() {
return new Instance();
}
/**
* Runs the {@link Runnable task} in the request scope initialized from the
* {@link RequestScope.Instance scope instance}. The {@link RequestScope.Instance
* scope instance} is NOT released by the method (this must be done explicitly). The
* current thread might be already in any request scope and in that case the scope
* will be changed to the scope defined by the {@link RequestScope.Instance scope
* instance}. At the end of the method the request scope is returned to its original
* state.
*
* @param scopeInstance The request scope instance from which the request scope will
* be initialized.
* @param task Task to be executed.
*/
public void runInScope(Instance scopeInstance, Runnable task) {
Instance oldInstance = currentScopeInstance.get();
try {
currentScopeInstance.set(scopeInstance.getReference());
task.run();
} finally {
currentScopeInstance.set(oldInstance);
scopeInstance.release();
}
}
/**
* Runs the {@link Runnable task} in the new request scope. The current thread might
* be already in any request scope and in that case the scope will be changed to the
* scope defined by the {@link RequestScope.Instance scope instance}. At the end of
* the method the request scope is returned to its original state. The newly created
* {@link RequestScope.Instance scope instance} will be implicitly released at the end
* of the method call except the task will call
* {@link RequestScope#suspendCurrent}.
*
* @param task Task to be executed.
*/
public void runInScope(Runnable task) {
Instance oldInstance = currentScopeInstance.get();
Instance instance = createInstance();
try {
currentScopeInstance.set(instance);
task.run();
} finally {
currentScopeInstance.set(oldInstance);
instance.release();
}
}
/**
* Runs the {@link Callable task} in the request scope initialized from the
* {@link RequestScope.Instance scope instance}. The {@link RequestScope.Instance
* scope instance} is NOT released by the method (this must be done explicitly). The
* current thread might be already in any request scope and in that case the scope
* will be changed to the scope defined by the {@link RequestScope.Instance scope
* instance}. At the end of the method the request scope is returned to its original
* state.
*
* @param scopeInstance The request scope instance from which the request scope will
* be initialized.
* @param task Task to be executed.
* @param {@code task} result type.
* @return result returned by the {@code task}.
* @throws Exception Exception thrown by the {@code task}.
*/
public T runInScope(Instance scopeInstance, Callable task) throws Exception {
Instance oldInstance = currentScopeInstance.get();
try {
currentScopeInstance.set(scopeInstance.getReference());
return task.call();
} finally {
currentScopeInstance.set(oldInstance);
scopeInstance.release();
}
}
/**
* Runs the {@link Callable task} in the new request scope. The current thread might
* be already in any request scope and in that case the scope will be changed to the
* scope defined by the {@link RequestScope.Instance scope instance}. At the end of
* the method the request scope is returned to its original state. The newly created
* {@link RequestScope.Instance scope instance} will be implicitly released at the end
* of the method call except the task will call
* {@link RequestScope#suspendCurrent}.
*
* @param task Task to be executed.
* @param {@code task} result type.
* @return result returned by the {@code task}.
* @throws Exception Exception thrown by the {@code task}.
*/
public T runInScope(Callable task) throws Exception {
Instance oldInstance = currentScopeInstance.get();
Instance instance = createInstance();
try {
currentScopeInstance.set(instance);
return task.call();
} finally {
currentScopeInstance.set(oldInstance);
instance.release();
}
}
/**
* Runs the {@link org.glassfish.jersey.internal.util.Producer task} in the request scope initialized
* from the {@link RequestScope.Instance scope instance}.
* The {@link RequestScope.Instance scope instance} is NOT released by the method (this
* must be done explicitly). The current thread might be already in any request scope
* and in that case the scope will be changed to the scope defined by the
* {@link RequestScope.Instance scope instance}. At the end of the method the request
* scope is returned to its original state.
*
* @param scopeInstance The request scope instance from which the request scope will
* be initialized.
* @param task Task to be executed.
* @param {@code task} result type.
* @return result returned by the {@code task}
*/
public T runInScope(Instance scopeInstance, Producer task) {
Instance oldInstance = currentScopeInstance.get();
try {
currentScopeInstance.set(scopeInstance.getReference());
return task.call();
} finally {
currentScopeInstance.set(oldInstance);
scopeInstance.release();
}
}
/**
* Runs the {@link org.glassfish.jersey.internal.util.Producer task} in the new request scope. The
* current thread might be already in any request scope and in that case the scope
* will be changed to the scope defined by the {@link RequestScope.Instance scope
* instance}. At the end of the method the request scope is returned to its original
* state. The newly created {@link RequestScope.Instance scope instance} will be
* implicitly released at the end of the method call except the task will call
* {@link RequestScope#suspendCurrent}.
*
* @param task Task to be executed.
* @param {@code task} result type.
* @return result returned by the {@code task}.
*/
public T runInScope(Producer task) {
Instance oldInstance = currentScopeInstance.get();
Instance instance = createInstance();
try {
currentScopeInstance.set(instance);
return task.call();
} finally {
currentScopeInstance.set(oldInstance);
instance.release();
}
}
/**
* Implementation of the request scope instance.
*/
public static final class Instance {
/*
* Scope instance UUID.
*
* For performance reasons, it's only generated if toString() method is invoked,
* e.g. as part of some low-level logging.
*/
private final LazyUid id = new LazyUid();
/**
* A map of injectable instances in this scope.
*/
private final Map, Object> store;
/**
* Holds the number of snapshots of this scope.
*/
private final AtomicInteger referenceCounter;
private Instance() {
this.store = new HashMap, Object>();
this.referenceCounter = new AtomicInteger(1);
}
/**
* Get a "new" reference of the scope instance. This will increase
* the internal reference counter which prevents the scope instance
* to be destroyed until a {@link #release()} method is explicitly
* called (once per each {@code getReference()} method call).
*
* @return referenced scope instance.
*/
private Instance getReference() {
// TODO: replace counter with a phantom reference + reference queue-based solution
referenceCounter.incrementAndGet();
return this;
}
/**
* Get an inhabitant stored in the scope instance that matches the active descriptor .
*
* @param inhabitant type.
* @param descriptor inhabitant descriptor.
* @return matched inhabitant stored in the scope instance or {@code null} if not matched.
*/
@SuppressWarnings("unchecked")
T get(ActiveDescriptor descriptor) {
return (T) store.get(descriptor);
}
/**
* Store a new inhabitant for the given descriptor.
*
* @param inhabitant type.
* @param descriptor inhabitant descriptor.
* @param value inhabitant value.
* @return old inhabitant previously stored for the given descriptor or
* {@code null} if none stored.
*/
@SuppressWarnings("unchecked")
T put(ActiveDescriptor descriptor, T value) {
checkState(!store.containsKey(descriptor),
"An instance for the descriptor %s was already seeded in this scope. Old instance: %s New instance: %s",
descriptor,
store.get(descriptor),
value);
return (T) store.put(descriptor, value);
}
/**
* Remove a value for the descriptor if present in the scope instance store.
*
* @param descriptor key for the value to be removed.
*/
void remove(ActiveDescriptor descriptor) {
store.remove(descriptor);
}
private boolean contains(ActiveDescriptor provider) {
return store.containsKey(provider);
}
/**
* Release a single reference to the current request scope instance.
*
* Once all instance references are released, the instance will be recycled.
*/
public void release() {
if (referenceCounter.decrementAndGet() < 1) {
try {
store.clear();
} finally {
logger.debugLog("Released scope instance {0}", this);
}
}
}
@Override
public String toString() {
return Objects.toStringHelper(this).add("id", id.value()).add("referenceCounter", referenceCounter.get())
.add("store size", store.size()).toString();
}
}
}