*/
package org.opendaylight.yangtools.concepts;
-import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
+import com.google.common.base.MoreObjects;
+import com.google.common.base.MoreObjects.ToStringHelper;
+import java.lang.invoke.MethodHandles;
+import java.lang.invoke.VarHandle;
/**
- * Utility registration handle. It is a convenience for register-style method
- * which can return an AutoCloseable realized by a subclass of this class.
- * Invoking the close() method triggers unregistration of the state the method
- * installed.
+ * Utility registration handle. It is a convenience for register-style method which can return an AutoCloseable realized
+ * by a subclass of this class. Invoking the close() method triggers unregistration of the state the method installed.
*/
-public abstract class AbstractRegistration implements AutoCloseable {
- private static final AtomicIntegerFieldUpdater<AbstractRegistration> CLOSED_UPDATER =
- AtomicIntegerFieldUpdater.newUpdater(AbstractRegistration.class, "closed");
+public abstract class AbstractRegistration implements Registration {
+ private static final VarHandle CLOSED;
- @SuppressWarnings("unused") // updated by CLOSED_UPDATER
- private volatile int closed = 0;
+ // All access needs to go through this handle
+ @SuppressWarnings("unused")
+ private volatile byte closed;
+
+ static {
+ try {
+ CLOSED = MethodHandles.lookup().findVarHandle(AbstractRegistration.class, "closed", byte.class);
+ } catch (ReflectiveOperationException e) {
+ throw new ExceptionInInitializerError(e);
+ }
+ }
/**
- * Remove the state referenced by this registration. This method is
- * guaranteed to be called at most once. The referenced state must be
- * retained until this method is invoked.
+ * Remove the state referenced by this registration. This method is guaranteed to be called at most once.
+ * Referenced state must be retained until this method is invoked.
*/
protected abstract void removeRegistration();
/**
- * Query the state of this registration. Returns true if it was
- * closed.
+ * Query the state of this registration. Returns true if it was closed. Equivalent of {@code !notClosed()}.
*
* @return true if the registration was closed, false otherwise.
*/
- protected final boolean isClosed() {
- return CLOSED_UPDATER.get(this) != 0;
+ public final boolean isClosed() {
+ return (byte) CLOSED.getAcquire(this) != 0;
+ }
+
+ /**
+ * Query the state of this registration. Returns false if it was closed. Equivalent of {@code !isClosed()}.
+ *
+ * @return false if the registration was closed, true otherwise.
+ */
+ public final boolean notClosed() {
+ return (byte) CLOSED.getAcquire(this) == 0;
}
@Override
public final void close() {
- if (CLOSED_UPDATER.compareAndSet(this, 0, 1)) {
+ // We want full setVolatile() memory semantics here, as all state before calling this method
+ // needs to be visible
+ if (CLOSED.compareAndSet(this, (byte) 0, (byte) 1)) {
removeRegistration();
}
}
+
+ @Override
+ public final String toString() {
+ return addToStringAttributes(MoreObjects.toStringHelper(this).omitNullValues()).toString();
+ }
+
+ protected ToStringHelper addToStringAttributes(final ToStringHelper toStringHelper) {
+ return toStringHelper.add("closed", isClosed());
+ }
}