import static java.util.Objects.requireNonNull;
-import java.util.HashMap;
-import java.util.Map;
+import com.google.common.collect.ImmutableClassToInstanceMap;
+import com.google.common.collect.ImmutableClassToInstanceMap.Builder;
import java.util.Optional;
-import javax.annotation.concurrent.GuardedBy;
+import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
import org.opendaylight.protocol.bgp.parser.spi.PeerConstraint;
import org.opendaylight.protocol.bgp.parser.spi.PeerSpecificParserConstraintProvider;
public class PeerSpecificParserConstraintImpl implements PeerSpecificParserConstraintProvider {
+ @SuppressWarnings("rawtypes")
+ private static final AtomicReferenceFieldUpdater<PeerSpecificParserConstraintImpl, ImmutableClassToInstanceMap>
+ CONSTRAINTS_UPDATER = AtomicReferenceFieldUpdater.newUpdater(PeerSpecificParserConstraintImpl.class,
+ ImmutableClassToInstanceMap.class, "constraints");
- @GuardedBy("this")
- private final Map<Class<? extends PeerConstraint>, PeerConstraint> constraints = new HashMap<>();
+ private volatile ImmutableClassToInstanceMap<PeerConstraint> constraints = ImmutableClassToInstanceMap.of();
@Override
- public synchronized <T extends PeerConstraint> Optional<T> getPeerConstraint(final Class<T> peerConstraintType) {
- return (Optional<T>) Optional.ofNullable(this.constraints.get(peerConstraintType));
+ public <T extends PeerConstraint> Optional<T> getPeerConstraint(final Class<T> peerConstraintType) {
+ return Optional.ofNullable(constraints.getInstance(peerConstraintType));
}
@Override
- public synchronized <T extends PeerConstraint> boolean addPeerConstraint(final Class<T> classType, final T peerConstraint) {
+ public <T extends PeerConstraint> boolean addPeerConstraint(final Class<T> classType, final T peerConstraint) {
requireNonNull(classType);
requireNonNull(peerConstraint);
- final PeerConstraint previous = this.constraints.putIfAbsent(classType, peerConstraint);
- return previous == null;
- }
+ ImmutableClassToInstanceMap<PeerConstraint> local = constraints;
+ while (!local.containsKey(classType)) {
+ final Builder<PeerConstraint> builder = ImmutableClassToInstanceMap.builder();
+ builder.putAll(local);
+ builder.put(classType, peerConstraint);
+ if (CONSTRAINTS_UPDATER.compareAndSet(this, local, builder.build())) {
+ // Successfully updated, finished
+ return true;
+ }
+
+ // Raced with another update, retry
+ local = constraints;
+ }
+ return false;
+ }
}