*/
package org.opendaylight.yangtools.objcache.spi;
+import java.util.concurrent.Callable;
+import java.util.concurrent.ExecutionException;
+
import org.opendaylight.yangtools.concepts.ProductAwareBuilder;
import org.opendaylight.yangtools.objcache.ObjectCache;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
+import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.FinalizableReferenceQueue;
import com.google.common.base.FinalizableSoftReference;
import com.google.common.base.Preconditions;
* a backing {@link Cache} instance and provide the
*/
public abstract class AbstractObjectCache implements ObjectCache {
- /**
- * Key used when looking up a ProductAwareBuilder product. We assume
- * the builder is not being modified for the duration of the lookup,
- * anything else is the user's fault.
- */
- private static final class BuilderKey {
- private final ProductAwareBuilder<?> builder;
-
- private BuilderKey(final ProductAwareBuilder<?> builder) {
- this.builder = Preconditions.checkNotNull(builder);
- }
-
- @Override
- public int hashCode() {
- return builder.productHashCode();
- }
-
- @Override
- public boolean equals(Object obj) {
- /*
- * We can tolerate null objects coming our way, but we need
- * to be on the lookout for WeakKeys, as we cannot pass them
- * directly to productEquals().
- */
- if (obj != null && obj instanceof SoftKey) {
- obj = ((SoftKey)obj).get();
- }
-
- return builder.productEquals(obj);
- }
- }
-
- /**
- * Key used in the underlying map. It is essentially a soft reference, with
- * slightly special properties.
- *
- * It acts as a proxy for the object it refers to and essentially delegates
- * to it. There are three exceptions here:
- *
- * 1) This key needs to have a cached hash code. The requirement is that the
- * key needs to be able to look itself up after the reference to the object
- * has been cleared (and thus we can no longer look it up from there). One
- * typical container where we are stored are HashMaps -- and they need it
- * to be constant.
- * 2) This key does not tolerate checks to see if its equal to null. While we
- * could return false, we want to catch offenders who try to store nulls
- * in the cache.
- * 3) This key inverts the check for equality, e.g. it calls equals() on the
- * object which was passed to its equals(). Instead of supplying itself,
- * it supplies the referent. If the soft reference is cleared, such check
- * will return false, which is fine as it prevents normal lookup from
- * seeing the cleared key. Removal is handled by the explicit identity
- * check.
- */
- private static abstract class SoftKey extends FinalizableSoftReference<Object> {
- private final int hashCode;
-
- public SoftKey(final Object referent, final FinalizableReferenceQueue q) {
- super(Preconditions.checkNotNull(referent), q);
- hashCode = referent.hashCode();
- }
-
- @Override
- public boolean equals(final Object obj) {
- Preconditions.checkState(obj != null);
-
- // Order is important: we do not want to call equals() on ourselves!
- return this == obj || obj.equals(get());
- }
-
- @Override
- public int hashCode() {
- return hashCode;
- }
- }
-
- private static final Logger LOG = LoggerFactory.getLogger(AbstractObjectCache.class);
- private final FinalizableReferenceQueue queue;
- private final Cache<Object, Object> cache;
-
- protected AbstractObjectCache(final Cache<Object, Object> cache, final FinalizableReferenceQueue queue) {
- this.queue = Preconditions.checkNotNull(queue);
- this.cache = Preconditions.checkNotNull(cache);
- }
-
- private <T> T put(final T object) {
- /*
- * This may look like a race (having a soft reference and not have
- * it in the cache). In fact this is protected by the fact we still
- * have a strong reference on the object in our arguments and that
- * reference survives past method return since we return it.
- */
- final Object key = new SoftKey(object, queue) {
- @Override
- public void finalizeReferent() {
- /*
- * NOTE: while it may be tempting to add "object" into this
- * trace message, do not ever do that: it would retain
- * a strong reference, preventing collection.
- */
- LOG.trace("Invalidating key {} for object {}", this);
- cache.invalidate(this);
- }
- };
- cache.put(key, object);
- LOG.debug("Cached key {} to object {}", key, object);
- return object;
- }
-
- @Override
- public final <B extends ProductAwareBuilder<P>, P> P getProduct(final B builder) {
- LOG.debug("Looking up product for {}", builder);
-
- @SuppressWarnings("unchecked")
- final P ret = (P) cache.getIfPresent(new BuilderKey(builder));
- return ret == null ? put(Preconditions.checkNotNull(builder.toInstance())) : ret;
- }
-
- @Override
- public final <T> T getReference(final T object) {
- LOG.debug("Looking up reference for {}", object);
- if (object == null) {
- return null;
- }
-
- @SuppressWarnings("unchecked")
- final T ret = (T) cache.getIfPresent(object);
- return ret == null ? put(object) : ret;
- }
+ /**
+ * Key used when looking up a ProductAwareBuilder product. We assume
+ * the builder is not being modified for the duration of the lookup,
+ * anything else is the user's fault.
+ */
+ @VisibleForTesting
+ static final class BuilderKey {
+ private final ProductAwareBuilder<?> builder;
+
+ private BuilderKey(final ProductAwareBuilder<?> builder) {
+ this.builder = Preconditions.checkNotNull(builder);
+ }
+
+ @Override
+ public int hashCode() {
+ return builder.productHashCode();
+ }
+
+ @Override
+ public boolean equals(Object obj) {
+ /*
+ * We can tolerate null objects coming our way, but we need
+ * to be on the lookout for WeakKeys, as we cannot pass them
+ * directly to productEquals().
+ */
+ if (obj != null && obj instanceof SoftKey) {
+ obj = ((SoftKey<?>)obj).get();
+ }
+
+ return builder.productEquals(obj);
+ }
+ }
+
+ /**
+ * Key used in the underlying map. It is essentially a soft reference, with
+ * slightly special properties.
+ *
+ * It acts as a proxy for the object it refers to and essentially delegates
+ * to it. There are three exceptions here:
+ *
+ * 1) This key needs to have a cached hash code. The requirement is that the
+ * key needs to be able to look itself up after the reference to the object
+ * has been cleared (and thus we can no longer look it up from there). One
+ * typical container where we are stored are HashMaps -- and they need it
+ * to be constant.
+ * 2) This key does not tolerate checks to see if its equal to null. While we
+ * could return false, we want to catch offenders who try to store nulls
+ * in the cache.
+ * 3) This key inverts the check for equality, e.g. it calls equals() on the
+ * object which was passed to its equals(). Instead of supplying itself,
+ * it supplies the referent. If the soft reference is cleared, such check
+ * will return false, which is fine as it prevents normal lookup from
+ * seeing the cleared key. Removal is handled by the explicit identity
+ * check.
+ */
+ protected abstract static class SoftKey<T> extends FinalizableSoftReference<T> {
+ private final int hashCode;
+
+ public SoftKey(final T referent, final FinalizableReferenceQueue q) {
+ super(Preconditions.checkNotNull(referent), q);
+ hashCode = referent.hashCode();
+ }
+
+ @Override
+ public boolean equals(final Object obj) {
+ if (obj == null) {
+ return false;
+ }
+
+ // Order is important: we do not want to call equals() on ourselves!
+ return this == obj || obj.equals(get());
+ }
+
+ @Override
+ public int hashCode() {
+ return hashCode;
+ }
+ }
+
+ private static final Logger LOG = LoggerFactory.getLogger(AbstractObjectCache.class);
+ private final FinalizableReferenceQueue queue;
+ private final Cache<SoftKey<?>, Object> cache;
+
+ protected AbstractObjectCache(final Cache<SoftKey<?>, Object> cache, final FinalizableReferenceQueue queue) {
+ this.queue = Preconditions.checkNotNull(queue);
+ this.cache = Preconditions.checkNotNull(cache);
+ }
+
+ protected <T> SoftKey<T> createSoftKey(final T object) {
+ /*
+ * This may look like a race (having a soft reference and not have
+ * it in the cache). In fact this is protected by the fact we still
+ * have a strong reference on the object in our arguments and that
+ * reference survives past method return since we return it.
+ */
+ return new SoftKey<T>(object, queue) {
+ @Override
+ public void finalizeReferent() {
+ /*
+ * NOTE: while it may be tempting to add "object" into this
+ * trace message, do not ever do that: it would retain
+ * a strong reference, preventing collection.
+ */
+ LOG.trace("Invalidating key {}", this);
+ cache.invalidate(this);
+ }
+ };
+ }
+
+ @Override
+ public final <B extends ProductAwareBuilder<P>, P> P getProduct(final B builder) {
+ throw new UnsupportedOperationException();
+// LOG.debug("Looking up product for {}", builder);
+//
+// @SuppressWarnings("unchecked")
+// final P ret = (P) cache.getIfPresent(new BuilderKey(builder));
+// return ret == null ? put(Preconditions.checkNotNull(builder.toInstance())) : ret;
+ }
+
+ @Override
+ @SuppressWarnings("unchecked")
+ public final <T> T getReference(final T object) {
+ LOG.debug("Looking up reference for {}", object);
+ if (object == null) {
+ return null;
+ }
+
+ final SoftKey<T> key = createSoftKey(object);
+ try {
+ return (T) cache.get(key, new Callable<T>() {
+ @Override
+ public T call() {
+ return object;
+ }
+ });
+ } catch (ExecutionException e) {
+ throw new IllegalStateException("Failed to load value", e);
+ }
+ }
}
Code Review / yangtools.git / blobdiff