*/
package org.opendaylight.controller.md.sal.binding.api;
+import com.google.common.base.Optional;
+import com.google.common.util.concurrent.CheckedFuture;
+import com.google.common.util.concurrent.Futures;
+import com.google.common.util.concurrent.MoreExecutors;
+import org.opendaylight.controller.md.sal.common.api.MappingCheckedFuture;
import org.opendaylight.controller.md.sal.common.api.data.AsyncReadTransaction;
import org.opendaylight.controller.md.sal.common.api.data.LogicalDatastoreType;
+import org.opendaylight.controller.md.sal.common.api.data.ReadFailedException;
import org.opendaylight.yangtools.yang.binding.DataObject;
import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
-import com.google.common.base.Optional;
-import com.google.common.util.concurrent.ListenableFuture;
-
/**
* A transaction that provides read access to a logical data store.
+ *
* <p>
* For more information on usage and examples, please see the documentation in {@link AsyncReadTransaction}.
+ *
+ * @deprecated Use {@link org.opendaylight.mdsal.binding.api.ReadTransaction} instead.
*/
+@Deprecated
public interface ReadTransaction extends AsyncReadTransaction<InstanceIdentifier<?>, DataObject> {
-
/**
* Reads data from the provided logical data store located at the provided path.
- *<p>
- * If the target is a subtree, then the whole subtree is read (and will be
- * accessible from the returned data object).
*
- * @param store
- * Logical data store from which read should occur.
- * @param path
- * Path which uniquely identifies subtree which client want to
- * read
- * @return Listenable Future which contains read result
+ * <p>
+ * If the target is a subtree, then the whole subtree is read (and will be accessible from the returned data
+ * object).
+ *
+ * @param store Logical data store from which read should occur.
+ * @param path Path which uniquely identifies subtree which client want to read
+ * @return a CheckFuture containing the result of the read. The Future blocks until the
+ * commit operation is complete. Once complete:
+ * <ul>
+ * <li>If the data at the supplied path exists, the Future returns an Optional object
+ * containing the data.</li>
+ * <li>If the data at the supplied path does not exist, the Future returns
+ * Optional#absent().</li>
+ * <li>If the read of the data fails, the Future will fail with a
+ * {@link ReadFailedException} or an exception derived from ReadFailedException.</li>
+ * </ul>
+ */
+ <T extends DataObject> CheckedFuture<Optional<T>, ReadFailedException> read(
+ LogicalDatastoreType store, InstanceIdentifier<T> path);
+
+ /**
+ * Checks if data is available in the logical data store located at provided path.
+ *
+ * <p>
+ * Note: a successful result from this method makes no guarantee that a subsequent call to {@link #read}
+ * will succeed. It is possible that the data resides in a data store on a remote node and, if that
+ * node goes down or a network failure occurs, a subsequent read would fail. Another scenario is if
+ * the data is deleted in between the calls to <code>exists</code> and <code>read</code>
+ *
+ * <p>
+ * Default implementation delegates to {@link #read(LogicalDatastoreType, InstanceIdentifier)}, implementations
+ * are advised to provide a more efficient override.
+ *
+ * @param store Logical data store from which read should occur.
+ * @param path Path which uniquely identifies subtree which client want to check existence of
+ * @return a CheckFuture containing the result of the check.
* <ul>
- * <li>If data at supplied path exists the
- * {@link ListeblaFuture#get()} returns Optional object containing
- * data once read is done.
- * <li>If data at supplied path does not exists the
- * {@link ListenbleFuture#get()} returns {@link Optional#absent()}.
+ * <li>If the data at the supplied path exists, the Future returns a Boolean
+ * whose value is true, false otherwise</li>
+ * <li>If checking for the data fails, the Future will fail with a
+ * {@link ReadFailedException} or an exception derived from ReadFailedException.</li>
* </ul>
*/
- <T extends DataObject> ListenableFuture<Optional<T>> read(LogicalDatastoreType store, InstanceIdentifier<T> path);
+ default CheckedFuture<Boolean, ReadFailedException> exists(final LogicalDatastoreType store,
+ final InstanceIdentifier<?> path) {
+ return MappingCheckedFuture.create(Futures.transform(read(store, path), Optional::isPresent,
+ MoreExecutors.directExecutor()), ReadFailedException.MAPPER);
+ }
}