org.opendaylight.mdsal.binding.javav2.api

Interface ReadTransaction

All Superinterfaces:

AutoCloseable, org.opendaylight.yangtools.concepts.Identifiable<Object>, org.opendaylight.yangtools.concepts.Registration, Transaction

All Known Implementing Classes:

BindingDOMReadTransactionAdapter, ForwardingReadTransaction

@Beta
public interface ReadTransaction
extends Transaction, org.opendaylight.yangtools.concepts.Registration

A transaction that provides read access to a logical data store.

View of the data tree is a stable point-in-time snapshot of the current data tree state when the transaction was created. It's state and underlying data tree is not affected by other concurrently running transactions.

Implementation Note: This interface is not intended to be implemented by users of MD-SAL, but only to be consumed by them.

Transaction isolation example

Lets assume initial state of data tree for PATH is A. txRead = broker.newReadOnlyTransaction(); // read Transaction is snapshot of data txWrite = broker.newReadWriteTransactoin(); // concurrent write transaction txRead.read(OPERATIONAL, PATH).get(); // will return Optional containing A txWrite = broker.put(OPERATIONAL, PATH, B); // writes B to PATH txRead.read(OPERATIONAL, PATH).get(); // still returns Optional containing A txWrite.submit().get(); // data tree is updated, PATH contains B txRead.read(OPERATIONAL, PATH).get(); // still returns Optional containing A txAfterCommit = broker.newReadOnlyTransaction(); // read Transaction is snapshot of new state txAfterCommit.read(OPERATIONAL, PATH).get(); // returns Optional containing B;

Note: example contains blocking calls on future only to illustrate that action happened after other asynchronous action. Use of blocking call Future.get() is discouraged for most uses and you should use FluentFuture.addCallback(com.google.common.util.concurrent.FutureCallback, java.util.concurrent.Executor) or other functions from Futures to register more specific listeners.

Method Summary

Modifier and Type	Method and Description
void	close() Closes this transaction and releases all resources associated with it.
<T extends TreeNode> void	read(LogicalDatastoreType store, InstanceIdentifier<T> path, BiConsumer<ReadFailedException,T> callback) Reads data from the provided logical data store located at the provided path.

Methods inherited from interface org.opendaylight.yangtools.concepts.Identifiable

getIdentifier

Method Detail

read

<T extends TreeNode> void read(LogicalDatastoreType store,
                               InstanceIdentifier<T> path,
                               BiConsumer<ReadFailedException,T> callback)

Reads data from the provided logical data store located at the provided path.

If the target is a subtree, then the whole subtree is read (and will be accessible from the returned data object).

Type Parameters:

T - result type

Parameters:

store - Logical data store from which read should occur.

path - Path which uniquely identifies subtree which client want to read

callback - result callback

close

void close()

Closes this transaction and releases all resources associated with it.

Specified by:

close in interface AutoCloseable

Specified by:

close in interface org.opendaylight.yangtools.concepts.Registration