org.opendaylight.controller.md.sal.common.api.data

Interface AsyncReadTransaction<P extends org.opendaylight.yangtools.concepts.Path<P>,D>

Type Parameters:

P - Type of path (subtree identifier), which represents location in tree

D - Type of data (payload), which represents data payload

All Superinterfaces:

AsyncTransaction<P,D>, org.opendaylight.yangtools.concepts.Identifiable<Object>

All Known Subinterfaces:

AsyncReadOnlyTransaction<P,D>, AsyncReadWriteTransaction<P,D>, DOMDataReadOnlyTransaction, DOMDataReadTransaction, DOMDataReadWriteTransaction, ReadOnlyTransaction, ReadTransaction, ReadWriteTransaction

All Known Implementing Classes:

ForwardingDOMDataReadOnlyTransaction, ForwardingDOMDataReadWriteTransaction, ForwardingReadOnlyTransaction, ForwardingReadWriteTransaction

public interface AsyncReadTransaction<P extends org.opendaylight.yangtools.concepts.Path<P>,D>
extends AsyncTransaction<P,D>

Marker interface for stateful read view of the data tree.

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.commit().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 Futures.addCallback(com.google.common.util.concurrent.ListenableFuture, com.google.common.util.concurrent.FutureCallback, java.util.concurrent.Executor) or other functions from Futures to register more specific listeners.

Method Summary

Methods inherited from interface org.opendaylight.controller.md.sal.common.api.data.AsyncTransaction

getIdentifier