e1e94ae9a3fdc8047586a4ffda79c9c7e9a36ec8
[controller.git] / opendaylight / md-sal / sal-common-api / src / main / java / org / opendaylight / controller / md / sal / common / api / data / AsyncReadTransaction.java
1 /*
2  * Copyright (c) 2014 Cisco Systems, Inc. and others.  All rights reserved.
3  *
4  * This program and the accompanying materials are made available under the
5  * terms of the Eclipse Public License v1.0 which accompanies this distribution,
6  * and is available at http://www.eclipse.org/legal/epl-v10.html
7  */
8 package org.opendaylight.controller.md.sal.common.api.data;
9
10 import org.opendaylight.yangtools.concepts.Path;
11
12 /**
13  * Marker interface for stateful read view of the data tree.
14  *
15  * <p>
16  * View of the data tree is a stable point-in-time snapshot of the current data tree state when
17  * the transaction was created. It's state and underlying data tree
18  * is not affected by other concurrently running transactions.
19  *
20  * <p>
21  * <b>Implementation Note:</b> This interface is not intended to be implemented
22  * by users of MD-SAL, but only to be consumed by them.
23  *
24  * <h2>Transaction isolation example</h2>
25  * Lets assume initial state of data tree for <code>PATH</code> is <code>A</code>.
26  *
27  * <pre>
28  * txRead = broker.newReadOnlyTransaction();   // read Transaction is snapshot of data
29  * txWrite = broker.newReadWriteTransactoin(); // concurrent write transaction
30  *
31  * txRead.read(OPERATIONAL,PATH).get();        // will return Optional containing A
32  * txWrite = broker.put(OPERATIONAL,PATH,B);   // writes B to PATH
33  *
34  * txRead.read(OPERATIONAL,PATH).get();        // still returns Optional containing A
35  *
36  * txWrite.commit().get();                     // data tree is updated, PATH contains B
37  * txRead.read(OPERATIONAL,PATH).get();        // still returns Optional containing A
38  *
39  * txAfterCommit = broker.newReadOnlyTransaction(); // read Transaction is snapshot of new state
40  * txAfterCommit.read(OPERATIONAL,PATH).get(); // returns Optional containing B;
41  * </pre>
42  *
43  * <p>
44  * <b>Note:</b> example contains blocking calls on future only to illustrate
45  * that action happened after other asynchronous action. Use of blocking call
46  * {@link com.google.common.util.concurrent.ListenableFuture#get()} is discouraged for most
47  * uses and you should use
48  * {@link com.google.common.util.concurrent.Futures#addCallback(com.google.common.util.concurrent.ListenableFuture,
49  * com.google.common.util.concurrent.FutureCallback, java.util.concurrent.Executor)}
50  * or other functions from {@link com.google.common.util.concurrent.Futures} to
51  * register more specific listeners.
52  *
53  * @param <P>
54  *            Type of path (subtree identifier), which represents location in
55  *            tree
56  * @param <D>
57  *            Type of data (payload), which represents data payload
58  */
59 @Deprecated
60 public interface AsyncReadTransaction<P extends Path<P>, D> extends AsyncTransaction<P, D> {
61
62 }

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