2 * Copyright (c) 2014 Cisco Systems, Inc. and others. All rights reserved.
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
8 package org.opendaylight.mdsal.dom.api;
10 import org.opendaylight.yangtools.concepts.Registration;
13 * A chain of transactions. Transactions in a chain need to be committed in sequence and each transaction should see
14 * the effects of previous committed transactions as they occurred. A chain makes no guarantees of atomicity across
15 * the chained transactions - the transactions are committed as soon as possible in the order that they were committed.
16 * This behaviour is different from the default AsyncDataBroker, where a transaction is always created from the current
17 * global state, not taking into account any transactions previously committed by the calling thread. Due to
18 * the asynchronous nature of transaction submission this can lead to surprising results. If a thread executes
19 * the following sequence sufficiently quickly:
22 * DOMWriteTransaction t1 = broker.newWriteOnlyTransaction();
26 * DOMReadTransaction t2 = broker.newReadOnlyTransaction();
27 * Optional<?> maybeData = t2.read(id).get();
29 * it may happen, that it sees maybeData.isPresent() == false, simply because t1 has not completed the processes
30 * of being applied and t2 is actually allocated from the previous state. This is obviously bad for users who create
31 * incremental state in the datastore and actually read what they write in subsequent transactions.
32 * Using a TransactionChain instead of a broker solves this particular problem, and leads to expected behavior: t2 will
33 * always see the data written in t1
36 public interface DOMTransactionChain extends Registration, DOMTransactionFactory {
38 * Create a new read only transaction which will continue the chain.
41 * The previous write transaction has to be either SUBMITTED ({@link DOMDataTreeWriteTransaction#commit commit} was
42 * invoked) or CANCELLED ({@link #close close} was invoked).
45 * The returned read-only transaction presents an isolated view of the data if the previous write transaction was
46 * successful - in other words, this read-only transaction will see the state changes made by the previous write
47 * transaction in the chain. However, state which was introduced by other transactions outside this transaction
48 * chain after creation of the previous transaction is not visible.
50 * @return New transaction in the chain.
51 * @throws IllegalStateException if the previous transaction was not SUBMITTED or CANCELLED.
52 * @throws DOMTransactionChainClosedException if the chain has been closed.
55 DOMDataTreeReadTransaction newReadOnlyTransaction();
58 * Create a new write-only transaction which will continue the chain.
61 * The previous write transaction has to be either SUBMITTED ({@link DOMDataTreeWriteTransaction#commit commit} was
62 * invoked) or CANCELLED ({@link #close close} was invoked)
65 * The returned write-only transaction presents an isolated view of the data if the previous write transaction was
66 * successful - in other words, this write-only transaction will see the state changes made by the previous write
67 * transaction in the chain. However, state which was introduced by other transactions outside this transaction
68 * chain after creation of the previous transaction is not visible
71 * Committing this write-only transaction using {@link DOMDataTreeWriteTransaction#commit commit} will commit
72 * the state changes in this transaction to be visible to any subsequent transaction in this chain and also to any
73 * transaction outside this chain.
75 * @return New transaction in the chain.
76 * @throws IllegalStateException if the previous transaction was not SUBMITTED or CANCELLED.
77 * @throws DOMTransactionChainClosedException if the chain has been closed.
80 DOMDataTreeWriteTransaction newWriteOnlyTransaction();
83 * Create a new read-write transaction which will continue the chain.
86 * The previous write transaction has to be either SUBMITTED ({@link DOMDataTreeWriteTransaction#commit commit} was
87 * invoked) or CANCELLED ({@link #close close} was invoked).
90 * The returned read-write transaction presents an isolated view of the data if the previous write transaction was
91 * successful - in other words, this read-write transaction will see the state changes made by the previous write
92 * transaction in the chain. However, state which was introduced by other transactions outside this transaction
93 * chain after creation of the previous transaction is not visible.
96 * Committing this read-write transaction using {@link DOMDataTreeReadWriteTransaction#commit commit} will commit
97 * the state changes in this transaction to be visible to any subsequent transaction in this chain and also to any
98 * transaction outside this chain.
100 * @return New transaction in the chain.
101 * @throws IllegalStateException if the previous transaction was not SUBMITTED or CANCELLED.
102 * @throws DOMTransactionChainClosedException if the chain has been closed.
105 DOMDataTreeReadWriteTransaction newReadWriteTransaction();