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.controller.md.sal.common.api.data;
10 import org.opendaylight.yangtools.concepts.Path;
13 * A chain of transactions. Transactions in a chain need to be committed in
14 * sequence and each transaction should see the effects of previous committed transactions
15 * as they occurred. A chain makes no guarantees of atomicity across the chained transactions -
16 * the transactions are committed as soon as possible in the order that they were submitted.
19 * This behaviour is different from the default AsyncDataBroker, where a
20 * transaction is always created from the current global state, not taking into
21 * account any transactions previously committed by the calling thread. Due to
22 * the asynchronous nature of transaction submission this can lead to surprising
23 * results. If a thread executes the following sequence sufficiently quickly:
26 * AsyncWriteTransaction t1 = broker.newWriteOnlyTransaction();
31 * AsyncReadTransaction t2 = broker.newReadOnlyTransaction();
32 * Optional<?> maybeData = t2.read(id).get();
35 * it may happen, that it sees maybeData.isPresent() == false, simply because
36 * t1 has not completed the processes of being applied and t2 is actually
37 * allocated from the previous state. This is obviously bad for users who create
38 * incremental state in the datastore and actually read what they write in
39 * subsequent transactions.
42 * Using a TransactionChain instead of a broker solves this particular problem,
43 * and leads to expected behavior: t2 will always see the data written in t1
47 public interface TransactionChain<P extends Path<P>, D> extends AutoCloseable, AsyncDataTransactionFactory<P, D> {
50 * Create a new read only transaction which will continue the chain.
53 * The previous write transaction has to be either SUBMITTED
54 * ({@link AsyncWriteTransaction#submit submit} was invoked) or CANCELLED
55 * ({@link #close close} was invoked).
58 * The returned read-only transaction presents an isolated view of the data if the previous
59 * write transaction was successful - in other words, this read-only transaction will see the
60 * state changes made by the previous write transaction in the chain. However, state which
61 * was introduced by other transactions outside this transaction chain after creation of
62 * the previous transaction is not visible.
64 * @return New transaction in the chain.
65 * @throws IllegalStateException
66 * if the previous transaction was not SUBMITTED or CANCELLED.
67 * @throws TransactionChainClosedException
68 * if the chain has been closed.
71 AsyncReadOnlyTransaction<P, D> newReadOnlyTransaction();
74 * Create a new read-write transaction which will continue the chain.
77 * The previous write transaction has to be either SUBMITTED
78 * ({@link AsyncWriteTransaction#submit submit} was invoked) or CANCELLED
79 * ({@link #close close} was invoked).
82 * The returned read-write transaction presents an isolated view of the data if the previous
83 * write transaction was successful - in other words, this read-write transaction will see the
84 * state changes made by the previous write transaction in the chain. However, state which
85 * was introduced by other transactions outside this transaction chain after creation of
86 * the previous transaction is not visible.
89 * Committing this read-write transaction using {@link AsyncWriteTransaction#submit submit}
90 * will submit the state changes in this transaction to be visible to any subsequent
91 * transaction in this chain and also to any transaction outside this chain.
93 * @return New transaction in the chain.
94 * @throws IllegalStateException
95 * if the previous transaction was not SUBMITTED or CANCELLED.
96 * @throws TransactionChainClosedException
97 * if the chain has been closed.
100 AsyncReadWriteTransaction<P, D> newReadWriteTransaction();
103 * Create a new write-only transaction which will continue the chain.
106 * The previous write transaction has to be either SUBMITTED
107 * ({@link AsyncWriteTransaction#submit submit} was invoked) or CANCELLED
108 * ({@link #close close} was invoked).
111 * The returned write-only transaction presents an isolated view of the data if the previous
112 * write transaction was successful - in other words, this write-only transaction will see the
113 * state changes made by the previous write transaction in the chain. However, state which
114 * was introduced by other transactions outside this transaction chain after creation of
115 * the previous transaction is not visible.
118 * Committing this write-only transaction using {@link AsyncWriteTransaction#submit submit}
119 * will submit the state changes in this transaction to be visible to any subsequent
120 * transaction in this chain and also to any transaction outside this chain.
122 * @return New transaction in the chain.
123 * @throws IllegalStateException
124 * if the previous transaction was not SUBMITTED or CANCELLED.
125 * @throws TransactionChainClosedException
126 * if the chain has been closed.
129 AsyncWriteTransaction<P, D> newWriteOnlyTransaction();