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.common.api;
10 import org.opendaylight.yangtools.concepts.Path;
13 * A factory which allocates new transactions to operate on the data tree.
16 * <b>Note:</b> This interface is not intended to be used directly, but rather via subinterfaces
17 * which introduces additional semantics to allocated transactions.
19 * <li> {@link AsyncDataBroker}
20 * <li> {@link TransactionChain}
24 * All operations on the data tree are performed via one of the transactions:
26 * <li>Read-Only - allocated using {@link #newReadOnlyTransaction()}
27 * <li>Write-Only - allocated using {@link #newWriteOnlyTransaction()}
28 * <li>Read-Write - allocated using {@link #newReadWriteTransaction()}
32 * These transactions provides a stable isolated view of the data tree, which is guaranteed to be
33 * not affected by other concurrent transactions, until transaction is committed.
36 * For a detailed explanation of how transaction are isolated and how transaction-local changes are
37 * committed to global data tree, see {@link AsyncReadTransaction}, {@link AsyncWriteTransaction},
38 * {@link AsyncReadWriteTransaction} and {@link AsyncWriteTransaction#submit()}.
41 * It is strongly recommended to use the type of transaction, which provides only the minimal
42 * capabilities you need. This allows for optimizations at the data broker / data store level. For
43 * example, implementations may optimize the transaction for reading if they know ahead of time that
44 * you only need to read data - such as not keeping additional meta-data, which may be required for
47 * <b>Implementation Note:</b> This interface is not intended to be implemented by users of MD-SAL,
48 * but only to be consumed by them.
50 * @see AsyncDataBroker
51 * @see TransactionChain
53 * @param <P> Type of path (subtree identifier), which represents location in tree
54 * @param <D> Type of data (payload), which represents data payload
56 public interface AsyncDataTransactionFactory<P extends Path<P>, D> {
59 * Allocates a new read-only transaction which provides an immutable snapshot of
62 * The view of data tree is an immutable snapshot of current data tree state when
63 * transaction was allocated.
65 * @return new read-only transaction
67 AsyncReadOnlyTransaction<P, D> newReadOnlyTransaction();
70 * Allocates new read-write transaction which provides a mutable view of the data tree.
73 * Preconditions for mutation of data tree are captured from the snapshot of data tree state,
74 * when the transaction is allocated. If data was changed during transaction in an incompatible
75 * way then the commit of this transaction will fail. See {@link AsyncWriteTransaction#submit()}
76 * for more details about conflicting and not-conflicting changes and failure scenarios.
78 * @return new read-write transaction
80 AsyncReadWriteTransaction<P, D> newReadWriteTransaction();
83 * Allocates new write-only transaction based on latest state of data tree.
86 * Preconditions for mutation of data tree are captured from the snapshot of data tree state,
87 * when the transaction is allocated. If data was changed during transaction in an incompatible
88 * way then the commit of this transaction will fail. See {@link AsyncWriteTransaction#submit()}
89 * for more details about conflicting and not-conflicting changes and failure scenarios.
92 * Since this transaction does not provide a view of the data it SHOULD BE used only by callers
93 * which are exclusive writers (exporters of data) to the subtree they modify. This prevents
94 * optimistic lock failures as described in {@link AsyncWriteTransaction#submit()}.
96 * Exclusivity of writers to particular subtree SHOULD BE enforced by external locking
99 * @return new write-only transaction
101 AsyncWriteTransaction<P, D> newWriteOnlyTransaction();