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;
14 * A factory which allocates new transactions to operate on the data tree.
17 * <b>Note:</b> This interface is not intended to be used directly, but rather via subinterfaces
18 * which introduces additional semantics to allocated transactions.
20 * <li> {@link AsyncDataBroker}
21 * <li> {@link TransactionChain}
25 * All operations on the data tree are performed via one of the transactions:
27 * <li>Read-Only - allocated using {@link #newReadOnlyTransaction()}
28 * <li>Write-Only - allocated using {@link #newWriteOnlyTransaction()}
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 * 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
48 * <b>Implementation Note:</b> This interface is not intended to be implemented by users of MD-SAL,
49 * but only to be consumed by them.
51 * @see AsyncDataBroker
52 * @see TransactionChain
54 * @param <P> Type of path (subtree identifier), which represents location in tree
55 * @param <D> Type of data (payload), which represents data payload
57 public interface AsyncDataTransactionFactory<P extends Path<P>, D> {
60 * Allocates a new read-only transaction which provides an immutable snapshot of
64 * The view of data tree is an immutable snapshot of current data tree state when
65 * transaction was allocated.
67 * @return new read-only transaction
69 AsyncReadTransaction<P, D> newReadOnlyTransaction();
72 * Allocates new write-only transaction based on latest state of data tree.
75 * Preconditions for mutation of data tree are captured from the snapshot of data tree state,
76 * when the transaction is allocated. If data was changed during transaction in an incompatible
77 * way then the commit of this transaction will fail. See {@link AsyncWriteTransaction#submit()}
78 * for more details about conflicting and not-conflicting changes and failure scenarios.
81 * Since this transaction does not provide a view of the data it SHOULD BE used only by callers
82 * which are exclusive writers (exporters of data) to the subtree they modify. This prevents
83 * optimistic lock failures as described in {@link AsyncWriteTransaction#submit()}.
86 * Exclusivity of writers to particular subtree SHOULD BE enforced by external locking
89 * @return new write-only transaction
91 AsyncWriteTransaction<P, D> newWriteOnlyTransaction();
94 * Allocates new read-write transaction which provides a mutable view of the data tree.
97 * Preconditions for mutation of data tree are captured from the snapshot of data tree state, when the transaction
98 * is allocated. If data was changed during transaction in an incompatible way then the commit of this transaction
99 * will fail. See {@link AsyncWriteTransaction#submit()} for more details about conflicting and not-conflicting
100 * changes and failure scenarios.
102 * @return new read-write transaction
104 AsyncReadWriteTransaction<P, D> newReadWriteTransaction();