/* * Copyright (c) 2014 Cisco Systems, Inc. and others. All rights reserved. * * This program and the accompanying materials are made available under the * terms of the Eclipse Public License v1.0 which accompanies this distribution, * and is available at http://www.eclipse.org/legal/epl-v10.html */ package org.opendaylight.controller.md.sal.common.api.data; import org.opendaylight.yangtools.concepts.Path; /** * A factory which allocates new transactions to operate on the data * tree. * *
* Note: This interface is not intended to be used directly, but rather * via subinterfaces which introduces additional semantics to allocated * transactions. *
* All operations on the data tree are performed via one of the transactions: *
* These transactions provides a stable isolated view of the data tree, which is * guaranteed to be not affected by other concurrent transactions, until * transaction is committed. * *
* For a detailed explanation of how transaction are isolated and how transaction-local * changes are committed to global data tree, see * {@link AsyncReadTransaction}, {@link AsyncWriteTransaction}, * {@link AsyncReadWriteTransaction} and {@link AsyncWriteTransaction#commit()}. * *
* It is strongly recommended to use the type of transaction, which * provides only the minimal capabilities you need. This allows for * optimizations at the data broker / data store level. For example, * implementations may optimize the transaction for reading if they know ahead * of time that you only need to read data - such as not keeping additional meta-data, * which may be required for write transactions. *
* Implementation Note: This interface is not intended to be implemented * by users of MD-SAL, but only to be consumed by them. * * @see AsyncDataBroker * @see TransactionChain * * @param
* Type of path (subtree identifier), which represents location in
* tree
* @param , D> {
/**
* Allocates a new read-only transaction which provides an immutable snapshot of
* the data tree.
*
* The view of data tree is an immutable snapshot of current data tree state when
* transaction was allocated.
*
* @return new read-only transaction
*/
AsyncReadOnlyTransaction newReadOnlyTransaction();
/**
* Allocates new read-write transaction which provides a mutable view of the data
* tree.
*
*
* Preconditions for mutation of data tree are captured from the snapshot of
* data tree state, when the transaction is allocated. If data was
* changed during transaction in an incompatible way then the commit of this transaction
* will fail. See {@link AsyncWriteTransaction#commit()} for more
* details about conflicting and not-conflicting changes and
* failure scenarios.
*
* @return new read-write transaction
*/
AsyncReadWriteTransaction newReadWriteTransaction();
/**
* Allocates new write-only transaction based on latest state of data
* tree.
*
*
* Preconditions for mutation of data tree are captured from the snapshot of
* data tree state, when the transaction is allocated. If data was
* changed during transaction in an incompatible way then the commit of this transaction
* will fail. See {@link AsyncWriteTransaction#commit()} for more
* details about conflicting and not-conflicting changes and
* failure scenarios.
*
*
* Since this transaction does not provide a view of the data it SHOULD BE
* used only by callers which are exclusive writers (exporters of data)
* to the subtree they modify. This prevents optimistic
* lock failures as described in {@link AsyncWriteTransaction#commit()}.
*
* Exclusivity of writers to particular subtree SHOULD BE enforced by
* external locking mechanism.
*
* @return new write-only transaction
*/
AsyncWriteTransaction newWriteOnlyTransaction();
}