| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package org.apache.jena.query; |
| |
| import java.util.Objects; |
| |
| import org.apache.jena.sparql.JenaTransactionException; |
| import org.apache.jena.sparql.core.Transactional; |
| |
| public enum TxnType { |
| /** Transaction mode: |
| * <ul> |
| * <li>{@code WRITE}: this guarantees a WRITE will complete if {@code commit()} is |
| * called. The same as {@code begin(ReadWrite.WRITE)}. |
| * |
| * <li>{@code READ}: the transaction can not promote to WRITE,ensuring read-only |
| * access to the data. The same as {@code begin(ReadWrite.READ)}. |
| * |
| * <li>{@code READ_PROMOTE}: the transaction will go from "read" to "write" if the |
| * dataset has not been modified but if it has, the promotion fails with |
| * exception. |
| * |
| * <li>{@code READ_COMMITTED_PROMOTE}: Use this with care. The promotion will succeed but |
| * changes from other transactions become visible. |
| * </ul> |
| * |
| * Read committed: at the point transaction attempts promotion from "read" to |
| * "write", the system checks if the dataset has changed since the transaction started |
| * (called {@code begin}). If {@code READ_PROMOTE}, the dataset must not have |
| * changed; if {@code READ_COMMITTED_PROMOTE} any intermediate changes are |
| * visible but the application can not assume any data it has read in the |
| * transaction is the same as it was at the point the transaction started. |
| */ |
| READ, WRITE, READ_PROMOTE, READ_COMMITTED_PROMOTE |
| ; |
| /** Convert a {@link ReadWrite} mode to {@code TxnType} */ |
| public static TxnType convert(ReadWrite rw) { |
| switch(rw) { |
| case READ: return READ; |
| case WRITE: return WRITE; |
| default: throw new NullPointerException(); |
| } |
| } |
| /** Convert a {@code TxnType} mode to {@link ReadWrite} : "promote" not supported. */ |
| public static ReadWrite convert(TxnType txnType) { |
| Objects.requireNonNull(txnType); |
| switch(txnType) { |
| case READ: return ReadWrite.READ; |
| case WRITE: return ReadWrite.WRITE; |
| default: throw new JenaTransactionException("Incompatible mode: "+txnType); |
| } |
| } |
| /** |
| * Translate a {@code TxnType} to it's initial {@link ReadWrite} mode. |
| * {@code WRITE -> WRITE}, {@code READ* -> READ} regardless of promotion setting. |
| */ |
| public static ReadWrite initial(TxnType txnType) { |
| Objects.requireNonNull(txnType); |
| return (txnType == TxnType.WRITE) ? ReadWrite.WRITE : ReadWrite.READ; |
| } |
| |
| /** Convert a {@code TxnType} mode to {@link ReadWrite} : "promote" not supported. */ |
| public static TxnType promote(Transactional.Promote promoteMode) { |
| Objects.requireNonNull(promoteMode); |
| return (promoteMode == Transactional.Promote.ISOLATED) ? READ_PROMOTE : READ_COMMITTED_PROMOTE; |
| } |
| } |