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ARQ is a SPARQL 1.1 query engine for Apache Jena
/*
* 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:
*
* - {@code WRITE}: this guarantees a WRITE will complete if {@code commit()} is
* called. The same as {@code begin(ReadWrite.WRITE)}.
*
*
- {@code READ}: the transaction can not promote to WRITE,ensuring read-only
* access to the data. The same as {@code begin(ReadWrite.READ)}.
*
*
- {@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.
*
*
- {@code READ_COMMITTED_PROMOTE}: Use this with care. The promotion will succeed but
* changes from other transactions become visible.
*
*
* 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;
}
}