001/*
002 * Copyright 2002-2018 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.transaction.annotation;
018
019import org.springframework.transaction.TransactionDefinition;
020
021/**
022 * Enumeration that represents transaction isolation levels for use
023 * with the {@link Transactional} annotation, corresponding to the
024 * {@link TransactionDefinition} interface.
025 *
026 * @author Colin Sampaleanu
027 * @author Juergen Hoeller
028 * @since 1.2
029 */
030public enum Isolation {
031
032        /**
033         * Use the default isolation level of the underlying datastore.
034         * All other levels correspond to the JDBC isolation levels.
035         * @see java.sql.Connection
036         */
037        DEFAULT(TransactionDefinition.ISOLATION_DEFAULT),
038
039        /**
040         * A constant indicating that dirty reads, non-repeatable reads and phantom reads
041         * can occur. This level allows a row changed by one transaction to be read by
042         * another transaction before any changes in that row have been committed
043         * (a "dirty read"). If any of the changes are rolled back, the second
044         * transaction will have retrieved an invalid row.
045         * @see java.sql.Connection#TRANSACTION_READ_UNCOMMITTED
046         */
047        READ_UNCOMMITTED(TransactionDefinition.ISOLATION_READ_UNCOMMITTED),
048
049        /**
050         * A constant indicating that dirty reads are prevented; non-repeatable reads
051         * and phantom reads can occur. This level only prohibits a transaction
052         * from reading a row with uncommitted changes in it.
053         * @see java.sql.Connection#TRANSACTION_READ_COMMITTED
054         */
055        READ_COMMITTED(TransactionDefinition.ISOLATION_READ_COMMITTED),
056
057        /**
058         * A constant indicating that dirty reads and non-repeatable reads are
059         * prevented; phantom reads can occur. This level prohibits a transaction
060         * from reading a row with uncommitted changes in it, and it also prohibits
061         * the situation where one transaction reads a row, a second transaction
062         * alters the row, and the first transaction rereads the row, getting
063         * different values the second time (a "non-repeatable read").
064         * @see java.sql.Connection#TRANSACTION_REPEATABLE_READ
065         */
066        REPEATABLE_READ(TransactionDefinition.ISOLATION_REPEATABLE_READ),
067
068        /**
069         * A constant indicating that dirty reads, non-repeatable reads and phantom
070         * reads are prevented. This level includes the prohibitions in
071         * {@code ISOLATION_REPEATABLE_READ} and further prohibits the situation
072         * where one transaction reads all rows that satisfy a {@code WHERE}
073         * condition, a second transaction inserts a row that satisfies that
074         * {@code WHERE} condition, and the first transaction rereads for the
075         * same condition, retrieving the additional "phantom" row in the second read.
076         * @see java.sql.Connection#TRANSACTION_SERIALIZABLE
077         */
078        SERIALIZABLE(TransactionDefinition.ISOLATION_SERIALIZABLE);
079
080
081        private final int value;
082
083
084        Isolation(int value) {
085                this.value = value;
086        }
087
088        public int value() {
089                return this.value;
090        }
091
092}