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Implementation of operational transformation technology. Allows building collaborative software systems.

There is a newer version: 6.0-rc2

/*
 * Copyright (C) 2020 ActiveJ LLC.
 *
 * Licensed 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 io.activej.ot.util;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public interface SqlAtomicSequence {
	default long getAndAdd(Connection connection, int stride) throws SQLException {
		return addAndGet(connection, stride) - stride;
	}

	default long addAndGet(Connection connection, int stride) throws SQLException {
		return getAndAdd(connection, stride) + stride;
	}

	static SqlAtomicSequence ofLastInsertID(String table, String field) {
		return ofLastInsertID(table, field, null);
	}

	static SqlAtomicSequence ofLastInsertID(String table, String field, String where) {
		String sql = "UPDATE {table} SET {field} = LAST_INSERT_ID({table}.{field}) + :stride"
				.replace("{table}", "`" + table + "`")
				.replace("{field}", "`" + field + "`");
		if (where != null) {
			sql += " WHERE " + where;
		}
		String finalSql = sql;
		return new SqlAtomicSequence() {
			@Override
			public long getAndAdd(Connection connection, int stride) throws SQLException {
				try (Statement statement = connection.createStatement()) {
					statement.execute(finalSql.replace(":stride", Integer.toString(stride)), Statement.RETURN_GENERATED_KEYS);
					try (ResultSet generatedKeys = statement.getGeneratedKeys()) {
						generatedKeys.next();
						return generatedKeys.getLong(1);
					}
				}
			}
		};
	}
}