log4j-nosql/src/main/java/org/apache/logging/log4j/nosql/appender/NoSqlConnection.java

/*
 * 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.logging.log4j.nosql.appender;

import java.io.Closeable;

/**
 * Represents a connection to the NoSQL database. Serves as a factory for new (empty) objects and an endpoint for
 * inserted objects.
 *
 * @param <T> Specifies which implementation of {@link NoSqlObject} this connection provides.
 * @param <W> Specifies which type of database object is wrapped by the {@link NoSqlObject} implementation provided.
 */
public interface NoSqlConnection<W, T extends NoSqlObject<W>> extends Closeable {
    /**
     * Instantiates and returns a {@link NoSqlObject} instance whose properties can be configured before ultimate
     * insertion via {@link #insertObject(NoSqlObject)}.
     *
     * @return a new object.
     * @see NoSqlObject
     */
    T createObject();

    /**
     * Creates an array of the specified length typed to match the {@link NoSqlObject} implementation appropriate for
     * this provider.
     *
     * @param length the length of the array to create.
     * @return a new array.
     * @see NoSqlObject
     */
    T[] createList(int length);

    /**
     * Inserts the given object into the underlying NoSQL database.
     *
     * @param object The object to insert.
     */
    void insertObject(NoSqlObject<W> object);

    /**
     * Closes the underlying connection. This method call should be idempotent. Only the first call should have any
     * effect; all further calls should be ignored. It's possible the underlying connection is stateless (such as an
     * HTTP web service), in which case this method would be a no-op. This method should also commit any open
     * transactions, if applicable and if not already committed.
     * <p>
     * If this connection is part of a connection pool, executing this method should commit the transaction and return
     * the connection to the pool, but it should not actually close the underlying connection.
     * </p>
     */
    @Override
    void close();

    /**
     * Indicates whether the underlying connection is closed. If the underlying connection is stateless (such as an
     * HTTP web service), this method would likely always return true. Essentially, this method should only return
     * {@code true} if a call to {@link #insertObject(NoSqlObject)} <b>will</b> fail due to the state of this object.
     *
     * @return {@code true} if this object is considered closed.
     */
    boolean isClosed();
}