| /* | |
| * 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.nifi.provenance.journaling.journals; | |
| import java.io.Closeable; | |
| import java.io.IOException; | |
| import org.apache.nifi.provenance.ProvenanceEventRecord; | |
| public interface JournalReader extends Closeable { | |
| /** | |
| * Retrieve a specific event from the journal, given the offset of the Block and the ID of the event | |
| * @param blockOffset | |
| * @param eventId | |
| * @return | |
| * @throws IOException | |
| */ | |
| ProvenanceEventRecord getEvent(long blockOffset, long eventId) throws IOException; | |
| /** | |
| * Retrieve the next event in the journal, or <code>null</code> if no more events exist | |
| * @return | |
| * @throws IOException | |
| */ | |
| ProvenanceEventRecord nextEvent() throws IOException; | |
| /** | |
| * Returns the current byte offset into the Journal from which the next event (if any) will be read | |
| * @return | |
| */ | |
| long getPosition(); | |
| /** | |
| * Retrieves the last event from the journal, given the offset of the last Block in the journal | |
| * @param blockOffset | |
| * @return | |
| * @throws IOException | |
| */ | |
| ProvenanceEventRecord getLastEvent(long blockOffset) throws IOException; | |
| } |