001/**
002 *
003 * Licensed to the Apache Software Foundation (ASF) under one
004 * or more contributor license agreements.  See the NOTICE file
005 * distributed with this work for additional information
006 * regarding copyright ownership.  The ASF licenses this file
007 * to you under the Apache License, Version 2.0 (the
008 * "License"); you may not use this file except in compliance
009 * with the License.  You may obtain a copy of the License at
010 *
011 *     http://www.apache.org/licenses/LICENSE-2.0
012 *
013 * Unless required by applicable law or agreed to in writing, software
014 * distributed under the License is distributed on an "AS IS" BASIS,
015 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
016 * See the License for the specific language governing permissions and
017 * limitations under the License.
018 */
019package org.apache.hadoop.hbase.wal;
020
021import java.io.Closeable;
022import java.io.IOException;
023import java.util.List;
024import java.util.OptionalLong;
025import java.util.concurrent.CompletableFuture;
026import org.apache.hadoop.conf.Configuration;
027import org.apache.hadoop.hbase.client.RegionInfo;
028import org.apache.hadoop.hbase.regionserver.wal.WALActionsListener;
029import org.apache.hadoop.hbase.replication.regionserver.WALFileLengthProvider;
030import org.apache.yetus.audience.InterfaceAudience;
031
032/**
033 * The Write Ahead Log (WAL) stores all durable edits to the HRegion. This interface provides the
034 * entry point for all WAL implementors.
035 * <p>
036 * See {@link FSHLogProvider} for an example implementation. A single WALProvider will be used for
037 * retrieving multiple WALs in a particular region server and must be threadsafe.
038 */
039@InterfaceAudience.Private
040public interface WALProvider {
041
042  /**
043   * Set up the provider to create wals. will only be called once per instance.
044   * @param factory factory that made us may not be null
045   * @param conf may not be null
046   * @param providerId differentiate between providers from one factory. may be null
047   */
048  void init(WALFactory factory, Configuration conf, String providerId) throws IOException;
049
050  /**
051   * @param region the region which we want to get a WAL for it. Could be null.
052   * @return a WAL for writing entries for the given region.
053   */
054  WAL getWAL(RegionInfo region) throws IOException;
055
056  /**
057   * @return the List of WALs that are used by this server
058   */
059  List<WAL> getWALs();
060
061  /**
062   * persist outstanding WALs to storage and stop accepting new appends. This method serves as
063   * shorthand for sending a sync to every WAL provided by a given implementation. Those WALs will
064   * also stop accepting new writes.
065   */
066  void shutdown() throws IOException;
067
068  /**
069   * shutdown utstanding WALs and clean up any persisted state. Call this method only when you will
070   * not need to replay any of the edits to the WALs from this provider. After this call completes,
071   * the underlying resources should have been reclaimed.
072   */
073  void close() throws IOException;
074
075  interface WriterBase extends Closeable {
076    long getLength();
077  }
078
079  // Writers are used internally. Users outside of the WAL should be relying on the
080  // interface provided by WAL.
081  interface Writer extends WriterBase {
082    void sync() throws IOException;
083
084    void append(WAL.Entry entry) throws IOException;
085  }
086
087  interface AsyncWriter extends WriterBase {
088    CompletableFuture<Long> sync();
089
090    void append(WAL.Entry entry);
091  }
092
093  /**
094   * Get number of the log files this provider is managing
095   */
096  long getNumLogFiles();
097
098  /**
099   * Get size of the log files this provider is managing
100   */
101  long getLogFileSize();
102
103  /**
104   * Add a {@link WALActionsListener}.
105   * <p>
106   * Notice that you must call this method before calling {@link #getWAL(RegionInfo)} as this method
107   * will not effect the {@link WAL} which has already been created. And as long as we can only it
108   * when initialization, it is not thread safe.
109   */
110  void addWALActionsListener(WALActionsListener listener);
111
112  default WALFileLengthProvider getWALFileLengthProvider() {
113    return path -> getWALs().stream().map(w -> w.getLogFileSizeIfBeingWritten(path))
114        .filter(o -> o.isPresent()).findAny().orElse(OptionalLong.empty());
115  }
116}