| /* |
| * 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.cassandra.db.commitlog; |
| |
| import java.io.IOException; |
| import java.nio.ByteBuffer; |
| import java.nio.MappedByteBuffer; |
| import java.nio.channels.FileChannel; |
| |
| import org.apache.cassandra.config.DatabaseDescriptor; |
| import org.apache.cassandra.io.FSWriteError; |
| import org.apache.cassandra.io.util.FileUtils; |
| import org.apache.cassandra.utils.NativeLibrary; |
| import org.apache.cassandra.utils.SyncUtil; |
| |
| /* |
| * Memory-mapped segment. Maps the destination channel into an appropriately-sized memory-mapped buffer in which the |
| * mutation threads write. On sync forces the buffer to disk. |
| * If possible, recycles used segment files to avoid reallocating large chunks of disk. |
| */ |
| public class MemoryMappedSegment extends CommitLogSegment |
| { |
| /** |
| * Constructs a new segment file. |
| * |
| * @param filePath if not null, recycles the existing file by renaming it and truncating it to CommitLog.SEGMENT_SIZE. |
| * @param commitLog the commit log it will be used with. |
| */ |
| MemoryMappedSegment(CommitLog commitLog) |
| { |
| super(commitLog); |
| // mark the initial sync marker as uninitialised |
| int firstSync = buffer.position(); |
| buffer.putInt(firstSync + 0, 0); |
| buffer.putInt(firstSync + 4, 0); |
| } |
| |
| ByteBuffer createBuffer(CommitLog commitLog) |
| { |
| try |
| { |
| MappedByteBuffer mappedFile = channel.map(FileChannel.MapMode.READ_WRITE, 0, DatabaseDescriptor.getCommitLogSegmentSize()); |
| commitLog.allocator.addSize(DatabaseDescriptor.getCommitLogSegmentSize()); |
| return mappedFile; |
| } |
| catch (IOException e) |
| { |
| throw new FSWriteError(e, logFile); |
| } |
| } |
| |
| @Override |
| void write(int startMarker, int nextMarker) |
| { |
| // if there's room in the discard section to write an empty header, |
| // zero out the next sync marker so replayer can cleanly exit |
| if (nextMarker <= buffer.capacity() - SYNC_MARKER_SIZE) |
| { |
| buffer.putInt(nextMarker, 0); |
| buffer.putInt(nextMarker + 4, 0); |
| } |
| |
| // write previous sync marker to point to next sync marker |
| // we don't chain the crcs here to ensure this method is idempotent if it fails |
| writeSyncMarker(id, buffer, startMarker, startMarker, nextMarker); |
| } |
| |
| @Override |
| protected void flush(int startMarker, int nextMarker) |
| { |
| try |
| { |
| SyncUtil.force((MappedByteBuffer) buffer); |
| } |
| catch (Exception e) // MappedByteBuffer.force() does not declare IOException but can actually throw it |
| { |
| throw new FSWriteError(e, getPath()); |
| } |
| NativeLibrary.trySkipCache(fd, startMarker, nextMarker, logFile.getAbsolutePath()); |
| } |
| |
| @Override |
| public long onDiskSize() |
| { |
| return DatabaseDescriptor.getCommitLogSegmentSize(); |
| } |
| |
| @Override |
| protected void internalClose() |
| { |
| if (FileUtils.isCleanerAvailable()) |
| FileUtils.clean(buffer); |
| super.internalClose(); |
| } |
| } |