| /* |
| * 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.io.util; |
| |
| import java.util.HashMap; |
| import java.util.Iterator; |
| import java.util.Map; |
| import javax.annotation.concurrent.NotThreadSafe; |
| |
| import com.google.common.base.Preconditions; |
| |
| import org.apache.cassandra.io.compress.CompressionMetadata; |
| |
| /** |
| * It is a utility class for caching {@link MmappedRegions} primarily used by a {@link FileHandle.Builder} when a handle |
| * to the same file is created multiple times (as when an sstable is opened early). |
| */ |
| @NotThreadSafe |
| public class MmappedRegionsCache implements AutoCloseable |
| { |
| private final Map<File, MmappedRegions> cache = new HashMap<>(); |
| private boolean closed = false; |
| |
| /** |
| * Looks for mmapped regions in cache. If found, a shared copy is created and extended to the provided length. |
| * If mmapped regions do not exist yet for the provided key, they are created and a shared copy is returned. |
| * |
| * @param channel channel for which the mmapped regions are requested |
| * @param length length of the file |
| * @return a shared copy of the cached mmapped regions |
| */ |
| @SuppressWarnings("resource") |
| public MmappedRegions getOrCreate(ChannelProxy channel, long length) |
| { |
| Preconditions.checkState(!closed); |
| MmappedRegions regions = cache.computeIfAbsent(channel.file(), ignored -> MmappedRegions.map(channel, length)); |
| Preconditions.checkArgument(regions.isValid(channel)); |
| regions.extend(length); |
| return regions.sharedCopy(); |
| } |
| |
| /** |
| * Looks for mmapped regions in cache. If found, a shared copy is created and extended according to the provided metadata. |
| * If mmapped regions do not exist yet for the provided key, they are created and a shared copy is returned. |
| * |
| * @param channel channel for which the mmapped regions are requested |
| * @param metadata compression metadata of the file |
| * @return a shared copy of the cached mmapped regions |
| */ |
| @SuppressWarnings("resource") |
| public MmappedRegions getOrCreate(ChannelProxy channel, CompressionMetadata metadata) |
| { |
| Preconditions.checkState(!closed); |
| MmappedRegions regions = cache.computeIfAbsent(channel.file(), ignored -> MmappedRegions.map(channel, metadata)); |
| Preconditions.checkArgument(regions.isValid(channel)); |
| regions.extend(metadata); |
| return regions.sharedCopy(); |
| } |
| |
| @Override |
| @SuppressWarnings("resource") |
| public void close() |
| { |
| closed = true; |
| Iterator<MmappedRegions> it = cache.values().iterator(); |
| while (it.hasNext()) |
| { |
| MmappedRegions region = it.next(); |
| region.closeQuietly(); |
| it.remove(); |
| } |
| } |
| } |