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/**
 * Copyright (C) 2011 the original author or authors.
 * See the notice.md file distributed with this work for additional
 * information regarding copyright ownership.
 *
 * Licensed 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.iq80.leveldb.impl;

import com.google.common.base.Preconditions;
import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;
import com.google.common.cache.RemovalListener;
import com.google.common.cache.RemovalNotification;
import org.iq80.leveldb.util.Closeables;
import org.iq80.leveldb.table.FileChannelTable;
import org.iq80.leveldb.table.MMapTable;
import org.iq80.leveldb.table.Table;
import org.iq80.leveldb.table.UserComparator;
import org.iq80.leveldb.util.Finalizer;
import org.iq80.leveldb.util.InternalTableIterator;
import org.iq80.leveldb.util.Slice;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.nio.channels.FileChannel;
import java.util.concurrent.ExecutionException;

public class TableCache
{
    private final LoadingCache cache;
    private final Finalizer finalizer = new Finalizer
(1); public TableCache(final File databaseDir, int tableCacheSize, final UserComparator userComparator, final boolean verifyChecksums) { Preconditions.checkNotNull(databaseDir, "databaseName is null"); cache = CacheBuilder.newBuilder() .maximumSize(tableCacheSize) .removalListener(new RemovalListener() { public void onRemoval(RemovalNotification notification) { Table table = notification.getValue().getTable(); finalizer.addCleanup(table, table.closer()); } }) .build(new CacheLoader() { public TableAndFile load(Long fileNumber) throws IOException { return new TableAndFile(databaseDir, fileNumber, userComparator, verifyChecksums); } }); } public InternalTableIterator newIterator(FileMetaData file) { return newIterator(file.getNumber()); } public InternalTableIterator newIterator(long number) { return new InternalTableIterator(getTable(number).iterator()); } public long getApproximateOffsetOf(FileMetaData file, Slice key) { return getTable(file.getNumber()).getApproximateOffsetOf(key); } private Table getTable(long number) { Table table; try { table = cache.get(number).getTable(); } catch (ExecutionException e) { Throwable cause = e; if (e.getCause() != null) { cause = e.getCause(); } throw new RuntimeException("Could not open table " + number, cause); } return table; } public void close() { cache.invalidateAll(); finalizer.destroy(); } public void evict(long number) { cache.invalidate(number); } private static final class TableAndFile { private final Table table; private final FileChannel fileChannel; private TableAndFile(File databaseDir, long fileNumber, UserComparator userComparator, boolean verifyChecksums) throws IOException { String tableFileName = Filename.tableFileName(fileNumber); File tableFile = new File(databaseDir, tableFileName); fileChannel = new FileInputStream(tableFile).getChannel(); try { if( Iq80DBFactory.USE_MMAP ) { table = new MMapTable(tableFile.getAbsolutePath(), fileChannel, userComparator, verifyChecksums); } else { table = new FileChannelTable(tableFile.getAbsolutePath(), fileChannel, userComparator, verifyChecksums); } } catch (IOException e) { Closeables.closeQuietly(fileChannel); throw e; } } public Table getTable() { return table; } } }