| /* |
| * 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.lucene.util.fst; |
| |
| import org.apache.lucene.store.DataInput; |
| import org.apache.lucene.store.DataOutput; |
| import org.apache.lucene.store.IndexInput; |
| import org.apache.lucene.util.RamUsageEstimator; |
| |
| import java.io.IOException; |
| |
| /** Provides off heap storage of finite state machine (FST), |
| * using underlying index input instead of byte store on heap |
| * |
| * @lucene.experimental |
| */ |
| public final class OffHeapFSTStore implements FSTStore { |
| |
| private static final long BASE_RAM_BYTES_USED = RamUsageEstimator.shallowSizeOfInstance(OffHeapFSTStore.class); |
| |
| private IndexInput in; |
| private long offset; |
| private long numBytes; |
| |
| @Override |
| public void init(DataInput in, long numBytes) throws IOException { |
| if (in instanceof IndexInput) { |
| this.in = (IndexInput) in; |
| this.numBytes = numBytes; |
| this.offset = this.in.getFilePointer(); |
| } else { |
| throw new IllegalArgumentException("parameter:in should be an instance of IndexInput for using OffHeapFSTStore, not a " |
| + in.getClass().getName()); |
| } |
| } |
| |
| @Override |
| public long ramBytesUsed() { |
| return BASE_RAM_BYTES_USED; |
| } |
| |
| @Override |
| public long size() { |
| return numBytes; |
| } |
| |
| @Override |
| public FST.BytesReader getReverseBytesReader() { |
| try { |
| return new ReverseRandomAccessReader(in.randomAccessSlice(offset, numBytes)); |
| } catch (IOException e) { |
| throw new RuntimeException(e); |
| } |
| } |
| |
| @Override |
| public void writeTo(DataOutput out) throws IOException { |
| throw new UnsupportedOperationException("writeToOutput operation is not supported for OffHeapFSTStore"); |
| } |
| } |