| /* |
| * 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.util.RamUsageEstimator; |
| |
| import java.io.IOException; |
| |
| /** Provides storage of finite state machine (FST), |
| * using byte array or byte store allocated on heap. |
| * |
| * @lucene.experimental |
| */ |
| public final class OnHeapFSTStore implements FSTStore { |
| |
| private static final long BASE_RAM_BYTES_USED = RamUsageEstimator.shallowSizeOfInstance(OnHeapFSTStore.class); |
| |
| /** A {@link BytesStore}, used during building, or during reading when |
| * the FST is very large (more than 1 GB). If the FST is less than 1 |
| * GB then bytesArray is set instead. */ |
| private BytesStore bytes; |
| |
| /** Used at read time when the FST fits into a single byte[]. */ |
| private byte[] bytesArray; |
| |
| private final int maxBlockBits; |
| |
| public OnHeapFSTStore(int maxBlockBits) { |
| if (maxBlockBits < 1 || maxBlockBits > 30) { |
| throw new IllegalArgumentException("maxBlockBits should be 1 .. 30; got " + maxBlockBits); |
| } |
| |
| this.maxBlockBits = maxBlockBits; |
| } |
| |
| @Override |
| public void init(DataInput in, long numBytes) throws IOException { |
| if (numBytes > 1 << this.maxBlockBits) { |
| // FST is big: we need multiple pages |
| bytes = new BytesStore(in, numBytes, 1<<this.maxBlockBits); |
| } else { |
| // FST fits into a single block: use ByteArrayBytesStoreReader for less overhead |
| bytesArray = new byte[(int) numBytes]; |
| in.readBytes(bytesArray, 0, bytesArray.length); |
| } |
| } |
| |
| @Override |
| public long size() { |
| if (bytesArray != null) { |
| return bytesArray.length; |
| } else { |
| return bytes.ramBytesUsed(); |
| } |
| } |
| |
| @Override |
| public long ramBytesUsed() { |
| return BASE_RAM_BYTES_USED + size(); |
| } |
| |
| @Override |
| public FST.BytesReader getReverseBytesReader() { |
| if (bytesArray != null) { |
| return new ReverseBytesReader(bytesArray); |
| } else { |
| return bytes.getReverseReader(); |
| } |
| } |
| |
| @Override |
| public void writeTo(DataOutput out) throws IOException { |
| if (bytes != null) { |
| long numBytes = bytes.getPosition(); |
| out.writeVLong(numBytes); |
| bytes.writeTo(out); |
| } else { |
| assert bytesArray != null; |
| out.writeVLong(bytesArray.length); |
| out.writeBytes(bytesArray, 0, bytesArray.length); |
| } |
| } |
| } |