dungba88 commented on code in PR #12624: URL: https://github.com/apache/lucene/pull/12624#discussion_r1415627354
########## lucene/core/src/java/org/apache/lucene/util/fst/ReadWriteDataOutput.java: ########## @@ -0,0 +1,82 @@ +/* + * 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 java.io.IOException; +import java.nio.ByteBuffer; +import java.util.List; +import org.apache.lucene.store.ByteBuffersDataInput; +import org.apache.lucene.store.ByteBuffersDataOutput; +import org.apache.lucene.store.DataOutput; + +/** + * An adapter class to use {@link ByteBuffersDataOutput} as a {@link FSTReader}. It allows the FST + * to be readable immediately after writing + */ +final class ReadWriteDataOutput extends DataOutput implements FSTReader, Freezable { + + private final ByteBuffersDataOutput dataOutput; + // the DataInput to read from in case the DataOutput has multiple blocks + private ByteBuffersDataInput dataInput; + // the ByteBuffers to read from in case the DataOutput has a single block + private ByteBuffer byteBuffer; + + public ReadWriteDataOutput(ByteBuffersDataOutput dataOutput) { + this.dataOutput = dataOutput; + } + + @Override + public void writeByte(byte b) { + dataOutput.writeByte(b); + } + + @Override + public void writeBytes(byte[] b, int offset, int length) { + dataOutput.writeBytes(b, offset, length); + } + + @Override + public long ramBytesUsed() { + return dataOutput.ramBytesUsed(); + } + + @Override + public void freeze() { + // these operations are costly, so we want to compute it once and cache + List<ByteBuffer> byteBuffers = dataOutput.toWriteableBufferList(); + if (byteBuffers.size() == 1) { Review Comment: I think it didn't handle the single buffer use case, and ByteBuffersDataInput would fall into the same performance regression problem as BytesStore with multiple blocks (which due to the fact that the method is size is larger and won't be inlined by JVM). -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
