rdblue commented on code in PR #3202: URL: https://github.com/apache/parquet-java/pull/3202#discussion_r2061041198
########## parquet-variant/src/main/java/org/apache/parquet/variant/VariantBuilder.java: ########## @@ -0,0 +1,590 @@ +/* + * 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.parquet.variant; + +import java.math.BigDecimal; +import java.math.BigInteger; +import java.nio.ByteBuffer; +import java.nio.ByteOrder; +import java.nio.charset.StandardCharsets; +import java.util.ArrayList; +import java.util.Arrays; +import java.util.Collections; +import java.util.Comparator; +import java.util.HashMap; + +/** + * Builder for creating Variant value and metadata. + */ +public class VariantBuilder { + /** + * Creates a VariantBuilder. + * @param allowDuplicateKeys if true, only the last occurrence of a duplicate key will be kept. + * Otherwise, an exception will be thrown. + */ + public VariantBuilder(boolean allowDuplicateKeys) { + this.allowDuplicateKeys = allowDuplicateKeys; + } + + /** + * @return the Variant value + */ + public Variant build() { + int numKeys = dictionaryKeys.size(); + // Use long to avoid overflow in accumulating lengths. + long dictionaryStringSize = 0; + for (byte[] key : dictionaryKeys) { + dictionaryStringSize += key.length; + } + // Determine the number of bytes required per offset entry. + // The largest offset is the one-past-the-end value, which is total string size. It's very + // unlikely that the number of keys could be larger, but incorporate that into the calculation + // in case of pathological data. + long maxSize = Math.max(dictionaryStringSize, numKeys); + int offsetSize = getMinIntegerSize((int) maxSize); + + int offsetStart = 1 + offsetSize; + int stringStart = offsetStart + (numKeys + 1) * offsetSize; + long metadataSize = stringStart + dictionaryStringSize; + + byte[] metadata = new byte[(int) metadataSize]; + int headerByte = VariantUtil.VERSION | ((offsetSize - 1) << 6); + VariantUtil.writeLong(metadata, 0, headerByte, 1); + VariantUtil.writeLong(metadata, 1, numKeys, offsetSize); + int currentOffset = 0; + for (int i = 0; i < numKeys; ++i) { + VariantUtil.writeLong(metadata, offsetStart + i * offsetSize, currentOffset, offsetSize); + byte[] key = dictionaryKeys.get(i); + System.arraycopy(key, 0, metadata, stringStart + currentOffset, key.length); + currentOffset += key.length; + } + VariantUtil.writeLong(metadata, offsetStart + numKeys * offsetSize, currentOffset, offsetSize); + return new Variant(Arrays.copyOfRange(writeBuffer, 0, writePos), metadata); + } + + /** + * Appends a string value to the Variant builder. + * @param str the string value to append + * @return this builder + */ + public VariantBuilder appendString(String str) { + byte[] text = str.getBytes(StandardCharsets.UTF_8); + boolean longStr = text.length > VariantUtil.MAX_SHORT_STR_SIZE; + checkCapacity((longStr ? 1 + VariantUtil.U32_SIZE : 1) + text.length); + if (longStr) { + writeBuffer[writePos++] = VariantUtil.primitiveHeader(VariantUtil.LONG_STR); + VariantUtil.writeLong(writeBuffer, writePos, text.length, VariantUtil.U32_SIZE); + writePos += VariantUtil.U32_SIZE; + } else { + writeBuffer[writePos++] = VariantUtil.shortStrHeader(text.length); + } + System.arraycopy(text, 0, writeBuffer, writePos, text.length); + writePos += text.length; + return this; + } + + /** + * Appends a null value to the Variant builder. + * @return this builder + */ + public VariantBuilder appendNull() { + checkCapacity(1); + writeBuffer[writePos++] = VariantUtil.primitiveHeader(VariantUtil.NULL); + return this; + } + + /** + * Appends a boolean value to the Variant builder. + * @param b the boolean value to append + * @return this builder + */ + public VariantBuilder appendBoolean(boolean b) { + checkCapacity(1); + writeBuffer[writePos++] = VariantUtil.primitiveHeader(b ? VariantUtil.TRUE : VariantUtil.FALSE); + return this; + } + + /** + * Appends a long value to the variant builder. The actual encoded integer type depends on the + * value range of the long value. + * @param l the long value to append + * @return this builder + */ + public VariantBuilder appendLong(long l) { + if (l == (byte) l) { + checkCapacity(1 + 1); + writeBuffer[writePos++] = VariantUtil.primitiveHeader(VariantUtil.INT8); + VariantUtil.writeLong(writeBuffer, writePos, l, 1); + writePos += 1; + } else if (l == (short) l) { + checkCapacity(1 + 2); + writeBuffer[writePos++] = VariantUtil.primitiveHeader(VariantUtil.INT16); + VariantUtil.writeLong(writeBuffer, writePos, l, 2); Review Comment: Wouldn't it be better to update `writePos` just once instead? This could write to `writePos + 1` and then increment by 3 on the next line. -- This is an automated message from the Apache Git Service. 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