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/**
* 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.
*/
#include "DictionaryLoader.hh"
#include "RLE.hh"
namespace orc {
namespace {
// Helper function to read data fully from a stream
void readFully(char* buffer, int64_t bufferSize, SeekableInputStream* stream) {
int64_t posn = 0;
while (posn < bufferSize) {
const void* chunk;
int length;
if (!stream->Next(&chunk, &length)) {
throw ParseError("bad read in readFully");
}
if (posn + length > bufferSize) {
throw ParseError("Corrupt dictionary blob");
}
memcpy(buffer + posn, chunk, static_cast<size_t>(length));
posn += length;
}
}
} // namespace
std::shared_ptr<StringDictionary> loadStringDictionary(uint64_t columnId, StripeStreams& stripe,
MemoryPool& pool) {
// Get encoding information
proto::ColumnEncoding encoding = stripe.getEncoding(columnId);
RleVersion rleVersion = convertRleVersion(encoding.kind());
uint32_t dictSize = encoding.dictionary_size();
// Create the dictionary object
auto dictionary = std::make_shared<StringDictionary>(pool);
// Read LENGTH stream to get dictionary entry lengths
std::unique_ptr<SeekableInputStream> stream =
stripe.getStream(columnId, proto::Stream_Kind_LENGTH, false);
if (dictSize > 0 && stream == nullptr) {
std::stringstream ss;
ss << "LENGTH stream not found in StringDictionaryColumn for column " << columnId;
throw ParseError(ss.str());
}
std::unique_ptr<RleDecoder> lengthDecoder =
createRleDecoder(std::move(stream), false, rleVersion, pool, stripe.getReaderMetrics());
// Decode dictionary entry lengths
dictionary->dictionaryOffset.resize(dictSize + 1);
int64_t* lengthArray = dictionary->dictionaryOffset.data();
lengthDecoder->next(lengthArray + 1, dictSize, nullptr);
lengthArray[0] = 0;
// Convert lengths to cumulative offsets
for (uint32_t i = 1; i < dictSize + 1; ++i) {
if (lengthArray[i] < 0) {
std::stringstream ss;
ss << "Negative dictionary entry length for column " << columnId;
throw ParseError(ss.str());
}
lengthArray[i] += lengthArray[i - 1];
}
int64_t blobSize = lengthArray[dictSize];
// Read DICTIONARY_DATA stream to get dictionary content
dictionary->dictionaryBlob.resize(static_cast<uint64_t>(blobSize));
std::unique_ptr<SeekableInputStream> blobStream =
stripe.getStream(columnId, proto::Stream_Kind_DICTIONARY_DATA, false);
if (blobSize > 0 && blobStream == nullptr) {
std::stringstream ss;
ss << "DICTIONARY_DATA stream not found in StringDictionaryColumn for column " << columnId;
throw ParseError(ss.str());
}
// Read the dictionary blob
readFully(dictionary->dictionaryBlob.data(), blobSize, blobStream.get());
return dictionary;
}
} // namespace orc
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