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GH-49069: [C++] Share Trie instances across CSV value decoders #49070

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Merged
kou merged 2 commits into from
Jan 30, 2026
Merged

GH-49069: [C++] Share Trie instances across CSV value decoders #49070

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GH-49069: [C++] Share Trie instances across CSV value decoders
HyukjinKwon Jan 30, 2026
ed65f92
Address a review comment
HyukjinKwon Jan 30, 2026
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107 changes: 63 additions & 44 deletions cpp/src/arrow/csv/converter.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -105,31 +105,45 @@ Status PresizeBuilder(const BlockParser& parser, BuilderType* builder) {
}
}

/////////////////////////////////////////////////////////////////////////
// Shared Tries cache to avoid rebuilding them for each decoder instance

struct TrieCache {
Trie null_trie;
Trie true_trie;
Trie false_trie;

static Result<std::shared_ptr<TrieCache>> Make(const ConvertOptions& options) {
auto cache = std::make_shared<TrieCache>();
RETURN_NOT_OK(InitializeTrie(options.null_values, &cache->null_trie));
RETURN_NOT_OK(InitializeTrie(options.true_values, &cache->true_trie));
RETURN_NOT_OK(InitializeTrie(options.false_values, &cache->false_trie));
return cache;
}
};

/////////////////////////////////////////////////////////////////////////
// Per-type value decoders

struct ValueDecoder {
explicit ValueDecoder(const std::shared_ptr<DataType>& type,
const ConvertOptions& options)
: type_(type), options_(options) {}
const ConvertOptions& options, const TrieCache* trie_cache)
: type_(type), options_(options), trie_cache_(trie_cache) {}

Status Initialize() {
// TODO no need to build a separate Trie for each instance
return InitializeTrie(options_.null_values, &null_trie_);
}
Status Initialize() { return Status::OK(); }

bool IsNull(const uint8_t* data, uint32_t size, bool quoted) {
if (quoted && !options_.quoted_strings_can_be_null) {
return false;
}
return null_trie_.Find(std::string_view(reinterpret_cast<const char*>(data), size)) >=
0;
return trie_cache_->null_trie.Find(
std::string_view(reinterpret_cast<const char*>(data), size)) >= 0;
}

protected:
Trie null_trie_;
const std::shared_ptr<DataType> type_;
const ConvertOptions& options_;
const TrieCache* trie_cache_;
};

//
Expand All @@ -140,8 +154,9 @@ struct FixedSizeBinaryValueDecoder : public ValueDecoder {
using value_type = const uint8_t*;

explicit FixedSizeBinaryValueDecoder(const std::shared_ptr<DataType>& type,
const ConvertOptions& options)
: ValueDecoder(type, options),
const ConvertOptions& options,
const TrieCache* trie_cache)
: ValueDecoder(type, options, trie_cache),
byte_width_(checked_cast<const FixedSizeBinaryType&>(*type).byte_width()) {}

Status Decode(const uint8_t* data, uint32_t size, bool quoted, value_type* out) {
Expand Down Expand Up @@ -207,8 +222,8 @@ struct NumericValueDecoder : public ValueDecoder {
using value_type = typename T::c_type;

NumericValueDecoder(const std::shared_ptr<DataType>& type,
const ConvertOptions& options)
: ValueDecoder(type, options),
const ConvertOptions& options, const TrieCache* trie_cache)
: ValueDecoder(type, options, trie_cache),
concrete_type_(checked_cast<const T&>(*type)),
string_converter_(MakeStringConverter<T>(options)) {}

Expand Down Expand Up @@ -236,31 +251,20 @@ struct BooleanValueDecoder : public ValueDecoder {

using ValueDecoder::ValueDecoder;

Status Initialize() {
// TODO no need to build separate Tries for each instance
RETURN_NOT_OK(InitializeTrie(options_.true_values, &true_trie_));
RETURN_NOT_OK(InitializeTrie(options_.false_values, &false_trie_));
return ValueDecoder::Initialize();
}

Status Decode(const uint8_t* data, uint32_t size, bool quoted, value_type* out) {
// XXX should quoted values be allowed at all?
if (false_trie_.Find(std::string_view(reinterpret_cast<const char*>(data), size)) >=
0) {
if (trie_cache_->false_trie.Find(
std::string_view(reinterpret_cast<const char*>(data), size)) >= 0) {
*out = false;
return Status::OK();
}
if (ARROW_PREDICT_TRUE(true_trie_.Find(std::string_view(
if (ARROW_PREDICT_TRUE(trie_cache_->true_trie.Find(std::string_view(
reinterpret_cast<const char*>(data), size)) >= 0)) {
*out = true;
return Status::OK();
}
return GenericConversionError(type_, data, size);
}

protected:
Trie true_trie_;
Trie false_trie_;
};

//
Expand All @@ -271,8 +275,8 @@ struct DecimalValueDecoder : public ValueDecoder {
using value_type = Decimal128;

explicit DecimalValueDecoder(const std::shared_ptr<DataType>& type,
const ConvertOptions& options)
: ValueDecoder(type, options),
const ConvertOptions& options, const TrieCache* trie_cache)
: ValueDecoder(type, options, trie_cache),
decimal_type_(internal::checked_cast<const DecimalType&>(*type_)),
type_precision_(decimal_type_.precision()),
type_scale_(decimal_type_.scale()) {}
Expand Down Expand Up @@ -310,8 +314,10 @@ struct CustomDecimalPointValueDecoder : public ValueDecoder {
using value_type = typename WrappedDecoder::value_type;

explicit CustomDecimalPointValueDecoder(const std::shared_ptr<DataType>& type,
const ConvertOptions& options)
: ValueDecoder(type, options), wrapped_decoder_(type, options) {}
const ConvertOptions& options,
const TrieCache* trie_cache)
: ValueDecoder(type, options, trie_cache),
wrapped_decoder_(type, options, trie_cache) {}

Status Initialize() {
RETURN_NOT_OK(wrapped_decoder_.Initialize());
Expand All @@ -321,7 +327,7 @@ struct CustomDecimalPointValueDecoder : public ValueDecoder {
mapping_[options_.decimal_point] = '.';
mapping_['.'] = options_.decimal_point; // error out on standard decimal point
temp_.resize(30);
return Status::OK();
return ValueDecoder::Initialize();
}

Status Decode(const uint8_t* data, uint32_t size, bool quoted, value_type* out) {
Expand Down Expand Up @@ -357,8 +363,9 @@ struct InlineISO8601ValueDecoder : public ValueDecoder {
using value_type = int64_t;

explicit InlineISO8601ValueDecoder(const std::shared_ptr<DataType>& type,
const ConvertOptions& options)
: ValueDecoder(type, options),
const ConvertOptions& options,
const TrieCache* trie_cache)
: ValueDecoder(type, options, trie_cache),
unit_(checked_cast<const TimestampType&>(*type_).unit()),
expect_timezone_(!checked_cast<const TimestampType&>(*type_).timezone().empty()) {
}
Expand Down Expand Up @@ -396,8 +403,9 @@ struct SingleParserTimestampValueDecoder : public ValueDecoder {
using value_type = int64_t;

explicit SingleParserTimestampValueDecoder(const std::shared_ptr<DataType>& type,
const ConvertOptions& options)
: ValueDecoder(type, options),
const ConvertOptions& options,
const TrieCache* trie_cache)
: ValueDecoder(type, options, trie_cache),
unit_(checked_cast<const TimestampType&>(*type_).unit()),
expect_timezone_(!checked_cast<const TimestampType&>(*type_).timezone().empty()),
parser_(*options_.timestamp_parsers[0]) {}
Expand Down Expand Up @@ -436,8 +444,9 @@ struct MultipleParsersTimestampValueDecoder : public ValueDecoder {
using value_type = int64_t;

explicit MultipleParsersTimestampValueDecoder(const std::shared_ptr<DataType>& type,
const ConvertOptions& options)
: ValueDecoder(type, options),
const ConvertOptions& options,
const TrieCache* trie_cache)
: ValueDecoder(type, options, trie_cache),
unit_(checked_cast<const TimestampType&>(*type_).unit()),
expect_timezone_(!checked_cast<const TimestampType&>(*type_).timezone().empty()),
parsers_(GetParsers(options_)) {}
Expand Down Expand Up @@ -477,8 +486,9 @@ struct DurationValueDecoder : public ValueDecoder {
using value_type = int64_t;

explicit DurationValueDecoder(const std::shared_ptr<DataType>& type,
const ConvertOptions& options)
: ValueDecoder(type, options),
const ConvertOptions& options,
const TrieCache* trie_cache)
: ValueDecoder(type, options, trie_cache),
concrete_type_(checked_cast<const DurationType&>(*type)),
string_converter_() {}

Expand Down Expand Up @@ -517,7 +527,8 @@ class NullConverter : public ConcreteConverter {
public:
NullConverter(const std::shared_ptr<DataType>& type, const ConvertOptions& options,
MemoryPool* pool)
: ConcreteConverter(type, options, pool), decoder_(type_, options_) {}
: ConcreteConverter(type, options, pool),
decoder_(type_, options_, static_cast<const TrieCache*>(trie_cache_.get())) {}

Result<std::shared_ptr<Array>> Convert(const BlockParser& parser,
int32_t col_index) override {
Expand Down Expand Up @@ -551,7 +562,8 @@ class PrimitiveConverter : public ConcreteConverter {
public:
PrimitiveConverter(const std::shared_ptr<DataType>& type, const ConvertOptions& options,
MemoryPool* pool)
: ConcreteConverter(type, options, pool), decoder_(type_, options_) {}
: ConcreteConverter(type, options, pool),
decoder_(type_, options_, static_cast<const TrieCache*>(trie_cache_.get())) {}

Result<std::shared_ptr<Array>> Convert(const BlockParser& parser,
int32_t col_index) override {
Expand Down Expand Up @@ -593,7 +605,8 @@ class TypedDictionaryConverter : public ConcreteDictionaryConverter {
TypedDictionaryConverter(const std::shared_ptr<DataType>& value_type,
const ConvertOptions& options, MemoryPool* pool)
: ConcreteDictionaryConverter(value_type, options, pool),
decoder_(value_type, options_) {}
decoder_(value_type, options_, static_cast<const TrieCache*>(trie_cache_.get())) {
}

Result<std::shared_ptr<Array>> Convert(const BlockParser& parser,
int32_t col_index) override {
Expand Down Expand Up @@ -684,7 +697,13 @@ std::shared_ptr<ConverterType> MakeRealConverter(const std::shared_ptr<DataType>

Converter::Converter(const std::shared_ptr<DataType>& type, const ConvertOptions& options,
MemoryPool* pool)
: options_(options), pool_(pool), type_(type) {}
: options_(options), pool_(pool), type_(type) {
// Build shared Trie cache (errors handled in Initialize())
auto maybe_cache = TrieCache::Make(options);
if (maybe_cache.ok()) {
trie_cache_ = std::static_pointer_cast<void>(*std::move(maybe_cache));
}
}

DictionaryConverter::DictionaryConverter(const std::shared_ptr<DataType>& value_type,
const ConvertOptions& options, MemoryPool* pool)
Expand Down
3 changes: 3 additions & 0 deletions cpp/src/arrow/csv/converter.h
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Expand Up @@ -57,6 +57,9 @@ class ARROW_EXPORT Converter {
const ConvertOptions& options_;
MemoryPool* pool_;
std::shared_ptr<DataType> type_;
// Opaque TrieCache pointer. TrieCache destructor is called via control block.
// https://en.cppreference.com/w/cpp/memory/shared_ptr
std::shared_ptr<void> trie_cache_;
};

class ARROW_EXPORT DictionaryConverter : public Converter {
Expand Down
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