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refactor: Remove const_cast and const_pointer_cast #734

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refactor: Remove const_cast and const_pointer_cast #734

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20 changes: 12 additions & 8 deletions axiom/connectors/ConnectorMetadata.h
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Original file line number Diff line number Diff line change
Expand Up @@ -135,7 +135,7 @@ class Column {
return latestStats_;
}

ColumnStatistics* mutableStats() {
ColumnStatistics* mutableStats() const {
std::lock_guard<std::mutex> l(mutex_);
if (!latestStats_) {
allStats_.push_back(std::make_unique<ColumnStatistics>());
Expand All @@ -145,7 +145,7 @@ class Column {
}

/// Sets statistics. May be called multiple times if table contents change.
void setStats(std::unique_ptr<ColumnStatistics> stats) {
void setStats(std::unique_ptr<ColumnStatistics> stats) const {
std::lock_guard<std::mutex> l(mutex_);
allStats_.push_back(std::move(stats));
latestStats_ = allStats_.back().get();
Expand Down Expand Up @@ -183,16 +183,20 @@ class Column {
const bool hidden_;
const velox::Variant defaultValue_;

// The latest element added to 'allStats_'.
velox::tsan_atomic<ColumnStatistics*> latestStats_{nullptr};
// The latest element added to 'allStats_'. Mutable because statistics are
// logically separate from the column's identity (name, type) and may be
// updated even on a const Column.
mutable velox::tsan_atomic<ColumnStatistics*> latestStats_{nullptr};

// All statistics recorded for this column. Old values can be purged when the
// containing Schema is not in use.
std::vector<std::unique_ptr<ColumnStatistics>> allStats_;
// containing Schema is not in use. Mutable for the same reason as
// latestStats_.
mutable std::vector<std::unique_ptr<ColumnStatistics>> allStats_;

private:
// Serializes changes to statistics.
std::mutex mutex_;
// Serializes changes to statistics. Mutable for the same reason as
// latestStats_.
mutable std::mutex mutex_;
};

class Table;
Expand Down
70 changes: 31 additions & 39 deletions axiom/connectors/hive/LocalHiveConnectorMetadata.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -177,13 +177,14 @@ std::vector<SplitSource::SplitAndGroup> LocalHiveSplitSource::getSplits(

LocalHiveConnectorMetadata::LocalHiveConnectorMetadata(
velox::connector::hive::HiveConnector* hiveConnector)
: HiveConnectorMetadata(hiveConnector), splitManager_(this) {}
: HiveConnectorMetadata(hiveConnector), splitManager_(this) {
initialize();
}

void LocalHiveConnectorMetadata::reinitialize() {
std::lock_guard<std::mutex> l(mutex_);
tables_.clear();
initialize();
initialized_ = true;
}

void LocalHiveConnectorMetadata::initialize() {
Expand All @@ -198,22 +199,14 @@ void LocalHiveConnectorMetadata::initialize() {
readTables(path);
}

void LocalHiveConnectorMetadata::ensureInitialized() const {
std::lock_guard<std::mutex> l(mutex_);
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@hdikeman hdikeman Jan 9, 2026

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Since this function was removed, do we still need the mutex?

I thought this was to guard against the case where multiple threads invoke ensureInitialized(). Could you double check

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@PingLiuPing PingLiuPing Jan 9, 2026

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@hdikeman Thanks for the comment.
I noticed that mutex_ is not only used here, it is used in many other places too such as findTable, dropTable etc.

if (initialized_) {
return;
}
const_cast<LocalHiveConnectorMetadata*>(this)->initialize();
initialized_ = true;
}

std::shared_ptr<velox::core::QueryCtx> LocalHiveConnectorMetadata::makeQueryCtx(
const std::string& queryId) {
const std::string& queryId) const {
std::unordered_map<std::string, std::string> config;
std::unordered_map<std::string, std::shared_ptr<velox::config::ConfigBase>>
connectorConfigs;
connectorConfigs[hiveConnector_->connectorId()] =
std::const_pointer_cast<velox::config::ConfigBase>(hiveConfig_->config());
std::make_shared<velox::config::ConfigBase>(
hiveConfig_->config()->rawConfigsCopy());

return velox::core::QueryCtx::create(
hiveConnector_->executor(),
Expand Down Expand Up @@ -269,8 +262,13 @@ std::pair<int64_t, int64_t> LocalHiveTableLayout::sample(
std::vector<ColumnStatistics>* statistics) const {
VELOX_CHECK(extraFilters.empty());

auto connectorQueryCtx = reinterpret_cast<LocalHiveConnectorMetadata*>(
ConnectorMetadata::metadata(connector()))
->connectorQueryCtx();

std::vector<std::unique_ptr<StatisticsBuilder>> builders;
auto result = sample(handle, pct, scanType, fields, allocator, &builders);
auto result = sample(
handle, pct, scanType, fields, allocator, &builders, connectorQueryCtx);
if (!statistics) {
return result;
}
Expand All @@ -292,7 +290,9 @@ std::pair<int64_t, int64_t> LocalHiveTableLayout::sample(
velox::RowTypePtr scanType,
const std::vector<velox::common::Subfield>& fields,
velox::HashStringAllocator* allocator,
std::vector<std::unique_ptr<StatisticsBuilder>>* statsBuilders) const {
std::vector<std::unique_ptr<StatisticsBuilder>>* statsBuilders,
const std::shared_ptr<velox::connector::ConnectorQueryCtx>&
connectorQueryCtx) const {
StatisticsBuilderOptions options = {
.maxStringLength = 100, .countDistincts = true, .allocator = allocator};

Expand All @@ -318,10 +318,6 @@ std::pair<int64_t, int64_t> LocalHiveTableLayout::sample(

const auto outputType = ROW(std::move(names), std::move(types));

auto connectorQueryCtx = reinterpret_cast<LocalHiveConnectorMetadata*>(
ConnectorMetadata::metadata(connector()))
->connectorQueryCtx();

const auto maxRowsToScan = table().numRows() * (pct / 100);

int64_t passingRows = 0;
Expand Down Expand Up @@ -364,7 +360,7 @@ std::pair<int64_t, int64_t> LocalHiveTableLayout::sample(

void LocalTable::makeDefaultLayout(
std::vector<std::unique_ptr<const FileInfo>> files,
LocalHiveConnectorMetadata& metadata) {
const LocalHiveConnectorMetadata& metadata) {
if (!layouts_.empty()) {
// The table already has a layout made from a schema file.
reinterpret_cast<LocalHiveTableLayout*>(layouts_[0].get())
Expand Down Expand Up @@ -904,7 +900,7 @@ void LocalHiveConnectorMetadata::loadTable(
VELOX_CHECK_NOT_NULL(column, "Column not found: {}", name);

if (auto readerStats = reader->columnStatistics(i)) {
auto* stats = const_cast<Column*>(column)->mutableStats();
auto* stats = column->mutableStats();
stats->numValues += readerStats->getNumberOfValues().value_or(0);

const auto numValues = readerStats->getNumberOfValues();
Expand All @@ -923,7 +919,7 @@ void LocalHiveConnectorMetadata::loadTable(
// Set pct to sample ~100K rows.
pct = 100 * 100'000 / table->numRows();
}
table->sampleNumDistincts(pct, schemaPool_.get());
table->sampleNumDistincts(pct, schemaPool_.get(), *this);
}

namespace {
Expand Down Expand Up @@ -980,7 +976,8 @@ LocalTable::LocalTable(

void LocalTable::sampleNumDistincts(
float samplePct,
velox::memory::MemoryPool* pool) {
velox::memory::MemoryPool* pool,
const LocalHiveConnectorMetadata& metadata) {
std::vector<velox::common::Subfield> fields;
fields.reserve(type()->size());
for (auto i = 0; i < type()->size(); ++i) {
Expand All @@ -991,19 +988,14 @@ void LocalTable::sampleNumDistincts(
auto allocator = std::make_unique<velox::HashStringAllocator>(pool);
auto* layout = layouts_[0].get();

auto* metadata = ConnectorMetadata::metadata(layout->connector());

std::vector<velox::connector::ColumnHandlePtr> columns;
columns.reserve(type()->size());
for (auto i = 0; i < type()->size(); ++i) {
columns.push_back(layout->createColumnHandle(
/*session=*/nullptr, type()->nameOf(i)));
}

auto* localHiveMetadata =
dynamic_cast<const LocalHiveConnectorMetadata*>(metadata);
auto& evaluator =
*localHiveMetadata->connectorQueryCtx()->expressionEvaluator();
auto& evaluator = *metadata.connectorQueryCtx()->expressionEvaluator();

std::vector<velox::core::TypedExprPtr> ignore;
auto handle = layout->createTableHandle(
Expand All @@ -1014,13 +1006,19 @@ void LocalTable::sampleNumDistincts(

std::vector<std::unique_ptr<StatisticsBuilder>> statsBuilders;
auto [sampled, passed] = localLayout->sample(
handle, samplePct, type(), fields, allocator.get(), &statsBuilders);
handle,
samplePct,
type(),
fields,
allocator.get(),
&statsBuilders,
metadata.connectorQueryCtx());

numSampledRows_ = sampled;
for (auto i = 0; i < statsBuilders.size(); ++i) {
if (statsBuilders[i]) {
auto* column = findColumn(type()->nameOf(i));
ColumnStatistics& stats = *const_cast<Column*>(column)->mutableStats();
const auto* column = findColumn(type()->nameOf(i));
ColumnStatistics& stats = *column->mutableStats();
statsBuilders[i]->build(stats);
auto estimate = stats.numDistinct;
int64_t approxNumDistinct =
Expand Down Expand Up @@ -1053,16 +1051,13 @@ void LocalTable::sampleNumDistincts(
}
}

const_cast<Column*>(findColumn(type()->nameOf(i)))
->mutableStats()
->numDistinct = approxNumDistinct;
column->mutableStats()->numDistinct = approxNumDistinct;
}
}
}
}

TablePtr LocalHiveConnectorMetadata::findTable(std::string_view name) {
ensureInitialized();
std::lock_guard<std::mutex> l(mutex_);
return findTableLocked(name);
}
Expand Down Expand Up @@ -1168,7 +1163,6 @@ TablePtr LocalHiveConnectorMetadata::createTable(
const velox::RowTypePtr& rowType,
const folly::F14FastMap<std::string, velox::Variant>& options) {
validateOptions(options);
ensureInitialized();
auto path = tablePath(tableName);
if (dirExists(path)) {
VELOX_USER_FAIL("Table {} already exists", tableName);
Expand Down Expand Up @@ -1269,8 +1263,6 @@ bool LocalHiveConnectorMetadata::dropTable(
const ConnectorSessionPtr& /* session */,
std::string_view tableName,
bool ifExists) {
ensureInitialized();

std::lock_guard<std::mutex> l(mutex_);
if (!tables_.contains(tableName)) {
if (ifExists) {
Expand Down
20 changes: 10 additions & 10 deletions axiom/connectors/hive/LocalHiveConnectorMetadata.h
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Original file line number Diff line number Diff line change
Expand Up @@ -138,7 +138,9 @@ class LocalHiveTableLayout : public HiveTableLayout {
velox::RowTypePtr scanType,
const std::vector<velox::common::Subfield>& fields,
velox::HashStringAllocator* allocator,
std::vector<std::unique_ptr<StatisticsBuilder>>* statsBuilders) const;
std::vector<std::unique_ptr<StatisticsBuilder>>* statsBuilders,
const std::shared_ptr<velox::connector::ConnectorQueryCtx>&
connectorQueryCtx) const;

private:
std::vector<std::unique_ptr<const FileInfo>> files_;
Expand All @@ -165,7 +167,7 @@ class LocalTable : public HiveTable {

void makeDefaultLayout(
std::vector<std::unique_ptr<const FileInfo>> files,
LocalHiveConnectorMetadata& metadata);
const LocalHiveConnectorMetadata& metadata);

uint64_t numRows() const override {
return numRows_;
Expand All @@ -177,7 +179,10 @@ class LocalTable : public HiveTable {

/// Samples 'samplePct' % rows of the table and sets the num distincts
/// estimate for the columns. uses 'pool' for temporary data.
void sampleNumDistincts(float samplePct, velox::memory::MemoryPool* pool);
void sampleNumDistincts(
float samplePct,
velox::memory::MemoryPool* pool,
const LocalHiveConnectorMetadata& metadata);

private:
// Serializes initialization, e.g. exportedColumns_.
Expand All @@ -202,7 +207,6 @@ class LocalHiveConnectorMetadata : public HiveConnectorMetadata {
TablePtr findTable(std::string_view name) override;

ConnectorSplitManager* splitManager() override {
ensureInitialized();
return &splitManager_;
}

Expand All @@ -229,12 +233,11 @@ class LocalHiveConnectorMetadata : public HiveConnectorMetadata {
/// tables for name resolution.
const folly::F14FastMap<std::string, std::shared_ptr<LocalTable>>& tables()
const {
ensureInitialized();
return tables_;
}

std::shared_ptr<velox::core::QueryCtx> makeQueryCtx(
const std::string& queryId);
const std::string& queryId) const;

TablePtr createTable(
const ConnectorSessionPtr& session,
Expand Down Expand Up @@ -273,10 +276,8 @@ class LocalHiveConnectorMetadata : public HiveConnectorMetadata {
void reloadTableFromPath(std::string_view tableName);

private:
// Used to lazy initialize this in ensureInitialized() and to implement
// reinitialize().
// Used to initialize this in constructor and to implement reinitialize().
void initialize();
void ensureInitialized() const override;
void makeQueryCtx();
void makeConnectorQueryCtx();
void readTables(std::string_view path);
Expand All @@ -285,7 +286,6 @@ class LocalHiveConnectorMetadata : public HiveConnectorMetadata {
std::shared_ptr<LocalTable> findTableLocked(std::string_view name) const;

mutable std::mutex mutex_;
mutable bool initialized_{false};
std::shared_ptr<velox::memory::MemoryPool> rootPool_{
velox::memory::memoryManager()->addRootPool()};
std::shared_ptr<velox::memory::MemoryPool> schemaPool_;
Expand Down