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fix: Reduce lock cost in AsciiInfo updates #12363

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fix: Reduce lock cost in AsciiInfo updates #12363

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71 changes: 51 additions & 20 deletions velox/vector/SimpleVector.h
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Original file line number Diff line number Diff line change
Expand Up @@ -57,6 +57,14 @@ struct AsciiInfo {
isAllAscii_ = f;
}

bool asciiComputedRowsEmpty() const {
return asciiComputedRowsEmpty_;
}

void setAsciiComputedRowsEmpty(bool value) {
asciiComputedRowsEmpty_ = value;
}

/// Returns locked for read bit vector with bits set for rows where ascii was
/// processed.
auto readLockedAsciiComputedRows() const {
Expand All @@ -69,12 +77,6 @@ struct AsciiInfo {
return asciiComputedRows_.wlock();
}

/// Returns upgradable locked bit vector with bits set for rows where ascii
/// was processed.
auto upgradableLockedAsciiComputedRows() {
return asciiComputedRows_.ulock();
}

private:
// isAllAscii_ and asciiComputedRows_ are thread-safe because input vectors
// can be shared across threads, hence this make their mutation thread safe.
Expand All @@ -84,6 +86,8 @@ struct AsciiInfo {
// True is all strings in asciiComputedRows_ are ASCII.
std::atomic_bool isAllAscii_{false};

std::atomic_bool asciiComputedRowsEmpty_{true};

// If T is StringView, store set of rows where we have computed asciiness.
// A set bit means the row was processed.
folly::Synchronized<SelectivityVector> asciiComputedRows_;
Expand Down Expand Up @@ -341,14 +345,21 @@ class SimpleVector : public BaseVector {
}

wlockedAsciiComputedRows->select(rows);
asciiInfo.setAsciiComputedRowsEmpty(
!wlockedAsciiComputedRows->hasSelections());
return asciiInfo.isAllAscii();
}

/// Clears asciiness state.
template <typename U = T>
typename std::enable_if_t<std::is_same_v<U, StringView>, void>
invalidateIsAscii() {
asciiInfo.writeLockedAsciiComputedRows()->clearAll();
if (asciiInfo.asciiComputedRowsEmpty()) {
return;
}
auto wlock = asciiInfo.writeLockedAsciiComputedRows();
wlock->clearAll();
asciiInfo.setAsciiComputedRowsEmpty(true);
asciiInfo.setIsAllAscii(false);
}

Expand All @@ -367,14 +378,18 @@ class SimpleVector : public BaseVector {
}

wlockedAsciiComputedRows->select(rows);
asciiInfo.setAsciiComputedRowsEmpty(
!wlockedAsciiComputedRows->hasSelections());
}

template <typename U = T>
typename std::enable_if_t<std::is_same_v<U, StringView>, void> setAllIsAscii(
bool ascii) {
ensureIsAsciiCapacity();
auto wlock = asciiInfo.writeLockedAsciiComputedRows();
wlock->setAll();
asciiInfo.setIsAllAscii(ascii);
asciiInfo.writeLockedAsciiComputedRows()->setAll();
asciiInfo.setAsciiComputedRowsEmpty(!wlock->hasSelections());
}

template <typename U = T>
Expand Down Expand Up @@ -438,26 +453,40 @@ class SimpleVector : public BaseVector {
template <typename U = T>
typename std::enable_if_t<std::is_same_v<U, StringView>, void>
ensureIsAsciiCapacity() {
auto ulockedAsciiComputedRows{
asciiInfo.upgradableLockedAsciiComputedRows()};
if (ulockedAsciiComputedRows->size() < length_) {
ulockedAsciiComputedRows.moveFromUpgradeToWrite()->resize(length_, false);
{
auto rlock = asciiInfo.readLockedAsciiComputedRows();
if (rlock->size() >= length_) {
return;
}
}
auto wlock = asciiInfo.writeLockedAsciiComputedRows();
if (wlock->size() >= length_) {
return;
}
wlock->resize(length_, false);
asciiInfo.setAsciiComputedRowsEmpty(!wlock->hasSelections());
}

/// Ensure asciiInfo is of the correct size. But only if it is not empty.
template <typename U = T>
typename std::enable_if_t<std::is_same_v<U, StringView>, void>
resizeIsAsciiIfNotEmpty(vector_size_t size, bool newAscii) {
auto ulockedAsciiComputedRows{
asciiInfo.upgradableLockedAsciiComputedRows()};
if (ulockedAsciiComputedRows->hasSelections()) {
if (ulockedAsciiComputedRows->size() < size) {
ulockedAsciiComputedRows.moveFromUpgradeToWrite()->resize(
size, newAscii);
asciiInfo.setIsAllAscii(asciiInfo.isAllAscii() & newAscii);
if (asciiInfo.asciiComputedRowsEmpty()) {
return;
}
{
auto rlock = asciiInfo.readLockedAsciiComputedRows();
if (!rlock->hasSelections() || rlock->size() >= size) {
return;
}
}
auto wlock = asciiInfo.writeLockedAsciiComputedRows();
if (!wlock->hasSelections() || wlock->size() >= size) {
return;
}
wlock->resize(size, newAscii);
asciiInfo.setIsAllAscii(asciiInfo.isAllAscii() & newAscii);
asciiInfo.setAsciiComputedRowsEmpty(!wlock->hasSelections());
}

/**
Expand Down Expand Up @@ -493,7 +522,9 @@ class SimpleVector : public BaseVector {

if constexpr (std::is_same_v<T, StringView>) {
if (rows) {
asciiInfo.writeLockedAsciiComputedRows()->deselect(*rows);
auto wlock = asciiInfo.writeLockedAsciiComputedRows();
wlock->deselect(*rows);
asciiInfo.setAsciiComputedRowsEmpty(!wlock->hasSelections());
} else {
invalidateIsAscii();
}
Expand Down
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