linrrzqqq commented on code in PR #68498:
URL: https://github.com/apache/doris/pull/68498#discussion_r4138170433
##########
be/src/core/value/quantile_state.cpp:
##########
@@ -28,7 +31,81 @@
#include "util/tdigest.h"
#include "util/unaligned.h"
+#ifdef BE_TEST
+#include "cpp/sync_point.h"
+#endif
+
namespace doris {
+
+// Shares a digest across QuantileState copies and detaches it before sample
+// writes. Readers use shared locks; compression uses an exclusive lock.
+struct QuantileState::TDigestHolder {
+ explicit TDigestHolder(float compression) : digest(compression) {}
+ TDigestHolder(const TDigestHolder& other) : digest(other.digest) {}
+
+ std::shared_lock<std::shared_mutex> lock_processed_digest() {
+ std::shared_lock read_lock(mutex);
+ if (digest.have_unprocessed()) {
+ read_lock.unlock();
+ {
+ std::unique_lock write_lock(mutex);
+ if (digest.have_unprocessed()) {
+ digest.compress();
+ }
+ }
+ read_lock.lock();
+ }
+ return read_lock;
+ }
+
+ TDigest digest;
+ std::shared_mutex mutex;
+};
+
+QuantileState QuantileState::copy_for_result() const {
+ if (_type != TDIGEST) {
+ return *this;
+ }
+ QuantileState result(_compression);
+ result._type = TDIGEST;
+ {
+ // Reuse processed centroids on the next row instead of sorting the
prefix again.
+ auto lock = _tdigest_ptr->lock_processed_digest();
+ result._tdigest_ptr = std::make_shared<TDigestHolder>(*_tdigest_ptr);
+ }
+ return result;
+}
+
+size_t QuantileState::allocated_bytes(const std::vector<QuantileState>&
states) {
+ size_t bytes = states.capacity() * sizeof(QuantileState);
+ std::unordered_set<const TDigestHolder*> counted;
Review Comment:
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