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Fix TSAN reports on AutoHCC (#11792) 

Summary:
Forgot to run TSAN test on latest revision of https://github.com/facebook/rocksdb/issues/11738

Pull Request resolved: https://github.com/facebook/rocksdb/pull/11792

Test Plan: Use cache_bench to reproduce TSAN errors and observe fix

Reviewed By: ajkr

Differential Revision: D48953196

Pulled By: pdillinger

fbshipit-source-id: 9e358b4768d8ddde86f84b451863263f661d7b80
This commit is contained in:
Peter Dillinger 2023-09-04 10:59:16 -07:00 committed by Facebook GitHub Bot
parent f66df58b9e
commit d01b1215bd
2 changed files with 12 additions and 10 deletions
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15
cache/clock_cache.cc vendored
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@ -3091,16 +3091,11 @@ AutoHyperClockTable::HandleImpl* AutoHyperClockTable::Lookup(
// false positive, which is re-checked after acquiring read ref, or false // false positive, which is re-checked after acquiring read ref, or false
// negative, which is re-checked in the full Lookup. // negative, which is re-checked in the full Lookup.
// We need to make the reads relaxed atomic to avoid TSAN reporting // ReadAllowRace suppresses TSAN report on these reads. Also, using
// race conditions. And we can skip the cheap key match optimization // & rather than && to give more flexibility to the compiler and CPU,
// altogether if 64-bit atomics not supported lock-free. Also, using // as it is safe to access [1] even if [0] doesn't match.
// & rather than && to give more flexibility to the compiler and CPU. if ((int{ReadAllowRace(h->hashed_key[0]) == hashed_key[0]} &
if (!std::atomic<uint64_t>::is_always_lock_free || int{ReadAllowRace(h->hashed_key[1]) == hashed_key[1]})) {
sizeof(std::atomic<uint64_t>) != sizeof(uint64_t) ||
(int{reinterpret_cast<std::atomic<uint64_t>&>(h->hashed_key[0])
.load(std::memory_order_relaxed) == hashed_key[0]} &
int{reinterpret_cast<std::atomic<uint64_t>&>(h->hashed_key[1])
.load(std::memory_order_relaxed) == hashed_key[1]})) {
// Increment acquire counter for definitive check // Increment acquire counter for definitive check
uint64_t old_meta = h->meta.fetch_add(ClockHandle::kAcquireIncrement, uint64_t old_meta = h->meta.fetch_add(ClockHandle::kAcquireIncrement,
std::memory_order_acquire); std::memory_order_acquire);

7
port/lang.h
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@ -69,6 +69,13 @@ constexpr bool kMustFreeHeapAllocations = false;
#define TSAN_SUPPRESSION #define TSAN_SUPPRESSION
#endif // TSAN_SUPPRESSION #endif // TSAN_SUPPRESSION
// Read memory while allowing data races. Only use where it is OK to read
// the wrong value, e.g. where reading the latest value improves performance.
template <typename T>
TSAN_SUPPRESSION inline T ReadAllowRace(const T& v) {
return v;
}
// Compile-time CPU feature testing compatibility // Compile-time CPU feature testing compatibility
// //
// A way to be extra sure these defines have been included. // A way to be extra sure these defines have been included.