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#pragma once
#include "public.h"
#include <yt/yt/core/profiling/timing.h>
#include <library/cpp/threading/thread_local/thread_local.h>
namespace NYT {
////////////////////////////////////////////////////////////////////////////////
//! An expiring cache with separate storage for each thread.
//!
//! It is useful when some cache entries are used very frequently. So, with a
//! regular cache for this task, we might spend more on lock contention inside
//! the cache rather than on cache misses.
template <class TKey, class TValue, size_t ShardCount = 128>
class TThreadLocalExpiringCache
{
public:
explicit TThreadLocalExpiringCache(TDuration expirationTimeout);
std::optional<TValue> Get(const TKey& key);
void Set(const TKey& key, TValue value);
private:
struct TEntry
{
TValue Value;
TCpuInstant LastUpdateTime;
};
class TCache
{
public:
explicit TCache(TDuration expirationTimeout);
std::optional<TValue> Get(const TKey& key);
void Set(const TKey& key, TValue value);
private:
THashMap<TKey, TEntry> Entries_;
i64 IterationsSinceCleanup_ = 0;
NProfiling::TCpuDuration ExpirationTimeout_;
static constexpr int CleanupAmortizationFactor = 3;
void TryCleanup();
void Cleanup();
};
const TDuration ExpirationTimeout_;
::NThreading::TThreadLocalValue<TCache, ::NThreading::EThreadLocalImpl::HotSwap, ShardCount> Cache_;
};
////////////////////////////////////////////////////////////////////////////////
} // namespace NYT
#define TLS_EXPIRING_CACHE_INL_H_
#include "tls_expiring_cache-inl.h"
#undef TLS_EXPIRING_CACHE_INL_H_
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