Mooncake/mooncake-store/include/tiered_cache/scheduler/lru_policy.h

37 lines
969 B
C++

#pragma once
#include "tiered_cache/scheduler/scheduler_policy.h"
namespace mooncake {
/**
* @class LRUPolicy
* @brief Recency-based promotion/eviction policy with watermark control.
*
* All keys are sorted by recency. The most recently used keys (up to target
* capacity) should be in fast tier, the rest in slow tier.
*/
class LRUPolicy : public SchedulerPolicy {
public:
struct Config {
double high_watermark = 0.90; // Trigger scheduling when above this
double low_watermark = 0.70; // Target usage after scheduling
};
explicit LRUPolicy(Config config);
void SetFastTier(UUID id) override;
bool IsFastTier(UUID id) const;
tl::expected<std::vector<SchedAction>, ErrorCode> Decide(
const std::unordered_map<UUID, TierStats>& tier_stats,
const std::vector<KeyContext>& active_keys) override;
private:
Config config_;
std::optional<UUID> fast_tier_id_;
};
} // namespace mooncake