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#pragma once
#include <Common/Exception.h>
#include <Common/ICachePolicyUserQuota.h>
#include <functional>
#include <memory>
#include <mutex>
namespace DB
{
template <typename T>
struct EqualWeightFunction
{
size_t operator()(const T &) const
{
return 1;
}
};
template <typename TKey, typename TMapped, typename HashFunction = std::hash<TKey>, typename WeightFunction = EqualWeightFunction<TMapped>>
class ICachePolicy
{
public:
using Key = TKey;
using Mapped = TMapped;
using MappedPtr = std::shared_ptr<Mapped>;
using OnWeightLossFunction = std::function<void(size_t)>;
struct KeyMapped
{
Key key;
MappedPtr mapped;
};
explicit ICachePolicy(CachePolicyUserQuotaPtr user_quotas_) : user_quotas(std::move(user_quotas_)) {}
virtual ~ICachePolicy() = default;
virtual size_t sizeInBytes() const = 0;
virtual size_t count() const = 0;
virtual size_t maxSizeInBytes() const = 0;
virtual void setMaxCount(size_t /*max_count*/) = 0;
virtual void setMaxSizeInBytes(size_t /*max_size_in_bytes*/) = 0;
virtual void setQuotaForUser(const String & user_name, size_t max_size_in_bytes, size_t max_entries) { user_quotas->setQuotaForUser(user_name, max_size_in_bytes, max_entries); }
/// HashFunction usually hashes the entire key and the found key will be equal the provided key. In such cases, use get(). It is also
/// possible to store other, non-hashed data in the key. In that case, the found key is potentially different from the provided key.
/// Then use getWithKey() to also return the found key including it's non-hashed data.
virtual MappedPtr get(const Key & key) = 0;
virtual std::optional<KeyMapped> getWithKey(const Key &) = 0;
virtual void set(const Key & key, const MappedPtr & mapped) = 0;
virtual void remove(const Key & key) = 0;
virtual void clear() = 0;
virtual std::vector<KeyMapped> dump() const = 0;
protected:
CachePolicyUserQuotaPtr user_quotas;
};
}
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