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#pragma once
#include "cache.h"
namespace NSQLComplete {
template <NPrivate::CCacheKey TKey, NPrivate::CCacheValue TValue>
class TCachedQuery {
public:
using TFunc = std::function<NThreading::TFuture<TValue>(const TKey& key)>;
TCachedQuery(ICache<TKey, TValue>::TPtr cache, TFunc query)
: Cache_(std::move(cache))
, Query_(std::move(query))
{
}
NThreading::TFuture<TValue> operator()(TKey key) const {
auto promise = NThreading::NewPromise<TValue>();
Cache_->Get(key).Apply([cache = Cache_,
query = Query_,
key = std::move(key),
promise](auto f) mutable {
typename ICache<TKey, TValue>::TEntry entry;
try {
entry = f.ExtractValue();
} catch (...) {
promise.SetException(std::current_exception());
return;
}
if (!entry.IsExpired) {
Y_ENSURE(entry.Value.Defined());
promise.SetValue(std::move(*entry.Value));
return;
}
bool isEmpty = entry.Value.Empty();
if (!isEmpty) {
promise.SetValue(std::move(*entry.Value));
}
query(key).Apply([cache, key = std::move(key), isEmpty, promise](auto f) mutable {
TValue value;
try {
value = f.ExtractValue();
} catch (...) {
promise.SetException(std::current_exception());
return;
}
if (isEmpty) {
promise.SetValue(value);
}
cache->Update(key, std::move(value));
});
});
return promise;
}
private:
ICache<TKey, TValue>::TPtr Cache_;
TFunc Query_;
};
} // namespace NSQLComplete
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