mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-11-17 13:13:36 +00:00
135 lines
3.6 KiB
C++
135 lines
3.6 KiB
C++
//
|
|
// UniqueExpireStrategy.h
|
|
//
|
|
// Library: Foundation
|
|
// Package: Cache
|
|
// Module: UniqueExpireStrategy
|
|
//
|
|
// Definition of the UniqueExpireStrategy class.
|
|
//
|
|
// Copyright (c) 2006, Applied Informatics Software Engineering GmbH.
|
|
// and Contributors.
|
|
//
|
|
// SPDX-License-Identifier: BSL-1.0
|
|
//
|
|
|
|
|
|
#ifndef Foundation_UniqueExpireStrategy_INCLUDED
|
|
#define Foundation_UniqueExpireStrategy_INCLUDED
|
|
|
|
|
|
#include <map>
|
|
#include <set>
|
|
#include "Poco/AbstractStrategy.h"
|
|
#include "Poco/Bugcheck.h"
|
|
#include "Poco/EventArgs.h"
|
|
#include "Poco/KeyValueArgs.h"
|
|
#include "Poco/Timestamp.h"
|
|
#include "Poco/ValidArgs.h"
|
|
|
|
|
|
namespace Poco
|
|
{
|
|
|
|
|
|
template <class TKey, class TValue>
|
|
class UniqueExpireStrategy : public AbstractStrategy<TKey, TValue>
|
|
/// An UniqueExpireStrategy implements time based expiration of cache entries. In contrast
|
|
/// to ExpireStrategy which only allows to set a per cache expiration value, it allows to define
|
|
/// expiration per CacheEntry.
|
|
/// Each TValue object must thus offer the following method:
|
|
///
|
|
/// const Poco::Timestamp& getExpiration() const;
|
|
///
|
|
/// which returns the absolute timepoint when the entry will be invalidated.
|
|
{
|
|
public:
|
|
typedef std::multimap<Timestamp, TKey> TimeIndex;
|
|
typedef typename TimeIndex::iterator IndexIterator;
|
|
typedef typename TimeIndex::const_iterator ConstIndexIterator;
|
|
typedef std::map<TKey, IndexIterator> Keys;
|
|
typedef typename Keys::iterator Iterator;
|
|
|
|
public:
|
|
UniqueExpireStrategy()
|
|
/// Create an unique expire strategy.
|
|
{
|
|
}
|
|
|
|
~UniqueExpireStrategy() { }
|
|
|
|
void onAdd(const void *, const KeyValueArgs<TKey, TValue> & args)
|
|
{
|
|
// note: we have to insert even if the expire timepoint is in the past (for StrategyCollection classes to avoid inconsistency with LRU)
|
|
// no problem: will be removed with next get
|
|
const Timestamp & expire = args.value().getExpiration();
|
|
IndexIterator it = _keyIndex.insert(std::make_pair(expire, args.key()));
|
|
std::pair<Iterator, bool> stat = _keys.insert(std::make_pair(args.key(), it));
|
|
if (!stat.second)
|
|
{
|
|
_keyIndex.erase(stat.first->second);
|
|
stat.first->second = it;
|
|
}
|
|
}
|
|
|
|
void onRemove(const void *, const TKey & key)
|
|
{
|
|
Iterator it = _keys.find(key);
|
|
if (it != _keys.end())
|
|
{
|
|
_keyIndex.erase(it->second);
|
|
_keys.erase(it);
|
|
}
|
|
}
|
|
|
|
void onGet(const void *, const TKey & key)
|
|
{
|
|
// get triggers no changes in an expire
|
|
}
|
|
|
|
void onClear(const void *, const EventArgs & args)
|
|
{
|
|
_keys.clear();
|
|
_keyIndex.clear();
|
|
}
|
|
|
|
void onIsValid(const void *, ValidArgs<TKey> & args)
|
|
{
|
|
Iterator it = _keys.find(args.key());
|
|
if (it != _keys.end())
|
|
{
|
|
Timestamp now;
|
|
if (it->second->first <= now)
|
|
{
|
|
args.invalidate();
|
|
}
|
|
}
|
|
else //not found: probably removed by onReplace
|
|
args.invalidate();
|
|
}
|
|
|
|
void onReplace(const void *, std::set<TKey> & elemsToRemove)
|
|
{
|
|
// Note: replace only informs the cache which elements
|
|
// it would like to remove!
|
|
// it does not remove them on its own!
|
|
IndexIterator it = _keyIndex.begin();
|
|
Timestamp now;
|
|
while (it != _keyIndex.end() && it->first < now)
|
|
{
|
|
elemsToRemove.insert(it->second);
|
|
++it;
|
|
}
|
|
}
|
|
|
|
protected:
|
|
Keys _keys; /// For faster replacement of keys, the iterator points to the _keyIndex map
|
|
TimeIndex _keyIndex; /// Maps time to key value
|
|
};
|
|
|
|
|
|
} // namespace Poco
|
|
|
|
|
|
#endif // Foundation_UniqueExpireStrategy_INCLUDED
|