116 lines
3.4 KiB
C++
116 lines
3.4 KiB
C++
/**
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* Orthanc - A Lightweight, RESTful DICOM Store
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* Copyright (C) 2012-2016 Sebastien Jodogne, Medical Physics
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* Department, University Hospital of Liege, Belgium
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* Copyright (C) 2017-2023 Osimis S.A., Belgium
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* Copyright (C) 2024-2025 Orthanc Team SRL, Belgium
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* Copyright (C) 2021-2025 Sebastien Jodogne, ICTEAM UCLouvain, Belgium
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*
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* This program is free software: you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public License
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* as published by the Free Software Foundation, either version 3 of
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* the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this program. If not, see
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* <http://www.gnu.org/licenses/>.
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**/
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#pragma once
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#include "../OrthancFramework.h"
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#include "ICacheable.h"
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#include "LeastRecentlyUsedIndex.h"
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#include <boost/thread/condition_variable.hpp>
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#include <boost/thread/mutex.hpp>
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namespace Orthanc
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{
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/**
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* Class that caches a dictionary
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* of strings, using the "fetch/add" paradigm of memcached.
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*
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* Starting from 1.12.2, if multiple clients are trying to access
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* an inexistent item at the same time, only one of them will load it
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* and the others will wait until the first one has loaded the data.
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*
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* The MemoryStringCache is only accessible through an Accessor.
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*
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* Note: this class is thread safe
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**/
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class ORTHANC_PUBLIC MemoryStringCache : public boost::noncopyable
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{
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public:
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class ORTHANC_PUBLIC Accessor : public boost::noncopyable
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{
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protected:
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MemoryStringCache& cache_;
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private:
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bool shouldAdd_; // when this accessor is the one who should load and add the data
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std::string keyToAdd_;
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public:
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explicit Accessor(MemoryStringCache& cache);
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~Accessor();
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bool Fetch(std::string& value, const std::string& key);
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void Add(const std::string& key, const std::string& value);
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void Add(const std::string& key,const char* buffer, size_t size);
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};
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private:
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class StringValue;
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mutable boost::mutex cacheMutex_; // note: we can not use recursive_mutex with condition_variable
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boost::condition_variable cacheCond_;
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std::set<std::string> itemsBeingLoaded_;
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size_t currentSize_;
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size_t maxSize_;
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LeastRecentlyUsedIndex<std::string, StringValue*> content_;
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void Recycle(size_t targetSize);
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public:
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MemoryStringCache();
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~MemoryStringCache();
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size_t GetMaximumSize();
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void SetMaximumSize(size_t size);
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void Invalidate(const std::string& key);
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size_t GetCurrentSize() const;
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size_t GetNumberOfItems() const;
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private:
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void Add(const std::string& key,
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const std::string& value);
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void Add(const std::string& key,
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const void* buffer,
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size_t size);
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bool Fetch(std::string& value,
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const std::string& key);
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void RemoveFromItemsBeingLoaded(const std::string& key);
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void RemoveFromItemsBeingLoadedInternal(const std::string& key);
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void AddToItemsBeingLoadedInternal(const std::string& key);
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};
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}
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