Mercurial > hg > orthanc
diff Core/Cache/MemoryCache.cpp @ 284:06aa7b7b6723
implementation of a single-threaded cache mechanism
author | Sebastien Jodogne <s.jodogne@gmail.com> |
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date | Wed, 12 Dec 2012 15:40:18 +0100 |
parents | |
children | 4031f73fe0e4 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/Core/Cache/MemoryCache.cpp Wed Dec 12 15:40:18 2012 +0100 @@ -0,0 +1,90 @@ +/** + * Orthanc - A Lightweight, RESTful DICOM Store + * Copyright (C) 2012 Medical Physics Department, CHU of Liege, + * Belgium + * + * This program is free software: you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation, either version 3 of the + * License, or (at your option) any later version. + * + * In addition, as a special exception, the copyright holders of this + * program give permission to link the code of its release with the + * OpenSSL project's "OpenSSL" library (or with modified versions of it + * that use the same license as the "OpenSSL" library), and distribute + * the linked executables. You must obey the GNU General Public License + * in all respects for all of the code used other than "OpenSSL". If you + * modify file(s) with this exception, you may extend this exception to + * your version of the file(s), but you are not obligated to do so. If + * you do not wish to do so, delete this exception statement from your + * version. If you delete this exception statement from all source files + * in the program, then also delete it here. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + **/ + + +#include "MemoryCache.h" + +namespace Orthanc +{ + MemoryCache::Page& MemoryCache::Load(const std::string& id) + { + // Reuse the cache entry if it already exists + Page* p = NULL; + if (index_.Contains(id, p)) + { + assert(p != NULL); + index_.TagAsMostRecent(id); + return *p; + } + + // The id is not in the cache yet. Make some room if the cache + // is full. + if (index_.GetSize() == cacheSize_) + { + index_.RemoveOldest(p); + delete p; + } + + // Create a new cache page + std::auto_ptr<Page> result(new Page); + result->id_ = id; + result->content_.reset(provider_.Provide(id)); + + // Add the newly create page to the cache + p = result.release(); + index_.Add(id, p); + return *p; + } + + MemoryCache::MemoryCache(ICachePageProvider& provider, + size_t cacheSize) : + provider_(provider), + cacheSize_(cacheSize) + { + } + + MemoryCache::~MemoryCache() + { + while (!index_.IsEmpty()) + { + Page* element = NULL; + index_.RemoveOldest(element); + assert(element != NULL); + delete element; + } + } + + MemoryCache::Accessor* MemoryCache::Access(const std::string& id) + { + Page& element = Load(id); + return new Accessor(element); + } +}