--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Core/Cache/MemoryObjectCache.h	Mon Nov 04 15:18:38 2019 +0100
@@ -0,0 +1,109 @@
+/**
+ * Orthanc - A Lightweight, RESTful DICOM Store
+ * Copyright (C) 2012-2016 Sebastien Jodogne, Medical Physics
+ * Department, University Hospital of Liege, Belgium
+ * Copyright (C) 2017-2019 Osimis S.A., 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/>.
+ **/
+
+
+#pragma once
+
+#include "ICacheable.h"
+#include "LeastRecentlyUsedIndex.h"
+
+#if !defined(__EMSCRIPTEN__)
+// Multithreading is not supported in WebAssembly
+#  include <boost/thread/shared_mutex.hpp>
+#endif
+
+#include <boost/date_time/posix_time/posix_time.hpp>
+
+
+namespace Orthanc
+{
+  class MemoryObjectCache : public boost::noncopyable
+  {
+  private:
+    class Item;
+
+#if !defined(__EMSCRIPTEN__)
+    typedef boost::unique_lock<boost::shared_mutex> WriterLock;
+    typedef boost::shared_lock<boost::shared_mutex> ReaderLock;
+
+    // This mutex protects modifications to the structure of the cache (monitor)
+    boost::mutex   cacheMutex_;
+
+    // This mutex protects modifications to the items that are stored in the cache
+    boost::shared_mutex contentMutex_;
+#endif
+
+    size_t currentSize_;
+    size_t maxSize_;
+    LeastRecentlyUsedIndex<std::string, Item*>  content_;
+
+    void Recycle(size_t targetSize);
+    
+  public:
+    MemoryObjectCache();
+
+    ~MemoryObjectCache();
+
+    size_t GetMaximumSize();
+
+    void SetMaximumSize(size_t size);
+
+    void Acquire(const std::string& key,
+                 ICacheable* value);
+
+    void Invalidate(const std::string& key);
+
+    class Reader : public boost::noncopyable
+    {
+    private:
+#if !defined(__EMSCRIPTEN__)
+      ReaderLock                 contentLock_;
+      boost::mutex::scoped_lock  cacheLock_;
+#endif
+      
+      Item*         item_;
+
+    public:
+      Reader(MemoryObjectCache& cache,
+             const std::string& key);
+
+      bool IsValid() const
+      {
+        return item_ != NULL;
+      }
+
+      ICacheable& GetValue() const;
+
+      const boost::posix_time::ptime& GetTime() const;
+    };
+  };
+}