--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Resources/Orthanc/Core/Cache/MemoryCache.cpp	Fri Mar 23 11:04:03 2018 +0100
@@ -0,0 +1,96 @@
+/**
+ * Orthanc - A Lightweight, RESTful DICOM Store
+ * Copyright (C) 2012-2016 Sebastien Jodogne, Medical Physics
+ * Department, University Hospital of Liege, Belgium
+ * Copyright (C) 2017-2018 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/>.
+ **/
+
+
+#include "../PrecompiledHeaders.h"
+#include "MemoryCache.h"
+
+#include "../Logging.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))
+    {
+      VLOG(1) << "Reusing a cache page";
+      assert(p != NULL);
+      index_.MakeMostRecent(id);
+      return *p;
+    }
+
+    // The id is not in the cache yet. Make some room if the cache
+    // is full.
+    if (index_.GetSize() == cacheSize_)
+    {
+      VLOG(1) << "Dropping the oldest cache page";
+      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
+    VLOG(1) << "Registering new data in a cache page";
+    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;
+    }
+  }
+
+  IDynamicObject& MemoryCache::Access(const std::string& id)
+  {
+    return *Load(id).content_;
+  }
+}