--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Orthanc/Plugins/Samples/GdcmDecoder/GdcmDecoderCache.cpp	Wed Dec 02 16:27:28 2015 +0100
@@ -0,0 +1,98 @@
+/**
+ * Orthanc - A Lightweight, RESTful DICOM Store
+ * Copyright (C) 2012-2015 Sebastien Jodogne, Medical Physics
+ * Department, University Hospital 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.
+ * 
+ * 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 "GdcmDecoderCache.h"
+
+#include "OrthancImageWrapper.h"
+
+namespace OrthancPlugins
+{
+  std::string GdcmDecoderCache::ComputeMd5(OrthancPluginContext* context,
+                                           const void* dicom,
+                                           size_t size)
+  {
+    std::string result;
+
+    char* md5 = OrthancPluginComputeMd5(context, dicom, size);
+
+    if (md5 == NULL)
+    {
+      throw std::runtime_error("Cannot compute MD5 hash");
+    }
+
+    bool ok = false;
+    try
+    {
+      result.assign(md5);
+      ok = true;
+    }
+    catch (...)
+    {
+    }
+
+    OrthancPluginFreeString(context, md5);
+
+    if (!ok)
+    {
+      throw std::runtime_error("Not enough memory");
+    }
+    else
+    {    
+      return result;
+    }
+  }
+
+
+  OrthancImageWrapper* GdcmDecoderCache::Decode(OrthancPluginContext* context,
+                                                const void* dicom,
+                                                const uint32_t size,
+                                                uint32_t frameIndex)
+  {
+    std::string md5 = ComputeMd5(context, dicom, size);
+
+    // First check whether the previously decoded image is the same
+    // as this one
+    {
+      boost::mutex::scoped_lock lock(mutex_);
+
+      if (decoder_.get() != NULL &&
+          size_ == size &&
+          md5_ == md5)
+      {
+        // This is the same image: Reuse the previous decoding
+        return new OrthancImageWrapper(context, decoder_->Decode(context, frameIndex));
+      }
+    }
+
+    // This is not the same image
+    std::auto_ptr<GdcmImageDecoder> decoder(new GdcmImageDecoder(dicom, size));
+    std::auto_ptr<OrthancImageWrapper> image(new OrthancImageWrapper(context, decoder->Decode(context, frameIndex)));
+
+    {
+      // Cache the newly created decoder for further use
+      boost::mutex::scoped_lock lock(mutex_);
+      decoder_ = decoder;
+      size_ = size;
+      md5_ = md5;
+    }
+
+    return image.release();
+  }
+}