--- a/CMakeLists.txt	Thu Jul 04 16:00:13 2013 +0200
+++ b/CMakeLists.txt	Thu Jul 04 16:10:42 2013 +0200
@@ -138,6 +138,7 @@
   Core/RestApi/RestApi.cpp
   Core/MultiThreading/BagOfRunnablesBySteps.cpp
   Core/MultiThreading/SharedMessageQueue.cpp
+  Core/MultiThreading/ThreadedCommandProcessor.cpp
   Core/FileFormats/PngReader.cpp
   Core/FileFormats/PngWriter.cpp
   Core/SQLite/Connection.cpp

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Core/ICommand.h	Thu Jul 04 16:10:42 2013 +0200
@@ -0,0 +1,48 @@
+/**
+ * Orthanc - A Lightweight, RESTful DICOM Store
+ * Copyright (C) 2012-2013 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/>.
+ **/
+
+
+#pragma once
+
+#include "IDynamicObject.h"
+
+namespace Orthanc
+{
+  /**
+   * This class is the base class for the "Command" design pattern.
+   * http://en.wikipedia.org/wiki/Command_pattern
+   **/
+  class ICommand : public IDynamicObject
+  {
+  public:
+    virtual void Execute() = 0;
+  };
+}

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Core/MultiThreading/ThreadedCommandProcessor.cpp	Thu Jul 04 16:10:42 2013 +0200
@@ -0,0 +1,128 @@
+/**
+ * Orthanc - A Lightweight, RESTful DICOM Store
+ * Copyright (C) 2012-2013 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 "ThreadedCommandProcessor.h"
+
+#include "../OrthancException.h"
+
+namespace Orthanc
+{
+  static const int32_t TIMEOUT = 10;
+
+
+  void ThreadedCommandProcessor::Processor(ThreadedCommandProcessor* that)
+  {
+    while (!that->done_)
+    {
+      std::auto_ptr<IDynamicObject> command(that->queue_.Dequeue(TIMEOUT));
+
+      if (command.get() != NULL)
+      {
+        try
+        {
+          dynamic_cast<ICommand&>(*command).Execute();
+        }
+        catch (OrthancException)
+        {
+        }
+
+        {
+          boost::mutex::scoped_lock lock(that->mutex_);
+          assert(that->remainingCommands_ > 0);
+          that->remainingCommands_--;
+          that->processedCommand_.notify_all();
+        }
+      }
+    }
+  }
+
+
+  ThreadedCommandProcessor::ThreadedCommandProcessor(unsigned int numThreads)
+  {
+    if (numThreads < 1)
+    {
+      throw OrthancException(ErrorCode_ParameterOutOfRange);
+    }
+
+    done_ = false;
+    threads_.resize(numThreads);
+    remainingCommands_ = 0;
+
+    for (unsigned int i = 0; i < numThreads; i++)
+    {
+      threads_[i] = new boost::thread(Processor, this);
+    }
+  }
+
+
+  ThreadedCommandProcessor::~ThreadedCommandProcessor()
+  {
+    done_ = true;
+      
+    for (unsigned int i = 0; i < threads_.size(); i++)
+    {
+      boost::thread* t = threads_[i];
+
+      if (t != NULL)
+      {
+        if (t->joinable())
+        {
+          t->join();
+        }
+
+        delete t;
+      }
+    }
+  }
+
+
+  void ThreadedCommandProcessor::Post(ICommand* command)
+  {
+    queue_.Enqueue(command);
+
+    {
+      boost::mutex::scoped_lock lock(mutex_);
+      remainingCommands_++;
+    }
+  }
+
+
+  void ThreadedCommandProcessor::Join()
+  {
+    boost::mutex::scoped_lock lock(mutex_);
+
+    while (!remainingCommands_ == 0)
+    {
+      processedCommand_.wait(lock);
+    }
+  }
+}

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Core/MultiThreading/ThreadedCommandProcessor.h	Thu Jul 04 16:10:42 2013 +0200
@@ -0,0 +1,64 @@
+/**
+ * Orthanc - A Lightweight, RESTful DICOM Store
+ * Copyright (C) 2012-2013 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/>.
+ **/
+
+
+#pragma once
+
+#include "../ICommand.h"
+
+#include "SharedMessageQueue.h"
+
+namespace Orthanc
+{
+  class ThreadedCommandProcessor
+  {
+  private:
+    SharedMessageQueue  queue_;
+    bool done_;
+    std::vector<boost::thread*>  threads_;
+
+    boost::mutex mutex_;
+    unsigned int remainingCommands_;
+    boost::condition_variable processedCommand_;
+
+    static void Processor(ThreadedCommandProcessor* that);
+
+  public:
+    ThreadedCommandProcessor(unsigned int numThreads);
+
+    ~ThreadedCommandProcessor();
+
+    // This takes the ownership of the command
+    void Post(ICommand* command);
+
+    void Join();
+  };
+}