--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Framework/Toolbox/DownloadStack.cpp	Fri Oct 14 15:34:11 2016 +0200
@@ -0,0 +1,209 @@
+/**
+ * Stone of Orthanc
+ * Copyright (C) 2012-2016 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.
+ *
+ * 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 "DownloadStack.h"
+
+#include "../Orthanc/Core/OrthancException.h"
+
+#include <cassert>
+
+namespace OrthancStone
+{
+  bool DownloadStack::CheckInvariants() const
+  {
+    std::vector<bool> dequeued(nodes_.size(), true);
+
+    int i = firstNode_;
+    while (i != NIL)
+    {
+      const Node& node = nodes_[i];
+
+      dequeued[i] = false;
+
+      if (node.next_ != NIL &&
+          nodes_[node.next_].prev_ != i)
+      {
+        return false;
+      }
+
+      if (node.prev_ != NIL &&
+          nodes_[node.prev_].next_ != i)
+      {
+        return false;
+      }
+
+      i = nodes_[i].next_;
+    }
+
+    for (size_t i = 0; i < nodes_.size(); i++)
+    {
+      if (nodes_[i].dequeued_ != dequeued[i])
+      {
+        return false;
+      }
+    }
+
+    return true;
+  }
+
+
+  DownloadStack::DownloadStack(unsigned int size)
+  {
+    nodes_.resize(size);
+
+    if (size == 0)
+    {
+      firstNode_ = NIL;
+    }
+    else
+    {
+      for (size_t i = 0; i < size; i++)
+      {
+        nodes_[i].prev_ = i - 1;
+        nodes_[i].next_ = i + 1;
+        nodes_[i].dequeued_ = false;
+      }
+
+      nodes_.front().prev_ = NIL;
+      nodes_.back().next_ = NIL;
+      firstNode_ = 0;
+    }
+
+    assert(CheckInvariants());
+  }
+
+
+  DownloadStack::~DownloadStack()
+  {
+    assert(CheckInvariants());    
+  }
+
+
+  bool DownloadStack::Pop(unsigned int& value)
+  {
+    boost::mutex::scoped_lock lock(mutex_);
+
+    assert(CheckInvariants());
+
+    if (firstNode_ == NIL)
+    {
+      for (size_t i = 0; i < nodes_.size(); i++)
+      {
+        assert(nodes_[i].dequeued_);
+      }
+
+      return false;
+    }
+    else
+    {
+      assert(firstNode_ >= 0 && firstNode_ < static_cast<int>(nodes_.size()));
+      value = firstNode_;
+
+      Node& node = nodes_[firstNode_];
+      assert(node.prev_ == NIL);
+      assert(!node.dequeued_);
+
+      node.dequeued_ = true;
+      firstNode_ = node.next_;
+
+      if (firstNode_ != NIL)
+      {
+        nodes_[firstNode_].prev_ = NIL;
+      }
+
+      return true;
+    }
+  }
+
+
+  void DownloadStack::SetTopNodeInternal(unsigned int value)
+  {
+    assert(CheckInvariants());
+
+    Node& node = nodes_[value];
+
+    if (node.dequeued_)
+    {
+      // This node has already been processed by the download thread, nothing to do
+      return;
+    }
+
+    // Remove the node from the list
+    if (node.prev_ == NIL)
+    {
+      assert(firstNode_ == static_cast<int>(value));
+      
+      // This is already the top node in the list, nothing to do
+      return;
+    }
+
+    nodes_[node.prev_].next_ = node.next_;
+
+    if (node.next_ != NIL)
+    {
+      nodes_[node.next_].prev_ = node.prev_;
+    }
+
+    // Add back the node at the top of the list
+    assert(firstNode_ != NIL);
+
+    Node& old = nodes_[firstNode_];
+    assert(old.prev_ == NIL);
+    assert(!old.dequeued_);
+    node.prev_ = NIL;
+    node.next_ = firstNode_;
+    old.prev_ = value;
+
+    firstNode_ = value;
+  }
+
+  
+  void DownloadStack::Writer::SetTopNode(unsigned int value)
+  {
+    if (value >= that_.nodes_.size())
+    {
+      throw Orthanc::OrthancException(Orthanc::ErrorCode_ParameterOutOfRange);
+    }
+
+    that_.SetTopNodeInternal(value);
+  }
+
+
+  void DownloadStack::Writer::SetTopNodePermissive(int value)
+  {
+    if (value >= 0 &&
+        value < static_cast<int>(that_.nodes_.size()))
+    {
+      that_.SetTopNodeInternal(value);
+    }
+  }
+}