diff --git a/src/libslic3r/Channel.hpp b/src/libslic3r/Channel.hpp
new file mode 100644
index 000000000..8d1a07d35
--- /dev/null
+++ b/src/libslic3r/Channel.hpp
@@ -0,0 +1,104 @@
+#ifndef slic3r_Channel_hpp_
+#define slic3r_Channel_hpp_
+
+#include <deque>
+#include <condition_variable>
+#include <mutex>
+#include <utility>
+#include <boost/optional.hpp>
+
+
+namespace Slic3r {
+
+
+template<class T> class Channel
+{
+private:
+    using UniqueLock = std::unique_lock<std::mutex>;
+    using Queue = std::deque<T>;
+public:
+    class Guard
+    {
+    public:
+        Guard(UniqueLock lock, const Queue &queue) : m_lock(std::move(lock)), m_queue(queue) {}
+        Guard(const Guard &other) = delete;
+        Guard(Guard &&other) = delete;
+        ~Guard() {}
+
+        // Access trampolines
+        size_t size() const noexcept { return m_queue.size(); }
+        bool empty() const noexcept { return m_queue.empty(); }
+        typename Queue::const_iterator begin() const noexcept { return m_queue.begin(); }
+        typename Queue::const_iterator end() const noexcept { return m_queue.end(); }
+        typename Queue::const_reference operator[](size_t i) const { return m_queue[i]; }
+
+        Guard& operator=(const Guard &other) = delete;
+        Guard& operator=(Guard &&other) = delete;
+    private:
+        UniqueLock m_lock;
+        const Queue &m_queue;
+    };
+
+
+    Channel() {}
+    ~Channel() {}
+
+    void push(const T& item, bool silent = false)
+    {
+        {
+            UniqueLock lock(m_mutex);
+            m_queue.push_back(item);
+        }
+        if (! silent) { m_condition.notify_one(); }
+    }
+
+    void push(T &&item, bool silent = false)
+    {
+        {
+            UniqueLock lock(m_mutex);
+            m_queue.push_back(std::forward(item));
+        }
+        if (! silent) { m_condition.notify_one(); }
+    }
+
+    T pop()
+    {
+        UniqueLock lock(m_mutex);
+        m_condition.wait(lock, [this]() { return !m_queue.empty(); });
+        auto item = std::move(m_queue.front());
+        m_queue.pop_front();
+        return item;
+    }
+
+    boost::optional<T> try_pop()
+    {
+        UniqueLock lock(m_mutex);
+        if (m_queue.empty()) {
+            return boost::none;
+        } else {
+            auto item = std::move(m_queue.front());
+            m_queue.pop();
+            return item;
+        }
+    }
+
+    // Unlocked observers
+    // Thread unsafe! Keep in mind you need to re-verify the result after acquiring lock!
+    size_t size() const noexcept { return m_queue.size(); }
+    bool empty() const noexcept { return m_queue.empty(); }
+
+    Guard read() const
+    {
+        return Guard(UniqueLock(m_mutex), m_queue);
+    }
+
+private:
+    Queue m_queue;
+    std::mutex m_mutex;
+    std::condition_variable m_condition;
+};
+
+
+} // namespace Slic3r
+
+#endif // slic3r_Channel_hpp_
diff --git a/src/slic3r/GUI/BackgroundSlicingProcess.cpp b/src/slic3r/GUI/BackgroundSlicingProcess.cpp
index 1829de959..3a34b3381 100644
--- a/src/slic3r/GUI/BackgroundSlicingProcess.cpp
+++ b/src/slic3r/GUI/BackgroundSlicingProcess.cpp
@@ -17,6 +17,7 @@
 #include "libslic3r/GCode/PostProcessor.hpp"
 
 //#undef NDEBUG
+#include <iostream>    // XXX
 #include <cassert>
 #include <stdexcept>
 #include <cctype>
@@ -79,6 +80,10 @@ void BackgroundSlicingProcess::process_fff()
 	wxQueueEvent(GUI::wxGetApp().mainframe->m_plater, new wxCommandEvent(m_event_slicing_completed_id));
 	m_fff_print->export_gcode(m_temp_output_path, m_gcode_preview_data);
 	if (this->set_step_started(bspsGCodeFinalize)) {
+
+		std::cerr << "BackgroundSlicingProcess: m_upload_job: " << !!m_upload_job << std::endl;
+		std::cerr << "BackgroundSlicingProcess: m_export_path: " << m_export_path << std::endl;
+
 	    if (! m_export_path.empty()) {
 	    	//FIXME localize the messages
 	    	// Perform the final post-processing of the export path by applying the print statistics over the file name.
@@ -387,7 +392,7 @@ void BackgroundSlicingProcess::schedule_upload(Slic3r::PrintHostJob upload_job)
 	if (! m_export_path.empty())
 		return;
 
-	const auto path = boost::filesystem::temp_directory_path()
+	const boost::filesystem::path path = boost::filesystem::temp_directory_path()
 		/ boost::filesystem::unique_path(".upload.%%%%-%%%%-%%%%-%%%%.gcode");
 
 	// Guard against entering the export step before changing the export path.
diff --git a/src/slic3r/Utils/PrintHost.hpp b/src/slic3r/Utils/PrintHost.hpp
index 2ccd1382a..115807e9a 100644
--- a/src/slic3r/Utils/PrintHost.hpp
+++ b/src/slic3r/Utils/PrintHost.hpp
@@ -43,10 +43,24 @@ struct PrintHostJob
     std::unique_ptr<PrintHost> printhost;
 
     PrintHostJob() {}
+    PrintHostJob(const PrintHostJob&) = delete;
+    PrintHostJob(PrintHostJob &&other)
+        : upload_data(std::move(other.upload_data))
+        , printhost(std::move(other.printhost))
+    {}
+
     PrintHostJob(DynamicPrintConfig *config)
         : printhost(PrintHost::get_print_host(config))
     {}
 
+    PrintHostJob& operator=(const PrintHostJob&) = delete;
+    PrintHostJob& operator=(PrintHostJob &&other)
+    {
+        upload_data = std::move(other.upload_data);
+        printhost = std::move(other.printhost);
+        return *this;
+    }
+
     bool empty() const { return !printhost; }
     operator bool() const { return !!printhost; }
 };