Merge branch 'theqvd-improved-logging' into 3.6.x

Attributes GH PR #193: https://github.com/ArcticaProject/nx-libs/pull/193

21 files changed, 2693 insertions, 2 deletions

diff --git a/m4/ax_cxx_compile_stdcxx.m4 b/m4/ax_cxx_compile_stdcxx.m4
new file mode 100644
index 000000000..5032bba80
--- /dev/null
+++ b/m4/ax_cxx_compile_stdcxx.m4
@@ -0,0 +1,982 @@
+# ===========================================================================
+#  https://www.gnu.org/software/autoconf-archive/ax_cxx_compile_stdcxx.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_CXX_COMPILE_STDCXX(VERSION, [ext|noext], [mandatory|optional])
+#
+# DESCRIPTION
+#
+#   Check for baseline language coverage in the compiler for the specified
+#   version of the C++ standard.  If necessary, add switches to CXX and
+#   CXXCPP to enable support.  VERSION may be '11' (for the C++11 standard)
+#   or '14' (for the C++14 standard).
+#
+#   The second argument, if specified, indicates whether you insist on an
+#   extended mode (e.g. -std=gnu++11) or a strict conformance mode (e.g.
+#   -std=c++11).  If neither is specified, you get whatever works, with
+#   preference for an extended mode.
+#
+#   The third argument, if specified 'mandatory' or if left unspecified,
+#   indicates that baseline support for the specified C++ standard is
+#   required and that the macro should error out if no mode with that
+#   support is found.  If specified 'optional', then configuration proceeds
+#   regardless, after defining HAVE_CXX${VERSION} if and only if a
+#   supporting mode is found.
+#
+# LICENSE
+#
+#   Copyright (c) 2008 Benjamin Kosnik <bkoz@redhat.com>
+#   Copyright (c) 2012 Zack Weinberg <zackw@panix.com>
+#   Copyright (c) 2013 Roy Stogner <roystgnr@ices.utexas.edu>
+#   Copyright (c) 2014, 2015 Google Inc.; contributed by Alexey Sokolov <sokolov@google.com>
+#   Copyright (c) 2015 Paul Norman <penorman@mac.com>
+#   Copyright (c) 2015 Moritz Klammler <moritz@klammler.eu>
+#   Copyright (c) 2016 Krzesimir Nowak <qdlacz@gmail.com>
+#
+#   Copying and distribution of this file, with or without modification, are
+#   permitted in any medium without royalty provided the copyright notice
+#   and this notice are preserved.  This file is offered as-is, without any
+#   warranty.
+
+#serial 7
+
+dnl  This macro is based on the code from the AX_CXX_COMPILE_STDCXX_11 macro
+dnl  (serial version number 13).
+
+AX_REQUIRE_DEFINED([AC_MSG_WARN])
+AC_DEFUN([AX_CXX_COMPILE_STDCXX], [dnl
+  m4_if([$1], [11], [ax_cxx_compile_alternatives="11 0x"],
+        [$1], [14], [ax_cxx_compile_alternatives="14 1y"],
+        [$1], [17], [ax_cxx_compile_alternatives="17 1z"],
+        [m4_fatal([invalid first argument `$1' to AX_CXX_COMPILE_STDCXX])])dnl
+  m4_if([$2], [], [],
+        [$2], [ext], [],
+        [$2], [noext], [],
+        [m4_fatal([invalid second argument `$2' to AX_CXX_COMPILE_STDCXX])])dnl
+  m4_if([$3], [], [ax_cxx_compile_cxx$1_required=true],
+        [$3], [mandatory], [ax_cxx_compile_cxx$1_required=true],
+        [$3], [optional], [ax_cxx_compile_cxx$1_required=false],
+        [m4_fatal([invalid third argument `$3' to AX_CXX_COMPILE_STDCXX])])
+  AC_LANG_PUSH([C++])dnl
+  ac_success=no
+  AC_CACHE_CHECK(whether $CXX supports C++$1 features by default,
+  ax_cv_cxx_compile_cxx$1,
+  [AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])],
+    [ax_cv_cxx_compile_cxx$1=yes],
+    [ax_cv_cxx_compile_cxx$1=no])])
+  if test x$ax_cv_cxx_compile_cxx$1 = xyes; then
+    ac_success=yes
+  fi
+
+  m4_if([$2], [noext], [], [dnl
+  if test x$ac_success = xno; then
+    for alternative in ${ax_cxx_compile_alternatives}; do
+      switch="-std=gnu++${alternative}"
+      cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_$switch])
+      AC_CACHE_CHECK(whether $CXX supports C++$1 features with $switch,
+                     $cachevar,
+        [ac_save_CXX="$CXX"
+         CXX="$CXX $switch"
+         AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])],
+          [eval $cachevar=yes],
+          [eval $cachevar=no])
+         CXX="$ac_save_CXX"])
+      if eval test x\$$cachevar = xyes; then
+        CXX="$CXX $switch"
+        if test -n "$CXXCPP" ; then
+          CXXCPP="$CXXCPP $switch"
+        fi
+        ac_success=yes
+        break
+      fi
+    done
+  fi])
+
+  m4_if([$2], [ext], [], [dnl
+  if test x$ac_success = xno; then
+    dnl HP's aCC needs +std=c++11 according to:
+    dnl http://h21007.www2.hp.com/portal/download/files/unprot/aCxx/PDF_Release_Notes/769149-001.pdf
+    dnl Cray's crayCC needs "-h std=c++11"
+    for alternative in ${ax_cxx_compile_alternatives}; do
+      for switch in -std=c++${alternative} +std=c++${alternative} "-h std=c++${alternative}"; do
+        cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_$switch])
+        AC_CACHE_CHECK(whether $CXX supports C++$1 features with $switch,
+                       $cachevar,
+          [ac_save_CXX="$CXX"
+           CXX="$CXX $switch"
+           AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])],
+            [eval $cachevar=yes],
+            [eval $cachevar=no])
+           CXX="$ac_save_CXX"])
+        if eval test x\$$cachevar = xyes; then
+          CXX="$CXX $switch"
+          if test -n "$CXXCPP" ; then
+            CXXCPP="$CXXCPP $switch"
+          fi
+          ac_success=yes
+          break
+        fi
+      done
+      if test x$ac_success = xyes; then
+        break
+      fi
+    done
+  fi])
+  AC_LANG_POP([C++])
+  if test x$ax_cxx_compile_cxx$1_required = xtrue; then
+    if test x$ac_success = xno; then
+      AC_MSG_ERROR([*** A compiler with support for C++$1 language features is required.])
+    fi
+  fi
+  if test x$ac_success = xno; then
+    HAVE_CXX$1=0
+    AC_MSG_NOTICE([No compiler with C++$1 support was found])
+  else
+    HAVE_CXX$1=1
+    AC_DEFINE(HAVE_CXX$1,1,
+              [define if the compiler supports basic C++$1 syntax])
+  fi
+  AC_SUBST(HAVE_CXX$1)
+  m4_if([$1], [17], [AC_MSG_WARN([C++17 is not yet standardized, so the checks may change in incompatible ways anytime])])
+])
+
+
+dnl  Test body for checking C++11 support
+
+m4_define([_AX_CXX_COMPILE_STDCXX_testbody_11],
+  _AX_CXX_COMPILE_STDCXX_testbody_new_in_11
+)
+
+
+dnl  Test body for checking C++14 support
+
+m4_define([_AX_CXX_COMPILE_STDCXX_testbody_14],
+  _AX_CXX_COMPILE_STDCXX_testbody_new_in_11
+  _AX_CXX_COMPILE_STDCXX_testbody_new_in_14
+)
+
+m4_define([_AX_CXX_COMPILE_STDCXX_testbody_17],
+  _AX_CXX_COMPILE_STDCXX_testbody_new_in_11
+  _AX_CXX_COMPILE_STDCXX_testbody_new_in_14
+  _AX_CXX_COMPILE_STDCXX_testbody_new_in_17
+)
+
+dnl  Tests for new features in C++11
+
+m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_11], [[
+
+// If the compiler admits that it is not ready for C++11, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+#elif __cplusplus < 201103L
+
+#error "This is not a C++11 compiler"
+
+#else
+
+namespace cxx11
+{
+
+  namespace test_static_assert
+  {
+
+    template <typename T>
+    struct check
+    {
+      static_assert(sizeof(int) <= sizeof(T), "not big enough");
+    };
+
+  }
+
+  namespace test_final_override
+  {
+
+    struct Base
+    {
+      virtual void f() {}
+    };
+
+    struct Derived : public Base
+    {
+      virtual void f() override {}
+    };
+
+  }
+
+  namespace test_double_right_angle_brackets
+  {
+
+    template < typename T >
+    struct check {};
+
+    typedef check<void> single_type;
+    typedef check<check<void>> double_type;
+    typedef check<check<check<void>>> triple_type;
+    typedef check<check<check<check<void>>>> quadruple_type;
+
+  }
+
+  namespace test_decltype
+  {
+
+    int
+    f()
+    {
+      int a = 1;
+      decltype(a) b = 2;
+      return a + b;
+    }
+
+  }
+
+  namespace test_type_deduction
+  {
+
+    template < typename T1, typename T2 >
+    struct is_same
+    {
+      static const bool value = false;
+    };
+
+    template < typename T >
+    struct is_same<T, T>
+    {
+      static const bool value = true;
+    };
+
+    template < typename T1, typename T2 >
+    auto
+    add(T1 a1, T2 a2) -> decltype(a1 + a2)
+    {
+      return a1 + a2;
+    }
+
+    int
+    test(const int c, volatile int v)
+    {
+      static_assert(is_same<int, decltype(0)>::value == true, "");
+      static_assert(is_same<int, decltype(c)>::value == false, "");
+      static_assert(is_same<int, decltype(v)>::value == false, "");
+      auto ac = c;
+      auto av = v;
+      auto sumi = ac + av + 'x';
+      auto sumf = ac + av + 1.0;
+      static_assert(is_same<int, decltype(ac)>::value == true, "");
+      static_assert(is_same<int, decltype(av)>::value == true, "");
+      static_assert(is_same<int, decltype(sumi)>::value == true, "");
+      static_assert(is_same<int, decltype(sumf)>::value == false, "");
+      static_assert(is_same<int, decltype(add(c, v))>::value == true, "");
+      return (sumf > 0.0) ? sumi : add(c, v);
+    }
+
+  }
+
+  namespace test_noexcept
+  {
+
+    int f() { return 0; }
+    int g() noexcept { return 0; }
+
+    static_assert(noexcept(f()) == false, "");
+    static_assert(noexcept(g()) == true, "");
+
+  }
+
+  namespace test_constexpr
+  {
+
+    template < typename CharT >
+    unsigned long constexpr
+    strlen_c_r(const CharT *const s, const unsigned long acc) noexcept
+    {
+      return *s ? strlen_c_r(s + 1, acc + 1) : acc;
+    }
+
+    template < typename CharT >
+    unsigned long constexpr
+    strlen_c(const CharT *const s) noexcept
+    {
+      return strlen_c_r(s, 0UL);
+    }
+
+    static_assert(strlen_c("") == 0UL, "");
+    static_assert(strlen_c("1") == 1UL, "");
+    static_assert(strlen_c("example") == 7UL, "");
+    static_assert(strlen_c("another\0example") == 7UL, "");
+
+  }
+
+  namespace test_rvalue_references
+  {
+
+    template < int N >
+    struct answer
+    {
+      static constexpr int value = N;
+    };
+
+    answer<1> f(int&)       { return answer<1>(); }
+    answer<2> f(const int&) { return answer<2>(); }
+    answer<3> f(int&&)      { return answer<3>(); }
+
+    void
+    test()
+    {
+      int i = 0;
+      const int c = 0;
+      static_assert(decltype(f(i))::value == 1, "");
+      static_assert(decltype(f(c))::value == 2, "");
+      static_assert(decltype(f(0))::value == 3, "");
+    }
+
+  }
+
+  namespace test_uniform_initialization
+  {
+
+    struct test
+    {
+      static const int zero {};
+      static const int one {1};
+    };
+
+    static_assert(test::zero == 0, "");
+    static_assert(test::one == 1, "");
+
+  }
+
+  namespace test_lambdas
+  {
+
+    void
+    test1()
+    {
+      auto lambda1 = [](){};
+      auto lambda2 = lambda1;
+      lambda1();
+      lambda2();
+    }
+
+    int
+    test2()
+    {
+      auto a = [](int i, int j){ return i + j; }(1, 2);
+      auto b = []() -> int { return '0'; }();
+      auto c = [=](){ return a + b; }();
+      auto d = [&](){ return c; }();
+      auto e = [a, &b](int x) mutable {
+        const auto identity = [](int y){ return y; };
+        for (auto i = 0; i < a; ++i)
+          a += b--;
+        return x + identity(a + b);
+      }(0);
+      return a + b + c + d + e;
+    }
+
+    int
+    test3()
+    {
+      const auto nullary = [](){ return 0; };
+      const auto unary = [](int x){ return x; };
+      using nullary_t = decltype(nullary);
+      using unary_t = decltype(unary);
+      const auto higher1st = [](nullary_t f){ return f(); };
+      const auto higher2nd = [unary](nullary_t f1){
+        return [unary, f1](unary_t f2){ return f2(unary(f1())); };
+      };
+      return higher1st(nullary) + higher2nd(nullary)(unary);
+    }
+
+  }
+
+  namespace test_variadic_templates
+  {
+
+    template <int...>
+    struct sum;
+
+    template <int N0, int... N1toN>
+    struct sum<N0, N1toN...>
+    {
+      static constexpr auto value = N0 + sum<N1toN...>::value;
+    };
+
+    template <>
+    struct sum<>
+    {
+      static constexpr auto value = 0;
+    };
+
+    static_assert(sum<>::value == 0, "");
+    static_assert(sum<1>::value == 1, "");
+    static_assert(sum<23>::value == 23, "");
+    static_assert(sum<1, 2>::value == 3, "");
+    static_assert(sum<5, 5, 11>::value == 21, "");
+    static_assert(sum<2, 3, 5, 7, 11, 13>::value == 41, "");
+
+  }
+
+  // http://stackoverflow.com/questions/13728184/template-aliases-and-sfinae
+  // Clang 3.1 fails with headers of libstd++ 4.8.3 when using std::function
+  // because of this.
+  namespace test_template_alias_sfinae
+  {
+
+    struct foo {};
+
+    template<typename T>
+    using member = typename T::member_type;
+
+    template<typename T>
+    void func(...) {}
+
+    template<typename T>
+    void func(member<T>*) {}
+
+    void test();
+
+    void test() { func<foo>(0); }
+
+  }
+
+}  // namespace cxx11
+
+#endif  // __cplusplus >= 201103L
+
+]])
+
+
+dnl  Tests for new features in C++14
+
+m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_14], [[
+
+// If the compiler admits that it is not ready for C++14, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+#elif __cplusplus < 201402L
+
+#error "This is not a C++14 compiler"
+
+#else
+
+namespace cxx14
+{
+
+  namespace test_polymorphic_lambdas
+  {
+
+    int
+    test()
+    {
+      const auto lambda = [](auto&&... args){
+        const auto istiny = [](auto x){
+          return (sizeof(x) == 1UL) ? 1 : 0;
+        };
+        const int aretiny[] = { istiny(args)... };
+        return aretiny[0];
+      };
+      return lambda(1, 1L, 1.0f, '1');
+    }
+
+  }
+
+  namespace test_binary_literals
+  {
+
+    constexpr auto ivii = 0b0000000000101010;
+    static_assert(ivii == 42, "wrong value");
+
+  }
+
+  namespace test_generalized_constexpr
+  {
+
+    template < typename CharT >
+    constexpr unsigned long
+    strlen_c(const CharT *const s) noexcept
+    {
+      auto length = 0UL;
+      for (auto p = s; *p; ++p)
+        ++length;
+      return length;
+    }
+
+    static_assert(strlen_c("") == 0UL, "");
+    static_assert(strlen_c("x") == 1UL, "");
+    static_assert(strlen_c("test") == 4UL, "");
+    static_assert(strlen_c("another\0test") == 7UL, "");
+
+  }
+
+  namespace test_lambda_init_capture
+  {
+
+    int
+    test()
+    {
+      auto x = 0;
+      const auto lambda1 = [a = x](int b){ return a + b; };
+      const auto lambda2 = [a = lambda1(x)](){ return a; };
+      return lambda2();
+    }
+
+  }
+
+  namespace test_digit_separators
+  {
+
+    constexpr auto ten_million = 100'000'000;
+    static_assert(ten_million == 100000000, "");
+
+  }
+
+  namespace test_return_type_deduction
+  {
+
+    auto f(int& x) { return x; }
+    decltype(auto) g(int& x) { return x; }
+
+    template < typename T1, typename T2 >
+    struct is_same
+    {
+      static constexpr auto value = false;
+    };
+
+    template < typename T >
+    struct is_same<T, T>
+    {
+      static constexpr auto value = true;
+    };
+
+    int
+    test()
+    {
+      auto x = 0;
+      static_assert(is_same<int, decltype(f(x))>::value, "");
+      static_assert(is_same<int&, decltype(g(x))>::value, "");
+      return x;
+    }
+
+  }
+
+}  // namespace cxx14
+
+#endif  // __cplusplus >= 201402L
+
+]])
+
+
+dnl  Tests for new features in C++17
+
+m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_17], [[
+
+// If the compiler admits that it is not ready for C++17, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+#elif __cplusplus <= 201402L
+
+#error "This is not a C++17 compiler"
+
+#else
+
+#if defined(__clang__)
+  #define REALLY_CLANG
+#else
+  #if defined(__GNUC__)
+    #define REALLY_GCC
+  #endif
+#endif
+
+#include <initializer_list>
+#include <utility>
+#include <type_traits>
+
+namespace cxx17
+{
+
+#if !defined(REALLY_CLANG)
+  namespace test_constexpr_lambdas
+  {
+
+    // TODO: test it with clang++ from git
+
+    constexpr int foo = [](){return 42;}();
+
+  }
+#endif // !defined(REALLY_CLANG)
+
+  namespace test::nested_namespace::definitions
+  {
+
+  }
+
+  namespace test_fold_expression
+  {
+
+    template<typename... Args>
+    int multiply(Args... args)
+    {
+      return (args * ... * 1);
+    }
+
+    template<typename... Args>
+    bool all(Args... args)
+    {
+      return (args && ...);
+    }
+
+  }
+
+  namespace test_extended_static_assert
+  {
+
+    static_assert (true);
+
+  }
+
+  namespace test_auto_brace_init_list
+  {
+
+    auto foo = {5};
+    auto bar {5};
+
+    static_assert(std::is_same<std::initializer_list<int>, decltype(foo)>::value);
+    static_assert(std::is_same<int, decltype(bar)>::value);
+  }
+
+  namespace test_typename_in_template_template_parameter
+  {
+
+    template<template<typename> typename X> struct D;
+
+  }
+
+  namespace test_fallthrough_nodiscard_maybe_unused_attributes
+  {
+
+    int f1()
+    {
+      return 42;
+    }
+
+    [[nodiscard]] int f2()
+    {
+      [[maybe_unused]] auto unused = f1();
+
+      switch (f1())
+      {
+      case 17:
+        f1();
+        [[fallthrough]];
+      case 42:
+        f1();
+      }
+      return f1();
+    }
+
+  }
+
+  namespace test_extended_aggregate_initialization
+  {
+
+    struct base1
+    {
+      int b1, b2 = 42;
+    };
+
+    struct base2
+    {
+      base2() {
+        b3 = 42;
+      }
+      int b3;
+    };
+
+    struct derived : base1, base2
+    {
+        int d;
+    };
+
+    derived d1 {{1, 2}, {}, 4};  // full initialization
+    derived d2 {{}, {}, 4};      // value-initialized bases
+
+  }
+
+  namespace test_general_range_based_for_loop
+  {
+
+    struct iter
+    {
+      int i;
+
+      int& operator* ()
+      {
+        return i;
+      }
+
+      const int& operator* () const
+      {
+        return i;
+      }
+
+      iter& operator++()
+      {
+        ++i;
+        return *this;
+      }
+    };
+
+    struct sentinel
+    {
+      int i;
+    };
+
+    bool operator== (const iter& i, const sentinel& s)
+    {
+      return i.i == s.i;
+    }
+
+    bool operator!= (const iter& i, const sentinel& s)
+    {
+      return !(i == s);
+    }
+
+    struct range
+    {
+      iter begin() const
+      {
+        return {0};
+      }
+
+      sentinel end() const
+      {
+        return {5};
+      }
+    };
+
+    void f()
+    {
+      range r {};
+
+      for (auto i : r)
+      {
+        [[maybe_unused]] auto v = i;
+      }
+    }
+
+  }
+
+  namespace test_lambda_capture_asterisk_this_by_value
+  {
+
+    struct t
+    {
+      int i;
+      int foo()
+      {
+        return [*this]()
+        {
+          return i;
+        }();
+      }
+    };
+
+  }
+
+  namespace test_enum_class_construction
+  {
+
+    enum class byte : unsigned char
+    {};
+
+    byte foo {42};
+
+  }
+
+  namespace test_constexpr_if
+  {
+
+    template <bool cond>
+    int f ()
+    {
+      if constexpr(cond)
+      {
+        return 13;
+      }
+      else
+      {
+        return 42;
+      }
+    }
+
+  }
+
+  namespace test_selection_statement_with_initializer
+  {
+
+    int f()
+    {
+      return 13;
+    }
+
+    int f2()
+    {
+      if (auto i = f(); i > 0)
+      {
+        return 3;
+      }
+
+      switch (auto i = f(); i + 4)
+      {
+      case 17:
+        return 2;
+
+      default:
+        return 1;
+      }
+    }
+
+  }
+
+#if !defined(REALLY_CLANG)
+  namespace test_template_argument_deduction_for_class_templates
+  {
+
+    // TODO: test it with clang++ from git
+
+    template <typename T1, typename T2>
+    struct pair
+    {
+      pair (T1 p1, T2 p2)
+        : m1 {p1},
+          m2 {p2}
+      {}
+
+      T1 m1;
+      T2 m2;
+    };
+
+    void f()
+    {
+      [[maybe_unused]] auto p = pair{13, 42u};
+    }
+
+  }
+#endif // !defined(REALLY_CLANG)
+
+  namespace test_non_type_auto_template_parameters
+  {
+
+    template <auto n>
+    struct B
+    {};
+
+    B<5> b1;
+    B<'a'> b2;
+
+  }
+
+#if !defined(REALLY_CLANG)
+  namespace test_structured_bindings
+  {
+
+    // TODO: test it with clang++ from git
+
+    int arr[2] = { 1, 2 };
+    std::pair<int, int> pr = { 1, 2 };
+
+    auto f1() -> int(&)[2]
+    {
+      return arr;
+    }
+
+    auto f2() -> std::pair<int, int>&
+    {
+      return pr;
+    }
+
+    struct S
+    {
+      int x1 : 2;
+      volatile double y1;
+    };
+
+    S f3()
+    {
+      return {};
+    }
+
+    auto [ x1, y1 ] = f1();
+    auto& [ xr1, yr1 ] = f1();
+    auto [ x2, y2 ] = f2();
+    auto& [ xr2, yr2 ] = f2();
+    const auto [ x3, y3 ] = f3();
+
+  }
+#endif // !defined(REALLY_CLANG)
+
+#if !defined(REALLY_CLANG)
+  namespace test_exception_spec_type_system
+  {
+
+    // TODO: test it with clang++ from git
+
+    struct Good {};
+    struct Bad {};
+
+    void g1() noexcept;
+    void g2();
+
+    template<typename T>
+    Bad
+    f(T*, T*);
+
+    template<typename T1, typename T2>
+    Good
+    f(T1*, T2*);
+
+    static_assert (std::is_same_v<Good, decltype(f(g1, g2))>);
+
+  }
+#endif // !defined(REALLY_CLANG)
+
+  namespace test_inline_variables
+  {
+
+    template<class T> void f(T)
+    {}
+
+    template<class T> inline T g(T)
+    {
+      return T{};
+    }
+
+    template<> inline void f<>(int)
+    {}
+
+    template<> int g<>(int)
+    {
+      return 5;
+    }
+
+  }
+
+}  // namespace cxx17
+
+#endif  // __cplusplus <= 201402L
+
+]])
diff --git a/m4/ax_cxx_compile_stdcxx_11.m4 b/m4/ax_cxx_compile_stdcxx_11.m4
new file mode 100644
index 000000000..1733fd85f
--- /dev/null
+++ b/m4/ax_cxx_compile_stdcxx_11.m4
@@ -0,0 +1,39 @@
+# =============================================================================
+#  https://www.gnu.org/software/autoconf-archive/ax_cxx_compile_stdcxx_11.html
+# =============================================================================
+#
+# SYNOPSIS
+#
+#   AX_CXX_COMPILE_STDCXX_11([ext|noext], [mandatory|optional])
+#
+# DESCRIPTION
+#
+#   Check for baseline language coverage in the compiler for the C++11
+#   standard; if necessary, add switches to CXX and CXXCPP to enable
+#   support.
+#
+#   This macro is a convenience alias for calling the AX_CXX_COMPILE_STDCXX
+#   macro with the version set to C++11.  The two optional arguments are
+#   forwarded literally as the second and third argument respectively.
+#   Please see the documentation for the AX_CXX_COMPILE_STDCXX macro for
+#   more information.  If you want to use this macro, you also need to
+#   download the ax_cxx_compile_stdcxx.m4 file.
+#
+# LICENSE
+#
+#   Copyright (c) 2008 Benjamin Kosnik <bkoz@redhat.com>
+#   Copyright (c) 2012 Zack Weinberg <zackw@panix.com>
+#   Copyright (c) 2013 Roy Stogner <roystgnr@ices.utexas.edu>
+#   Copyright (c) 2014, 2015 Google Inc.; contributed by Alexey Sokolov <sokolov@google.com>
+#   Copyright (c) 2015 Paul Norman <penorman@mac.com>
+#   Copyright (c) 2015 Moritz Klammler <moritz@klammler.eu>
+#
+#   Copying and distribution of this file, with or without modification, are
+#   permitted in any medium without royalty provided the copyright notice
+#   and this notice are preserved. This file is offered as-is, without any
+#   warranty.
+
+#serial 18
+
+AX_REQUIRE_DEFINED([AX_CXX_COMPILE_STDCXX])
+AC_DEFUN([AX_CXX_COMPILE_STDCXX_11], [AX_CXX_COMPILE_STDCXX([11], [$1], [$2])])
diff --git a/nxcomp/.gitignore b/nxcomp/.gitignore
index 019202342..1d00b755b 100644
--- a/nxcomp/.gitignore
+++ b/nxcomp/.gitignore
@@ -19,3 +19,7 @@ m4/lt~obsolete.m4
 nxcomp.pc
 src/Makefile
 src/Makefile.in
+test/.deps/
+test/Makefile
+test/Makefile.in
+test/logging_test
diff --git a/nxcomp/Makefile.am b/nxcomp/Makefile.am
index ae5991c3d..c1f6226bc 100644
--- a/nxcomp/Makefile.am
+++ b/nxcomp/Makefile.am
@@ -1,4 +1,4 @@
-SUBDIRS = src
+SUBDIRS = src test
 
 pkgconfig_DATA = nxcomp.pc
 
diff --git a/nxcomp/configure.ac b/nxcomp/configure.ac
index 0b30915c2..3ae81f0d1 100644
--- a/nxcomp/configure.ac
+++ b/nxcomp/configure.ac
@@ -63,9 +63,34 @@ if test "$FreeBSD" = yes; then
   CPPFLAGS="$CPPFLAGS -I/usr/local/include"
 fi
 
+AX_PTHREAD([], AC_MSG_ERROR([no POSIX threads support detected]))
+
 # If in_addr_t is not defined use unsigned int.
 AC_CHECK_TYPES([in_addr_t], [], [], [[#include <netinet/in.h>]])
 
+AC_ARG_ENABLE([cxx11],
+              [AS_HELP_STRING([--enable-cxx11],
+                              [enable optional features requiring C++11 support (disabled by default)])],
+              [AS_IF([test x$enableval = xyes],
+                    [AX_CXX_COMPILE_STDCXX_11([], [mandatory])])])
+
+# Check if std::put_time is available.
+AC_MSG_CHECKING([if std::put_time is available])
+AC_COMPILE_IFELSE([AC_LANG_PROGRAM(
+[[
+#include <iomanip>
+#include <ctime>
+]],
+[[
+std::time_t t = std::time(NULL);
+std::tm tm = *std::localtime(&t);
+(void) std::put_time(&tm, "%c");
+]])],
+                  [AC_MSG_RESULT([yes])
+                   AC_DEFINE(HAVE_STD_PUT_TIME, [1],
+                             [Use std::put_time to format times, must be made available by the compiler if turned on.])],
+                  [AC_MSG_RESULT([no])])
+
 AC_ARG_ENABLE([debug],
               [AS_HELP_STRING([--enable-debug],
                               [enable to get info session log output (disabled by default)])],
@@ -83,6 +108,7 @@ AC_ARG_ENABLE([valgrind],
 AC_CONFIG_FILES([
 Makefile
 src/Makefile
+test/Makefile
 nxcomp.pc
 ])
 
diff --git a/nxcomp/m4/ax_cxx_compile_stdcxx.m4 b/nxcomp/m4/ax_cxx_compile_stdcxx.m4
new file mode 120000
index 000000000..28ebfd1a6
--- /dev/null
+++ b/nxcomp/m4/ax_cxx_compile_stdcxx.m4
@@ -0,0 +1 @@
+../../m4/ax_cxx_compile_stdcxx.m4
\ No newline at end of file
diff --git a/nxcomp/m4/ax_cxx_compile_stdcxx_11.m4 b/nxcomp/m4/ax_cxx_compile_stdcxx_11.m4
new file mode 120000
index 000000000..5fbe8790d
--- /dev/null
+++ b/nxcomp/m4/ax_cxx_compile_stdcxx_11.m4
@@ -0,0 +1 @@
+../../m4/ax_cxx_compile_stdcxx_11.m4
\ No newline at end of file
diff --git a/nxcomp/m4/ax_pthread.m4 b/nxcomp/m4/ax_pthread.m4
new file mode 100644
index 000000000..5fbf9fe0d
--- /dev/null
+++ b/nxcomp/m4/ax_pthread.m4
@@ -0,0 +1,485 @@
+# ===========================================================================
+#        https://www.gnu.org/software/autoconf-archive/ax_pthread.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_PTHREAD([ACTION-IF-FOUND[, ACTION-IF-NOT-FOUND]])
+#
+# DESCRIPTION
+#
+#   This macro figures out how to build C programs using POSIX threads. It
+#   sets the PTHREAD_LIBS output variable to the threads library and linker
+#   flags, and the PTHREAD_CFLAGS output variable to any special C compiler
+#   flags that are needed. (The user can also force certain compiler
+#   flags/libs to be tested by setting these environment variables.)
+#
+#   Also sets PTHREAD_CC to any special C compiler that is needed for
+#   multi-threaded programs (defaults to the value of CC otherwise). (This
+#   is necessary on AIX to use the special cc_r compiler alias.)
+#
+#   NOTE: You are assumed to not only compile your program with these flags,
+#   but also to link with them as well. For example, you might link with
+#   $PTHREAD_CC $CFLAGS $PTHREAD_CFLAGS $LDFLAGS ... $PTHREAD_LIBS $LIBS
+#
+#   If you are only building threaded programs, you may wish to use these
+#   variables in your default LIBS, CFLAGS, and CC:
+#
+#     LIBS="$PTHREAD_LIBS $LIBS"
+#     CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
+#     CC="$PTHREAD_CC"
+#
+#   In addition, if the PTHREAD_CREATE_JOINABLE thread-attribute constant
+#   has a nonstandard name, this macro defines PTHREAD_CREATE_JOINABLE to
+#   that name (e.g. PTHREAD_CREATE_UNDETACHED on AIX).
+#
+#   Also HAVE_PTHREAD_PRIO_INHERIT is defined if pthread is found and the
+#   PTHREAD_PRIO_INHERIT symbol is defined when compiling with
+#   PTHREAD_CFLAGS.
+#
+#   ACTION-IF-FOUND is a list of shell commands to run if a threads library
+#   is found, and ACTION-IF-NOT-FOUND is a list of commands to run it if it
+#   is not found. If ACTION-IF-FOUND is not specified, the default action
+#   will define HAVE_PTHREAD.
+#
+#   Please let the authors know if this macro fails on any platform, or if
+#   you have any other suggestions or comments. This macro was based on work
+#   by SGJ on autoconf scripts for FFTW (http://www.fftw.org/) (with help
+#   from M. Frigo), as well as ac_pthread and hb_pthread macros posted by
+#   Alejandro Forero Cuervo to the autoconf macro repository. We are also
+#   grateful for the helpful feedback of numerous users.
+#
+#   Updated for Autoconf 2.68 by Daniel Richard G.
+#
+# LICENSE
+#
+#   Copyright (c) 2008 Steven G. Johnson <stevenj@alum.mit.edu>
+#   Copyright (c) 2011 Daniel Richard G. <skunk@iSKUNK.ORG>
+#
+#   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 <https://www.gnu.org/licenses/>.
+#
+#   As a special exception, the respective Autoconf Macro's copyright owner
+#   gives unlimited permission to copy, distribute and modify the configure
+#   scripts that are the output of Autoconf when processing the Macro. You
+#   need not follow the terms of the GNU General Public License when using
+#   or distributing such scripts, even though portions of the text of the
+#   Macro appear in them. The GNU General Public License (GPL) does govern
+#   all other use of the material that constitutes the Autoconf Macro.
+#
+#   This special exception to the GPL applies to versions of the Autoconf
+#   Macro released by the Autoconf Archive. When you make and distribute a
+#   modified version of the Autoconf Macro, you may extend this special
+#   exception to the GPL to apply to your modified version as well.
+
+#serial 24
+
+AU_ALIAS([ACX_PTHREAD], [AX_PTHREAD])
+AC_DEFUN([AX_PTHREAD], [
+AC_REQUIRE([AC_CANONICAL_HOST])
+AC_REQUIRE([AC_PROG_CC])
+AC_REQUIRE([AC_PROG_SED])
+AC_LANG_PUSH([C])
+ax_pthread_ok=no
+
+# We used to check for pthread.h first, but this fails if pthread.h
+# requires special compiler flags (e.g. on Tru64 or Sequent).
+# It gets checked for in the link test anyway.
+
+# First of all, check if the user has set any of the PTHREAD_LIBS,
+# etcetera environment variables, and if threads linking works using
+# them:
+if test "x$PTHREAD_CFLAGS$PTHREAD_LIBS" != "x"; then
+        ax_pthread_save_CC="$CC"
+        ax_pthread_save_CFLAGS="$CFLAGS"
+        ax_pthread_save_LIBS="$LIBS"
+        AS_IF([test "x$PTHREAD_CC" != "x"], [CC="$PTHREAD_CC"])
+        CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
+        LIBS="$PTHREAD_LIBS $LIBS"
+        AC_MSG_CHECKING([for pthread_join using $CC $PTHREAD_CFLAGS $PTHREAD_LIBS])
+        AC_LINK_IFELSE([AC_LANG_CALL([], [pthread_join])], [ax_pthread_ok=yes])
+        AC_MSG_RESULT([$ax_pthread_ok])
+        if test "x$ax_pthread_ok" = "xno"; then
+                PTHREAD_LIBS=""
+                PTHREAD_CFLAGS=""
+        fi
+        CC="$ax_pthread_save_CC"
+        CFLAGS="$ax_pthread_save_CFLAGS"
+        LIBS="$ax_pthread_save_LIBS"
+fi
+
+# We must check for the threads library under a number of different
+# names; the ordering is very important because some systems
+# (e.g. DEC) have both -lpthread and -lpthreads, where one of the
+# libraries is broken (non-POSIX).
+
+# Create a list of thread flags to try.  Items starting with a "-" are
+# C compiler flags, and other items are library names, except for "none"
+# which indicates that we try without any flags at all, and "pthread-config"
+# which is a program returning the flags for the Pth emulation library.
+
+ax_pthread_flags="pthreads none -Kthread -pthread -pthreads -mthreads pthread --thread-safe -mt pthread-config"
+
+# The ordering *is* (sometimes) important.  Some notes on the
+# individual items follow:
+
+# pthreads: AIX (must check this before -lpthread)
+# none: in case threads are in libc; should be tried before -Kthread and
+#       other compiler flags to prevent continual compiler warnings
+# -Kthread: Sequent (threads in libc, but -Kthread needed for pthread.h)
+# -pthread: Linux/gcc (kernel threads), BSD/gcc (userland threads), Tru64
+#           (Note: HP C rejects this with "bad form for `-t' option")
+# -pthreads: Solaris/gcc (Note: HP C also rejects)
+# -mt: Sun Workshop C (may only link SunOS threads [-lthread], but it
+#      doesn't hurt to check since this sometimes defines pthreads and
+#      -D_REENTRANT too), HP C (must be checked before -lpthread, which
+#      is present but should not be used directly; and before -mthreads,
+#      because the compiler interprets this as "-mt" + "-hreads")
+# -mthreads: Mingw32/gcc, Lynx/gcc
+# pthread: Linux, etcetera
+# --thread-safe: KAI C++
+# pthread-config: use pthread-config program (for GNU Pth library)
+
+case $host_os in
+
+        freebsd*)
+
+        # -kthread: FreeBSD kernel threads (preferred to -pthread since SMP-able)
+        # lthread: LinuxThreads port on FreeBSD (also preferred to -pthread)
+
+        ax_pthread_flags="-kthread lthread $ax_pthread_flags"
+        ;;
+
+        hpux*)
+
+        # From the cc(1) man page: "[-mt] Sets various -D flags to enable
+        # multi-threading and also sets -lpthread."
+
+        ax_pthread_flags="-mt -pthread pthread $ax_pthread_flags"
+        ;;
+
+        openedition*)
+
+        # IBM z/OS requires a feature-test macro to be defined in order to
+        # enable POSIX threads at all, so give the user a hint if this is
+        # not set. (We don't define these ourselves, as they can affect
+        # other portions of the system API in unpredictable ways.)
+
+        AC_EGREP_CPP([AX_PTHREAD_ZOS_MISSING],
+            [
+#            if !defined(_OPEN_THREADS) && !defined(_UNIX03_THREADS)
+             AX_PTHREAD_ZOS_MISSING
+#            endif
+            ],
+            [AC_MSG_WARN([IBM z/OS requires -D_OPEN_THREADS or -D_UNIX03_THREADS to enable pthreads support.])])
+        ;;
+
+        solaris*)
+
+        # On Solaris (at least, for some versions), libc contains stubbed
+        # (non-functional) versions of the pthreads routines, so link-based
+        # tests will erroneously succeed. (N.B.: The stubs are missing
+        # pthread_cleanup_push, or rather a function called by this macro,
+        # so we could check for that, but who knows whether they'll stub
+        # that too in a future libc.)  So we'll check first for the
+        # standard Solaris way of linking pthreads (-mt -lpthread).
+
+        ax_pthread_flags="-mt,pthread pthread $ax_pthread_flags"
+        ;;
+esac
+
+# GCC generally uses -pthread, or -pthreads on some platforms (e.g. SPARC)
+
+AS_IF([test "x$GCC" = "xyes"],
+      [ax_pthread_flags="-pthread -pthreads $ax_pthread_flags"])
+
+# The presence of a feature test macro requesting re-entrant function
+# definitions is, on some systems, a strong hint that pthreads support is
+# correctly enabled
+
+case $host_os in
+        darwin* | hpux* | linux* | osf* | solaris*)
+        ax_pthread_check_macro="_REENTRANT"
+        ;;
+
+        aix*)
+        ax_pthread_check_macro="_THREAD_SAFE"
+        ;;
+
+        *)
+        ax_pthread_check_macro="--"
+        ;;
+esac
+AS_IF([test "x$ax_pthread_check_macro" = "x--"],
+      [ax_pthread_check_cond=0],
+      [ax_pthread_check_cond="!defined($ax_pthread_check_macro)"])
+
+# Are we compiling with Clang?
+
+AC_CACHE_CHECK([whether $CC is Clang],
+    [ax_cv_PTHREAD_CLANG],
+    [ax_cv_PTHREAD_CLANG=no
+     # Note that Autoconf sets GCC=yes for Clang as well as GCC
+     if test "x$GCC" = "xyes"; then
+        AC_EGREP_CPP([AX_PTHREAD_CC_IS_CLANG],
+            [/* Note: Clang 2.7 lacks __clang_[a-z]+__ */
+#            if defined(__clang__) && defined(__llvm__)
+             AX_PTHREAD_CC_IS_CLANG
+#            endif
+            ],
+            [ax_cv_PTHREAD_CLANG=yes])
+     fi
+    ])
+ax_pthread_clang="$ax_cv_PTHREAD_CLANG"
+
+ax_pthread_clang_warning=no
+
+# Clang needs special handling, because older versions handle the -pthread
+# option in a rather... idiosyncratic way
+
+if test "x$ax_pthread_clang" = "xyes"; then
+
+        # Clang takes -pthread; it has never supported any other flag
+
+        # (Note 1: This will need to be revisited if a system that Clang
+        # supports has POSIX threads in a separate library.  This tends not
+        # to be the way of modern systems, but it's conceivable.)
+
+        # (Note 2: On some systems, notably Darwin, -pthread is not needed
+        # to get POSIX threads support; the API is always present and
+        # active.  We could reasonably leave PTHREAD_CFLAGS empty.  But
+        # -pthread does define _REENTRANT, and while the Darwin headers
+        # ignore this macro, third-party headers might not.)
+
+        PTHREAD_CFLAGS="-pthread"
+        PTHREAD_LIBS=
+
+        ax_pthread_ok=yes
+
+        # However, older versions of Clang make a point of warning the user
+        # that, in an invocation where only linking and no compilation is
+        # taking place, the -pthread option has no effect ("argument unused
+        # during compilation").  They expect -pthread to be passed in only
+        # when source code is being compiled.
+        #
+        # Problem is, this is at odds with the way Automake and most other
+        # C build frameworks function, which is that the same flags used in
+        # compilation (CFLAGS) are also used in linking.  Many systems
+        # supported by AX_PTHREAD require exactly this for POSIX threads
+        # support, and in fact it is often not straightforward to specify a
+        # flag that is used only in the compilation phase and not in
+        # linking.  Such a scenario is extremely rare in practice.
+        #
+        # Even though use of the -pthread flag in linking would only print
+        # a warning, this can be a nuisance for well-run software projects
+        # that build with -Werror.  So if the active version of Clang has
+        # this misfeature, we search for an option to squash it.
+
+        AC_CACHE_CHECK([whether Clang needs flag to prevent "argument unused" warning when linking with -pthread],
+            [ax_cv_PTHREAD_CLANG_NO_WARN_FLAG],
+            [ax_cv_PTHREAD_CLANG_NO_WARN_FLAG=unknown
+             # Create an alternate version of $ac_link that compiles and
+             # links in two steps (.c -> .o, .o -> exe) instead of one
+             # (.c -> exe), because the warning occurs only in the second
+             # step
+             ax_pthread_save_ac_link="$ac_link"
+             ax_pthread_sed='s/conftest\.\$ac_ext/conftest.$ac_objext/g'
+             ax_pthread_link_step=`$as_echo "$ac_link" | sed "$ax_pthread_sed"`
+             ax_pthread_2step_ac_link="($ac_compile) && (echo ==== >&5) && ($ax_pthread_link_step)"
+             ax_pthread_save_CFLAGS="$CFLAGS"
+             for ax_pthread_try in '' -Qunused-arguments -Wno-unused-command-line-argument unknown; do
+                AS_IF([test "x$ax_pthread_try" = "xunknown"], [break])
+                CFLAGS="-Werror -Wunknown-warning-option $ax_pthread_try -pthread $ax_pthread_save_CFLAGS"
+                ac_link="$ax_pthread_save_ac_link"
+                AC_LINK_IFELSE([AC_LANG_SOURCE([[int main(void){return 0;}]])],
+                    [ac_link="$ax_pthread_2step_ac_link"
+                     AC_LINK_IFELSE([AC_LANG_SOURCE([[int main(void){return 0;}]])],
+                         [break])
+                    ])
+             done
+             ac_link="$ax_pthread_save_ac_link"
+             CFLAGS="$ax_pthread_save_CFLAGS"
+             AS_IF([test "x$ax_pthread_try" = "x"], [ax_pthread_try=no])
+             ax_cv_PTHREAD_CLANG_NO_WARN_FLAG="$ax_pthread_try"
+            ])
+
+        case "$ax_cv_PTHREAD_CLANG_NO_WARN_FLAG" in
+                no | unknown) ;;
+                *) PTHREAD_CFLAGS="$ax_cv_PTHREAD_CLANG_NO_WARN_FLAG $PTHREAD_CFLAGS" ;;
+        esac
+
+fi # $ax_pthread_clang = yes
+
+if test "x$ax_pthread_ok" = "xno"; then
+for ax_pthread_try_flag in $ax_pthread_flags; do
+
+        case $ax_pthread_try_flag in
+                none)
+                AC_MSG_CHECKING([whether pthreads work without any flags])
+                ;;
+
+                -mt,pthread)
+                AC_MSG_CHECKING([whether pthreads work with -mt -lpthread])
+                PTHREAD_CFLAGS="-mt"
+                PTHREAD_LIBS="-lpthread"
+                ;;
+
+                -*)
+                AC_MSG_CHECKING([whether pthreads work with $ax_pthread_try_flag])
+                PTHREAD_CFLAGS="$ax_pthread_try_flag"
+                ;;
+
+                pthread-config)
+                AC_CHECK_PROG([ax_pthread_config], [pthread-config], [yes], [no])
+                AS_IF([test "x$ax_pthread_config" = "xno"], [continue])
+                PTHREAD_CFLAGS="`pthread-config --cflags`"
+                PTHREAD_LIBS="`pthread-config --ldflags` `pthread-config --libs`"
+                ;;
+
+                *)
+                AC_MSG_CHECKING([for the pthreads library -l$ax_pthread_try_flag])
+                PTHREAD_LIBS="-l$ax_pthread_try_flag"
+                ;;
+        esac
+
+        ax_pthread_save_CFLAGS="$CFLAGS"
+        ax_pthread_save_LIBS="$LIBS"
+        CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
+        LIBS="$PTHREAD_LIBS $LIBS"
+
+        # Check for various functions.  We must include pthread.h,
+        # since some functions may be macros.  (On the Sequent, we
+        # need a special flag -Kthread to make this header compile.)
+        # We check for pthread_join because it is in -lpthread on IRIX
+        # while pthread_create is in libc.  We check for pthread_attr_init
+        # due to DEC craziness with -lpthreads.  We check for
+        # pthread_cleanup_push because it is one of the few pthread
+        # functions on Solaris that doesn't have a non-functional libc stub.
+        # We try pthread_create on general principles.
+
+        AC_LINK_IFELSE([AC_LANG_PROGRAM([#include <pthread.h>
+#                       if $ax_pthread_check_cond
+#                        error "$ax_pthread_check_macro must be defined"
+#                       endif
+                        static void routine(void *a) { a = 0; }
+                        static void *start_routine(void *a) { return a; }],
+                       [pthread_t th; pthread_attr_t attr;
+                        pthread_create(&th, 0, start_routine, 0);
+                        pthread_join(th, 0);
+                        pthread_attr_init(&attr);
+                        pthread_cleanup_push(routine, 0);
+                        pthread_cleanup_pop(0) /* ; */])],
+            [ax_pthread_ok=yes],
+            [])
+
+        CFLAGS="$ax_pthread_save_CFLAGS"
+        LIBS="$ax_pthread_save_LIBS"
+
+        AC_MSG_RESULT([$ax_pthread_ok])
+        AS_IF([test "x$ax_pthread_ok" = "xyes"], [break])
+
+        PTHREAD_LIBS=""
+        PTHREAD_CFLAGS=""
+done
+fi
+
+# Various other checks:
+if test "x$ax_pthread_ok" = "xyes"; then
+        ax_pthread_save_CFLAGS="$CFLAGS"
+        ax_pthread_save_LIBS="$LIBS"
+        CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
+        LIBS="$PTHREAD_LIBS $LIBS"
+
+        # Detect AIX lossage: JOINABLE attribute is called UNDETACHED.
+        AC_CACHE_CHECK([for joinable pthread attribute],
+            [ax_cv_PTHREAD_JOINABLE_ATTR],
+            [ax_cv_PTHREAD_JOINABLE_ATTR=unknown
+             for ax_pthread_attr in PTHREAD_CREATE_JOINABLE PTHREAD_CREATE_UNDETACHED; do
+                 AC_LINK_IFELSE([AC_LANG_PROGRAM([#include <pthread.h>],
+                                                 [int attr = $ax_pthread_attr; return attr /* ; */])],
+                                [ax_cv_PTHREAD_JOINABLE_ATTR=$ax_pthread_attr; break],
+                                [])
+             done
+            ])
+        AS_IF([test "x$ax_cv_PTHREAD_JOINABLE_ATTR" != "xunknown" && \
+               test "x$ax_cv_PTHREAD_JOINABLE_ATTR" != "xPTHREAD_CREATE_JOINABLE" && \
+               test "x$ax_pthread_joinable_attr_defined" != "xyes"],
+              [AC_DEFINE_UNQUOTED([PTHREAD_CREATE_JOINABLE],
+                                  [$ax_cv_PTHREAD_JOINABLE_ATTR],
+                                  [Define to necessary symbol if this constant
+                                   uses a non-standard name on your system.])
+               ax_pthread_joinable_attr_defined=yes
+              ])
+
+        AC_CACHE_CHECK([whether more special flags are required for pthreads],
+            [ax_cv_PTHREAD_SPECIAL_FLAGS],
+            [ax_cv_PTHREAD_SPECIAL_FLAGS=no
+             case $host_os in
+             solaris*)
+             ax_cv_PTHREAD_SPECIAL_FLAGS="-D_POSIX_PTHREAD_SEMANTICS"
+             ;;
+             esac
+            ])
+        AS_IF([test "x$ax_cv_PTHREAD_SPECIAL_FLAGS" != "xno" && \
+               test "x$ax_pthread_special_flags_added" != "xyes"],
+              [PTHREAD_CFLAGS="$ax_cv_PTHREAD_SPECIAL_FLAGS $PTHREAD_CFLAGS"
+               ax_pthread_special_flags_added=yes])
+
+        AC_CACHE_CHECK([for PTHREAD_PRIO_INHERIT],
+            [ax_cv_PTHREAD_PRIO_INHERIT],
+            [AC_LINK_IFELSE([AC_LANG_PROGRAM([[#include <pthread.h>]],
+                                             [[int i = PTHREAD_PRIO_INHERIT;]])],
+                            [ax_cv_PTHREAD_PRIO_INHERIT=yes],
+                            [ax_cv_PTHREAD_PRIO_INHERIT=no])
+            ])
+        AS_IF([test "x$ax_cv_PTHREAD_PRIO_INHERIT" = "xyes" && \
+               test "x$ax_pthread_prio_inherit_defined" != "xyes"],
+              [AC_DEFINE([HAVE_PTHREAD_PRIO_INHERIT], [1], [Have PTHREAD_PRIO_INHERIT.])
+               ax_pthread_prio_inherit_defined=yes
+              ])
+
+        CFLAGS="$ax_pthread_save_CFLAGS"
+        LIBS="$ax_pthread_save_LIBS"
+
+        # More AIX lossage: compile with *_r variant
+        if test "x$GCC" != "xyes"; then
+            case $host_os in
+                aix*)
+                AS_CASE(["x/$CC"],
+                    [x*/c89|x*/c89_128|x*/c99|x*/c99_128|x*/cc|x*/cc128|x*/xlc|x*/xlc_v6|x*/xlc128|x*/xlc128_v6],
+                    [#handle absolute path differently from PATH based program lookup
+                     AS_CASE(["x$CC"],
+                         [x/*],
+                         [AS_IF([AS_EXECUTABLE_P([${CC}_r])],[PTHREAD_CC="${CC}_r"])],
+                         [AC_CHECK_PROGS([PTHREAD_CC],[${CC}_r],[$CC])])])
+                ;;
+            esac
+        fi
+fi
+
+test -n "$PTHREAD_CC" || PTHREAD_CC="$CC"
+
+AC_SUBST([PTHREAD_LIBS])
+AC_SUBST([PTHREAD_CFLAGS])
+AC_SUBST([PTHREAD_CC])
+
+# Finally, execute ACTION-IF-FOUND/ACTION-IF-NOT-FOUND:
+if test "x$ax_pthread_ok" = "xyes"; then
+        ifelse([$1],,[AC_DEFINE([HAVE_PTHREAD],[1],[Define if you have POSIX threads libraries and header files.])],[$1])
+        :
+else
+        ax_pthread_ok=no
+        $2
+fi
+AC_LANG_POP
+])dnl AX_PTHREAD
diff --git a/nxcomp/src/Log.cpp b/nxcomp/src/Log.cpp
new file mode 100644
index 000000000..951c10a04
--- /dev/null
+++ b/nxcomp/src/Log.cpp
@@ -0,0 +1,121 @@
+/**************************************************************************/
+/*                                                                        */
+/* Copyright (c) 2001, 2011 NoMachine (http://www.nomachine.com)          */
+/* Copyright (c) 2008-2014 Oleksandr Shneyder <o.shneyder@phoca-gmbh.de>  */
+/* Copyright (c) 2014-2016 Ulrich Sibiller <uli42@gmx.de>                 */
+/* Copyright (c) 2014-2016 Mihai Moldovan <ionic@ionic.de>                */
+/* Copyright (c) 2011-2016 Mike Gabriel <mike.gabriel@das-netzwerkteam.de>*/
+/* Copyright (c) 2015-2016 Qindel Group (http://www.qindel.com)           */
+/*                                                                        */
+/* NXCOMP, NX protocol compression and NX extensions to this software     */
+/* are copyright of the aforementioned persons and companies.             */
+/*                                                                        */
+/* Redistribution and use of the present software is allowed according    */
+/* to terms specified in the file LICENSE.nxcomp which comes in the       */
+/* source distribution.                                                   */
+/*                                                                        */
+/* All rights reserved.                                                   */
+/*                                                                        */
+/* NOTE: This software has received contributions from various other      */
+/* contributors, only the core maintainers and supporters are listed as   */
+/* copyright holders. Please contact us, if you feel you should be listed */
+/* as copyright holder, as well.                                          */
+/*                                                                        */
+/**************************************************************************/
+
+
+#include <stdio.h>
+#include <iostream>
+#include <fstream>
+#include <sstream>
+#include <iomanip>
+#include <unistd.h>
+
+#include "Log.h"
+#include "config.h"
+
+NXLog nx_log;
+
+
+bool NXLog::will_log() const
+{
+    std::map<std::string, NXLogLevel>::const_iterator item = per_file_levels_.find(current_file());
+
+    if ( item != per_file_levels_.end() )
+    {
+        return current_level() <= item->second;
+    }
+    else
+    {
+        return current_level() <= level();
+    }
+}
+
+
+std::string NXLog::stamp_to_string(const NXLogStamp& stamp) const
+{
+    std::ostringstream oss;
+
+    static const char* level_names[] = {
+        "FATAL",
+        "ERROR",
+        "WARN ",
+        "INFO ",
+        "DEBUG"
+    };
+
+    if ( log_level() )
+        oss << ((stamp.level() >=0 && stamp.level() < NXLOG_LEVEL_COUNT ) ? level_names[stamp.level()] : "???") << " ";
+
+    if ( log_time() )
+    {
+        struct timeval timestamp = stamp.timestamp();
+        struct tm timeinfo;
+
+        localtime_r(&timestamp.tv_sec, &timeinfo);
+
+        if ( log_unix_time() )
+        {
+            oss << timestamp.tv_sec;
+        }
+        else
+        {
+            #if HAVE_STD_PUT_TIME
+            oss << " " << std::put_time(&timeinfo, "%Y/%m/%d %H:%M:%S");
+            #else
+            oss << timestamp.tv_sec;
+            #endif
+        }
+
+        oss << "." << std::setw(3) << std::setfill('0') << (int)(timestamp.tv_usec / 1000) << " ";
+    }
+
+    if ( log_location() )
+        oss << stamp.file() << "/" << stamp.function() << ":" << stamp.line()  << " ";
+
+    if ( log_thread_id() )
+    {
+        if ( thread_name().empty() )
+            oss << getpid() << "/" << pthread_self() << " ";
+        else
+            oss << "[" << thread_name() << "] ";
+    }
+
+    return oss.str();
+}
+
+NXLog& operator<< (NXLog& out, const NXLogStamp& value)
+{
+    out.current_level( value.level() );
+    out.current_file( value.file() );
+
+    // Writing an NXLogStamp to the stream indicates the start of a new entry.
+    // If there's any content in the buffer, create a new entry in the output
+    // queue.
+    if ( out.synchronized() )
+        out.new_stack_entry();
+
+    out << out.stamp_to_string(value);
+
+    return out;
+}
diff --git a/nxcomp/src/Log.h b/nxcomp/src/Log.h
new file mode 100644
index 000000000..aed929b31
--- /dev/null
+++ b/nxcomp/src/Log.h
@@ -0,0 +1,545 @@
+/**************************************************************************/
+/*                                                                        */
+/* Copyright (c) 2001, 2011 NoMachine (http://www.nomachine.com)          */
+/* Copyright (c) 2008-2014 Oleksandr Shneyder <o.shneyder@phoca-gmbh.de>  */
+/* Copyright (c) 2014-2016 Ulrich Sibiller <uli42@gmx.de>                 */
+/* Copyright (c) 2014-2016 Mihai Moldovan <ionic@ionic.de>                */
+/* Copyright (c) 2011-2016 Mike Gabriel <mike.gabriel@das-netzwerkteam.de>*/
+/* Copyright (c) 2015-2016 Qindel Group (http://www.qindel.com)           */
+/*                                                                        */
+/* NXCOMP, NX protocol compression and NX extensions to this software     */
+/* are copyright of the aforementioned persons and companies.             */
+/*                                                                        */
+/* Redistribution and use of the present software is allowed according    */
+/* to terms specified in the file LICENSE.nxcomp which comes in the       */
+/* source distribution.                                                   */
+/*                                                                        */
+/* All rights reserved.                                                   */
+/*                                                                        */
+/* NOTE: This software has received contributions from various other      */
+/* contributors, only the core maintainers and supporters are listed as   */
+/* copyright holders. Please contact us, if you feel you should be listed */
+/* as copyright holder, as well.                                          */
+/*                                                                        */
+/**************************************************************************/
+
+
+#ifndef NXLog_H
+#define NXLog_H
+
+#include <iostream>
+#include <fstream>
+#include <sstream>
+#include <sys/time.h>
+
+#include <map>
+#include <stdlib.h>
+#include <string.h>
+#include <signal.h>
+#include <assert.h>
+#include <stack>
+
+/** Log severity level */
+enum NXLogLevel
+{
+    NXFATAL,
+    NXERROR,
+    NXWARNING,
+    NXINFO,
+    NXDEBUG,
+    NXLOG_LEVEL_COUNT
+};
+
+
+/**
+ * Log timestamp class
+ *
+ * Stores the timestamp, file, function, line number and log level.
+ * Acts as a manipulator on the NXLog class, telling it a new log
+ * severity level. For instance:
+ *
+ *     nx_log << NXLogStamp(...,NXINFO)
+ *
+ * Tells nx_log that now NXINFO type messages are being logged. This
+ * will be applied until a new NXLogStamp with a different level
+ * is sent to the NXLog.
+ */
+class NXLogStamp
+{
+    private:
+    std::string file_;
+    std::string function_;
+    size_t line_;
+    NXLogLevel level_;
+    struct timeval timestamp_;
+
+    public:
+    /** File where the event occurred */
+    std::string file() const
+    {
+        return file_;
+    }
+
+    /** Function where the event occurred */
+    std::string function() const
+    {
+        return function_;
+    }
+
+    /** Line where the event occurred */
+    size_t line() const
+    {
+        return line_;
+    }
+
+    /** Severity level of the event */
+    NXLogLevel level() const
+    {
+        return level_;
+    }
+
+    /** Time of the event */
+    struct timeval timestamp() const
+    {
+        return timestamp_;
+    }
+
+
+    NXLogStamp(const char *file, const char *function, int line, NXLogLevel level)
+    {
+        file_      = std::string(file);
+        function_  = std::string(function);
+        line_      = line;
+        level_     = level;
+        gettimeofday(&timestamp_, NULL);
+    }
+
+};
+
+
+/**
+ * Log class
+ *
+ * Logs events to a stream, filters by file/level
+ */
+class NXLog
+{
+#ifdef INTERNAL_LOGGING_TEST
+    protected:
+#endif
+    NXLogLevel level_;
+
+    std::ostream *stream_;
+    std::map< std::string, NXLogLevel > per_file_levels_;
+    bool synchronized_;
+    size_t  thread_buffer_size_;
+    pthread_mutex_t output_lock_;
+    pthread_key_t tls_key_;
+
+    bool log_level_;
+    bool log_time_;
+    bool log_unix_time_;
+    bool log_location_;
+    bool log_thread_id_;
+
+    typedef struct per_thread_data_s
+    {
+        NXLogLevel                      current_level;
+        std::string*                    current_file;
+        std::string*                    thread_name;
+        std::stack<std::stringstream*>  buffer;
+        NXLog*                          log_obj;
+    } per_thread_data;
+
+
+    static void free_thread_data(void* arg)
+    {
+        per_thread_data *pdt = (per_thread_data*)arg;
+
+        if ( !pdt )
+            return;
+
+        if ( pdt->log_obj ) {
+            // Ensure the buffer is flushed before thread deletion
+            pdt->log_obj->flush(pdt);
+        }
+
+        delete pdt->current_file;
+        delete pdt->thread_name;
+
+        while (!pdt->buffer.empty()) {
+            (void) pdt->buffer.pop ();
+        }
+
+        delete pdt;
+    }
+
+    per_thread_data* get_data_int() const
+    {
+        per_thread_data *ret = NULL;
+
+        if ( (ret = (per_thread_data*)pthread_getspecific(tls_key_)) == NULL )
+        {
+            ret = new per_thread_data;
+            ret->current_level = NXDEBUG;
+            ret->current_file = new std::string();
+            ret->thread_name = new std::string();
+            ret->log_obj = const_cast<NXLog*>(this);
+            pthread_setspecific(tls_key_, ret);
+        }
+
+        return ret;
+    }
+
+    per_thread_data* get_data()
+    {
+        return get_data_int();
+    }
+
+    const per_thread_data* get_data() const
+    {
+        return get_data_int();
+    }
+
+    /** Convert NXLogStamp to string according to the current configuration */
+    std::string stamp_to_string(const NXLogStamp& stamp) const;
+
+    void new_stack_entry()
+    {
+        per_thread_data *pdt = get_data();
+        pdt->buffer.push(new std::stringstream());
+    }
+
+    /**
+     * Internal flush function
+     *
+     * When a thread is being terminated and free_thread_data gets called,
+     * the TLS key gets set to NULL before the call to free_thread_data,
+     * and the destructor function gets the old value.
+     *
+     * This means that get_data() stops working correctly, and we need
+     * to be able to pass the old pointer.
+     */
+    virtual /* Note: this function needs to be virtual for the logging test application. Don't remove. */
+    void flush(per_thread_data *pdt)
+    {
+         /*
+          * Block all signals until we are dong printing data.
+          * Ensures that a signal handler won't interrupt us
+          * and overwrite the buffer data mid-print, leading
+          * to confusing output.
+          */
+        sigset_t orig_signal_mask,
+                 tmp_signal_mask;
+        sigemptyset(&orig_signal_mask);
+
+        /* Set up new mask to block all signals. */
+        sigfillset(&tmp_signal_mask);
+
+        /* Block all signals. */
+        pthread_sigmask(SIG_BLOCK, &tmp_signal_mask, &orig_signal_mask);
+
+        if (!pdt->buffer.empty ()) {
+            const std::string str = pdt->buffer.top()->str();
+
+            if (!str.empty())
+            {
+                pthread_mutex_lock(&output_lock_);
+                (*stream()) << str;
+                pthread_mutex_unlock(&output_lock_);
+            }
+
+            /* Remove from stack. */
+            pdt->buffer.pop();
+        }
+
+        /* Restore old signal mask. */
+        pthread_sigmask(SIG_SETMASK, &orig_signal_mask, NULL);
+    }
+
+
+    public:
+    NXLog()
+    {
+        stream_             = &std::cerr;
+        level_              = NXWARNING;
+        synchronized_       = true;
+        thread_buffer_size_ = 1024;
+        log_level_          = false;
+        log_time_           = false;
+        log_unix_time_      = false;
+        log_location_       = false;
+        log_thread_id_      = false;
+
+        if ( pthread_key_create(&tls_key_, free_thread_data) != 0 )
+        {
+            std::cerr << "pthread_key_create failed" << std::endl;
+            abort();
+        }
+
+    }
+
+    ~NXLog()
+    {
+        per_thread_data *pdt = get_data();
+
+        // Flush any remaining output and delete TLS data
+        free_thread_data(pdt);
+
+        pthread_key_delete(tls_key_);
+
+        if ((stream_) && (stream_ != &std::cerr)) {
+            delete stream_;
+        }
+    }
+
+    /** Minimum severity level to output */
+    NXLogLevel level() const
+    {
+        return level_;
+    }
+
+    void level(NXLogLevel level)
+    {
+        level_ = level;
+    }
+
+
+    /** Current severity level */
+    NXLogLevel current_level() const
+    {
+        return get_data()->current_level;
+    }
+
+    void current_level(NXLogLevel level)
+    {
+        get_data()->current_level = level;
+    }
+
+    /** Source file from which messages are currently originating */
+    std::string current_file() const
+    {
+        return *get_data()->current_file;
+    }
+
+    void current_file(std::string val)
+    {
+        *get_data()->current_file = val;
+    }
+
+    std::ostream* stream() const
+    {
+        return stream_;
+    }
+
+    void stream(std::ostream *stream)
+    {
+        flush();
+        stream_ = stream;
+    }
+
+    bool synchronized() const {
+        return synchronized_;
+    }
+
+    void synchronized(bool val) {
+        synchronized_ = val;
+    }
+
+    bool log_level() const
+    {
+        return log_level_;
+    }
+
+    void log_level(bool val)
+    {
+        log_level_ = val;
+    }
+
+    bool log_time() const
+    {
+        return log_time_;
+    }
+
+    void log_time(bool val)
+    {
+        log_time_ = val;
+    }
+
+    bool log_unix_time() const
+    {
+        return log_unix_time_;
+    }
+
+    void log_unix_time(bool val)
+    {
+        log_unix_time_ = val;
+    }
+
+    bool log_location() const
+    {
+        return log_location_;
+    }
+
+    void log_location(bool val)
+    {
+        log_location_ = val;
+    }
+
+    bool log_thread_id() const
+    {
+        return log_thread_id_;
+    }
+
+    void log_thread_id(bool val)
+    {
+        log_thread_id_ = val;
+    }
+
+
+    void flush()
+    {
+        per_thread_data *pdt = get_data();
+        flush(pdt);
+    }
+
+    std::string thread_name() const
+    {
+        return *get_data()->thread_name;
+    }
+
+    void thread_name(std::string str)
+    {
+        *get_data()->thread_name = str;
+    }
+
+    void thread_name(const char *str)
+    {
+        *get_data()->thread_name = str;
+    }
+
+    /**
+     * True if a message sent to the NXLog object will be sent to the output
+     *
+     * This considers two things:
+     *
+     * If there's a per-file log level, then it is used
+     * Otherwise the global log level is used.
+     *
+     * If the log level permits the current message to be output, then the
+     * return value is true.
+     */
+    bool will_log() const;
+
+
+    /**
+     * This catches std::flush
+     */
+    NXLog&  operator<<(std::ostream& (*F)(std::ostream&))
+    {
+        if ( will_log() )
+        {
+            if ( synchronized() )
+            {
+                per_thread_data *pdt = get_data();
+                assert (!pdt->buffer.empty ());
+                (*pdt->buffer.top()) << F;
+                flush();
+            }
+            else
+            {
+                *(stream()) << F;
+            }
+        }
+
+        return *this;
+    }
+
+    template<typename T>
+    friend NXLog& operator<<(NXLog& out, const T& value);
+
+    friend NXLog& operator<< (NXLog& out, const NXLogStamp& value);
+};
+
+
+extern NXLog nx_log;
+
+
+#define nxstamp(l) NXLogStamp(__FILE__, __func__, __LINE__, l)
+
+
+#define nxdbg    nx_log << nxstamp(NXDEBUG)
+#define nxinfo   nx_log << nxstamp(NXINFO)
+#define nxwarn   nx_log << nxstamp(NXWARNING)
+#define nxerr    nx_log << nxstamp(NXERROR)
+#define nxfatal  nx_log << nxstamp(NXFATAL)
+
+
+NXLog& operator<< (NXLog& out, const NXLogStamp& value);
+
+
+template <typename T>
+bool has_newline(T value)
+{
+    return false;
+}
+
+template <char*>
+static bool has_newline(char *value)
+{
+    return strstr(value, "\n") != NULL;
+}
+
+template <char>
+static bool has_newline(char value)
+{
+    return value == '\n';
+}
+
+template <std::string&>
+static bool has_newline(std::string &value)
+{
+    return value.find_first_of("\n") != std::string::npos;
+}
+
+static size_t ss_length(std::stringstream *ss)
+{
+    size_t pos = ss->tellg();
+    size_t ret = 0;
+    ss->seekg(0, std::ios::end);
+    ret = ss->tellg();
+    ss->seekg(pos, std::ios::beg);
+    return ret;
+}
+
+template <typename T>
+NXLog& operator<<(NXLog& out, const T& value)
+{
+    if ( out.will_log() )
+    {
+        if ( out.synchronized() )
+        {
+            // In synchronized mode, we buffer data until a newline, std::flush, or the buffer
+            // gets full. Then we dump the whole thing at once to the output stream, synchronizing
+            // with a mutex.
+            NXLog::per_thread_data *pdt = out.get_data();
+            assert (!pdt->buffer.empty ());
+            (*pdt->buffer.top()) << value;
+
+            if ( ss_length(pdt->buffer.top()) >= out.thread_buffer_size_ || has_newline(value) )
+                out.flush();
+
+        }
+        else
+        {
+            // In async mode we just dump data on the output stream as-is.
+            // Multithreaded code will have ugly output.
+            *(out.stream()) << value;
+        }
+
+    }
+
+    return out;
+}
+
+#endif
diff --git a/nxcomp/src/Loop.cpp b/nxcomp/src/Loop.cpp
index 4292e7b9a..681a5a1ef 100644
--- a/nxcomp/src/Loop.cpp
+++ b/nxcomp/src/Loop.cpp
@@ -101,6 +101,7 @@ typedef int socklen_t;
 
 #include "Message.h"
 #include "ChannelEndPoint.h"
+#include "Log.h"
 
 //
 // System specific defines.
@@ -9339,6 +9340,102 @@ int ParseCommandLineOptions(int argc, const char **argv)
 
           return -1;
         }
+        case 'd':
+        {
+          if ( argi+1 >= argc )
+          {
+            PrintUsageInfo(nextArg, 0);
+            return -1;
+          }
+
+          int level = 0;
+          errno = 0;
+          level = strtol(argv[argi+1], NULL, 10);
+
+          if ( errno && (level == 0) )
+          {
+            cerr << "Warning: Failed to parse log level. Ignoring option." << std::endl;
+          }
+          if ( level < 0 )
+          {
+            cerr << "Warning: Log level must be a positive integer. Ignoring option." << std::endl;
+            level = nx_log.level();
+          }
+          else if ( level >= NXLOG_LEVEL_COUNT )
+          {
+            cerr << "Warning: Log level is greater than the maximum " << NXLOG_LEVEL_COUNT-1 << ". Setting to the maximum." << std::endl;
+            level = NXLOG_LEVEL_COUNT-1;
+          }
+
+          nx_log.level( (NXLogLevel)level );
+
+          argi++;
+          break;
+
+        }
+        case 'o':
+        {
+          if ( argi + 1 >= argc )
+          {
+            PrintUsageInfo(nextArg, 0);
+            return -1;
+          }
+
+          std::ofstream *logfile = new std::ofstream();
+
+          // Unbuffered output
+          logfile->rdbuf()->pubsetbuf(0, 0);
+          logfile->open(argv[argi+1], std::ofstream::app);
+
+          if ( logfile->is_open() )
+          {
+            nx_log.stream(logfile);
+          }
+          else
+          {
+            cerr << "Failed to open log file " << argv[argi+1] << endl;
+            return -1;
+          }
+
+          argi++;
+          break;
+        }
+        case 'f':
+        {
+          if ( argi + 1 >= argc )
+          {
+            PrintUsageInfo(nextArg, 0);
+            return -1;
+          }
+
+          const char *format = argv[argi+1];
+          size_t pos = 0;
+
+          nx_log.log_level(false);
+          nx_log.log_time(false);
+          nx_log.log_unix_time(false);
+          nx_log.log_location(false);
+          nx_log.log_thread_id(false);
+
+          for(pos =0;pos<strlen(format);pos++)
+          {
+            switch(format[pos])
+            {
+              case '0': break;
+              case 't': nx_log.log_time(true); break;
+              case 'u': nx_log.log_time(true); nx_log.log_unix_time(true); break;
+              case 'l': nx_log.log_level(true); break;
+              case 'T': nx_log.log_thread_id(true); break;
+              case 'L': nx_log.log_location(true); break;
+              default : cerr << "Unrecognized format specifier: " << format[pos] << endl; break;
+            }
+          }
+
+          argi++;
+          break;
+        }
+
+
         default:
         {
           PrintUsageInfo(nextArg, 1);
diff --git a/nxcomp/src/Makefile.am b/nxcomp/src/Makefile.am
index 2264cb347..682ddbaca 100644
--- a/nxcomp/src/Makefile.am
+++ b/nxcomp/src/Makefile.am
@@ -114,12 +114,14 @@ libXcomp_la_SOURCES =					\
     WriteBuffer.cpp					\
     XidCache.cpp					\
     Z.cpp						\
+    Log.cpp						\
     $(NULL)
 
 libXcomp_la_LIBADD =					\
     @JPEG_LIBS@						\
     @PNG_LIBS@						\
     @Z_LIBS@						\
+    @PTHREAD_LIBS@					\
     $(NULL)
 
 AM_CXXFLAGS = 						\
@@ -127,13 +129,18 @@ AM_CXXFLAGS = 						\
     $(JPEG_CFLAGS)					\
     $(PNG_CFLAGS)					\
     $(Z_CFLAGS)						\
+    $(PTHREAD_CFLAGS)					\
     $(NULL)
 
 AM_CPPFLAGS =						\
     -I$(top_srcdir)/include				\
     $(NULL)
 
-libXcomp_la_LDFLAGS = -version-number @LT_COMP_VERSION@ -no-undefined
+libXcomp_la_LDFLAGS =					\
+    -version-number @LT_COMP_VERSION@			\
+    -no-undefined					\
+    $(PTHREAD_LDFLAGS)					\
+    $(NULL)
 
 libXcompincludedir = $(includedir)/nx
 libXcompinclude_HEADERS =				\
diff --git a/nxcomp/test/Makefile.am b/nxcomp/test/Makefile.am
new file mode 100644
index 000000000..412b8ea94
--- /dev/null
+++ b/nxcomp/test/Makefile.am
@@ -0,0 +1,22 @@
+NULL =
+
+noinst_PROGRAMS = logging_test
+EXTRA_DIST = logging_test
+
+AM_CPPFLAGS = -I$(top_srcdir)/src
+AM_CXXFLAGS =		\
+  @PTHREAD_CFLAGS@	\
+  $(NULL)
+
+logging_test_SOURCES = logging_test.cpp
+logging_test_LDADD =			\
+    $(top_srcdir)/src/.libs/libXcomp.a	\
+    @PTHREAD_LIBS@			\
+    $(NULL)
+
+logging_test_LDFLAGS =	\
+    $(PTHREAD_LDFLAGS)	\
+    $(NULL)
+
+check: all
+	./logging_test
diff --git a/nxcomp/test/logging_test.cpp b/nxcomp/test/logging_test.cpp
new file mode 100644
index 000000000..7e2d7d213
--- /dev/null
+++ b/nxcomp/test/logging_test.cpp
@@ -0,0 +1,224 @@
+#include <cstddef>
+#include <pthread.h>
+#include <signal.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <cstdlib>
+#include <ctime>
+#include <climits>
+#include <vector>
+#include <cstring>
+
+#include "logging_test.h"
+
+Faulty_Logger faulty_logger;
+NXLog good_logger;
+
+void print_sigmask () {
+  sigset_t orig_mask;
+  sigemptyset (&orig_mask);
+
+  pthread_sigmask (SIG_SETMASK, NULL, &orig_mask);
+
+  bool empty = true;
+  for (std::size_t i = 0; i < NSIG; ++i) {
+    if (sigismember (&orig_mask, i)) {
+      nxdbg_good << "Signal i (" << i << ") in signal mask." << std::endl;
+      empty = false;
+    }
+  }
+
+  if (empty) {
+    nxdbg_good << "Signal mask empty.";
+  }
+}
+
+void* log_task (void* /* unused */) {
+  /* print_sigmask (); */
+
+  for (std::size_t i = 0; i < 10; ++i) {
+    nxinfo << "Log message " << i << std::endl;
+  }
+}
+
+void sig_handler (int signo) {
+  nxinfo << "Received signal " << signo << std::endl;
+}
+
+void setup_faulty_logger () {
+  faulty_logger.log_level (true);
+  faulty_logger.log_unix_time (false);
+  faulty_logger.log_time (true);
+  faulty_logger.log_location (true);
+  faulty_logger.log_thread_id (true);
+  faulty_logger.level (NXDEBUG);
+}
+
+void setup_good_logger () {
+  good_logger.log_level (true);
+  good_logger.log_unix_time (false);
+  good_logger.log_time (true);
+  good_logger.log_location (true);
+  good_logger.log_thread_id (true);
+  good_logger.level (NXDEBUG);
+}
+
+pthread_t spawn_thread () {
+  pthread_t thread_id;
+  int pthread_ret;
+
+  sigset_t block_mask, orig_mask;
+  sigemptyset (&orig_mask);
+  sigfillset (&block_mask);
+
+  pthread_sigmask (SIG_BLOCK, &block_mask, &orig_mask);
+
+  pthread_ret = pthread_create (&thread_id, NULL, log_task, NULL);
+
+  pthread_sigmask (SIG_SETMASK, &orig_mask, NULL);
+
+  return (thread_id);
+}
+
+void install_signal_handler () {
+  struct sigaction sa;
+  sa.sa_handler = sig_handler;
+  sigemptyset (&sa.sa_mask);
+  sa.sa_flags = SA_RESTART;
+
+  if (-1 == sigaction (SIGUSR1, &sa, NULL)) {
+    nxerr_good << "Unable to install signal handler!" << std::endl;
+  }
+  else {
+    nxdbg_good << "Signal handler registered successfully for SIGUSR1." << std::endl;
+  }
+}
+
+void killing_process_work (pid_t parent_pid) {
+  /* Seed PRNG. */
+  std::srand (std::time (0));
+
+  for (std::size_t i = 0; i < 25; ++i) {
+    /* Sleep for 4 seconds + some random number up to a second. */
+    std::size_t rand_add = (std::rand () % 1000000);
+    usleep (4000000 + rand_add);
+
+    /* Send SIGUSR1 to parent process. */
+    nxdbg_good << "Sending SIGUSR1 (" << SIGUSR1 << ") to parent_pid (" << parent_pid << ")" << std::endl;
+
+    if (kill (parent_pid, SIGUSR1)) {
+      int saved_errno = errno;
+      nxerr_good << "Failed to deliver signal to parent, aborting." << std::endl;
+      nxerr_good << "Error " << saved_errno << ": " << strerror (saved_errno) << std::endl;
+      exit (EXIT_FAILURE);
+    }
+  }
+
+  exit (EXIT_SUCCESS);
+}
+
+void killing_process_init (int argc, char **argv) {
+  /* We're in the "killing process". */
+  pid_t parent_pid = getppid ();
+
+  setup_good_logger ();
+
+  for (std::size_t i = 0; i < argc; ++i) {
+    nxdbg_good << "argv[" << i << "]: " << argv[i] << std::endl;
+  }
+
+  char *end = NULL;
+
+  errno = 0;
+  long parent_pid_check = std::strtol (argv[1], &end, 0);
+
+  if ((errno == ERANGE) && (parent_pid_check == LONG_MAX)) {
+    /* Overflow, handle gracefully. */
+    parent_pid_check = 1;
+  }
+
+  if ((errno == ERANGE) && (parent_pid_check == LONG_MIN)) {
+    /* Underflow, handle gracefully. */
+    parent_pid_check = 1;
+  }
+
+  if (*end) {
+    /* Conversion error (for inputs like "<number>X", end will point to X.) */
+    parent_pid_check = 1;
+  }
+
+  if (parent_pid != parent_pid_check) {
+    nxinfo_good << "Parent PID verification via first argument failed, trusting getppid ()." << std::endl;
+  }
+
+  killing_process_work (parent_pid);
+}
+
+int main (int argc, char **argv) {
+  if (argc > 1) {
+    killing_process_init (argc, argv);
+  }
+  else {
+    /* That's the main process. */
+
+    /* First, fork and create the "killing process". */
+    pid_t pid = fork ();
+
+    if (0 == pid) {
+      /* Child process. */
+      pid_t parent_pid = getppid ();
+
+      /* Prepare to pass-through parent PID. */
+      std::stringstream ss;
+      ss << parent_pid;
+
+      std::vector<std::string> new_argv;
+      new_argv.push_back (std::string (argv[0]));
+      new_argv.push_back (ss.str ());
+
+      std::vector<char *> new_argv_c_str;
+      for (std::vector<std::string>::iterator it = new_argv.begin (); it != new_argv.end (); ++it) {
+        const char *elem = (*it).c_str ();
+        new_argv_c_str.push_back (strndup (elem, std::strlen (elem)));
+      }
+
+      /* Add null pointer as last element. */
+      new_argv_c_str.push_back (0);
+
+      /* Relaunch, with argv[1] containing the ppid. */
+      if (0 != execvp (new_argv_c_str.front (), &(new_argv_c_str.front ()))) {
+        const int saved_errno = errno;
+        std::cerr << "Failed to start \"killing process\"! Panic!" << std::endl;
+        std::cerr << "System error: " << std::strerror (saved_errno) << std::endl;
+        exit (EXIT_FAILURE);
+      }
+    }
+    else if (0 > pid) {
+      const int saved_errno = errno;
+      std::cerr << "Error while forking main process! Panic!" << std::endl;
+      std::cerr << "System error: " << std::strerror (saved_errno) << std::endl;
+      exit (EXIT_FAILURE);
+    }
+    else {
+      /* Main process. */
+      /* Falls through to general code below. */
+    }
+  }
+
+  setup_faulty_logger ();
+
+  pthread_t thread_id = spawn_thread ();
+
+  setup_good_logger ();
+
+  install_signal_handler ();
+
+  /* print_sigmask (); */
+
+  log_task (NULL);
+
+  pthread_join (thread_id, NULL);
+
+  exit (EXIT_SUCCESS);
+}
diff --git a/nxcomp/test/logging_test.h b/nxcomp/test/logging_test.h
new file mode 100644
index 000000000..239fbfe2b
--- /dev/null
+++ b/nxcomp/test/logging_test.h
@@ -0,0 +1,121 @@
+#ifndef LOGGING_TEST_H
+#define LOGGING_TEST_H
+
+#include <unistd.h>
+
+#define INTERNAL_LOGGING_TEST
+#include "Log.h"
+
+class Faulty_Logger : public NXLog {
+    /* Copied from base class, inserted "fault" within critical section. */
+    using NXLog::flush;
+    void flush(per_thread_data *pdt)
+    {
+        sigset_t orig_signal_mask,
+                 tmp_signal_mask;
+        sigemptyset(&orig_signal_mask);
+
+        sigfillset(&tmp_signal_mask);
+
+        pthread_sigmask(SIG_BLOCK, &tmp_signal_mask, &orig_signal_mask);
+
+        if (!pdt->buffer.empty ()) {
+            const std::string str = pdt->buffer.top()->str();
+
+            if (!str.empty())
+            {
+                pthread_mutex_lock(&output_lock_);
+                usleep (3000000);
+                (*stream()) << str;
+                pthread_mutex_unlock(&output_lock_);
+            }
+
+            pdt->buffer.pop();
+        }
+
+        pthread_sigmask(SIG_SETMASK, &orig_signal_mask, NULL);
+    }
+
+    template<typename T>
+    friend Faulty_Logger& operator<<(Faulty_Logger& out, const T& value);
+
+    friend Faulty_Logger& operator<< (Faulty_Logger& out, const NXLogStamp& value);
+};
+
+template <typename T>
+Faulty_Logger& operator<<(Faulty_Logger& out, const T& value) {
+  if ( out.will_log() ) {
+    if ( out.synchronized() ) {
+      // In synchronized mode, we buffer data until a newline, std::flush, or the buffer
+      // gets full. Then we dump the whole thing at once to the output stream, synchronizing
+      // with a mutex.
+      Faulty_Logger::per_thread_data *pdt = out.get_data();
+      assert (!pdt->buffer.empty ());
+      usleep (1000000);
+      (*pdt->buffer.top()) << value;
+
+      if ( ss_length(pdt->buffer.top()) >= out.thread_buffer_size_ || has_newline(value) )
+          out.flush();
+    }
+    else {
+        // In async mode we just dump data on the output stream as-is.
+        // Multithreaded code will have ugly output.
+        *(out.stream()) << value;
+    }
+  }
+
+  return out;
+}
+
+Faulty_Logger& operator<< (Faulty_Logger& out, const NXLogStamp& value)
+{
+    out.current_level( value.level() );
+    out.current_file( value.file() );
+
+    // Writing an NXLogStamp to the stream indicates the start of a new entry.
+    // If there's any content in the buffer, create a new entry in the output
+    // queue.
+    if ( out.synchronized() )
+        out.new_stack_entry();
+
+    out << out.stamp_to_string(value);
+
+    return out;
+}
+
+#undef nxdbg
+#undef nxinfo
+#undef nxwarn
+#undef nxerr
+#undef nxfatal
+
+#define nxdbg    faulty_logger << nxstamp(NXDEBUG)
+#define nxinfo   faulty_logger << nxstamp(NXINFO)
+#define nxwarn   faulty_logger << nxstamp(NXWARNING)
+#define nxerr    faulty_logger << nxstamp(NXERROR)
+#define nxfatal  faulty_logger << nxstamp(NXFATAL)
+
+#define nxdbg_good    good_logger << nxstamp(NXDEBUG)
+#define nxinfo_good   good_logger << nxstamp(NXINFO)
+#define nxwarn_good   good_logger << nxstamp(NXWARNING)
+#define nxerr_good    good_logger << nxstamp(NXERROR)
+#define nxfatal_good  good_logger << nxstamp(NXFATAL)
+
+/* Helper functions used by all component. */
+void print_sigmask ();
+void setup_faulty_logger ();
+void setup_good_logger ();
+
+/* Functions used by both main and auxiliary threads. */
+void* log_task (void* /* unused */);
+
+/* Functions used in main thread only. */
+pthread_t spawn_thread ();
+void install_signal_handler ();
+void sig_handler (int signo);
+
+/* Functions used by "killing" process. */
+void killing_process_init (int argc, char **argv);
+void killing_process_work (pid_t parent_pid);
+
+#endif /* !defined (LOGGING_TEST_H) */
diff --git a/nxcompshad/configure.ac b/nxcompshad/configure.ac
index 34b1c053c..966add584 100644
--- a/nxcompshad/configure.ac
+++ b/nxcompshad/configure.ac
@@ -44,6 +44,12 @@ AC_LANG([C++])
 NX_COMPILER_BRAND
 NX_DEFAULT_OPTIONS
 
+AC_ARG_ENABLE([cxx11],
+              [AS_HELP_STRING([--enable-cxx11],
+                              [enable optional features requiring C++11 support (disabled by default)])],
+              [AS_IF([test x$enableval = xyes],
+                     [AX_CXX_COMPILE_STDCXX_11([], [mandatory])])])
+
 AC_CONFIG_FILES([
 Makefile
 src/Makefile
diff --git a/nxcompshad/m4/ax_cxx_compile_stdcxx.m4 b/nxcompshad/m4/ax_cxx_compile_stdcxx.m4
new file mode 120000
index 000000000..28ebfd1a6
--- /dev/null
+++ b/nxcompshad/m4/ax_cxx_compile_stdcxx.m4
@@ -0,0 +1 @@
+../../m4/ax_cxx_compile_stdcxx.m4
\ No newline at end of file
diff --git a/nxcompshad/m4/ax_cxx_compile_stdcxx_11.m4 b/nxcompshad/m4/ax_cxx_compile_stdcxx_11.m4
new file mode 120000
index 000000000..5fbe8790d
--- /dev/null
+++ b/nxcompshad/m4/ax_cxx_compile_stdcxx_11.m4
@@ -0,0 +1 @@
+../../m4/ax_cxx_compile_stdcxx_11.m4
\ No newline at end of file
diff --git a/nxproxy/configure.ac b/nxproxy/configure.ac
index 9663fb4a8..cc8e898fc 100644
--- a/nxproxy/configure.ac
+++ b/nxproxy/configure.ac
@@ -23,6 +23,12 @@ AC_LANG([C])
 NX_COMPILER_BRAND
 NX_DEFAULT_OPTIONS
 
+AC_ARG_ENABLE([cxx11],
+              [AS_HELP_STRING([--enable-cxx11],
+                              [enable optional features requiring C++11 support (disabled by default)])],
+              [AS_IF([test x$enableval = xyes],
+                     [AX_CXX_COMPILE_STDCXX_11([], [mandatory])])])
+
 AC_CONFIG_FILES([
 Makefile
 man/Makefile
diff --git a/nxproxy/m4/ax_cxx_compile_stdcxx.m4 b/nxproxy/m4/ax_cxx_compile_stdcxx.m4
new file mode 120000
index 000000000..28ebfd1a6
--- /dev/null
+++ b/nxproxy/m4/ax_cxx_compile_stdcxx.m4
@@ -0,0 +1 @@
+../../m4/ax_cxx_compile_stdcxx.m4
\ No newline at end of file
diff --git a/nxproxy/m4/ax_cxx_compile_stdcxx_11.m4 b/nxproxy/m4/ax_cxx_compile_stdcxx_11.m4
new file mode 120000
index 000000000..5fbe8790d
--- /dev/null
+++ b/nxproxy/m4/ax_cxx_compile_stdcxx_11.m4
@@ -0,0 +1 @@
+../../m4/ax_cxx_compile_stdcxx_11.m4
\ No newline at end of file