Add code to drop the GIL. Demostrate usefulness on reads/writes.

README.rst

@@ -76,6 +76,7 @@ On ubuntu you can install these with::
   this::
 
     CFLAGS="-std=c++11 \
+            -lpthread \
             -I/usr/local/Cellar/boost/1.68.0/include/ \
             -I/usr/local/include/  \
             -L/usr/local/Cellar/boost/1.68.0/lib \

setup.py

@@ -233,7 +233,8 @@ def get_extensions():
                                     library_dirs=library_dirs,
                                     include_dirs=include_dirs,
                                     # Since casacore 3.0.0 we have to be C++11
-                                    extra_compile_args=['-std=c++11']))
+                                    extra_compile_args=['-std=c++11',
+                                                        '-lpthread']))
     return extensions
 
 

src/guards.h

@@ -0,0 +1,115 @@
+#include <iostream>
+
+#include <boost/function.hpp>
+#include <boost/function_types/components.hpp>
+#include <boost/function_types/function_type.hpp>
+#include <boost/function_types/result_type.hpp>
+#include <boost/python.hpp>
+#include <boost/tuple/tuple.hpp>
+
+namespace details {
+
+/// @brief Functor that will invoke a function while holding a guard.
+///        Upon returning from the function, the guard is released.
+template <typename Signature,
+          typename Guard>
+class guarded_function
+{
+public:
+
+  typedef typename boost::function_types::result_type<Signature>::type
+      result_type;
+
+  template <typename Fn>
+  guarded_function(Fn fn)
+    : fn_(fn)
+  {}
+
+  template <typename... Args>
+  result_type operator()(Args... args)
+  {
+    Guard g;
+    return fn_(args...);
+  } 
+
+private:
+  boost::function<Signature> fn_;
+};
+
+/// @brief Provides signature type.
+template <typename Signature>
+struct mpl_signature
+{
+  typedef typename boost::function_types::components<Signature>::type type;
+};
+
+// Support boost::function.
+template <typename Signature>
+struct mpl_signature<boost::function<Signature> >:
+  public mpl_signature<Signature>
+{};
+
+/// @brief Create a callable object with guards.
+template <typename Guard,
+          typename Fn,
+          typename Policy>
+boost::python::object with_aux(Fn fn, const Policy& policy)
+{
+  // Obtain the components of the Fn.  This will decompose non-member
+  // and member functions into an mpl sequence.
+  //   R (*)(A1)    => R, A1
+  //   R (C::*)(A1) => R, C*, A1
+  typedef typename mpl_signature<Fn>::type mpl_signature_type;
+
+  // Synthesize the components into a function type.  This process
+  // causes member functions to require the instance argument.
+  // This is necessary because member functions will be explicitly
+  // provided the 'self' argument.
+  //   R, A1     => R (*)(A1)
+  //   R, C*, A1 => R (*)(C*, A1)
+  typedef typename boost::function_types::function_type<
+      mpl_signature_type>::type signature_type;
+
+  // Create a callable boost::python::object that delegates to the
+  // guarded_function.
+  return boost::python::make_function(
+    guarded_function<signature_type, Guard>(fn),
+    policy, mpl_signature_type());
+}
+
+} // namespace details
+
+/// @brief Create a callable object with guards.
+template <typename Guard,
+          typename Fn,
+          typename Policy>
+boost::python::object with(const Fn& fn, const Policy& policy)
+{
+  return details::with_aux<Guard>(fn, policy);
+}
+
+/// @brief Create a callable object with guards.
+template <typename Guard,
+          typename Fn>
+boost::python::object with(const Fn& fn)
+{
+  return with<Guard>(fn, boost::python::default_call_policies());
+}
+
+/// @brief Guard that will unlock the GIL upon construction, and
+///        reacquire it upon destruction.
+struct no_gil
+{
+public:
+  no_gil()  { state_ = PyEval_SaveThread(); }
+  ~no_gil() { PyEval_RestoreThread(state_); }
+private:
+  PyThreadState* state_;
+};
+
+/// @brief Guard that prints to std::cout.
+struct echo_guard 
+{
+  echo_guard()  { std::cout << "echo_guard()" << std::endl;  }
+  ~echo_guard() { std::cout << "~echo_guard()" << std::endl; }
+};

src/pytable.cc

@@ -33,6 +33,7 @@
 
 #include <boost/python.hpp>
 #include <boost/python/args.hpp>
+#include "guards.h"
 
 using namespace boost::python;
 
@@ -139,91 +140,20 @@ namespace casacore { namespace python {
       .def ("_iscelldefined", &TableProxy::cellContentsDefined,
 	    (boost::python::arg("columnname"),
 	     boost::python::arg("rownr")))
-      .def ("_getcell", &TableProxy::getCell,
-	    (boost::python::arg("columnname"),
-	     boost::python::arg("rownr")))
-      .def ("_getcellvh", &TableProxy::getCellVH,
-	    (boost::python::arg("columnname"),
-	     boost::python::arg("rownr"),
-             boost::python::arg("value")))
-      .def ("_getcellslice", &TableProxy::getCellSliceIP,
-	    (boost::python::arg("columnname"),
-	     boost::python::arg("rownr"),
-	     boost::python::arg("blc"),
-	     boost::python::arg("trc"),
-	     boost::python::arg("inc")))
-      .def ("_getcellslicevh", &TableProxy::getCellSliceVHIP,
-	    (boost::python::arg("columnname"),
-	     boost::python::arg("rownr"),
-	     boost::python::arg("blc"),
-	     boost::python::arg("trc"),
-	     boost::python::arg("inc"),
-             boost::python::arg("value")))
-      .def ("_getcol", &TableProxy::getColumn,
-	    (boost::python::arg("columnname"),
-	     boost::python::arg("startrow"),
-	     boost::python::arg("nrow"),
-	     boost::python::arg("rowincr")))
-      .def ("_getcolvh", &TableProxy::getColumnVH,
-	    (boost::python::arg("columnname"),
-	     boost::python::arg("startrow"),
-	     boost::python::arg("nrow"),
-	     boost::python::arg("rowincr"),
-             boost::python::arg("value")))
-      .def ("_getvarcol", &TableProxy::getVarColumn,
-	    (boost::python::arg("columnname"),
-	     boost::python::arg("startrow"),
-	     boost::python::arg("nrow"),
-	     boost::python::arg("rowincr")))
-      .def ("_getcolslice", &TableProxy::getColumnSliceIP,
-	    (boost::python::arg("columnname"),
-	     boost::python::arg("blc"),
-	     boost::python::arg("trc"),
-	     boost::python::arg("inc"),
-	     boost::python::arg("startrow"),
-	     boost::python::arg("nrow"),
-	     boost::python::arg("rowincr")))
-      .def ("_getcolslicevh", &TableProxy::getColumnSliceVHIP,
-	    (boost::python::arg("columnname"),
-	     boost::python::arg("blc"),
-	     boost::python::arg("trc"),
-	     boost::python::arg("inc"),
-	     boost::python::arg("startrow"),
-	     boost::python::arg("nrow"),
-	     boost::python::arg("rowincr"),
-             boost::python::arg("value")))
-      .def ("_putcell", &TableProxy::putCell,
-	    (boost::python::arg("columnname"),
-	     boost::python::arg("rownr"),
-	     boost::python::arg("value")))
-      .def ("_putcellslice", &TableProxy::putCellSliceIP,
-	    (boost::python::arg("columnname"),
-	     boost::python::arg("rownr"),
-	     boost::python::arg("value"),
-	     boost::python::arg("blc"),
-	     boost::python::arg("trc"),
-	     boost::python::arg("inc")))
-      .def ("_putcol", &TableProxy::putColumn,
-	    (boost::python::arg("columnname"),
-	     boost::python::arg("startrow"),
-	     boost::python::arg("nrow"),
-	     boost::python::arg("rowincr"),
-	     boost::python::arg("value")))
-      .def ("_putvarcol", &TableProxy::putVarColumn,
-	    (boost::python::arg("columnname"),
-	     boost::python::arg("startrow"),
-	     boost::python::arg("nrow"),
-	     boost::python::arg("rowincr"),
-	     boost::python::arg("value")))
-      .def ("_putcolslice", &TableProxy::putColumnSliceIP,
-	    (boost::python::arg("columnname"),
-	     boost::python::arg("value"),
-	     boost::python::arg("blc"),
-	     boost::python::arg("trc"),
-	     boost::python::arg("inc"),
-	     boost::python::arg("startrow"),
-	     boost::python::arg("nrow"),
-	     boost::python::arg("rowincr")))
+      .def ("_getcell", with<no_gil>(&TableProxy::getCell))
+      .def ("_getcellvh", with<no_gil>(&TableProxy::getCellVH))
+      .def ("_getcellslice", with<no_gil>(&TableProxy::getCellSliceIP))
+      .def ("_getcellslicevh", with<no_gil>(&TableProxy::getCellSliceVHIP))
+      .def ("_getcol", with<no_gil>(&TableProxy::getColumn))
+      .def ("_getcolvh", with<no_gil>(&TableProxy::getColumnVH))
+      .def ("_getvarcol", with<no_gil>(&TableProxy::getVarColumn))
+      .def ("_getcolslice", with<no_gil>(&TableProxy::getColumnSliceIP))
+      .def ("_getcolslicevh", with<no_gil>(&TableProxy::getColumnSliceVHIP))
+      .def ("_putcell", with<no_gil>(&TableProxy::putCell))
+      .def ("_putcellslice", with<no_gil>(&TableProxy::putCellSliceIP))
+      .def ("_putcol", with<no_gil>(&TableProxy::putColumn))
+      .def ("_putvarcol", with<no_gil>(&TableProxy::putVarColumn))
+      .def ("_putcolslice", with<no_gil>(&TableProxy::putColumnSliceIP))
       .def ("_getcolshapestring", &TableProxy::getColumnShapeString,
 	    (boost::python::arg("columnname"),
 	     boost::python::arg("startrow"),

src/tables.cc

@@ -32,15 +32,18 @@
 #include <casacore/python/Converters/PycValueHolder.h>
 #include <casacore/python/Converters/PycRecord.h>
 #include <casacore/python/Converters/PycArray.h>
+#include <casacore/python/Converters/PyNotThreadSafe.h>
 #include <casacore/tables/Tables/TableProxy.h>
 
 #include <casacore/meas/MeasUDF/Register.h>
 #include <casacore/derivedmscal/DerivedMC/Register.h>
 
 #include <boost/python.hpp>
+#include <string>
 
 BOOST_PYTHON_MODULE(_tables)
 {
+  casacore::python::registerNotThreadSafeException();
   casacore::python::register_convert_excp();
   casacore::python::register_convert_basicdata();
   casacore::python::register_convert_casa_valueholder();