python_callbacks.hpp

/* Copyright © 2017 Apple Inc. All rights reserved.
 *
 * Use of this source code is governed by a BSD-3-clause license that can
 * be found in the LICENSE.txt file or at https://opensource.org/licenses/BSD-3-Clause
 */
#ifndef TURI_PYTHON_CALLBACKS_H_
#define TURI_PYTHON_CALLBACKS_H_

#include <core/util/code_optimization.hpp>
#include <string>
#include <core/export.hpp>

/** Provides a generic interface to call cython functions (which can
 *  in turn call python functions) from the C++ code and properly
 *  handle exceptions.
 */

namespace turi { namespace python {

struct python_exception_info {
  std::string exception_pickle;
  std::string exception_string;
};

// Registers the exception
void register_python_exception(const python_exception_info*);
extern bool _python_exception_occured;

void _process_registered_exception() GL_COLD_NOINLINE;

/**
 * Processes exceptions raised by the above functions.  To use, do
 *
 * On the cython side:
 *
 * from cy_callbacks cipmort register_exception
 *
 * cdef void my_func(...):
 *     try:
 *         # Do stuff...
 *
 *     except Exception, e:
 *         register_exception(e)
 *         return
 *
 *
 *   On the C++ side.
 *
 *   cython_function_struct.my_func(...);
 *   check_for_python_exception();
 */
static inline GL_HOT_INLINE void check_for_python_exception() {
  if(UNLIKELY(_python_exception_occured)) {
    _process_registered_exception();
  }
}

}}

#endif /* TURI_PYTHON_CALLBACKS_H_ */