svn commit: r1155571 - /subversion/branches/fs-py/subversion/libsvn_fs_py/py_util.c

[hw...@apache.org]

Author: hwright
Date: Tue Aug  9 22:01:28 2011
New Revision: 1155571

URL: http://svn.apache.org/viewvc?rev=1155571&view=rev
Log:
On the fs-py branch:
Add a helper function which calls a given func/baton pair, and then wraps any
resulting Python exception in a Subversion error.  We were already doing this
before for method calls, but this is a more generalized approach.

* subversion/libsvn_fs_py/py_util.c
  (py_exc_func_t): New.
  (catch_py_exception): New.
  (call_method_baton, call_method): New.
  (svn_fs_py__call_method): Use the helper function to do error handling.

Modified:
    subversion/branches/fs-py/subversion/libsvn_fs_py/py_util.c

Modified: subversion/branches/fs-py/subversion/libsvn_fs_py/py_util.c
URL: http://svn.apache.org/viewvc/subversion/branches/fs-py/subversion/libsvn_fs_py/py_util.c?rev=1155571&r1=1155570&r2=1155571&view=diff
==============================================================================
--- subversion/branches/fs-py/subversion/libsvn_fs_py/py_util.c (original)
+++ subversion/branches/fs-py/subversion/libsvn_fs_py/py_util.c Tue Aug  9 22:01:28 2011
@@ -122,6 +122,49 @@ create_py_stack(PyObject *p_exception,
   return err;
 }
 
+typedef void (*py_exc_func_t)(void *baton, va_list argp);
+
+/* Call FUNC with BATON, and upon returning check to see if the Python
+   interpreter has a pending exception.  If it does, convert that exception
+   to an svn_error_t and return it (or SVN_NO_ERROR if no error), resetting
+   the interpreter state and releasing the exception.
+   
+   Note: This function assumes whatever locking we need for the interpreter
+   has already happened and will be released after it is done. */
+static svn_error_t *
+catch_py_exception(py_exc_func_t func,
+                   void *baton,
+                   va_list argp)
+{
+  PyObject *p_type;
+  PyObject *p_exception;
+  PyObject *p_traceback;
+  svn_error_t *err;
+
+  /* Call the handler. */
+  func(baton, argp);
+
+  /* Early out if we didn't have any errors. */
+  if (!PyErr_Occurred())
+    return SVN_NO_ERROR;
+
+  PyErr_Fetch(&p_type, &p_exception, &p_traceback);
+
+  if (p_exception && p_traceback)
+    err = create_py_stack(p_exception, p_traceback);
+  else
+    err = svn_error_create(SVN_ERR_BAD_PYTHON, NULL,
+                           _("Python error."));
+
+  PyErr_Clear();
+
+  Py_DECREF(p_type);
+  Py_XDECREF(p_exception);
+  Py_XDECREF(p_traceback);
+
+  return err;
+}
+
 static svn_error_t *
 load_module(PyObject **p_module_out,
             const char *module_name)
@@ -215,75 +258,77 @@ svn_fs_py__destroy_py_object(void *data)
 }
 
 
-svn_error_t*
-svn_fs_py__call_method(PyObject **p_result,
-                       PyObject *p_obj,
-                       const char *name,
-                       const char *format,
-                       ...)
+struct call_method_baton
 {
-  PyObject *p_func = NULL;
-  PyObject *p_value = NULL;
-  PyObject *p_args = NULL;
-  va_list argp;
+  PyObject **p_result;
+  PyObject *p_obj;
+  const char *name;
+  const char *format;
+};
 
-  SVN_ERR_ASSERT(p_obj != NULL);
 
-  va_start(argp, format);
+static void
+call_method(void *baton, va_list argp)
+{
+  struct call_method_baton *cmb = baton;
+  PyObject *p_args = NULL;
+  PyObject *p_func = NULL;
+  PyObject *p_value = NULL;
 
-  p_args = Py_VaBuildValue(format, argp);
+  p_args = Py_VaBuildValue(cmb->format, argp);
   if (PyErr_Occurred())
-    goto create_error;
+    goto cm_free_objs;
 
-  p_func = PyObject_GetAttrString(p_obj, name);
+  p_func = PyObject_GetAttrString(cmb->p_obj, cmb->name);
   if (PyErr_Occurred())
-    goto create_error;
-    
-  /* ### Need a callable check here? */
+    goto cm_free_objs;
 
   p_value = PyObject_CallObject(p_func, p_args);
   Py_DECREF(p_args);
   p_args = NULL;
+  Py_DECREF(p_func);
+  p_func = NULL;
   if (PyErr_Occurred())
-    goto create_error;
+    goto cm_free_objs;
 
-  if (p_result)
-    *p_result = p_value;
+  if (cmb->p_result)
+    *cmb->p_result = p_value;
   else
     Py_DECREF(p_value);
 
-  Py_DECREF(p_func);
+  return;
 
-  va_end(argp);
-  return SVN_NO_ERROR;
+cm_free_objs:
+  /* Error handler, decrefs all python objects we may have. */
+  Py_XDECREF(p_args);
+  Py_XDECREF(p_func);
+}
 
-create_error:
-  {
-    PyObject *p_type = NULL;
-    PyObject *p_exception = NULL;
-    PyObject *p_traceback = NULL;
-    svn_error_t *err;
 
-    va_end(argp);
-    Py_XDECREF(p_args);
-    Py_XDECREF(p_func);
+svn_error_t*
+svn_fs_py__call_method(PyObject **p_result,
+                       PyObject *p_obj,
+                       const char *name,
+                       const char *format,
+                       ...)
+{
+  svn_error_t *err;
+  va_list argp;
+  struct call_method_baton cmb;
 
-    PyErr_Fetch(&p_type, &p_exception, &p_traceback);
+  SVN_ERR_ASSERT(p_obj != NULL);
 
-    if (p_exception && p_traceback)
-      err = create_py_stack(p_exception, p_traceback);
-    else
-      err = svn_error_create(SVN_ERR_BAD_PYTHON, NULL,
-                             _("Error calling method"));
+  va_start(argp, format);
 
-    PyErr_Clear();
+  cmb.p_result = p_result;
+  cmb.p_obj = p_obj;
+  cmb.name = name;
+  cmb.format = format;
 
-    Py_DECREF(p_type);
-    Py_XDECREF(p_exception);
-    Py_XDECREF(p_traceback);
+  err = catch_py_exception(call_method, &cmb, argp);
 
-    return err;
-  }
+  va_end(argp);
+  return err;
 }
 
 PyObject *