Translate log_to_postgres ERROR/FATAL into Python exceptions to pass through interpreter

Author: mfenniak

python/multicorn/utils.py

@@ -20,9 +20,25 @@ def _log_to_postgres(message, level=0, hint=None, detail=None):
 }
 
 
+class MulticornException(Exception):
+    def __init__(self, message, code, hint, detail):
+        self._is_multicorn_exception = True
+        self.message = message
+        self.code = code
+        self.hint = hint
+        self.detail = detail
+
+
 def log_to_postgres(message, level=INFO, hint=None, detail=None):
     code = REPORT_CODES.get(level, None)
     if code is None:
         raise KeyError("Not a valid log level")
-    _log_to_postgres(message, code, hint=hint, detail=detail)
-
+    if level in (ERROR, CRITICAL):
+        # if we sent an ERROR or FATAL(=CRITICAL) message to _log_to_postgres, we would trigger the PostgreSQL C-level
+        # exception handling, which would prevent us from cleanly exiting whatever Python context we're currently in.
+        # To avoid this, these log levels are replaced with exceptions which are bubbled back to Multicorn's entry
+        # points, and those exceptions are translated into appropriate logging after we exit the method at the top of
+        # the multicorn stack.
+        raise MulticornException(message, code, hint, detail)
+    else:
+        _log_to_postgres(message, code, hint=hint, detail=detail)

src/errors.c

@@ -17,6 +17,7 @@ void reportException(PyObject *pErrType,
 				PyObject *pErrValue,
 				PyObject *pErrTraceback);
 
+void reportMulticornException(PyObject *pErrValue);
 
 PGDLLEXPORT void
 errorCheck()
@@ -28,7 +29,22 @@ errorCheck()
 	PyErr_Fetch(&pErrType, &pErrValue, &pErrTraceback);
 	if (pErrType)
 	{
-		reportException(pErrType, pErrValue, pErrTraceback);
+		// if the error value has a property _is_multicorn_exception and a boolean value True, then we don't report the
+		// error as a generic exception with a stack trace -- instead we just take the message, code(severity), hint,
+		// and detail, and log it to Postgres.  These exceptions are generated in utils.py to intercept ERROR/FATAL log
+		// messages.  So, first detect whether that's the case, and call a new reporting function...
+		PyObject *is_multicorn_exception = PyObject_GetAttrString(pErrValue, "_is_multicorn_exception");
+		if (is_multicorn_exception != NULL && PyObject_IsTrue(is_multicorn_exception))
+		{
+			Py_DECREF(is_multicorn_exception);
+			Py_DECREF(pErrType);
+			Py_DECREF(pErrTraceback);
+			reportMulticornException(pErrValue);
+		}
+		else
+		{
+			reportException(pErrType, pErrValue, pErrTraceback);
+		}
 	}
 }
 
@@ -92,3 +108,64 @@ reportException(PyObject *pErrType, PyObject *pErrValue, PyObject *pErrTraceback
 		errfinish(0);
 #endif
 }
+
+void reportMulticornException(PyObject* pErrValue)
+{
+	int severity;
+	PyObject *message = PyObject_GetAttrString(pErrValue, "message");
+	PyObject *hint = PyObject_GetAttrString(pErrValue, "hint");
+	PyObject *detail = PyObject_GetAttrString(pErrValue, "detail");
+	PyObject *code = PyObject_GetAttrString(pErrValue, "code");
+	int level = PyLong_AsLong(code);
+
+	// Matches up with REPORT_CODES in utils.py
+	switch (level)
+	{
+		case 3:
+			severity = ERROR;
+			break;
+		default:
+		case 4:
+			severity = FATAL;
+			break;
+	}
+
+	PG_TRY();
+	{
+
+	#if PG_VERSION_NUM >= 130000
+		if (errstart(severity, TEXTDOMAIN))
+	#else
+		if (errstart(severity, __FILE__, __LINE__, PG_FUNCNAME_MACRO, TEXTDOMAIN))
+	#endif
+		{
+			errmsg("%s", PyString_AsString(message));
+			if (hint != NULL && hint != Py_None)
+			{
+				char* hintstr = PyString_AsString(hint);
+				errhint("%s", hintstr);
+			}
+			if (detail != NULL && detail != Py_None)
+			{
+				char* detailstr = PyString_AsString(detail);
+				errdetail("%s", detailstr);
+			}
+	#if PG_VERSION_NUM >= 130000
+			errfinish(__FILE__, __LINE__, PG_FUNCNAME_MACRO);
+	#else
+			errfinish(0);
+	#endif
+		}
+
+	}
+	PG_CATCH();
+	{
+		Py_DECREF(message);
+		Py_DECREF(hint);
+		Py_DECREF(detail);
+		Py_DECREF(code);
+		Py_DECREF(pErrValue);
+		PG_RE_THROW();
+	}
+	PG_END_TRY();
+}