Add `src/py-common`, containing bt_py_common_format_exception() for now
authorPhilippe Proulx <eeppeliteloop@gmail.com>
Thu, 27 Jun 2019 16:24:23 +0000 (12:24 -0400)
committerJérémie Galarneau <jeremie.galarneau@efficios.com>
Thu, 18 Jul 2019 15:53:33 +0000 (11:53 -0400)
This new convenience library is meant to contain functions used by
Python bindings and the Python plugin provider.

As of this patch, it only offers bt_py_common_format_exception(), which
is similar to what bt2_py_loge_exception() used to do in
`native_bt_component_class.i`, except that it returns the formatted
exception string instead of logging it directly. Now
bt2_py_loge_exception() uses bt_py_common_format_exception().

bt_py_common_format_exception() will be needed in a future patch to set
the message of an error cause when appending from the Python plugin
provider.

No functional change intended.

Signed-off-by: Philippe Proulx <eeppeliteloop@gmail.com>
Change-Id: Iaa9dc081e7d8a3d6c85420fcbbfc045a9d79bf27
Reviewed-on: https://review.lttng.org/c/babeltrace/+/1556
Tested-by: jenkins <jenkins@lttng.org>
configure.ac
src/Makefile.am
src/bindings/python/bt2/bt2/native_bt.i
src/bindings/python/bt2/bt2/native_bt_component_class.i
src/bindings/python/bt2/setup.py.in
src/py-common/Makefile.am [new file with mode: 0644]
src/py-common/py-common.c [new file with mode: 0644]
src/py-common/py-common.h [new file with mode: 0644]

index 3bbc0c7fac52198666c6a52fc10f4c029dd0d726..dfa385aa44106fbe103686a10b0c4f992a546015 100644 (file)
@@ -490,7 +490,7 @@ AM_CONDITIONAL([ENABLE_API_DOC], [test "x$enable_api_doc" = xyes])
 AM_CONDITIONAL([ENABLE_BUILT_IN_PLUGINS], [test "x$enable_built_in_plugins" = xyes])
 AM_CONDITIONAL([ENABLE_BUILT_IN_PYTHON_PLUGIN_SUPPORT], [test "x$enable_built_in_python_plugin_support" = xyes])
 AM_CONDITIONAL([ENABLE_MAN_PAGES], [test "x$enable_man_pages" = xyes])
-
+AM_CONDITIONAL([HAVE_PYTHON], [test "x$enable_python_bindings" = xyes || test "x$enable_python_plugins" = xyes])
 
 # Set defines for optionnal features conditionnals in the source code
 
@@ -773,6 +773,7 @@ AC_CONFIG_FILES([
        src/plugins/utils/Makefile
        src/plugins/utils/muxer/Makefile
        src/plugins/utils/trimmer/Makefile
+       src/py-common/Makefile
        src/python-plugin-provider/Makefile
        tests/ctf-writer/Makefile
        tests/lib/Makefile
index 28b7bd4caa36188d5f4bb317f94c12ea5ca5aa70..90619a2fd4bae9cf1aef009b71f041b945f0e2f1 100644 (file)
@@ -1,5 +1,6 @@
 SUBDIRS = \
        common \
+       py-common \
        ctfser \
        fd-cache \
        compat \
index c062f34ab8c46ddc00a40c79b32a9c6e24729936..293189d619c3c0ff34daba2c096a4b1163cff55f 100644 (file)
@@ -35,6 +35,7 @@
 #include <babeltrace2/babeltrace.h>
 #include <babeltrace2/property.h>
 #include "common/assert.h"
+#include "py-common/py-common.h"
 
 typedef const uint8_t *bt_uuid;
 %}
index bed4602e6d016a0c81204e1dce9879c8342758f1..18078eead697748619da42c0756ffb0cd4d1d95c 100644 (file)
@@ -167,88 +167,24 @@ void bt_py3_native_comp_class_dtor(void) {
        }
 }
 
-
-// TODO: maybe we can wrap code in the Python methods (e.g. _query_from_native)
-// in a try catch and print the error there instead, it would be simpler.
 static
 void bt2_py_loge_exception(void)
 {
-       PyObject *type = NULL;
-       PyObject *value = NULL;
-       PyObject *traceback = NULL;
-       PyObject *traceback_module = NULL;
-       PyObject *format_exception_func = NULL;
-       PyObject *exc_str_list = NULL;
-       GString *msg_buf = NULL;
-       Py_ssize_t i;
+       GString *gstr;
 
        BT_ASSERT(PyErr_Occurred() != NULL);
-
-       PyErr_Fetch(&type, &value, &traceback);
-
-       BT_ASSERT(type != NULL);
-
-       /*
-       * traceback can be NULL, when we fail to call a Python function from the
-       * native code (there is no Python stack at that point).  E.g.:
-       *
-       *   TypeError: _query_from_native() takes 5 positional arguments but 8 were given
-       */
-
-
-       /* Make sure `value` is what we expected - an instance of `type`. */
-       PyErr_NormalizeException(&type, &value, &traceback);
-
-       traceback_module = PyImport_ImportModule("traceback");
-       if (!traceback_module) {
-               BT_LOGE_STR("Failed to log Python exception (could not import traceback module).");
-               goto end;
-       }
-
-       format_exception_func = PyObject_GetAttrString(traceback_module,
-               traceback ? "format_exception" : "format_exception_only");
-       if (!format_exception_func) {
-               BT_LOGE_STR("Failed to log Python exception (could not find format_exception).");
-               goto end;
-       }
-
-       if (!PyCallable_Check(format_exception_func)) {
-               BT_LOGE_STR("Failed to log Python exception (format_exception is not callable).");
-               goto end;
-       }
-
-       exc_str_list = PyObject_CallFunctionObjArgs(format_exception_func, type, value, traceback, NULL);
-       if (!exc_str_list) {
-               PyErr_Print();
-               BT_LOGE_STR("Failed to log Python exception (call to format_exception failed).");
+       gstr = bt_py_common_format_exception(BT_LOG_OUTPUT_LEVEL);
+       if (!gstr) {
+               /* bt_py_common_format_exception() logs errors */
                goto end;
        }
 
-       msg_buf = g_string_new(NULL);
-
-       for (i = 0; i < PyList_Size(exc_str_list); i++) {
-               PyObject *exc_str = PyList_GetItem(exc_str_list, i);
-               const char *str = PyUnicode_AsUTF8(exc_str);
-               if (!str) {
-                       BT_LOGE_STR("Failed to log Python exception (failed to convert exception to string).");
-                       goto end;
-               }
-
-               g_string_append(msg_buf, str);
-       }
-
-       BT_LOGE_STR(msg_buf->str);
+       BT_LOGE_STR(gstr->str);
 
 end:
-       if (msg_buf) {
-               g_string_free(msg_buf, TRUE);
+       if (gstr) {
+               g_string_free(gstr, TRUE);
        }
-       Py_XDECREF(exc_str_list);
-       Py_XDECREF(format_exception_func);
-       Py_XDECREF(traceback_module);
-
-       /* PyErr_Restore takes our references. */
-       PyErr_Restore(type, value, traceback);
 }
 
 static
index 78398605fc67488d4d04b0e4dc85bd0bb4b20191..e57ac024dd6e399c4be1f4f902c3df9b0579f59b 100644 (file)
@@ -39,7 +39,8 @@ def main():
                         sources=['bt2/native_bt.i', 'bt2/logging.c'],
                         libraries=['babeltrace2', 'glib-2.0'],
                         extra_objects=['@top_builddir@/src/logging/.libs/libbabeltrace2-logging.a',
-                            '@top_builddir@/src/common/.libs/libbabeltrace2-common.a'],
+                            '@top_builddir@/src/common/.libs/libbabeltrace2-common.a',
+                            '@top_builddir@/src/py-common/.libs/libbabeltrace2-py-common.a'],
                         swig_opts=['-I@top_srcdir@/include'])
 
     dist = setup(name='bt2',
diff --git a/src/py-common/Makefile.am b/src/py-common/Makefile.am
new file mode 100644 (file)
index 0000000..bc52700
--- /dev/null
@@ -0,0 +1,9 @@
+if HAVE_PYTHON
+AM_CPPFLAGS += $(PYTHON_INCLUDE)
+
+noinst_LTLIBRARIES = libbabeltrace2-py-common.la
+
+libbabeltrace2_py_common_la_SOURCES = \
+       py-common.c \
+       py-common.h
+endif # HAVE_PYTHON
diff --git a/src/py-common/py-common.c b/src/py-common/py-common.c
new file mode 100644 (file)
index 0000000..ac78003
--- /dev/null
@@ -0,0 +1,152 @@
+/*
+ * Copyright (c) 2019 EfficiOS Inc. and Linux Foundation
+ * Copyright (c) 2019 Philippe Proulx <pproulx@efficios.com>
+ * Copyright (c) 2019 Simon Marchi <simon.marchi@efficios.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#define BT_LOG_OUTPUT_LEVEL log_level
+#define BT_LOG_TAG "PY-COMMON"
+#include "logging/log.h"
+
+#include <Python.h>
+
+#include "common/assert.h"
+#include "py-common.h"
+
+BT_HIDDEN
+GString *bt_py_common_format_exception(int log_level)
+{
+       PyObject *type = NULL;
+       PyObject *value = NULL;
+       PyObject *traceback = NULL;
+       PyObject *traceback_module = NULL;
+       PyObject *format_exception_func = NULL;
+       PyObject *exc_str_list = NULL;
+       GString *msg_buf = NULL;
+       const char *format_exc_func_name;
+       Py_ssize_t i;
+
+       BT_ASSERT(PyErr_Occurred() != NULL);
+       PyErr_Fetch(&type, &value, &traceback);
+       BT_ASSERT(type != NULL);
+
+       /* Make sure `value` is what we expected: an instance of `type` */
+       PyErr_NormalizeException(&type, &value, &traceback);
+
+       /*
+        * Import the standard `traceback` module which contains the
+        * functions to format an exception.
+        */
+       traceback_module = PyImport_ImportModule("traceback");
+       if (!traceback_module) {
+               BT_LOGE_STR("Failed to import `traceback` module.");
+               goto error;
+       }
+
+       /*
+        * `traceback` can be `NULL`, when we fail to call a Python
+        * function from native code (there is no Python stack at that
+        * point). For example, a function which takes 5 positional
+        * arguments, but 8 were given.
+        */
+       format_exc_func_name = traceback ? "format_exception" :
+               "format_exception_only";
+       format_exception_func = PyObject_GetAttrString(traceback_module,
+               format_exc_func_name);
+       if (!format_exception_func) {
+               BT_LOGE("Cannot find `%s` attribute in `traceback` module.",
+                       format_exc_func_name);
+               goto error;
+       }
+
+       if (!PyCallable_Check(format_exception_func)) {
+               BT_LOGE("`traceback.%s` attribute is not callable.",
+                       format_exc_func_name);
+               goto error;
+       }
+
+       exc_str_list = PyObject_CallFunctionObjArgs(format_exception_func,
+               type, value, traceback, NULL);
+       if (!exc_str_list) {
+               if (BT_LOG_ON_ERROR) {
+                       BT_LOGE("Failed to call `traceback.%s` function:",
+                               format_exc_func_name);
+                       PyErr_Print();
+               }
+
+               goto error;
+       }
+
+       msg_buf = g_string_new(NULL);
+
+       for (i = 0; i < PyList_Size(exc_str_list); i++) {
+               PyObject *exc_str;
+               const char *str;
+
+               exc_str = PyList_GetItem(exc_str_list, i);
+               BT_ASSERT(exc_str);
+
+               /* `str` is owned by `exc_str`, not by us */
+               str = PyUnicode_AsUTF8(exc_str);
+               if (!str) {
+                       if (BT_LOG_ON_ERROR) {
+                               BT_LOGE_STR("PyUnicode_AsUTF8() failed:");
+                               PyErr_Print();
+                       }
+
+                       goto error;
+               }
+
+               /* `str` has a trailing newline */
+               g_string_append(msg_buf, str);
+       }
+
+       if (msg_buf->len > 0) {
+               /* Remove trailing newline if any */
+               if (msg_buf->str[msg_buf->len - 1] == '\n') {
+                       g_string_truncate(msg_buf, msg_buf->len - 1);
+               }
+       }
+
+       goto end;
+
+error:
+       if (msg_buf) {
+               g_string_free(msg_buf, TRUE);
+               msg_buf = NULL;
+       }
+
+end:
+       Py_XDECREF(exc_str_list);
+       Py_XDECREF(format_exception_func);
+       Py_XDECREF(traceback_module);
+
+       /*
+        * We can safely call PyErr_Restore() because we always call
+        * PyErr_Fetch(), and having an error indicator is a function's
+        * precondition.
+        *
+        * PyErr_Restore() steals our references.
+        */
+       PyErr_Restore(type, value, traceback);
+
+       return msg_buf;
+}
diff --git a/src/py-common/py-common.h b/src/py-common/py-common.h
new file mode 100644 (file)
index 0000000..dbfd882
--- /dev/null
@@ -0,0 +1,46 @@
+#ifndef BABELTRACE_PY_COMMON_INTERNAL_H
+#define BABELTRACE_PY_COMMON_INTERNAL_H
+
+/*
+ * Copyright (c) 2019 EfficiOS Inc. and Linux Foundation
+ * Copyright (c) 2019 Philippe Proulx <pproulx@efficios.com>
+ * Copyright (c) 2019 Simon Marchi <simon.marchi@efficios.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include <glib.h>
+
+#include "common/macros.h"
+
+/*
+ * Formats the Python error indicator (exception) and returns the
+ * formatted string, or `NULL` on error. The returned string does NOT
+ * end with a newline.
+ *
+ * You must ensure that the error indicator is set with PyErr_Occurred()
+ * before you call this function.
+ *
+ * This function does not modify the error indicator, that is, anything
+ * that is fetched is always restored.
+ */
+BT_HIDDEN
+GString *bt_py_common_format_exception(int log_level);
+
+#endif /* BABELTRACE_PY_COMMON_INTERNAL_H */
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