# Copyright 2018 The dm_control Authors.

#

# Licensed under the Apache License, Version 2.0 (the "License");

# you may not use this file except in compliance with the License.

# You may obtain a copy of the License at

#

# http://www.apache.org/licenses/LICENSE-2.0

#

# Unless required by applicable law or agreed to in writing, software

# distributed under the License is distributed on an "AS IS" BASIS,

# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

# See the License for the specific language governing permissions and

# limitations under the License.

# ============================================================================

"""Implements PyMJCF debug mode.

PyMJCF debug mode stores a stack trace each time the MJCF object is modified.

If Mujoco raises a compile error on the generated XML model, we would then be

able to find the original source line that created the offending element.

"""

import collections

import contextlib

import copy

import os

import re

import sys

import traceback

from absl import flags

from lxml import etree

FLAGS = flags.FLAGS

flags.DEFINE_boolean(

'pymjcf_debug', False,

'Enables PyMJCF debug mode (SLOW!). In this mode, a stack trace is logged '

'each the MJCF object is modified. This may be helpful in locating the '

'Python source line corresponding to a problematic element in the '

'generated XML.')

flags.DEFINE_string(

'pymjcf_debug_full_dump_dir', '',

'Path to dump full debug info when Mujoco error is encountered.')

StackTraceEntry = collections.namedtuple(

'StackTraceEntry', ('filename', 'line_number', 'function_name', 'text'))

ElementDebugInfo = collections.namedtuple(

'ElementDebugInfo', ('element', 'init_stack', 'attribute_stacks'))

MODULE_PATH = os.path.dirname(sys.modules[__name__].__file__)

DEBUG_METADATA_PREFIX = 'pymjcfdebug'

_DEBUG_METADATA_TAG_PREFIX = '<!--' + DEBUG_METADATA_PREFIX

_DEBUG_METADATA_SEARCH_PATTERN = re.compile(

r'<!--{}:(\d+)-->'.format(DEBUG_METADATA_PREFIX))

# Modified by `freeze_current_stack_trace`.

_CURRENT_FROZEN_STACK = None

# These globals will take their default values from the `--pymjcf_debug` and

# `--pymjcf_debug_full_dump_dir` flags respectively. We cannot use `FLAGS` as

# global variables because flag parsing might not have taken place (e.g. when

# running `nosetests`).

_DEBUG_MODE_ENABLED = None

_DEBUG_FULL_DUMP_DIR = None

def debug_mode():

"""Returns a boolean that indicates whether PyMJCF debug mode is enabled."""

global _DEBUG_MODE_ENABLED

if _DEBUG_MODE_ENABLED is None:

if FLAGS.is_parsed():

_DEBUG_MODE_ENABLED = FLAGS.pymjcf_debug

else:

_DEBUG_MODE_ENABLED = FLAGS['pymjcf_debug'].default

return _DEBUG_MODE_ENABLED

def enable_debug_mode():

"""Enables PyMJCF debug mode."""

global _DEBUG_MODE_ENABLED

_DEBUG_MODE_ENABLED = True

def disable_debug_mode():

"""Disables PyMJCF debug mode."""

global _DEBUG_MODE_ENABLED

_DEBUG_MODE_ENABLED = False

def get_full_dump_dir():

"""Gets the directory to dump full debug info files."""

global _DEBUG_FULL_DUMP_DIR

if _DEBUG_FULL_DUMP_DIR is None:

if FLAGS.is_parsed():

_DEBUG_FULL_DUMP_DIR = FLAGS.pymjcf_debug_full_dump_dir

else:

_DEBUG_FULL_DUMP_DIR = FLAGS['pymjcf_debug_full_dump_dir'].default

return _DEBUG_FULL_DUMP_DIR

def set_full_dump_dir(dump_path):

"""Sets the directory to dump full debug info files."""

global _DEBUG_FULL_DUMP_DIR

_DEBUG_FULL_DUMP_DIR = dump_path

def get_current_stack_trace():

"""Returns the stack trace of the current execution frame.

Returns:

A list of `StackTraceEntry` named tuples corresponding to the current stack

trace of the process, truncated to immediately before entry into

PyMJCF internal code.

"""

if _CURRENT_FROZEN_STACK:

return copy.deepcopy(_CURRENT_FROZEN_STACK)

else:

return _get_actual_current_stack_trace()

def _get_actual_current_stack_trace():

"""Returns the stack trace of the current execution frame.

Returns:

A list of `StackTraceEntry` named tuples corresponding to the current stack

trace of the process, truncated to immediately before entry into

PyMJCF internal code.

"""

raw_stack = traceback.extract_stack()

processed_stack = []

for raw_stack_item in raw_stack:

stack_item = StackTraceEntry(*raw_stack_item)

if (stack_item.filename.startswith(MODULE_PATH)

and not stack_item.filename.endswith('_test.py')):

break

else:

processed_stack.append(stack_item)

return processed_stack

@contextlib.contextmanager

def freeze_current_stack_trace():

"""A context manager that freezes the stack trace.

AVOID USING THIS CONTEXT MANAGER OUTSIDE OF INTERNAL PYMJCF IMPLEMENTATION,

AS IT REDUCES THE USEFULNESS OF DEBUG MODE.

If PyMJCF debug mode is enabled, calls to `debugging.get_current_stack_trace`

within this context will always return the stack trace from when this context

was entered.

The frozen stack is global to this debugging module. That is, if the context

is entered while another one is still active, then the stack trace of the

outermost one is returned.

This context significantly speeds up bulk operations in debug mode, e.g.

parsing an existing XML string or creating a deeply-nested element, as it

prevents the same stack trace from being repeatedly constructed.

Yields:

`None`

"""

global _CURRENT_FROZEN_STACK

if debug_mode() and _CURRENT_FROZEN_STACK is None:

_CURRENT_FROZEN_STACK = _get_actual_current_stack_trace()

yield

_CURRENT_FROZEN_STACK = None

else:

yield

class DebugContext:

"""A helper object to store debug information for a generated XML string.

This class is intended for internal use within the PyMJCF implementation.

"""

def __init__(self):

self._xml_string = None

self._debug_info_for_element_ids = {}

def register_element_for_debugging(self, elem):

"""Registers an `Element` and returns debugging metadata for the XML.

Args:

elem: An `mjcf.Element`.

Returns:

An `lxml.etree.Comment` that represents debugging metadata in the

generated XML.

"""

if not debug_mode():

return None

else:

self._debug_info_for_element_ids[id(elem)] = ElementDebugInfo(

elem,

copy.deepcopy(elem.get_init_stack()),

copy.deepcopy(elem.get_last_modified_stacks_for_all_attributes()))

return etree.Comment('{}:{}'.format(DEBUG_METADATA_PREFIX, id(elem)))

def commit_xml_string(self, xml_string):

"""Commits the XML string associated with this debug context.

This function also formats the XML string to make sure that the debugging

metadata appears on the same line as the corresponding XML element.

Args:

xml_string: A pretty-printed XML string.

Returns:

A reformatted XML string where all debugging metadata appears on the same

line as the corresponding XML element.

"""

formatted = re.sub(r'\n\s*' + _DEBUG_METADATA_TAG_PREFIX,

_DEBUG_METADATA_TAG_PREFIX, xml_string)

self._xml_string = formatted

return formatted

def process_and_raise_last_exception(self):

"""Processes and re-raises the last ValueError caught.

This function will insert the relevant line from the source XML to the error

message. If debug mode is enabled, additional debugging information is

appended to the error message. If debug mode is not enabled, the error

message instructs the user to enable it by rerunning the executable with an

appropriate flag.

"""

err_type, err, tb = sys.exc_info()

line_number_match = re.search(r'[Ll][Ii][Nn][Ee]\s*[:=]?\s*(\d+)', str(err))

if line_number_match:

xml_line_number = int(line_number_match.group(1))

xml_line = self._xml_string.split('\n')[xml_line_number - 1]

stripped_xml_line = xml_line.strip()

comment_match = re.search(_DEBUG_METADATA_TAG_PREFIX, stripped_xml_line)

if comment_match:

stripped_xml_line = stripped_xml_line[:comment_match.start()]

else:

xml_line = ''

stripped_xml_line = ''

message_lines = []

if debug_mode():

if get_full_dump_dir():

self.dump_full_debug_info_to_disk()

message_lines.extend([

'Compile error raised by Mujoco.',

str(err)])

if xml_line:

message_lines.extend([

stripped_xml_line,

self._generate_debug_message_from_xml_line(xml_line)])

else:

message_lines.extend([

'Compile error raised by Mujoco; ' +

'run again with --pymjcf_debug for additional debug information.',

str(err)

])

if xml_line:

message_lines.append(stripped_xml_line)

raise err_type('\n'.join(message_lines)).with_traceback(tb)

@property

def default_dump_dir(self):

return get_full_dump_dir()

@property

def debug_mode(self):

return debug_mode()

def dump_full_debug_info_to_disk(self, dump_dir=None):

"""Dumps full debug information to disk.

Full debug information consists of an XML file whose elements are tagged

with a unique ID, and a stack trace file for each element ID. Each stack

trace file consists of a stack trace for when the element was created, and

when each attribute was last modified.

Args:

dump_dir: Full path to the directory in which dump files are created.

Raises:

ValueError: If neither `dump_dir` nor the global dump path is given. The

global dump path can be specified either via the

--pymjcf_debug_full_dump_dir flag or via `debugging.set_full_dump_dir`.

"""

dump_dir = dump_dir or self.default_dump_dir

if not dump_dir:

raise ValueError('`dump_dir` is not specified')

section_separator = '\n' + ('=' * 80) + '\n'

def dump_stack(header, stack, f):

indent = ' '

f.write(header + '\n')

for stack_entry in stack:

f.write(indent + '`{}` at {}:{}\n'

.format(stack_entry.function_name,

stack_entry.filename, stack_entry.line_number))

f.write((indent * 2) + str(stack_entry.text) + '\n')

f.write(section_separator)

with open(os.path.join(dump_dir, 'model.xml'), 'w') as f:

f.write(self._xml_string)

for elem_id, debug_info in self._debug_info_for_element_ids.items():

with open(os.path.join(dump_dir, str(elem_id) + '.dump'), 'w') as f:

f.write('{}:{}\n'.format(DEBUG_METADATA_PREFIX, elem_id))

f.write(str(debug_info.element) + '\n')

dump_stack('Element creation', debug_info.init_stack, f)

for attrib_name, stack in debug_info.attribute_stacks.items():

attrib_value = (

debug_info.element.get_attribute_xml_string(attrib_name))

if stack[-1] == debug_info.init_stack[-1]:

if attrib_value is not None:

f.write('Attribute {}="{}"\n'.format(attrib_name, attrib_value))

f.write(' was set when the element was created\n')

f.write(section_separator)

else:

if attrib_value is not None:

dump_stack('Attribute {}="{}"'.format(attrib_name, attrib_value),

stack, f)

else:

dump_stack(

'Attribute {} was CLEARED'.format(attrib_name), stack, f)

def _generate_debug_message_from_xml_line(self, xml_line):

"""Generates a debug message by parsing the metadata on an XML line."""

metadata_match = _DEBUG_METADATA_SEARCH_PATTERN.search(xml_line)

if metadata_match:

elem_id = int(metadata_match.group(1))

return self._generate_debug_message_from_element_id(elem_id)

else:

return ''

def _generate_debug_message_from_element_id(self, elem_id):

"""Generates a debug message for the specified Element."""

out = []

debug_info = self._debug_info_for_element_ids[elem_id]

out.append('Debug summary for element:')

if not get_full_dump_dir():

out.append(

' * Full debug info can be dumped to disk by setting the '

'flag --pymjcf_debug_full_dump_dir=path/to/dump>')

out.append(' * Element object was created by `{}` at {}:{}'

.format(debug_info.init_stack[-1].function_name,

debug_info.init_stack[-1].filename,

debug_info.init_stack[-1].line_number))

for attrib_name, stack in debug_info.attribute_stacks.items():

attrib_value = debug_info.element.get_attribute_xml_string(attrib_name)

if stack[-1] == debug_info.init_stack[-1]:

if attrib_value is not None:

out.append(' * {}="{}" was set when the element was created'

.format(attrib_name, attrib_value))

else:

if attrib_value is not None:

out.append(' * {}="{}" was set by `{}` at `{}:{}`'

.format(attrib_name, attrib_value,

stack[-1].function_name, stack[-1].filename,

stack[-1].line_number))

else:

out.append(' * {} was CLEARED by `{}` at {}:{}'

.format(attrib_name, stack[-1].function_name,

stack[-1].filename, stack[-1].line_number))

return '\n'.join(out)