memgraph/tools/gdb-plugins/operator_tree.py
florijan ce902e7a86 GDB operator tree plugin improvement suggestion
Summary: The previous version didn't seemt to be able to print the operator tree below the `Expand` operator. It seems it was unable to reach the `input_` field because it's a member of the `ExpandCommon` super-type. The proposed fix handles that. @teon, please test, verify, modify, whatever, just ensure printing works below `Expand` operators.

Reviewers: teon.banek, buda

Reviewed By: teon.banek

Subscribers: pullbot

Differential Revision: https://phabricator.memgraph.io/D679
2017-08-21 10:54:43 +02:00

93 lines
3.6 KiB
Python

import io
import re
import gdb
def _logical_operator_type():
'''Returns the LogicalOperator gdb.Type'''
# This is a function, because the type may appear during gdb runtime.
# Therefore, we cannot assign it on import.
return gdb.lookup_type('query::plan::LogicalOperator')
# Pattern for matching std::unique_ptr<T, Deleter> and std::shared_ptr<T>
_SMART_PTR_TYPE_PATTERN = \
re.compile('^std::(unique|shared)_ptr<(?P<pointee_type>[\w:]*)')
def _is_smart_ptr(maybe_smart_ptr, type_name=None):
if maybe_smart_ptr.type.name is None:
return False
match = _SMART_PTR_TYPE_PATTERN.match(maybe_smart_ptr.type.name)
if match is None or type_name is None:
return bool(match)
return type_name == match.group('pointee_type')
def _smart_ptr_pointee(smart_ptr):
'''Returns the address of the pointed to object in shared_ptr/unique_ptr.'''
# This function may not be needed when gdb adds dereferencing
# shared_ptr/unique_ptr via Python API.
with io.StringIO() as string_io:
print(smart_ptr, file=string_io)
addr = string_io.getvalue().split()[-1]
return int(addr, base=16)
def _get_operator_input(operator):
'''Returns the input operator of given operator, if it has any.'''
types_to_process = [operator.type]
all_fields = []
while types_to_process:
for field in types_to_process.pop().fields():
if field.is_base_class:
types_to_process.append(field.type)
else:
all_fields.append(field)
if "input_" not in [f.name for f in all_fields]:
return None
input_addr = _smart_ptr_pointee(operator['input_'])
pointer_type = _logical_operator_type().pointer()
input_op = gdb.Value(input_addr).cast(pointer_type).dereference()
return input_op.cast(input_op.dynamic_type)
class PrintOperatorTree(gdb.Command):
'''Print the tree of logical operators from the expression.'''
def __init__(self):
super(PrintOperatorTree, self).__init__("print-operator-tree",
gdb.COMMAND_USER,
gdb.COMPLETE_EXPRESSION)
def invoke(self, argument, from_tty):
try:
operator = gdb.parse_and_eval(argument)
except gdb.error as e:
raise gdb.GdbError(*e.args)
logical_operator_type = _logical_operator_type()
if _is_smart_ptr(operator, 'query::plan::LogicalOperator'):
pointee = gdb.Value(_smart_ptr_pointee(operator))
if pointee == 0:
raise gdb.GdbError("Expected a '%s', but got nullptr" %
logical_operator_type)
operator = \
pointee.cast(logical_operator_type.pointer()).dereference()
elif operator.type == logical_operator_type.pointer():
operator = operator.dereference()
# Currently, gdb doesn't provide API to check if the dynamic_type is
# subtype of a base type. So, this check will fail, for example if we
# get 'query::plan::ScanAll'. The user can avoid this by up-casting.
if operator.type != logical_operator_type:
raise gdb.GdbError("Expected a '%s', but got '%s'" %
(logical_operator_type, operator.type))
next_op = operator.cast(operator.dynamic_type)
tree = []
while next_op is not None:
tree.append('* %s <%s>' % (next_op.type.name, next_op.address))
next_op = _get_operator_input(next_op)
print('\n'.join(tree))
PrintOperatorTree()