[pypy-commit] pypy refactor-wrapped-del: Detect cases were an rpython __del__ method calls "too much".

[arigo]

Author: Armin Rigo <arigo at tunes.org>
Branch: refactor-wrapped-del
Changeset: r45466:b484c65880dc
Date: 2011-07-11 11:20 +0200
http://bitbucket.org/pypy/pypy/changeset/b484c65880dc/

Log:	Detect cases were an rpython __del__ method calls "too much". "Too
	much" is undefined so far; it will be "something with a
	jit_merge_point".

diff --git a/pypy/rlib/jit.py b/pypy/rlib/jit.py
--- a/pypy/rlib/jit.py
+++ b/pypy/rlib/jit.py
@@ -482,6 +482,13 @@
                                    key[2:])
             cache[key] = s_value
 
+        # add the attribute _dont_reach_me_in_del_ (see pypy.rpython.rclass)
+        try:
+            graph = self.bookkeeper.position_key[0]
+            graph.func._dont_reach_me_in_del_ = True
+        except (TypeError, AttributeError):
+            pass
+
         return annmodel.s_None
 
     def annotate_hooks(self, **kwds_s):
diff --git a/pypy/rpython/lltypesystem/rclass.py b/pypy/rpython/lltypesystem/rclass.py
--- a/pypy/rpython/lltypesystem/rclass.py
+++ b/pypy/rpython/lltypesystem/rclass.py
@@ -400,6 +400,7 @@
                 assert len(s_func.descriptions) == 1
                 funcdesc, = s_func.descriptions
                 graph = funcdesc.getuniquegraph()
+                self.check_graph_of_del_does_not_call_too_much(graph)
                 FUNCTYPE = FuncType([Ptr(source_repr.object_type)], Void)
                 destrptr = functionptr(FUNCTYPE, graph.name,
                                        graph=graph,
diff --git a/pypy/rpython/rclass.py b/pypy/rpython/rclass.py
--- a/pypy/rpython/rclass.py
+++ b/pypy/rpython/rclass.py
@@ -374,6 +374,35 @@
     def can_ll_be_null(self, s_value):
         return s_value.can_be_none()
 
+    def check_graph_of_del_does_not_call_too_much(self, graph):
+        # RPython-level __del__() methods should not do "too much".
+        # In the PyPy Python interpreter, they usually do simple things
+        # like file.__del__() closing the file descriptor; or if they
+        # want to do more like call an app-level __del__() method, they
+        # enqueue the object instead, and the actual call is done later.
+        #
+        # Here, as a quick way to check "not doing too much", we check
+        # that from no RPython-level __del__() method we can reach a
+        # JitDriver.
+        #
+        # XXX wrong complexity, but good enough because the set of
+        # reachable graphs should be small
+        callgraph = self.rtyper.annotator.translator.callgraph.values()
+        seen = set([graph])
+        while True:
+            oldlength = len(seen)
+            for caller, callee in callgraph:
+                if caller in seen:
+                    seen.add(callee)
+            if len(seen) == oldlength:
+                break
+        for reachable_graph in seen:
+            if (hasattr(reachable_graph, 'func') and
+                getattr(reachable_graph.func, '_dont_reach_me_in_del_',False)):
+                raise TyperError("the RPython-level __del__() method in %r "
+                                 "ends up indirectly calling %r" % (
+                    graph, reachable_graph))
+
 # ____________________________________________________________
 
 def rtype_new_instance(rtyper, classdef, llops, classcallhop=None):
diff --git a/pypy/rpython/test/test_rclass.py b/pypy/rpython/test/test_rclass.py
--- a/pypy/rpython/test/test_rclass.py
+++ b/pypy/rpython/test/test_rclass.py
@@ -7,6 +7,7 @@
 from pypy.rpython.test.tool import BaseRtypingTest, LLRtypeMixin, OORtypeMixin
 from pypy.rpython.rclass import IR_IMMUTABLE, IR_IMMUTABLE_ARRAY
 from pypy.rpython.rclass import IR_QUASIIMMUTABLE, IR_QUASIIMMUTABLE_ARRAY
+from pypy.rpython.error import TyperError
 from pypy.objspace.flow.model import summary
 
 class EmptyBase(object):
@@ -1021,7 +1022,24 @@
         assert typeOf(destrptra).TO.ARGS[0] != typeOf(destrptrb).TO.ARGS[0]
         assert destrptra is not None
         assert destrptrb is not None
-        
+
+    def test_del_forbidden(self):
+        class A(object):
+            def __del__(self):
+                self.foo()
+            def foo(self):
+                self.bar()
+            def bar(self):
+                pass
+            bar._dont_reach_me_in_del_ = True
+        def f():
+            a = A()
+            a.foo()
+            a.bar()
+        t = TranslationContext()
+        t.buildannotator().build_types(f, [])
+        py.test.raises(TyperError, t.buildrtyper().specialize)
+
     def test_instance_repr(self):
         from pypy.rlib.objectmodel import current_object_addr_as_int
         class FooBar(object):