On 2020/05/22 8:02, Yasuhito FUTATSUKI wrote:
> On 2020/05/20 21:54, Jun Omae wrote:
>> On Mon, May 18, 2020 at 8:25 AM Yasuhito FUTATSUKI <futat...@poem.co.jp> 
>> wrote:

>>> Jun and I found it is caused by long existing bug on SWIG Python bindings,
>>> since before swig-py3 branch was merged (thus this bug exists on 1.13.x
>>> and 1.10.3 branches). On SWIG Python bindings, APIs which have multiple
>>> apr_pool_t * argments cannot be wrapped correctly.
>>>
>>> If we call such a wrapper function with specifying multiple pool argments
>>> explicitly, only last one is used for *all* apr_pool_t * arguments when
>>> it calls C API.
>>
>> Created global-py-pool-ref-count.diff patch to solve the multiple apr_pool *
>> pointers issue in Python bindings.
>>
>> Verified no assertions while running check-swig-py with the following
>> environments:
>>
>>  - (Python 3.5.2, 3.6.10, 3.7.7, 3.8.3, 3.9.0a6) x (SWIG 4.0.1)
>>  - (Python 2.7.12) x (SWIG 1.3.40, 2.0.12, 3.0.12)
> 
> Thank you very much!
> 
> With this patch, I confirmed that each apr_pool * argment in C API supplied
> from corresponding pool object if it is supplied by the Python wrapper 
> function
> (by reading _wrap_svn_client_propget5() in svn_client.c generated by
> SWIG 3.0.12, for Python 2). 
> 
> However, I couldn't confirm that the "_parent_pool" attribute in wrapper
> object returned by wrapper function point to "result_pool" object in such 
> case,
> yet.  I doubt it still points to "scratch_pool" object because variable
> "_global_py_pool" points to "scratch_pool" object when both of "result_pool"
> and "scratch_pool" are provided on such APIs. 

In "out" and "argout" typemaps, "_parent_pool" attribute of wrapper objects
are set from "_global_py_pool".

With this additional hunks for SubversionClientTestCase.test_conflict(),
[[[
Index: subversion/bindings/swig/python/tests/client.py
===================================================================
--- subversion/bindings/swig/python/tests/client.py     (revision 1877963)
+++ subversion/bindings/swig/python/tests/client.py     (working copy)
@@ -592,10 +603,14 @@
     client.update4((path,), rev, core.svn_depth_unknown, True, False, False,
                    False, False, self.client_ctx)
 
-    pool = core.Pool()
-    conflict = client.conflict_get(trunk_path, self.client_ctx, pool)
+    result_pool = core.Pool()
+    scratch_pool = core.Pool()
+    conflict = client.conflict_get(trunk_path, self.client_ctx,
+                                   result_pool, scratch_pool)
 
     self.assertTrue(isinstance(conflict, client.svn_client_conflict_t))
+    self.assertNotEqual(conflict._parent_pool, scratch_pool)
+    self.assertEqual(conflict._parent_pool, result_pool)
 
     conflict_opts = client.conflict_tree_get_resolution_options(conflict, 
self.client_ctx)
 
@@ -602,7 +617,8 @@
     self.assertTrue(isinstance(conflict_opts, list))
     self.assert_all_instances_of(conflict_opts, 
client.svn_client_conflict_option_t)
 
-    pool.clear()
+    scratch_pool.clear()
+    result_pool.clear()
 
   @unittest.skip("experimental API, not currently exposed")
   def test_shelf(self):
]]]
this test fails.

[[[
======================================================================
FAIL: test_conflict (client.SubversionClientTestCase)
Test conflict api.
----------------------------------------------------------------------
Traceback (most recent call last):
  File 
"/home/futatuki/work/subversion/vwc/trunk/subversion/bindings/swig/python/tests/client.py",
 line 612, in test_conflict
    self.assertNotEqual(conflict._parent_pool, scratch_pool)
AssertionError: <libsvn.core.apr_pool_t; proxy of <Swig Object of type 
'apr_pool_t *' at 0x80acf5180> > == <libsvn.core.apr_pool_t; proxy of <Swig 
Object of type 'apr_pool_t *' at 0x80acf5180> >

----------------------------------------------------------------------
]]]

I think it can be fixed by overriding _global_py_pool to $input in "in"
typemap, when $1 is updated. It assumes that there are no APIs that
uses two or more result_pool like apr_pool_t * argument for allocationg
return value.

I tweaked Jun's patch to do it.
(Attached file: global-py-pool-ref-count2-diff.txt)

Tested on FreeBSD 11, with Python 2.7(debug), Python 3.7(non debug)

Cheers,
-- 
Yasuhito FUTATSUKI <futat...@poem.co.jp>/<futat...@yf.bsdclub.org>
Handle correctly multiple apr_pool_t * arguments of function in Python
bindings to fix negative ref count of _global_py_pool object.

* subversion/bindings/swig/include/svn_types.swg
  (%typemap(default) apr_pool_t *): Retrieve apr_pool_t * pointer from args
  parameter only when _global_pool is NULL in order to increase correctly ref
  count.
  (%typemap(in) apr_pool_t *): Retrieve apr_pool_t * pointer from the Python
  object and override _global_py_pool when an argument is not the last
  apr_pool_t * argument.
  (%typemap(in) apr_pool_t *scratch_pool): New typemap.
  (%typemap(freearg) apr_pool_t *): Decreament ref count of Python object only
  once.

* subversion/bindings/swig/python/tests/client.py
  (test_inherited_props): Add tests which TypeError raises when passing non
  apr_pool_t * object to function which has multiple apr_pool_t * arguments.
  (test_conflict): Add tests that the _parent_pool attribute of the result 
  wrapper object doesn't point scratch pool object but points result pool
  object. 

Patch by: jun66j5
(tewaked by futatuki)

Index: subversion/bindings/swig/include/svn_types.swg
===================================================================
--- subversion/bindings/swig/include/svn_types.swg      (revision 1877963)
+++ subversion/bindings/swig/include/svn_types.swg      (working copy)
@@ -554,23 +554,55 @@
 %typemap(default, noblock=1) apr_pool_t
   *(apr_pool_t *_global_pool = NULL, PyObject *_global_py_pool = NULL)
 {
-  if (svn_swig_py_get_pool_arg(args, $descriptor,
-      &_global_py_pool, &_global_pool))
+  if (_global_pool == NULL &&
+      svn_swig_py_get_pool_arg(args, $descriptor, &_global_py_pool,
+                               &_global_pool))
     SWIG_fail;
   $1 = _global_pool;
 }
 
 %typemap(in, noblock=1) apr_pool_t * {
-  /* Verify that the user supplied a valid pool */
-  if ($input != Py_None && $input != _global_py_pool) {
-    SWIG_Python_TypeError(SWIG_TypePrettyName($descriptor), $input);
-    SWIG_arg_fail($svn_argnum);
-    SWIG_fail;
-  }
+  if ($input != Py_None && $input != _global_py_pool)
+    {
+      apr_pool_t *ptr;
+      if (svn_swig_py_convert_ptr($input, (void **)&ptr, $descriptor) == 0)
+        {
+          $1 = ptr;
+        }
+      else
+        {
+          SWIG_Python_TypeError(SWIG_TypePrettyName($descriptor), $input);
+          SWIG_arg_fail($svn_argnum);
+          SWIG_fail;
+        }
+      Py_DECREF(_global_py_pool);
+      _global_py_pool = $input;
+      Py_INCREF(_global_py_pool);
+    }
 }
 
+/* scratch_pool is always set by "default" typemap, however type check
+ * is still needed.
+ */
+%typemap(in, noblock=1) apr_pool_t *scratch_pool {
+  if ($input != Py_None)
+    {
+      apr_pool_t *ptr;
+      if (svn_swig_py_convert_ptr($input, (void **)&ptr, $descriptor) != 0)
+        {
+          SWIG_Python_TypeError(SWIG_TypePrettyName($descriptor), $input);
+          SWIG_arg_fail($svn_argnum);
+          SWIG_fail;
+        }
+    }
+}
+
 %typemap(freearg) apr_pool_t * {
-  Py_XDECREF(_global_py_pool);
+  if (_global_py_pool != NULL)
+    {
+      Py_XDECREF(_global_py_pool);
+      _global_py_pool = NULL;
+    }
 }
 #endif
 
Index: subversion/bindings/swig/python/tests/client.py
===================================================================
--- subversion/bindings/swig/python/tests/client.py     (revision 1877963)
+++ subversion/bindings/swig/python/tests/client.py     (working copy)
@@ -477,6 +477,10 @@
   def test_inherited_props(self):
     """Test inherited props"""
 
+    pool = core.Pool()
+    result_pool = core.Pool(pool)
+    scratch_pool = core.Pool(pool)
+
     trunk_url = self.repos_uri + b'/trunk'
     client.propset_remote(b'svn:global-ignores', b'*.q', trunk_url,
                           False, 12, {}, None, self.client_ctx)
@@ -483,6 +487,12 @@
 
     head = core.svn_opt_revision_t()
     head.kind = core.svn_opt_revision_head
+    self.assertRaises(TypeError, client.propget5, b'svn:global-ignores',
+                      trunk_url, head, head, core.svn_depth_infinity, None,
+                      self.client_ctx, 42)
+    self.assertRaises(TypeError, client.propget5, b'svn:global-ignores',
+                      trunk_url, head, head, core.svn_depth_infinity, None,
+                      self.client_ctx, None, 42)
     props, iprops, rev = client.propget5(b'svn:global-ignores', trunk_url,
                                          head, head, core.svn_depth_infinity,
                                          None, self.client_ctx)
@@ -491,7 +501,8 @@
     dir1_url = trunk_url + b'/dir1'
     props, iprops, rev = client.propget5(b'svn:global-ignores', dir1_url,
                                          head, head, core.svn_depth_infinity,
-                                         None, self.client_ctx)
+                                         None, self.client_ctx, result_pool,
+                                         scratch_pool)
     self.assertEqual(iprops[trunk_url], {b'svn:global-ignores':b'*.q\n'})
 
     self.proplist_receiver_trunk_calls = 0
@@ -592,10 +603,15 @@
     client.update4((path,), rev, core.svn_depth_unknown, True, False, False,
                    False, False, self.client_ctx)
 
-    pool = core.Pool()
-    conflict = client.conflict_get(trunk_path, self.client_ctx, pool)
+    # New pools, only for examination where the result comes from. 
+    result_pool = core.Pool()
+    scratch_pool = core.Pool()
+    conflict = client.conflict_get(trunk_path, self.client_ctx,
+                                   result_pool, scratch_pool)
 
     self.assertTrue(isinstance(conflict, client.svn_client_conflict_t))
+    self.assertNotEqual(conflict._parent_pool, scratch_pool)
+    self.assertEqual(conflict._parent_pool, result_pool)
 
     conflict_opts = client.conflict_tree_get_resolution_options(conflict, 
self.client_ctx)
 
@@ -602,8 +618,6 @@
     self.assertTrue(isinstance(conflict_opts, list))
     self.assert_all_instances_of(conflict_opts, 
client.svn_client_conflict_option_t)
 
-    pool.clear()
-
   @unittest.skip("experimental API, not currently exposed")
   def test_shelf(self):
     """Test shelf api."""

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