From 902f10a4fad9778b616a9c720cec8c4dc49335d9 Mon Sep 17 00:00:00 2001
From: pavel-zotov <p519446@yandex.ru>
Date: Sat, 18 Jan 2025 16:18:15 +0300
Subject: [PATCH] Added/Updated tests\bugs\gh_6947_test.py: Resultset of cursor
 that executes using instance of selectable PreparedStatement must be stored
 in some variable in order to have ability close it EXPLICITLY, before PS will
 be freed. Otherwise access violation can raises when Python runs garbage
 collection.

---
 tests/bugs/gh_6947_test.py | 84 +++++++++++++++++++++++++-------------
 1 file changed, 55 insertions(+), 29 deletions(-)

diff --git a/tests/bugs/gh_6947_test.py b/tests/bugs/gh_6947_test.py
index de7e70ae..34d55274 100644
--- a/tests/bugs/gh_6947_test.py
+++ b/tests/bugs/gh_6947_test.py
@@ -28,6 +28,13 @@ NOTES:
     [11.03.2023] pzotov
     Marked as SKIPPED because covered by core_6048_test.
     Probably will be deleted soon.
+
+    [18.01.2025] pzotov
+    Resultset of cursor that executes using instance of selectable PreparedStatement must be stored
+    in some variable in order to have ability close it EXPLICITLY (before PS will be freed).
+    Otherwise access violation raises during Python GC and pytest hangs at final point (does not return control to OS).
+    This occurs at least for: Python 3.11.2 / pytest: 7.4.4 / firebird.driver: 1.10.6 / Firebird.Qa: 0.19.3
+    The reason of that was explained by Vlad, 26.10.24 17:42 ("oddities when use instances of selective statements").
 """
 import os
 import datetime as py_dt
@@ -118,38 +125,57 @@ def test_1(act: Action, capsys):
         cur = con.cursor()
         cu2 = con.cursor()
 
-        ps = cur.prepare('select mon$crypt_page from mon$database')
-
-        while encryption_started:
-            t2=py_dt.datetime.now()
-            d1=t2-t1
-            if d1.seconds*1000 + d1.microseconds//1000 > MAX_WAITING_ENCR_FINISH:
-                print(f'TIMEOUT EXPIRATION: encryption took {d1.seconds*1000 + d1.microseconds//1000} ms which exceeds limit = {MAX_WAITING_ENCR_FINISH} ms.')
-                break
-
-            cur.execute(ps)
-            p = cur.fetchone()[0]
-            cu2.callproc('sp_tmp', [ p, ] )
-            con.commit()
-
-            if p > 0:
-                encrypted_pages_set.add(p)
-                if len(encrypted_pages_set) >= MIN_DISTINCT_ENCRYPTED_PAGES:
-                    # We got enough data from mon$database to conclude that encryption is in PROGRESS.
+        ps, rs = None, None
+        try:
+            ps = cur.prepare('select mon$crypt_page from mon$database')
+            while encryption_started:
+                t2=py_dt.datetime.now()
+                d1=t2-t1
+                if d1.seconds*1000 + d1.microseconds//1000 > MAX_WAITING_ENCR_FINISH:
+                    print(f'TIMEOUT EXPIRATION: encryption took {d1.seconds*1000 + d1.microseconds//1000} ms which exceeds limit = {MAX_WAITING_ENCR_FINISH} ms.')
                     break
 
-            # Possible output:
-            #     Database not encrypted
-            #     Database encrypted, crypt thread not complete
-            act.isql(switches=['-q'], input = 'show database;', combine_output = True)
-            if 'Database encrypted' in act.stdout:
-                if 'not complete' in act.stdout:
-                    pass
-                else:
-                    encryption_finished = True
-                    break
-            act.reset()
+                # ::: NB ::: 'ps' returns data, i.e. this is SELECTABLE expression.
+                # We have to store result of cur.execute(<psInstance>) in order to
+                # close it explicitly.
+                # Otherwise AV can occur during Python garbage collection and this
+                # causes pytest to hang on its final point.
+                # Explained by hvlad, email 26.10.24 17:42
+                rs = cur.execute(ps)
+                for r in rs:
+                    p = r[0]
 
+                cu2.callproc('sp_tmp', [ p, ] )
+                con.commit()
+
+                if p > 0:
+                    encrypted_pages_set.add(p)
+                    if len(encrypted_pages_set) >= MIN_DISTINCT_ENCRYPTED_PAGES:
+                        # We got enough data from mon$database to conclude that encryption is in PROGRESS.
+                        break
+
+                # Possible output:
+                #     Database not encrypted
+                #     Database encrypted, crypt thread not complete
+                act.isql(switches=['-q'], input = 'show database;', combine_output = True)
+                if 'Database encrypted' in act.stdout:
+                    if 'not complete' in act.stdout:
+                        pass
+                    else:
+                        encryption_finished = True
+                        break
+                act.reset()
+
+        except DatabaseError as e:
+            print( e.__str__() )
+            print(e.gds_codes)
+        finally:
+            if rs:
+                rs.close() # <<< EXPLICITLY CLOSING CURSOR RESULTS
+            if ps:
+                ps.free()
+
+    
     if encryption_started:
         if len(encrypted_pages_set) >= MIN_DISTINCT_ENCRYPTED_PAGES:
             print(expected_stdout)