dsdb: Add test showing a search can't start while a transaction is already repared

Pair-programmed-with: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>

Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Signed-off-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Stefan Metzmacher <metze@samba.org>

1 files changed, 53 insertions, 1 deletions

diff --git a/python/samba/tests/dsdb.py b/python/samba/tests/dsdb.py
index 4a34bacb73f..bafd040d865 100644
--- a/python/samba/tests/dsdb.py
+++ b/python/samba/tests/dsdb.py
@@ -26,7 +26,8 @@ from samba.dcerpc import drsblobs
 import ldb
 import os
 import samba
-
+import gc
+import time
 
 class DsdbTests(TestCase):
 
@@ -149,3 +150,54 @@ class DsdbTests(TestCase):
         version = self.samdb.get_attribute_replmetadata_version(dn, "description")
         self.samdb.set_attribute_replmetadata_version(dn, "description", version + 2)
         self.assertEqual(self.samdb.get_attribute_replmetadata_version(dn, "description"), version + 2)
+
+    def test_db_lock(self):
+        basedn = self.samdb.get_default_basedn()
+        (r1, w1) = os.pipe()
+
+        pid = os.fork()
+        if pid == 0:
+            # In the child, close the main DB, re-open just one DB
+            del(self.samdb)
+            gc.collect()
+            self.samdb = SamDB(session_info=self.session,
+                               credentials=self.creds,
+                               lp=self.lp)
+
+            self.samdb.transaction_start()
+
+            self.samdb.add({
+                 "dn": "cn=test_db_lock_user,cn=users," + str(basedn),
+                 "objectclass": "user",
+            })
+
+            # Obtain a write lock
+            self.samdb.transaction_prepare_commit()
+            os.write(w1, b"added")
+            time.sleep(2)
+
+            # Drop the write lock
+            self.samdb.transaction_cancel()
+            os._exit(0)
+
+        self.assertEqual(os.read(r1, 5), b"added")
+
+        start = time.time()
+
+        # We need to hold this iterator open to hold the all-record lock.
+        res = self.samdb.search_iterator()
+
+        # This should take at least 2 seconds because the transaction
+        # has a write lock on one backend db open
+
+        # Release the locks
+        for l in res:
+            pass
+
+        end = time.time()
+        self.assertGreater(end - start, 1.9)
+
+        (got_pid, status) = os.waitpid(pid, 0)
+        self.assertEqual(got_pid, pid)
+        self.assertTrue(os.WIFEXITED(status))
+        self.assertEqual(os.WEXITSTATUS(status), 0)