PostgresNode._C_MAX_START_ATEMPTS=5 is added (+ 1 new test)

Also
- TestgresTests.test_the_same_port is updated
- TestgresTests.test_port_rereserve_during_node_start is updated
- TestgresTests.test_port_conflict is added

Author: dmitry-lipetsk

testgres/node.py

@@ -128,6 +128,9 @@ def __repr__(self):
 
 
 class PostgresNode(object):
+    # a max number of node start attempts
+    _C_MAX_START_ATEMPTS = 5
+
     def __init__(self, name=None, base_dir=None, port=None, conn_params: ConnectionParams = ConnectionParams(), bin_dir=None, prefix=None):
         """
         PostgresNode constructor.
@@ -774,6 +777,9 @@ def start(self, params=[], wait=True):
         Returns:
             This instance of :class:`.PostgresNode`.
         """
+
+        assert __class__._C_MAX_START_ATEMPTS > 1
+
         if self.is_started:
             return self
 
@@ -789,13 +795,17 @@ def start(self, params=[], wait=True):
         nAttempt = 0
         timeout = 1
         while True:
+            assert nAttempt >= 0
+            assert nAttempt < __class__._C_MAX_START_ATEMPTS
             nAttempt += 1
             try:
                 exit_status, out, error = execute_utility(_params, self.utils_log_file, verbose=True)
                 if error and 'does not exist' in error:
                     raise Exception
             except Exception as e:
-                if self._should_free_port and nAttempt < 5:
+                assert nAttempt > 0
+                assert nAttempt <= __class__._C_MAX_START_ATEMPTS
+                if self._should_free_port and nAttempt < __class__._C_MAX_START_ATEMPTS:
                     log_files1 = self._collect_log_files()
                     if self._detect_port_conflict(log_files0, log_files1):
                         log_files0 = log_files1
@@ -806,7 +816,7 @@ def start(self, params=[], wait=True):
                         time.sleep(timeout)
                         timeout = min(2 * timeout, 5)
                         cur_port = self.port
-                        new_port = utils.reserve_port()  # throw
+                        new_port = utils.reserve_port()  # can raise
                         try:
                             options = {'port': str(new_port)}
                             self.set_auto_conf(options)

tests/test_simple.py

@@ -1053,6 +1053,8 @@ def test_the_same_port(self):
             node.init().start()
             self.assertTrue(node._should_free_port)
             self.assertEqual(type(node.port), int)
+            node_port_copy = node.port
+            self.assertEqual(node.safe_psql("SELECT 1;"), b'1\n')
 
             with get_new_node(port=node.port) as node2:
                 self.assertEqual(type(node2.port), int)
@@ -1064,6 +1066,11 @@ def test_the_same_port(self):
 
                 self.assertIn("Cannot start node", str(ctx.exception))
 
+            # node is still working
+            self.assertEqual(node.port, node_port_copy)
+            self.assertTrue(node._should_free_port)
+            self.assertEqual(node.safe_psql("SELECT 3;"), b'3\n')
+
     class tagPortManagerProxy:
         sm_prev_testgres_reserve_port = None
         sm_prev_testgres_release_port = None
@@ -1159,13 +1166,16 @@ def _proxy__release_port(dummyPortNumber):
             return __class__.sm_prev_testgres_release_port(dummyPortNumber)
 
     def test_port_rereserve_during_node_start(self):
+        assert testgres.PostgresNode._C_MAX_START_ATEMPTS == 5
+
         C_COUNT_OF_BAD_PORT_USAGE = 3
 
         with get_new_node() as node1:
             node1.init().start()
             self.assertTrue(node1._should_free_port)
             self.assertEqual(type(node1.port), int)  # noqa: E721
-            node1.safe_psql("SELECT 1;")
+            node1_port_copy = node1.port
+            self.assertEqual(node1.safe_psql("SELECT 1;"), b'1\n')
 
             with __class__.tagPortManagerProxy(node1.port, C_COUNT_OF_BAD_PORT_USAGE):
                 assert __class__.tagPortManagerProxy.sm_DummyPortNumber == node1.port
@@ -1176,10 +1186,54 @@ def test_port_rereserve_during_node_start(self):
                     node2.init().start()
 
                     self.assertNotEqual(node2.port, node1.port)
+                    self.assertTrue(node2._should_free_port)
                     self.assertEqual(__class__.tagPortManagerProxy.sm_DummyPortCurrentUsage, 0)
                     self.assertEqual(__class__.tagPortManagerProxy.sm_DummyPortTotalUsage, C_COUNT_OF_BAD_PORT_USAGE)
+                    self.assertTrue(node2.is_started)
+
+                    self.assertEqual(node2.safe_psql("SELECT 2;"), b'2\n')
+
+            # node1 is still working
+            self.assertEqual(node1.port, node1_port_copy)
+            self.assertTrue(node1._should_free_port)
+            self.assertEqual(node1.safe_psql("SELECT 3;"), b'3\n')
+
+    def test_port_conflict(self):
+        assert testgres.PostgresNode._C_MAX_START_ATEMPTS > 1
+
+        C_COUNT_OF_BAD_PORT_USAGE = testgres.PostgresNode._C_MAX_START_ATEMPTS
+
+        with get_new_node() as node1:
+            node1.init().start()
+            self.assertTrue(node1._should_free_port)
+            self.assertEqual(type(node1.port), int)  # noqa: E721
+            node1_port_copy = node1.port
+            self.assertEqual(node1.safe_psql("SELECT 1;"), b'1\n')
+
+            with __class__.tagPortManagerProxy(node1.port, C_COUNT_OF_BAD_PORT_USAGE):
+                assert __class__.tagPortManagerProxy.sm_DummyPortNumber == node1.port
+                with get_new_node() as node2:
+                    self.assertTrue(node2._should_free_port)
+                    self.assertEqual(node2.port, node1.port)
+
+                    with self.assertRaises(StartNodeException) as ctx:
+                        node2.init().start()
+
+                    self.assertIn("Cannot start node", str(ctx.exception))
+
+                    self.assertEqual(node2.port, node1.port)
+                    self.assertTrue(node2._should_free_port)
+                    self.assertEqual(__class__.tagPortManagerProxy.sm_DummyPortCurrentUsage, 1)
+                    self.assertEqual(__class__.tagPortManagerProxy.sm_DummyPortTotalUsage, C_COUNT_OF_BAD_PORT_USAGE)
+                    self.assertFalse(node2.is_started)
+
+                # node2 must release our dummyPort (node1.port)
+                self.assertEqual(__class__.tagPortManagerProxy.sm_DummyPortCurrentUsage, 0)
 
-                    node2.safe_psql("SELECT 1;")
+            # node1 is still working
+            self.assertEqual(node1.port, node1_port_copy)
+            self.assertTrue(node1._should_free_port)
+            self.assertEqual(node1.safe_psql("SELECT 3;"), b'3\n')
 
     def test_simple_with_bin_dir(self):
         with get_new_node() as node: