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Fixed #29243 -- Improved efficiency of migration graph algorithm.
This commit is contained in:
Krzysztof Gogolewski
committed by
Tim Graham
Tim Graham
parent
a48bc0cec9
commit
db926a0048
@@ -1,9 +1,7 @@
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from django.db.migrations.exceptions import (
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CircularDependencyError, NodeNotFoundError,
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)
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from django.db.migrations.graph import (
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RECURSION_DEPTH_WARNING, DummyNode, MigrationGraph, Node,
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)
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from django.db.migrations.graph import DummyNode, MigrationGraph, Node
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from django.test import SimpleTestCase
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@@ -145,7 +143,7 @@ class GraphTests(SimpleTestCase):
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graph.add_dependency("app_b.0001", ("app_b", "0001"), ("app_a", "0003"))
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# Test whole graph
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with self.assertRaises(CircularDependencyError):
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graph.forwards_plan(("app_a", "0003"))
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graph.ensure_not_cyclic()
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def test_circular_graph_2(self):
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graph = MigrationGraph()
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@@ -157,9 +155,9 @@ class GraphTests(SimpleTestCase):
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graph.add_dependency('C.0001', ('C', '0001'), ('B', '0001'))
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with self.assertRaises(CircularDependencyError):
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graph.forwards_plan(('C', '0001'))
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graph.ensure_not_cyclic()
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def test_graph_recursive(self):
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def test_iterative_dfs(self):
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graph = MigrationGraph()
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root = ("app_a", "1")
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graph.add_node(root, None)
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@@ -178,28 +176,29 @@ class GraphTests(SimpleTestCase):
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backwards_plan = graph.backwards_plan(root)
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self.assertEqual(expected[::-1], backwards_plan)
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def test_graph_iterative(self):
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def test_iterative_dfs_complexity(self):
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"""
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In a graph with merge migrations, iterative_dfs() traverses each node
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only once even if there are multiple paths leading to it.
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"""
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n = 50
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graph = MigrationGraph()
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root = ("app_a", "1")
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graph.add_node(root, None)
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expected = [root]
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for i in range(2, 1000):
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parent = ("app_a", str(i - 1))
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child = ("app_a", str(i))
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graph.add_node(child, None)
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graph.add_dependency(str(i), child, parent)
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expected.append(child)
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leaf = expected[-1]
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with self.assertWarnsMessage(RuntimeWarning, RECURSION_DEPTH_WARNING):
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forwards_plan = graph.forwards_plan(leaf)
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self.assertEqual(expected, forwards_plan)
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with self.assertWarnsMessage(RuntimeWarning, RECURSION_DEPTH_WARNING):
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backwards_plan = graph.backwards_plan(root)
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self.assertEqual(expected[::-1], backwards_plan)
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for i in range(1, n + 1):
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graph.add_node(('app_a', str(i)), None)
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graph.add_node(('app_b', str(i)), None)
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graph.add_node(('app_c', str(i)), None)
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for i in range(1, n):
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graph.add_dependency(None, ('app_b', str(i)), ('app_a', str(i)))
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graph.add_dependency(None, ('app_c', str(i)), ('app_a', str(i)))
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graph.add_dependency(None, ('app_a', str(i + 1)), ('app_b', str(i)))
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graph.add_dependency(None, ('app_a', str(i + 1)), ('app_c', str(i)))
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plan = graph.forwards_plan(('app_a', str(n)))
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expected = [
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(app, str(i))
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for i in range(1, n)
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for app in ['app_a', 'app_c', 'app_b']
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] + [('app_a', str(n))]
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self.assertEqual(plan, expected)
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def test_plan_invalid_node(self):
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"""
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@@ -241,34 +240,39 @@ class GraphTests(SimpleTestCase):
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with self.assertRaisesMessage(NodeNotFoundError, msg):
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graph.add_dependency("app_a.0002", ("app_a", "0002"), ("app_a", "0001"))
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def test_validate_consistency(self):
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"""
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Tests for missing nodes, using `validate_consistency()` to raise the error.
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"""
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# Build graph
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def test_validate_consistency_missing_parent(self):
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graph = MigrationGraph()
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graph.add_node(("app_a", "0001"), None)
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# Add dependency with missing parent node (skipping validation).
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graph.add_dependency("app_a.0001", ("app_a", "0001"), ("app_b", "0002"), skip_validation=True)
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msg = "Migration app_a.0001 dependencies reference nonexistent parent node ('app_b', '0002')"
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with self.assertRaisesMessage(NodeNotFoundError, msg):
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graph.validate_consistency()
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# Add missing parent node and ensure `validate_consistency()` no longer raises error.
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def test_validate_consistency_missing_child(self):
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graph = MigrationGraph()
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graph.add_node(("app_b", "0002"), None)
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graph.validate_consistency()
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# Add dependency with missing child node (skipping validation).
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graph.add_dependency("app_a.0002", ("app_a", "0002"), ("app_a", "0001"), skip_validation=True)
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msg = "Migration app_a.0002 dependencies reference nonexistent child node ('app_a', '0002')"
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graph.add_dependency("app_b.0002", ("app_a", "0001"), ("app_b", "0002"), skip_validation=True)
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msg = "Migration app_b.0002 dependencies reference nonexistent child node ('app_a', '0001')"
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with self.assertRaisesMessage(NodeNotFoundError, msg):
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graph.validate_consistency()
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# Add missing child node and ensure `validate_consistency()` no longer raises error.
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graph.add_node(("app_a", "0002"), None)
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def test_validate_consistency_no_error(self):
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graph = MigrationGraph()
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graph.add_node(("app_a", "0001"), None)
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graph.add_node(("app_b", "0002"), None)
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graph.add_dependency("app_a.0001", ("app_a", "0001"), ("app_b", "0002"), skip_validation=True)
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graph.validate_consistency()
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# Rawly add dummy node.
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msg = "app_a.0001 (req'd by app_a.0002) is missing!"
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def test_validate_consistency_dummy(self):
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"""
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validate_consistency() raises an error if there's an isolated dummy
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node.
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"""
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msg = "app_a.0001 (req'd by app_b.0002) is missing!"
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graph = MigrationGraph()
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graph.add_dummy_node(
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key=("app_a", "0001"),
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origin="app_a.0002",
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origin="app_b.0002",
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error_message=msg
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)
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with self.assertRaisesMessage(NodeNotFoundError, msg):
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@@ -382,7 +386,7 @@ class GraphTests(SimpleTestCase):
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graph.add_dependency("app_c.0001_squashed_0002", ("app_c", "0001_squashed_0002"), ("app_b", "0002"))
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with self.assertRaises(CircularDependencyError):
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graph.forwards_plan(("app_c", "0001_squashed_0002"))
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graph.ensure_not_cyclic()
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def test_stringify(self):
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graph = MigrationGraph()
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@@ -413,14 +417,3 @@ class NodeTests(SimpleTestCase):
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error_message='x is missing',
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)
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self.assertEqual(repr(node), "<DummyNode: ('app_a', '0001')>")
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def test_dummynode_promote(self):
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dummy = DummyNode(
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key=('app_a', '0001'),
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origin='app_a.0002',
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error_message="app_a.0001 (req'd by app_a.0002) is missing!",
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)
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dummy.promote()
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self.assertIsInstance(dummy, Node)
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self.assertFalse(hasattr(dummy, 'origin'))
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self.assertFalse(hasattr(dummy, 'error_message'))
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