Loading django/db/migrations/operations/base.py +13 −0 Original line number Diff line number Diff line Loading @@ -63,3 +63,16 @@ class Operation(object): Outputs a brief summary of what the action does. """ return "%s: %s" % (self.__class__.__name__, self._constructor_args) def __repr__(self): return "<%s %s%s>" % ( self.__class__.__name__, ", ".join(map(repr, self._constructor_args[0])), ",".join(" %s=%r" % x for x in self._constructor_args[1].items()), ) def __eq__(self, other): return (self.__class__ == other.__class__) and (self.deconstruct() == other.deconstruct()) def __ne__(self, other): return not (self == other) django/db/migrations/operations/fields.py +16 −0 Original line number Diff line number Diff line Loading @@ -29,6 +29,14 @@ class AddField(Operation): def describe(self): return "Add field %s to %s" % (self.name, self.model_name) def __eq__(self, other): return ( (self.__class__ == other.__class__) and (self.name == other.name) and (self.model_name == other.model_name) and (self.field.deconstruct()[1:] == other.field.deconstruct()[1:]) ) class RemoveField(Operation): """ Loading Loading @@ -92,6 +100,14 @@ class AlterField(Operation): def describe(self): return "Alter field %s on %s" % (self.name, self.model_name) def __eq__(self, other): return ( (self.__class__ == other.__class__) and (self.name == other.name) and (self.model_name == other.model_name) and (self.field.deconstruct()[1:] == other.field.deconstruct()[1:]) ) class RenameField(Operation): """ Loading django/db/migrations/operations/models.py +9 −0 Original line number Diff line number Diff line Loading @@ -32,6 +32,15 @@ class CreateModel(Operation): def describe(self): return "Create model %s" % (self.name, ) def __eq__(self, other): return ( (self.__class__ == other.__class__) and (self.name == other.name) and (self.options == other.options) and (self.bases == other.bases) and ([(k, f.deconstruct()[1:]) for k, f in self.fields] == [(k, f.deconstruct()[1:]) for k, f in other.fields]) ) class DeleteModel(Operation): """ Loading django/db/migrations/optimizer.py 0 → 100644 +104 −0 Original line number Diff line number Diff line from django.db import migrations class MigrationOptimizer(object): """ Powers the optimization process, where you provide a list of Operations and you are returned a list of equal or shorter length - operations are merged into one if possible. For example, a CreateModel and an AddField can be optimised into a new CreateModel, and CreateModel and DeleteModel can be optimised into nothing. """ def optimize(self, operations): """ Main optimization entry point. Pass in a list of Operation instances, get out a new list of Operation instances. Unfortunately, due to the scope of the optimisation (two combinable operations might be separated by several hundred others), this can't be done as a peephole optimisation with checks/output implemented on the Operations themselves; instead, the optimizer looks at each individual operation and scans forwards in the list to see if there are any matches, stopping at boundaries - operations which can't be optimized over (RunSQL, operations on the same field/model, etc.) The inner loop is run until the starting list is the same as the result list, and then the result is returned. This means that operation optimization must be stable and always return an equal or shorter list. """ # Internal tracking variable for test assertions about # of loops self._iterations = 0 while True: result = self.optimize_inner(operations) self._iterations += 1 if result == operations: return result operations = result def optimize_inner(self, operations): """ Inner optimization loop. """ new_operations = [] for i, operation in enumerate(operations): # Compare it to each operation after it for j, other in enumerate(operations[i+1:]): result = self.reduce(operation, other) if result is not None: # Optimize! Add result, then remaining others, then return new_operations.extend(result) new_operations.extend(operations[i+1:i+1+j]) new_operations.extend(operations[i+j+2:]) return new_operations if not self.can_optimize_through(operation, other): new_operations.append(operation) break else: new_operations.append(operation) return new_operations #### REDUCTION #### def reduce(self, operation, other): """ Either returns a list of zero, one or two operations, or None, meaning this pair cannot be optimized. """ submethods = [ (migrations.CreateModel, migrations.DeleteModel, self.reduce_model_create_delete), (migrations.AlterModelTable, migrations.DeleteModel, self.reduce_model_alter_delete), (migrations.AlterUniqueTogether, migrations.DeleteModel, self.reduce_model_alter_delete), (migrations.AlterIndexTogether, migrations.DeleteModel, self.reduce_model_alter_delete), ] for ia, ib, om in submethods: if isinstance(operation, ia) and isinstance(other, ib): return om(operation, other) return None def reduce_model_create_delete(self, operation, other): """ Folds a CreateModel and a DeleteModel into nothing. """ if operation.name == other.name: return [] return None def reduce_model_alter_delete(self, operation, other): """ Folds an AlterModelSomething and a DeleteModel into nothing. """ if operation.name == other.name: return [other] return None #### THROUGH CHECKS #### def can_optimize_through(self, operation, other): """ Returns True if it's possible to optimize 'operation' with something the other side of 'other'. This is possible if, for example, they affect different models. """ return False tests/migrations/test_optimizer.py 0 → 100644 +95 −0 Original line number Diff line number Diff line # encoding: utf8 import operator from django.test import TestCase from django.db.migrations.optimizer import MigrationOptimizer from django.db import migrations from django.db import models class OptimizerTests(TestCase): """ Tests the migration autodetector. """ def optimize(self, operations): """ Handy shortcut for getting results + number of loops """ optimizer = MigrationOptimizer() return optimizer.optimize(operations), optimizer._iterations def assertOptimizesTo(self, operations, expected, exact=None, less_than=None): result, iterations = self.optimize(operations) self.assertEqual(expected, result) if exact is not None and iterations != exact: raise self.failureException("Optimization did not take exactly %s iterations (it took %s)" % (exact, iterations)) if less_than is not None and iterations >= less_than: raise self.failureException("Optimization did not take less than %s iterations (it took %s)" % (less_than, iterations)) def test_operation_equality(self): """ Tests the equality operator on lists of operations. If this is broken, then the optimizer will get stuck in an infinite loop, so it's kind of important. """ self.assertEqual( [migrations.DeleteModel("Test")], [migrations.DeleteModel("Test")], ) self.assertEqual( [migrations.CreateModel("Test", [("name", models.CharField(max_length=255))])], [migrations.CreateModel("Test", [("name", models.CharField(max_length=255))])], ) self.assertNotEqual( [migrations.CreateModel("Test", [("name", models.CharField(max_length=255))])], [migrations.CreateModel("Test", [("name", models.CharField(max_length=100))])], ) self.assertEqual( [migrations.AddField("Test", "name", models.CharField(max_length=255))], [migrations.AddField("Test", "name", models.CharField(max_length=255))], ) self.assertNotEqual( [migrations.AddField("Test", "name", models.CharField(max_length=255))], [migrations.AddField("Test", "name", models.CharField(max_length=100))], ) self.assertNotEqual( [migrations.AddField("Test", "name", models.CharField(max_length=255))], [migrations.AlterField("Test", "name", models.CharField(max_length=255))], ) def test_single(self): """ Tests that the optimizer does nothing on a single operation, and that it does it in just one pass. """ self.assertOptimizesTo( [migrations.DeleteModel("Foo")], [migrations.DeleteModel("Foo")], exact = 1, ) def test_create_delete_model(self): """ CreateModel and DeleteModel should collapse into nothing. """ self.assertOptimizesTo( [ migrations.CreateModel("Foo", [("name", models.CharField(max_length=255))]), migrations.DeleteModel("Foo"), ], [], ) def test_create_alter_delete_model(self): """ CreateModel, AlterModelTable, AlterUniqueTogether, and DeleteModel should collapse into nothing. """ self.assertOptimizesTo( [ migrations.CreateModel("Foo", [("name", models.CharField(max_length=255))]), migrations.AlterModelTable("Foo", "woohoo"), migrations.AlterUniqueTogether("Foo", [["a", "b"]]), migrations.DeleteModel("Foo"), ], [], ) Loading
django/db/migrations/operations/base.py +13 −0 Original line number Diff line number Diff line Loading @@ -63,3 +63,16 @@ class Operation(object): Outputs a brief summary of what the action does. """ return "%s: %s" % (self.__class__.__name__, self._constructor_args) def __repr__(self): return "<%s %s%s>" % ( self.__class__.__name__, ", ".join(map(repr, self._constructor_args[0])), ",".join(" %s=%r" % x for x in self._constructor_args[1].items()), ) def __eq__(self, other): return (self.__class__ == other.__class__) and (self.deconstruct() == other.deconstruct()) def __ne__(self, other): return not (self == other)
django/db/migrations/operations/fields.py +16 −0 Original line number Diff line number Diff line Loading @@ -29,6 +29,14 @@ class AddField(Operation): def describe(self): return "Add field %s to %s" % (self.name, self.model_name) def __eq__(self, other): return ( (self.__class__ == other.__class__) and (self.name == other.name) and (self.model_name == other.model_name) and (self.field.deconstruct()[1:] == other.field.deconstruct()[1:]) ) class RemoveField(Operation): """ Loading Loading @@ -92,6 +100,14 @@ class AlterField(Operation): def describe(self): return "Alter field %s on %s" % (self.name, self.model_name) def __eq__(self, other): return ( (self.__class__ == other.__class__) and (self.name == other.name) and (self.model_name == other.model_name) and (self.field.deconstruct()[1:] == other.field.deconstruct()[1:]) ) class RenameField(Operation): """ Loading
django/db/migrations/operations/models.py +9 −0 Original line number Diff line number Diff line Loading @@ -32,6 +32,15 @@ class CreateModel(Operation): def describe(self): return "Create model %s" % (self.name, ) def __eq__(self, other): return ( (self.__class__ == other.__class__) and (self.name == other.name) and (self.options == other.options) and (self.bases == other.bases) and ([(k, f.deconstruct()[1:]) for k, f in self.fields] == [(k, f.deconstruct()[1:]) for k, f in other.fields]) ) class DeleteModel(Operation): """ Loading
django/db/migrations/optimizer.py 0 → 100644 +104 −0 Original line number Diff line number Diff line from django.db import migrations class MigrationOptimizer(object): """ Powers the optimization process, where you provide a list of Operations and you are returned a list of equal or shorter length - operations are merged into one if possible. For example, a CreateModel and an AddField can be optimised into a new CreateModel, and CreateModel and DeleteModel can be optimised into nothing. """ def optimize(self, operations): """ Main optimization entry point. Pass in a list of Operation instances, get out a new list of Operation instances. Unfortunately, due to the scope of the optimisation (two combinable operations might be separated by several hundred others), this can't be done as a peephole optimisation with checks/output implemented on the Operations themselves; instead, the optimizer looks at each individual operation and scans forwards in the list to see if there are any matches, stopping at boundaries - operations which can't be optimized over (RunSQL, operations on the same field/model, etc.) The inner loop is run until the starting list is the same as the result list, and then the result is returned. This means that operation optimization must be stable and always return an equal or shorter list. """ # Internal tracking variable for test assertions about # of loops self._iterations = 0 while True: result = self.optimize_inner(operations) self._iterations += 1 if result == operations: return result operations = result def optimize_inner(self, operations): """ Inner optimization loop. """ new_operations = [] for i, operation in enumerate(operations): # Compare it to each operation after it for j, other in enumerate(operations[i+1:]): result = self.reduce(operation, other) if result is not None: # Optimize! Add result, then remaining others, then return new_operations.extend(result) new_operations.extend(operations[i+1:i+1+j]) new_operations.extend(operations[i+j+2:]) return new_operations if not self.can_optimize_through(operation, other): new_operations.append(operation) break else: new_operations.append(operation) return new_operations #### REDUCTION #### def reduce(self, operation, other): """ Either returns a list of zero, one or two operations, or None, meaning this pair cannot be optimized. """ submethods = [ (migrations.CreateModel, migrations.DeleteModel, self.reduce_model_create_delete), (migrations.AlterModelTable, migrations.DeleteModel, self.reduce_model_alter_delete), (migrations.AlterUniqueTogether, migrations.DeleteModel, self.reduce_model_alter_delete), (migrations.AlterIndexTogether, migrations.DeleteModel, self.reduce_model_alter_delete), ] for ia, ib, om in submethods: if isinstance(operation, ia) and isinstance(other, ib): return om(operation, other) return None def reduce_model_create_delete(self, operation, other): """ Folds a CreateModel and a DeleteModel into nothing. """ if operation.name == other.name: return [] return None def reduce_model_alter_delete(self, operation, other): """ Folds an AlterModelSomething and a DeleteModel into nothing. """ if operation.name == other.name: return [other] return None #### THROUGH CHECKS #### def can_optimize_through(self, operation, other): """ Returns True if it's possible to optimize 'operation' with something the other side of 'other'. This is possible if, for example, they affect different models. """ return False
tests/migrations/test_optimizer.py 0 → 100644 +95 −0 Original line number Diff line number Diff line # encoding: utf8 import operator from django.test import TestCase from django.db.migrations.optimizer import MigrationOptimizer from django.db import migrations from django.db import models class OptimizerTests(TestCase): """ Tests the migration autodetector. """ def optimize(self, operations): """ Handy shortcut for getting results + number of loops """ optimizer = MigrationOptimizer() return optimizer.optimize(operations), optimizer._iterations def assertOptimizesTo(self, operations, expected, exact=None, less_than=None): result, iterations = self.optimize(operations) self.assertEqual(expected, result) if exact is not None and iterations != exact: raise self.failureException("Optimization did not take exactly %s iterations (it took %s)" % (exact, iterations)) if less_than is not None and iterations >= less_than: raise self.failureException("Optimization did not take less than %s iterations (it took %s)" % (less_than, iterations)) def test_operation_equality(self): """ Tests the equality operator on lists of operations. If this is broken, then the optimizer will get stuck in an infinite loop, so it's kind of important. """ self.assertEqual( [migrations.DeleteModel("Test")], [migrations.DeleteModel("Test")], ) self.assertEqual( [migrations.CreateModel("Test", [("name", models.CharField(max_length=255))])], [migrations.CreateModel("Test", [("name", models.CharField(max_length=255))])], ) self.assertNotEqual( [migrations.CreateModel("Test", [("name", models.CharField(max_length=255))])], [migrations.CreateModel("Test", [("name", models.CharField(max_length=100))])], ) self.assertEqual( [migrations.AddField("Test", "name", models.CharField(max_length=255))], [migrations.AddField("Test", "name", models.CharField(max_length=255))], ) self.assertNotEqual( [migrations.AddField("Test", "name", models.CharField(max_length=255))], [migrations.AddField("Test", "name", models.CharField(max_length=100))], ) self.assertNotEqual( [migrations.AddField("Test", "name", models.CharField(max_length=255))], [migrations.AlterField("Test", "name", models.CharField(max_length=255))], ) def test_single(self): """ Tests that the optimizer does nothing on a single operation, and that it does it in just one pass. """ self.assertOptimizesTo( [migrations.DeleteModel("Foo")], [migrations.DeleteModel("Foo")], exact = 1, ) def test_create_delete_model(self): """ CreateModel and DeleteModel should collapse into nothing. """ self.assertOptimizesTo( [ migrations.CreateModel("Foo", [("name", models.CharField(max_length=255))]), migrations.DeleteModel("Foo"), ], [], ) def test_create_alter_delete_model(self): """ CreateModel, AlterModelTable, AlterUniqueTogether, and DeleteModel should collapse into nothing. """ self.assertOptimizesTo( [ migrations.CreateModel("Foo", [("name", models.CharField(max_length=255))]), migrations.AlterModelTable("Foo", "woohoo"), migrations.AlterUniqueTogether("Foo", [["a", "b"]]), migrations.DeleteModel("Foo"), ], [], )
