Add benchmarking test suite and greatly improve performance in a few cases (#948)

* Add benchmarking test suite

* Improve amortized time of model relation loads with a large number of rows

* Improve performance of loading models with many related models

* Improve performance of loading models with many related models to O(N)ish

* Fix bug where N model creation with shared related model would build in N^2 time

* Lower blocking time for queryset results

* Add docstrings and streamline hash code

Co-authored-by: haydeec1 <Eric.Haydel@jhuapl.edu>

tests/test_model_definition/test_equality_and_hash.py

@@ -0,0 +1,67 @@
+# type: ignore
+import databases
+import pytest
+import sqlalchemy
+
+import ormar
+from ormar import ModelDefinitionError, property_field
+from tests.settings import DATABASE_URL
+
+database = databases.Database(DATABASE_URL, force_rollback=True)
+metadata = sqlalchemy.MetaData()
+
+
+class Song(ormar.Model):
+    class Meta:
+        tablename = "songs"
+        metadata = metadata
+        database = database
+
+    id: int = ormar.Integer(primary_key=True)
+    name: str = ormar.String(max_length=100)
+
+
+@pytest.fixture(autouse=True, scope="module")
+def create_test_database():
+    engine = sqlalchemy.create_engine(DATABASE_URL)
+    metadata.drop_all(engine)
+    metadata.create_all(engine)
+    yield
+    metadata.drop_all(engine)
+
+
+@pytest.mark.asyncio
+async def test_equality():
+    async with database:
+        song1 = await Song.objects.create(name="Song")
+        song2 = await Song.objects.create(name="Song")
+        song3 = Song(name="Song")
+        song4 = Song(name="Song")
+
+        assert song1 == song1
+        assert song3 == song4
+
+        assert song1 != song2
+        assert song1 != song3
+        assert song3 != song1
+        assert song1 is not None
+
+
+@pytest.mark.asyncio
+async def test_hash_doesnt_change_with_fields_if_pk():
+    async with database:
+        song1 = await Song.objects.create(name="Song")
+        prev_hash = hash(song1)
+
+        await song1.update(name="Song 2")
+        assert hash(song1) == prev_hash
+
+
+@pytest.mark.asyncio
+async def test_hash_changes_with_fields_if_no_pk():
+    async with database:
+        song1 = Song(name="Song")
+        prev_hash = hash(song1)
+
+        song1.name = "Song 2"
+        assert hash(song1) != prev_hash

tests/test_relations/test_weakref_checking.py

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+from typing import Optional, Type
+
+import databases
+import pytest
+import pytest_asyncio
+import sqlalchemy
+
+import ormar
+from tests.settings import DATABASE_URL
+
+database = databases.Database(DATABASE_URL)
+metadata = sqlalchemy.MetaData()
+
+
+class Band(ormar.Model):
+    class Meta:
+        tablename = "bands"
+        metadata = metadata
+        database = database
+
+    id: int = ormar.Integer(primary_key=True)
+    name: str = ormar.String(max_length=100)
+
+
+class Artist(ormar.Model):
+    class Meta:
+        tablename = "artists"
+        metadata = metadata
+        database = database
+
+    id: int = ormar.Integer(primary_key=True)
+    name: str = ormar.String(max_length=100)
+
+    band: Band = ormar.ForeignKey(Band)
+
+
+def test_weakref_init():
+    band = Band(name="Band")
+    artist1 = Artist(name="Artist 1", band=band)
+    artist2 = Artist(name="Artist 2", band=band)
+    artist3 = Artist(name="Artist 3", band=band)
+
+    del artist1
+    Artist(
+        name="Artist 2", band=band
+    )  # Force it to check for weakly-referenced objects
+    del artist3
+
+    band.artists  # Force it to clean
+
+    assert len(band.artists) == 1
+    assert band.artists[0].name == "Artist 2"