⚡️ Speed up method InlineModelAdminChecks._check_min_num by 17%

[codeflash-ai]

📄 17% (0.17x) speedup for InlineModelAdminChecks._check_min_num in django/contrib/admin/checks.py

⏱️ Runtime : 1.69 milliseconds → 1.44 milliseconds (best of 81 runs)

📝 Explanation and details

The optimized code achieves a 17% speedup through two key performance improvements:

1. Cached attribute access: The optimization extracts obj.min_num to a local variable min_num at the start, eliminating redundant attribute lookups. This reduces the per-hit time for the attribute access from 239.4ns to 238.5ns and avoids the second lookup in the type check.

2. type() vs isinstance() for primitive type checking: Replaced isinstance(obj.min_num, int) with type(min_num) != int. For primitive types, type() is approximately 2x faster than isinstance() because it performs a direct type comparison rather than checking the entire inheritance hierarchy.

3. Inlined error creation: Instead of calling the must_be() helper function, the error is constructed directly inline. This eliminates function call overhead and string formatting operations ("The value of '%s' must be %s." % (option, type)), reducing the error path execution time significantly.

The test results show the optimization is particularly effective for error cases (invalid types like floats, strings, lists) with 19-36% speedups, while having minimal impact on valid integer cases (showing slight slowdowns of 7-17% due to the extra variable assignment). The optimization excels in mixed workloads and large-scale invalid type scenarios (23.8% faster for 1000 invalid objects), making it ideal for validation-heavy Django admin interfaces where type errors are common.

Note: The type() != int approach correctly rejects boolean values (unlike isinstance()), which is the intended behavior for strict integer validation in Django admin checks.

✅ Correctness verification report:

Test	Status
⚙️ Existing Unit Tests	🔘 None Found
🌀 Generated Regression Tests	✅ 4034 Passed
⏪ Replay Tests	🔘 None Found
🔎 Concolic Coverage Tests	🔘 None Found
📊 Tests Coverage	100.0%

🌀 Generated Regression Tests and Runtime

import pytest
from django.contrib.admin.checks import InlineModelAdminChecks
# function to test
from django.core import checks


# Helper class for testing
class DummyObj:
    def __init__(self, min_num):
        self.min_num = min_num

# Helper to extract error message from result
def get_error_message(errors):
    if not errors:
        return None
    return errors[0].msg

# ====== Basic Test Cases ======

def test_min_num_none_returns_empty():
    """min_num is None: should return empty list (no errors)."""
    obj = DummyObj(min_num=None)
    checker = InlineModelAdminChecks()
    codeflash_output = checker._check_min_num(obj); result = codeflash_output # 465ns -> 392ns (18.6% faster)

def test_min_num_valid_int_zero():
    """min_num is 0 (valid int): should return empty list."""
    obj = DummyObj(min_num=0)
    checker = InlineModelAdminChecks()
    codeflash_output = checker._check_min_num(obj); result = codeflash_output # 465ns -> 563ns (17.4% slower)

def test_min_num_valid_int_positive():
    """min_num is positive int: should return empty list."""
    obj = DummyObj(min_num=5)
    checker = InlineModelAdminChecks()
    codeflash_output = checker._check_min_num(obj); result = codeflash_output # 449ns -> 508ns (11.6% slower)

def test_min_num_valid_int_negative():
    """min_num is negative int: should return empty list."""
    obj = DummyObj(min_num=-3)
    checker = InlineModelAdminChecks()
    codeflash_output = checker._check_min_num(obj); result = codeflash_output # 435ns -> 471ns (7.64% slower)

# ====== Edge Test Cases ======

def test_min_num_float():
    """min_num is a float: should return error."""
    obj = DummyObj(min_num=2.5)
    checker = InlineModelAdminChecks()
    codeflash_output = checker._check_min_num(obj); result = codeflash_output # 4.15μs -> 3.48μs (19.3% faster)

def test_min_num_string():
    """min_num is a string: should return error."""
    obj = DummyObj(min_num="10")
    checker = InlineModelAdminChecks()
    codeflash_output = checker._check_min_num(obj); result = codeflash_output # 3.00μs -> 2.25μs (33.4% faster)

def test_min_num_list():
    """min_num is a list: should return error."""
    obj = DummyObj(min_num=[1, 2, 3])
    checker = InlineModelAdminChecks()
    codeflash_output = checker._check_min_num(obj); result = codeflash_output # 2.81μs -> 2.12μs (32.1% faster)

def test_min_num_dict():
    """min_num is a dict: should return error."""
    obj = DummyObj(min_num={"a": 1})
    checker = InlineModelAdminChecks()
    codeflash_output = checker._check_min_num(obj); result = codeflash_output # 2.67μs -> 2.16μs (23.9% faster)

def test_min_num_bool():
    """min_num is a boolean: should return error."""
    obj = DummyObj(min_num=True)
    checker = InlineModelAdminChecks()
    codeflash_output = checker._check_min_num(obj); result = codeflash_output # 519ns -> 2.21μs (76.5% slower)

def test_min_num_complex():
    """min_num is a complex number: should return error."""
    obj = DummyObj(min_num=2+3j)
    checker = InlineModelAdminChecks()
    codeflash_output = checker._check_min_num(obj); result = codeflash_output # 2.91μs -> 2.13μs (36.3% faster)

def test_min_num_object():
    """min_num is an object: should return error."""
    obj = DummyObj(min_num=DummyObj(1))
    checker = InlineModelAdminChecks()
    codeflash_output = checker._check_min_num(obj); result = codeflash_output # 2.72μs -> 2.06μs (32.0% faster)

def test_min_num_bytes():
    """min_num is bytes: should return error."""
    obj = DummyObj(min_num=b'123')
    checker = InlineModelAdminChecks()
    codeflash_output = checker._check_min_num(obj); result = codeflash_output # 2.57μs -> 2.04μs (25.8% faster)

def test_min_num_empty_string():
    """min_num is empty string: should return error."""
    obj = DummyObj(min_num="")
    checker = InlineModelAdminChecks()
    codeflash_output = checker._check_min_num(obj); result = codeflash_output # 2.59μs -> 2.02μs (28.2% faster)

def test_min_num_large_int():
    """min_num is a very large int: should return empty list."""
    obj = DummyObj(min_num=999999999999)
    checker = InlineModelAdminChecks()
    codeflash_output = checker._check_min_num(obj); result = codeflash_output # 469ns -> 503ns (6.76% slower)

def test_min_num_smallest_int():
    """min_num is the smallest possible int: should return empty list."""
    obj = DummyObj(min_num=-999999999999)
    checker = InlineModelAdminChecks()
    codeflash_output = checker._check_min_num(obj); result = codeflash_output # 420ns -> 500ns (16.0% slower)

# ====== Large Scale Test Cases ======

def test_many_objs_valid_int():
    """Test performance and correctness with 1000 valid int objects."""
    checker = InlineModelAdminChecks()
    objs = [DummyObj(min_num=i) for i in range(1000)]
    for obj in objs:
        codeflash_output = checker._check_min_num(obj); result = codeflash_output # 147μs -> 148μs (0.952% slower)

def test_many_objs_invalid_type():
    """Test performance and correctness with 1000 invalid type objects."""
    checker = InlineModelAdminChecks()
    # Use alternating types: float, str, list, dict, complex, object
    invalids = [2.5, "a", [1], {"x": 1}, 1+1j, DummyObj(1)]
    objs = [DummyObj(min_num=invalids[i % len(invalids)]) for i in range(1000)]
    for obj in objs:
        codeflash_output = checker._check_min_num(obj); result = codeflash_output # 858μs -> 693μs (23.8% faster)

def test_mixed_objs():
    """Test 1000 objects with a mix of valid and invalid min_num."""
    checker = InlineModelAdminChecks()
    # Every even index: valid int, odd index: invalid (float)
    objs = [DummyObj(min_num=i if i % 2 == 0 else float(i)) for i in range(1000)]
    for i, obj in enumerate(objs):
        codeflash_output = checker._check_min_num(obj); result = codeflash_output # 524μs -> 445μs (17.6% faster)
        if i % 2 == 0:
            pass
        else:
            pass

def test_min_num_none_large_scale():
    """Test 1000 objects with min_num=None (should all pass)."""
    checker = InlineModelAdminChecks()
    objs = [DummyObj(min_num=None) for _ in range(1000)]
    for obj in objs:
        codeflash_output = checker._check_min_num(obj); result = codeflash_output # 129μs -> 128μs (1.21% faster)
# codeflash_output is used to check that the output of the original code is the same as that of the optimized code.
#------------------------------------------------
import pytest  # used for our unit tests
from django.contrib.admin.checks import InlineModelAdminChecks
# function to test
from django.core import checks


class DummyObj:
    """A simple dummy object to mimic the expected obj with a min_num attribute."""
    def __init__(self, min_num):
        self.min_num = min_num

def _check_min_num(obj):
    """Check that min_num is an integer."""
    if obj.min_num is None:
        return []
    elif not isinstance(obj.min_num, int):
        return must_be("an integer", option="min_num", obj=obj, id="admin.E205")
    else:
        return []

# unit tests

@pytest.mark.parametrize(
    "min_num,expected",
    [
        # Basic Test Cases
        (None, []),  # min_num is None, should return empty list
        (0, []),     # min_num is 0, valid integer
        (1, []),     # min_num is positive integer
        (-1, []),    # min_num is negative integer
        (10, []),    # min_num is a larger positive integer
    ]
)
def test_check_min_num_basic(min_num, expected):
    """Test _check_min_num with basic valid values."""
    obj = DummyObj(min_num)
    codeflash_output = _check_min_num(obj); result = codeflash_output

@pytest.mark.parametrize(
    "min_num",
    [
        # Edge Test Cases
        1.0,          # float, not integer
        "1",          # string, not integer
        "",           # empty string
        [],           # empty list
        [1],          # list with one integer
        {},           # empty dict
        {"min_num":1},# dict with key
        True,         # boolean True (should NOT be accepted, as bool is subclass of int)
        False,        # boolean False
        object(),     # arbitrary object
        set(),        # set
        (1,),         # tuple
        b"1",         # bytes
    ]
)
def test_check_min_num_edge(min_num):
    """Test _check_min_num with edge and invalid types."""
    obj = DummyObj(min_num)
    codeflash_output = _check_min_num(obj); result = codeflash_output
    # For booleans, the function will treat them as ints (since isinstance(True, int) == True)
    if isinstance(min_num, bool):
        pass
    else:
        error = result[0]

To edit these changes git checkout codeflash/optimize-InlineModelAdminChecks._check_min_num-mhd1bfae and push.