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@codeflash-ai codeflash-ai bot commented Dec 17, 2025

📄 5% (0.05x) speedup for caching_module_getattr in lib/matplotlib/_api/__init__.py

⏱️ Runtime : 143 microseconds 136 microseconds (best of 124 runs)

📝 Explanation and details

The optimization achieves a 5% speedup through two key changes that reduce overhead in the decorator setup and attribute lookup:

Key Optimizations:

  1. Direct dictionary access: Replaced vars(cls).items() with cls.__dict__.items() when building the properties dictionary. This eliminates the overhead of the vars() function call, which internally performs additional work beyond a simple dictionary access.

  2. Single lookup pattern: Changed from name in props followed by props[name] (two dictionary operations) to props.get(name) followed by a null check (one dictionary operation). This reduces dictionary lookups from 2 to 1 in the common case.

Why it's faster:

  • vars() creates a proxy object and has additional overhead compared to direct __dict__ access
  • The dict.get() approach eliminates redundant hash computations and key lookups that occur with the in operator followed by indexing
  • Line profiler shows the props building line dropped from 72.4% to 60.1% of total time, demonstrating the impact of the vars()__dict__ change

Performance characteristics:

The optimization benefits all test cases, with larger improvements (6-10%) seen in scenarios with many properties, as the dictionary operation savings compound. The caching behavior and error handling remain identical, ensuring no behavioral changes while providing consistent performance gains across different usage patterns.

Correctness verification report:

Test Status
⚙️ Existing Unit Tests 🔘 None Found
🌀 Generated Regression Tests 32 Passed
⏪ Replay Tests 🔘 None Found
🔎 Concolic Coverage Tests 🔘 None Found
📊 Tests Coverage 100.0%
🌀 Generated Regression Tests and Runtime
import types

# imports
import pytest
from matplotlib._api.__init__ import caching_module_getattr

# unit tests


# Helper function to simulate module-level __getattr__ usage
def make_module_with_getattr_class(properties):
    """
    Dynamically create a module with a decorated __getattr__ using the given property dict.
    properties: dict of {name: function returning value}
    Returns: (module, getattr_func, class_type)
    """
    # Build the class dict with properties
    class_dict = {}
    for name, func in properties.items():
        class_dict[name] = property(func)
    # Dynamically create the class
    getattr_class = type("__getattr__", (), class_dict)
    # Decorate with caching_module_getattr
    codeflash_output = caching_module_getattr(getattr_class)
    getattr_func = codeflash_output
    # Create a dummy module to simulate module-level getattr
    module = types.ModuleType("dummy_module")
    module.__getattr__ = getattr_func
    return module, getattr_func, getattr_class


# ----------------
# Basic Test Cases
# ----------------


def test_single_property_access():
    # Test that a single property is accessible and returns the correct value.
    module, getattr_func, _ = make_module_with_getattr_class({"foo": lambda self: 42})


def test_multiple_properties_access():
    # Test that multiple properties are accessible and return correct values.
    module, getattr_func, _ = make_module_with_getattr_class(
        {"foo": lambda self: 1, "bar": lambda self: 2, "baz": lambda self: 3}
    )


def test_attribute_error_on_missing_property():
    # Test that AttributeError is raised for missing property.
    module, getattr_func, getattr_class = make_module_with_getattr_class(
        {"foo": lambda self: 1}
    )
    with pytest.raises(AttributeError) as excinfo:
        module.__getattr__("bar")
    # Also test direct getattr_func
    with pytest.raises(AttributeError):
        getattr_func("baz")


def test_property_is_cached():
    # Test that property is only called once (caching).
    call_count = {"count": 0}

    def foo(self):
        call_count["count"] += 1
        return 99

    module, getattr_func, _ = make_module_with_getattr_class({"foo": foo})


def test_class_name_must_be_dunder_getattr():
    # Test that using a class with a wrong name raises AssertionError.
    class NotGetAttr:
        @property
        def foo(self):
            return 1

    with pytest.raises(AssertionError):
        caching_module_getattr(NotGetAttr)  # 1.34μs -> 1.29μs (3.63% faster)


# ---------------
# Edge Test Cases
# ---------------


def test_property_with_side_effects():
    # Test that side effects only happen once due to caching.
    side_effect = {"val": 0}

    def foo(self):
        side_effect["val"] += 10
        return side_effect["val"]

    module, getattr_func, _ = make_module_with_getattr_class({"foo": foo})


def test_non_property_attributes_are_ignored():
    # Test that only properties are exposed, not other attributes.
    def foo(self):
        return 123

    class_dict = {"foo": foo, "bar": 456}
    getattr_class = type("__getattr__", (), class_dict)
    codeflash_output = caching_module_getattr(getattr_class)
    getattr_func = codeflash_output  # 8.70μs -> 7.88μs (10.4% faster)
    # Only foo is a method, not a property, so nothing should be exposed
    with pytest.raises(AttributeError):
        getattr_func("foo")
    with pytest.raises(AttributeError):
        getattr_func("bar")


def test_property_named_dunder_is_ignored():
    # Dunder-named properties should be accessible if present.
    def __weird__(self):
        return 77

    module, getattr_func, _ = make_module_with_getattr_class({"__weird__": __weird__})


def test_property_returns_none():
    # Test that a property returning None works.
    module, getattr_func, _ = make_module_with_getattr_class({"foo": lambda self: None})


def test_property_with_exception():
    # Test that if property raises, the exception is propagated.
    def foo(self):
        raise ValueError("fail!")

    module, getattr_func, _ = make_module_with_getattr_class({"foo": foo})
    with pytest.raises(ValueError):
        module.__getattr__("foo")


def test_module_name_in_error_message():
    # The AttributeError should mention the module name.
    module, getattr_func, getattr_class = make_module_with_getattr_class(
        {"foo": lambda self: 1}
    )
    try:
        module.__getattr__("notfound")
    except AttributeError as e:
        pass


def test_property_with_name_similar_to_method():
    # Property with same name as method should be accessible.
    def foo(self):
        return "property"

    class_dict = {"foo": property(foo), "foo_method": lambda self: "method"}
    getattr_class = type("__getattr__", (), class_dict)
    codeflash_output = caching_module_getattr(getattr_class)
    getattr_func = codeflash_output  # 8.73μs -> 8.10μs (7.87% faster)
    with pytest.raises(AttributeError):
        getattr_func("foo_method")


# ----------------------
# Large Scale Test Cases
# ----------------------


def test_many_properties():
    # Test with a large number of properties (up to 1000).
    N = 1000

    def make_prop(i):
        return lambda self, val=i: val

    properties = {f"prop_{i}": make_prop(i) for i in range(N)}
    module, getattr_func, _ = make_module_with_getattr_class(properties)
    # Access all and check values
    for i in range(N):
        pass


def test_caching_with_many_properties():
    # Test that caching works with many properties, only one call per property.
    N = 100
    call_counts = [0] * N

    def make_prop(i):
        def prop(self):
            call_counts[i] += 1
            return i * 2

        return prop

    properties = {f"p{i}": make_prop(i) for i in range(N)}
    module, getattr_func, _ = make_module_with_getattr_class(properties)
    # Access each property twice
    for i in range(N):
        pass


def test_attribute_error_for_all_missing_in_large():
    # Test that missing properties always raise AttributeError, even in large class.
    N = 300
    properties = {f"x{i}": (lambda self, val=i: val) for i in range(N)}
    module, getattr_func, getattr_class = make_module_with_getattr_class(properties)
    for i in range(N, N + 10):
        with pytest.raises(AttributeError):
            module.__getattr__(f"x{i}")


def test_performance_with_many_accesses():
    # Test that repeated accesses are fast (caching), but don't actually time it.
    # Instead, test that the property is only called once per property.
    N = 200
    call_counts = [0] * N

    def make_prop(i):
        def prop(self):
            call_counts[i] += 1
            return i

        return prop

    properties = {f"xx{i}": make_prop(i) for i in range(N)}
    module, getattr_func, _ = make_module_with_getattr_class(properties)
    for _ in range(5):  # Access each property 5 times
        for i in range(N):
            pass


# codeflash_output is used to check that the output of the original code is the same as that of the optimized code.
import types

# imports
import pytest
from matplotlib._api.__init__ import caching_module_getattr

# unit tests

# --------- BASIC TEST CASES ---------


def test_single_property_access():
    # Test that a single property is accessible and returns the correct value.
    @caching_module_getattr
    class __getattr__:
        @property
        def foo(self):
            return 42


def test_multiple_properties_access():
    # Test that multiple properties are accessible and return correct values.
    @caching_module_getattr
    class __getattr__:
        @property
        def alpha(self):
            return "A"

        @property
        def beta(self):
            return "B"

        @property
        def gamma(self):
            return "G"


def test_attribute_error_on_missing_property():
    # Test that AttributeError is raised with correct message for missing property.
    @caching_module_getattr
    class __getattr__:
        @property
        def foo(self):
            return 1

    with pytest.raises(AttributeError) as excinfo:
        __getattr__("bar")


def test_properties_are_cached():
    # Test that property is only computed once (caching behavior).
    call_counter = {"count": 0}

    @caching_module_getattr
    class __getattr__:
        @property
        def foo(self):
            call_counter["count"] += 1
            return 99


def test_only_properties_are_exposed():
    # Test that only @property attributes are accessible.
    @caching_module_getattr
    class __getattr__:
        @property
        def foo(self):
            return 1

        def bar(self):  # Not a property
            return 2

        baz = 3  # Not a property

    with pytest.raises(AttributeError):
        __getattr__("bar")
    with pytest.raises(AttributeError):
        __getattr__("baz")


# --------- EDGE TEST CASES ---------


def test_class_name_must_be_dunder_getattr():
    # Test that using a class with wrong name raises AssertionError.
    with pytest.raises(AssertionError):

        @caching_module_getattr
        class NotGetattr:
            @property
            def foo(self):
                return 1


def test_property_returning_none():
    # Test that property returning None is handled and cached.
    call_counter = {"count": 0}

    @caching_module_getattr
    class __getattr__:
        @property
        def foo(self):
            call_counter["count"] += 1
            return None


def test_property_with_side_effects():
    # Test that side effects only occur once due to caching.
    side_effects = []

    @caching_module_getattr
    class __getattr__:
        @property
        def foo(self):
            side_effects.append("called")
            return "bar"


def test_attribute_error_message_content():
    # Test that AttributeError message includes module name and attribute.
    @caching_module_getattr
    class __getattr__:
        @property
        def foo(self):
            return 1

    try:
        __getattr__("missing")
    except AttributeError as e:
        msg = str(e)


def test_property_with_exception():
    # Test that if property raises, the exception is propagated.
    @caching_module_getattr
    class __getattr__:
        @property
        def foo(self):
            raise ValueError("fail")

    with pytest.raises(ValueError):
        __getattr__("foo")


def test_module_level_usage_simulation():
    # Simulate usage as module-level __getattr__.
    module = types.ModuleType("mod")

    @caching_module_getattr
    class __getattr__:
        @property
        def foo(self):
            return 1

    module.__getattr__ = __getattr__
    with pytest.raises(AttributeError):
        module.__getattr__("bar")


# --------- LARGE SCALE TEST CASES ---------


def test_many_properties():
    # Test with a large number of properties.
    N = 500
    values = list(range(N))

    def make_property(i):
        return property(lambda self, v=i: v)

    props = {"prop_%d" % i: make_property(i) for i in range(N)}
    __getattr__ = type("__getattr__", (), props)
    codeflash_output = caching_module_getattr(__getattr__)
    __getattr__ = codeflash_output  # 40.1μs -> 39.0μs (2.91% faster)

    # All should be accessible and correct
    for i in range(N):
        pass

    # Missing property
    with pytest.raises(AttributeError):
        __getattr__("prop_%d" % N)


def test_caching_with_many_properties():
    # Test that caching works with many properties and only one call per property.
    N = 200
    call_counts = [0] * N

    def make_property(i):
        def getter(self):
            call_counts[i] += 1
            return i

        return property(getter)

    props = {"p%d" % i: make_property(i) for i in range(N)}
    __getattr__ = type("__getattr__", (), props)
    codeflash_output = caching_module_getattr(__getattr__)
    __getattr__ = codeflash_output  # 23.3μs -> 22.3μs (4.37% faster)

    for i in range(N):
        pass


def test_large_scale_attribute_error():
    # Test that AttributeError is still correct with many properties.
    N = 100
    props = {"a%d" % i: property(lambda self, v=i: v) for i in range(N)}
    __getattr__ = type("__getattr__", (), props)
    codeflash_output = caching_module_getattr(__getattr__)
    __getattr__ = codeflash_output  # 16.0μs -> 15.0μs (6.60% faster)

    with pytest.raises(AttributeError):
        __getattr__("not_present")


def test_large_scale_random_access():
    # Test random access order to properties.
    import random

    N = 300
    values = list(range(N))
    random.shuffle(values)
    props = {"x%d" % v: property(lambda self, val=v: val) for v in values}
    __getattr__ = type("__getattr__", (), props)
    codeflash_output = caching_module_getattr(__getattr__)
    __getattr__ = codeflash_output  # 27.8μs -> 26.4μs (5.35% faster)

    for v in values:
        pass
    for v in values:
        pass


def test_large_scale_property_with_side_effects():
    # Test that side effect for each property only occurs once with many properties.
    N = 100
    calls = [0] * N

    def make_property(i):
        def getter(self):
            calls[i] += 1
            return i

        return property(getter)

    props = {"y%d" % i: make_property(i) for i in range(N)}
    __getattr__ = type("__getattr__", (), props)
    codeflash_output = caching_module_getattr(__getattr__)
    __getattr__ = codeflash_output  # 16.9μs -> 15.6μs (8.55% faster)

    for i in range(N):
        pass


# codeflash_output is used to check that the output of the original code is the same as that of the optimized code.

To edit these changes git checkout codeflash/optimize-caching_module_getattr-mja6yf63 and push.

Codeflash Static Badge

The optimization achieves a **5% speedup** through two key changes that reduce overhead in the decorator setup and attribute lookup:

**Key Optimizations:**

1. **Direct dictionary access**: Replaced `vars(cls).items()` with `cls.__dict__.items()` when building the properties dictionary. This eliminates the overhead of the `vars()` function call, which internally performs additional work beyond a simple dictionary access.

2. **Single lookup pattern**: Changed from `name in props` followed by `props[name]` (two dictionary operations) to `props.get(name)` followed by a null check (one dictionary operation). This reduces dictionary lookups from 2 to 1 in the common case.

**Why it's faster:**

- `vars()` creates a proxy object and has additional overhead compared to direct `__dict__` access
- The `dict.get()` approach eliminates redundant hash computations and key lookups that occur with the `in` operator followed by indexing
- Line profiler shows the props building line dropped from 72.4% to 60.1% of total time, demonstrating the impact of the `vars()` → `__dict__` change

**Performance characteristics:**

The optimization benefits all test cases, with larger improvements (6-10%) seen in scenarios with many properties, as the dictionary operation savings compound. The caching behavior and error handling remain identical, ensuring no behavioral changes while providing consistent performance gains across different usage patterns.
@codeflash-ai codeflash-ai bot requested a review from mashraf-222 December 17, 2025 15:53
@codeflash-ai codeflash-ai bot added ⚡️ codeflash Optimization PR opened by Codeflash AI 🎯 Quality: Medium Optimization Quality according to Codeflash labels Dec 17, 2025
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