⚡️ Speed up method Cache.get by 50%

[codeflash-ai]

📄 50% (0.50x) speedup for Cache.get in electrum/lrucache.py

⏱️ Runtime : 960 microseconds → 640 microseconds (best of 244 runs)

📝 Explanation and details

The optimized code achieves a 49% speedup by eliminating redundant dictionary lookups in the get() method. The key optimization replaces the pattern if key in self: return self[key] with val = self.__data.get(key, None); if val is not None or key in self.__data: return val.

Key Performance Improvements:

1. Reduced Dictionary Operations: The original code performs up to 3 dictionary operations per get() call:

   • key in self (triggers __contains__ → key in self.__data)
   • self[key] (triggers __getitem__ → self.__data[key])
   • Plus potential __missing__ handling

   The optimized version uses just 1-2 operations:

   • self.__data.get(key, None) (single lookup with default)
   • key in self.__data (only when value is None to distinguish missing keys from None values)

2. Direct Data Access: Bypasses the MutableMapping protocol overhead by accessing self.__data directly rather than going through self[key] which involves method dispatch.

3. Proper None Handling: The val is not None or key in self.__data check correctly handles cases where the stored value is actually None, ensuring semantic correctness while maintaining performance.

Test Results Show Consistent Gains:

• Existing key lookups: 67-106% faster (most common case)
• Missing key lookups: Slight overhead (2-20% slower) due to the additional None check, but this is the less common path
• Falsy values (0, '', False): 51-98% faster, demonstrating the optimization handles edge cases well

The optimization is particularly effective for cache hit scenarios (existing keys), which are typically the most frequent operations in cache usage patterns. The minor slowdown for cache misses is acceptable given the substantial gains for cache hits.

✅ Correctness verification report:

Test	Status
⚙️ Existing Unit Tests	🔘 None Found
🌀 Generated Regression Tests	✅ 3735 Passed
⏪ Replay Tests	🔘 None Found
🔎 Concolic Coverage Tests	✅ 2 Passed
📊 Tests Coverage	100.0%

🌀 Generated Regression Tests and Runtime

import collections.abc
from typing import TypeVar

# imports
import pytest
from electrum.lrucache import Cache

_KT = TypeVar("_KT")
_VT = TypeVar("_VT")

class _DefaultSize(dict):
    def __missing__(self, key):
        return 1
from electrum.lrucache import Cache

# unit tests

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

def test_get_existing_key_returns_value():
    # Test that get returns the correct value for an existing key
    c = Cache(10)
    c['a'] = 1
    codeflash_output = c.get('a') # 778ns -> 417ns (86.6% faster)

def test_get_nonexisting_key_returns_none():
    # Test that get returns None for a missing key and no default
    c = Cache(10)
    codeflash_output = c.get('missing') # 572ns -> 559ns (2.33% faster)

def test_get_nonexisting_key_returns_default():
    # Test that get returns the specified default for missing key
    c = Cache(10)
    codeflash_output = c.get('missing', 42) # 588ns -> 542ns (8.49% faster)

def test_get_existing_key_with_default_ignores_default():
    # Test that get returns the value, not the default, for existing key
    c = Cache(10)
    c['x'] = 'y'
    codeflash_output = c.get('x', 'z') # 781ns -> 430ns (81.6% faster)

def test_get_with_various_types_of_keys_and_values():
    # Test get with int, str, tuple as keys and values
    c = Cache(10)
    c[123] = 'abc'
    c['foo'] = 456
    c[(1,2)] = [3,4]
    codeflash_output = c.get(123) # 809ns -> 470ns (72.1% faster)
    codeflash_output = c.get('foo') # 430ns -> 257ns (67.3% faster)
    codeflash_output = c.get((1,2)) # 386ns -> 256ns (50.8% faster)
    codeflash_output = c.get('notfound', 'default') # 307ns -> 369ns (16.8% slower)

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

def test_get_empty_cache():
    # Test get on an empty cache
    c = Cache(5)
    codeflash_output = c.get('nope') # 568ns -> 543ns (4.60% faster)
    codeflash_output = c.get('nope', 99) # 308ns -> 286ns (7.69% faster)

def test_get_after_eviction():
    # Test get after items are evicted due to maxsize
    c = Cache(2)
    c['a'] = 1
    c['b'] = 2
    c['c'] = 3  # This should evict 'a'
    codeflash_output = c.get('a') # 541ns -> 524ns (3.24% faster)
    codeflash_output = c.get('b') # 585ns -> 294ns (99.0% faster)
    codeflash_output = c.get('c') # 282ns -> 183ns (54.1% faster)

def test_get_after_deletion():
    # Test get after an item has been deleted
    c = Cache(3)
    c['foo'] = 'bar'
    del c['foo']
    codeflash_output = c.get('foo') # 499ns -> 520ns (4.04% slower)

def test_get_with_none_as_key_and_value():
    # Test get with None as key and value
    c = Cache(2)
    c[None] = None
    codeflash_output = c.get(None) # 792ns -> 535ns (48.0% faster)
    codeflash_output = c.get('missing', None) # 392ns -> 391ns (0.256% faster)

def test_get_with_falsey_values():
    # Test get with values that are falsey (0, '', False)
    c = Cache(3)
    c['zero'] = 0
    c['empty'] = ''
    c['false'] = False
    codeflash_output = c.get('zero') # 767ns -> 387ns (98.2% faster)
    codeflash_output = c.get('empty') # 353ns -> 220ns (60.5% faster)
    codeflash_output = c.get('false') # 277ns -> 171ns (62.0% faster)
    codeflash_output = c.get('missing', 0) # 291ns -> 343ns (15.2% slower)

def test_get_with_custom_getsizeof():
    # Test get with a custom getsizeof function
    def getsizeof(val):
        return len(str(val))
    c = Cache(5, getsizeof=getsizeof)
    c['a'] = 'xx'
    c['b'] = 'yyy'
    # 'a' size 2, 'b' size 3, total 5
    codeflash_output = c.get('a') # 672ns -> 380ns (76.8% faster)
    codeflash_output = c.get('b') # 350ns -> 211ns (65.9% faster)
    c['c'] = 'zzzz'  # size 4, should evict 'a' and/or 'b'
    # Only one of 'a' or 'b' can remain, depending on eviction order
    codeflash_output = c.get('c') # 373ns -> 256ns (45.7% faster)


def test_get_with_object_key():
    # Test get with a key that is a custom object
    class Key:
        def __init__(self, v): self.v = v
        def __hash__(self): return hash(self.v)
        def __eq__(self, other): return isinstance(other, Key) and self.v == other.v
    c = Cache(3)
    k = Key(5)
    c[k] = 'val'
    codeflash_output = c.get(Key(5)) # 2.10μs -> 1.26μs (67.0% faster)
    codeflash_output = c.get(Key(6)) # 419ns -> 524ns (20.0% slower)


def test_get_large_number_of_keys():
    # Test get with a large number of keys
    c = Cache(1000)
    for i in range(1000):
        c[i] = i * 2
    # All keys should be present
    for i in range(1000):
        codeflash_output = c.get(i) # 275μs -> 162μs (69.3% faster)
    # A missing key
    codeflash_output = c.get(1001) # 278ns -> 322ns (13.7% slower)

def test_get_large_number_of_evictions():
    # Test get with many evictions
    c = Cache(10)
    for i in range(20):
        c[i] = i
    # Only last 10 keys should be present
    for i in range(10):
        codeflash_output = c.get(i) # 2.72μs -> 2.70μs (0.666% faster)
    for i in range(10, 20):
        codeflash_output = c.get(i) # 2.82μs -> 1.65μs (71.2% faster)

def test_get_large_scale_with_custom_getsizeof():
    # Test get with large scale and custom getsizeof
    def getsizeof(val): return val
    c = Cache(100, getsizeof=getsizeof)
    # Insert values with varying sizes
    for i in range(1, 21):
        c[i] = i  # sizes 1..20, total 210, so evictions will happen
    # Only values that fit should remain
    currsize = sum(c._Cache__size.values())
    for k in c:
        codeflash_output = c.get(k) # 1.81μs -> 1.11μs (63.6% faster)
    # Try to get a key that was likely evicted
    codeflash_output = c.get(1) # 275ns -> 289ns (4.84% slower)

def test_get_performance_with_many_gets():
    # Test that get is fast for many lookups (functional, not timing)
    c = Cache(500)
    for i in range(500):
        c[i] = i
    # Do many gets
    for i in range(500):
        codeflash_output = c.get(i) # 135μs -> 81.4μs (66.4% faster)
    for i in range(500, 600):
        codeflash_output = c.get(i, 'notfound') # 18.6μs -> 17.8μs (4.74% faster)

def test_get_with_large_keys_and_values():
    # Test get with large (but <1000) keys and values
    c = Cache(1000)
    big_key = tuple(range(500))
    big_val = list(range(500))
    c[big_key] = big_val
    codeflash_output = c.get(big_key) # 2.70μs -> 1.39μs (94.0% faster)
    codeflash_output = c.get(tuple(range(499))) # 1.18μs -> 2.06μs (42.8% slower)
# codeflash_output is used to check that the output of the original code is the same as that of the optimized code.
#------------------------------------------------
import collections.abc
from typing import TypeVar

# imports
import pytest  # used for our unit tests
from electrum.lrucache import Cache


# function to test
class _DefaultSize:
    def __getitem__(self, key):
        return 1
    def __setitem__(self, key, value):
        pass
    def __delitem__(self, key):
        pass


_KT = TypeVar("_KT")
_VT = TypeVar("_VT")
from electrum.lrucache import Cache

# unit tests

# Basic Test Cases

def test_get_existing_key_returns_value():
    # Test that get returns the value for an existing key
    cache = Cache(maxsize=10)
    cache["a"] = 1
    codeflash_output = cache.get("a") # 910ns -> 441ns (106% faster)

def test_get_nonexistent_key_returns_default_none():
    # Test that get returns None for a missing key if no default provided
    cache = Cache(maxsize=10)
    codeflash_output = cache.get("missing") # 567ns -> 596ns (4.87% slower)

def test_get_nonexistent_key_returns_specified_default():
    # Test that get returns the specified default for a missing key
    cache = Cache(maxsize=10)
    codeflash_output = cache.get("missing", default=42) # 787ns -> 805ns (2.24% slower)

def test_get_existing_key_with_default_returns_value():
    # Test that get returns the value for an existing key, even if default is given
    cache = Cache(maxsize=10)
    cache["x"] = 99
    codeflash_output = cache.get("x", default=123) # 1.02μs -> 600ns (70.8% faster)

def test_get_after_deletion():
    # Test that get returns default after key is deleted
    cache = Cache(maxsize=10)
    cache["y"] = "test"
    del cache["y"]
    codeflash_output = cache.get("y", default="deleted") # 708ns -> 734ns (3.54% slower)

# Edge Test Cases

def test_get_key_with_none_value():
    # Test that get returns None if value is actually None
    cache = Cache(maxsize=10)
    cache["none"] = None
    # Should distinguish between missing key and key with None value
    codeflash_output = cache.get("none") # 800ns -> 525ns (52.4% faster)

def test_get_with_unhashable_key_raises():
    # Test that get raises TypeError for unhashable key
    cache = Cache(maxsize=10)
    with pytest.raises(TypeError):
        cache.get(["unhashable"]) # 1.28μs -> 1.12μs (14.6% faster)

def test_get_with_key_of_different_type():
    # Test that get works for keys of different types
    cache = Cache(maxsize=10)
    cache[1] = "int"
    cache[(2, 3)] = "tuple"
    codeflash_output = cache.get(1) # 930ns -> 535ns (73.8% faster)
    codeflash_output = cache.get((2, 3)) # 488ns -> 341ns (43.1% faster)
    codeflash_output = cache.get("string") # 295ns -> 364ns (19.0% slower)

def test_get_with_custom_default_types():
    # Test that get returns custom default types
    cache = Cache(maxsize=10)
    default_list = [1, 2]
    codeflash_output = cache.get("missing", default=default_list) # 764ns -> 751ns (1.73% faster)
    default_dict = {"a": 1}
    codeflash_output = cache.get("missing", default=default_dict) # 330ns -> 326ns (1.23% faster)

def test_get_with_key_deleted_after_insertion():
    # Test that get returns default after key is deleted immediately after insertion
    cache = Cache(maxsize=10)
    cache["temp"] = "value"
    del cache["temp"]
    codeflash_output = cache.get("temp", default="gone") # 702ns -> 690ns (1.74% faster)

def test_get_with_maxsize_zero():
    # Test that cache with maxsize=0 cannot store any value
    cache = Cache(maxsize=0)
    with pytest.raises(ValueError):
        cache["a"] = 1
    codeflash_output = cache.get("a") # 542ns -> 502ns (7.97% faster)

def test_get_with_value_too_large():
    # Test that cache raises ValueError if value is too large
    def getsizeof(value):
        return 5
    cache = Cache(maxsize=4, getsizeof=getsizeof)
    with pytest.raises(ValueError):
        cache["big"] = "large"
    codeflash_output = cache.get("big") # 538ns -> 520ns (3.46% faster)

def test_get_with_key_set_to_false_like_value():
    # Test that get correctly returns false-like values
    cache = Cache(maxsize=10)
    cache["zero"] = 0
    cache["empty"] = ""
    cache["false"] = False
    codeflash_output = cache.get("zero") # 814ns -> 454ns (79.3% faster)
    codeflash_output = cache.get("empty") # 364ns -> 229ns (59.0% faster)
    codeflash_output = cache.get("false") # 262ns -> 173ns (51.4% faster)

def test_get_with_key_set_to_object():
    # Test that get works for object values
    cache = Cache(maxsize=10)
    obj = object()
    cache["obj"] = obj
    codeflash_output = cache.get("obj") # 725ns -> 395ns (83.5% faster)

def test_get_with_key_set_to_none_and_default_none():
    # Test that get returns None for existing key with None value, not the default
    cache = Cache(maxsize=10)
    cache["foo"] = None
    codeflash_output = cache.get("foo", default="bar") # 955ns -> 714ns (33.8% faster)

# Large Scale Test Cases

def test_get_many_keys():
    # Test that get works for many keys (scalability)
    cache = Cache(maxsize=1000)
    for i in range(1000):
        cache[i] = i * 2
    # Check several keys at boundaries and in the middle
    codeflash_output = cache.get(0) # 843ns -> 555ns (51.9% faster)
    codeflash_output = cache.get(999) # 518ns -> 347ns (49.3% faster)
    codeflash_output = cache.get(500) # 316ns -> 173ns (82.7% faster)
    codeflash_output = cache.get(1001) # 269ns -> 301ns (10.6% slower)

def test_get_after_eviction():
    # Test that get returns default after eviction due to maxsize
    cache = Cache(maxsize=10)
    for i in range(15):
        cache[i] = i
    # Only last 10 keys should remain, others evicted
    for i in range(5):
        codeflash_output = cache.get(i) # 1.45μs -> 1.52μs (4.92% slower)
    for i in range(5, 15):
        codeflash_output = cache.get(i) # 2.80μs -> 1.68μs (67.0% faster)

def test_get_with_large_values_and_custom_getsizeof():
    # Test that get works with custom getsizeof and large values
    def getsizeof(value):
        return len(str(value))
    cache = Cache(maxsize=1000, getsizeof=getsizeof)
    for i in range(1000):
        cache[i] = "x" * (i % 10 + 1)
    # All keys should be present, as each value's size is <= 10
    for i in range(1000):
        codeflash_output = cache.get(i) # 207μs -> 176μs (17.7% faster)
    # Try a value that is too big
    with pytest.raises(ValueError):
        cache[1001] = "y" * 1001
    codeflash_output = cache.get(1001) # 281ns -> 265ns (6.04% faster)

def test_get_with_large_number_of_false_like_values():
    # Test that get works for many keys with false-like values
    cache = Cache(maxsize=1000)
    for i in range(1000):
        cache[i] = 0
    for i in range(1000):
        codeflash_output = cache.get(i) # 274μs -> 165μs (66.5% faster)

def test_get_performance_with_large_cache():
    # Test that get is fast for large cache (no actual timing, just correctness)
    cache = Cache(maxsize=1000)
    for i in range(1000):
        cache[i] = i
    # Spot check a few keys
    for i in [0, 499, 999]:
        codeflash_output = cache.get(i) # 1.71μs -> 973ns (76.1% faster)
    # Check missing key
    codeflash_output = cache.get(1001) # 266ns -> 300ns (11.3% slower)
# codeflash_output is used to check that the output of the original code is the same as that of the optimized code.
#------------------------------------------------
from electrum.lrucache import Cache

def test_Cache_get():
    Cache.get(Cache(0, getsizeof=2), 0, default=0)

🔎 Concolic Coverage Tests and Runtime

Test File::Test Function	Original ⏱️	Optimized ⏱️	Speedup
codeflash_concolic__t1ksq9u/tmpkr0paslk/test_concolic_coverage.py::test_Cache_get	861ns	830ns	3.73%✅

To edit these changes git checkout codeflash/optimize-Cache.get-mhlhflgp and push.