⚡️ Speed up method Cache.pop by 24%

[codeflash-ai]

📄 24% (0.24x) speedup for Cache.pop in electrum/lrucache.py

⏱️ Runtime : 1.57 milliseconds → 1.27 milliseconds (best of 250 runs)

📝 Explanation and details

The optimization replaces a conditional check-then-access pattern with a try-except approach, achieving a 24% speedup by eliminating redundant dictionary lookups.

Key Changes:

• Original: Uses if key in self: followed by self[key] - this performs two dictionary lookups for existing keys
• Optimized: Uses try: self.__data[key] with exception handling - this performs only one dictionary lookup

Why It's Faster:

1. Eliminates redundant lookups: The original code does key in self (lookup ⚡️ Speed up function to_hexstr by 15% #1) then self[key] (lookup ⚡️ Speed up function derive_keys by 18% #2) for existing keys. The optimized version accesses self.__data[key] directly (single lookup).
2. Avoids method call overhead: Direct dictionary access (self.__data[key]) is faster than the __getitem__ method call (self[key]).
3. Leverages EAFP principle: "Easier to Ask for Forgiveness than Permission" - Python's exception handling is optimized for the common case where exceptions don't occur.

Performance Impact by Test Case:

• Existing keys (most common): 31-67% faster due to eliminating the redundant lookup
• Missing keys with defaults: 1-13% slower due to exception overhead, but this is the less common path
• Large-scale operations: 22-28% faster, showing consistent benefits under load

The line profiler confirms this: the original if key in self: line took 22.8% of total time and value = self[key] took 27%, totaling ~50% for two lookups. The optimized version reduces this to just 16.2% for the single self.__data[key] access.

This optimization follows the common Python pattern of optimizing for the success case while handling failures through exceptions, making it particularly effective for cache implementations where successful lookups are the dominant operation.

✅ Correctness verification report:

Test	Status
⚙️ Existing Unit Tests	🔘 None Found
🌀 Generated Regression Tests	✅ 3243 Passed
⏪ Replay Tests	🔘 None Found
🔎 Concolic Coverage Tests	🔘 None Found
📊 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 __getitem__(self, key):
        return 1
from electrum.lrucache import Cache  # --- End electrum/lrucache.py ---

# unit tests

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

def test_pop_existing_key_removes_and_returns_value():
    # Test removal and return of an existing key
    cache = Cache(maxsize=10)
    cache['a'] = 1
    cache['b'] = 2
    codeflash_output = cache.pop('a'); val = codeflash_output # 1.64μs -> 1.03μs (59.5% faster)

def test_pop_non_existing_key_raises_keyerror():
    # Test popping a non-existing key raises KeyError
    cache = Cache(maxsize=10)
    cache['x'] = 42
    with pytest.raises(KeyError):
        cache.pop('y') # 1.15μs -> 1.24μs (7.17% slower)

def test_pop_non_existing_key_with_default_returns_default():
    # Test popping a non-existing key with default returns default
    cache = Cache(maxsize=10)
    cache['x'] = 42
    codeflash_output = cache.pop('y', default='default_value'); result = codeflash_output # 1.00μs -> 1.10μs (9.06% slower)

def test_pop_existing_key_with_default_returns_value():
    # Test popping an existing key with default returns value, not default
    cache = Cache(maxsize=10)
    cache['foo'] = 'bar'
    codeflash_output = cache.pop('foo', default='baz'); result = codeflash_output # 1.80μs -> 1.30μs (38.4% faster)

def test_pop_reduces_length_and_currsize():
    # Test that pop reduces both length and currsize
    cache = Cache(maxsize=10)
    cache['a'] = 1
    cache['b'] = 2
    old_len = len(cache)
    old_currsize = cache._Cache__currsize
    cache.pop('a') # 1.30μs -> 994ns (31.1% faster)

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

def test_pop_on_empty_cache_raises_keyerror():
    # Edge case: pop from an empty cache
    cache = Cache(maxsize=10)
    with pytest.raises(KeyError):
        cache.pop('nope') # 1.21μs -> 1.24μs (1.94% slower)

def test_pop_on_empty_cache_with_default_returns_default():
    # Edge case: pop from empty cache with default
    cache = Cache(maxsize=10)
    codeflash_output = cache.pop('nope', default=123); result = codeflash_output # 1.06μs -> 1.08μs (1.39% slower)

def test_pop_with_none_key():
    # Edge case: None as a key
    cache = Cache(maxsize=10)
    cache[None] = 'value'
    codeflash_output = cache.pop(None); val = codeflash_output # 1.58μs -> 1.09μs (44.5% faster)

def test_pop_with_zero_key():
    # Edge case: 0 as a key
    cache = Cache(maxsize=10)
    cache[0] = 'zero'
    codeflash_output = cache.pop(0); val = codeflash_output # 1.48μs -> 1.03μs (43.0% faster)

def test_pop_with_tuple_key():
    # Edge case: tuple as a key
    cache = Cache(maxsize=10)
    key = (1, 2, 3)
    cache[key] = 'tuple'
    codeflash_output = cache.pop(key); val = codeflash_output # 1.49μs -> 1.08μs (38.1% faster)

def test_pop_with_false_and_true_keys():
    # Edge case: False and True as keys
    cache = Cache(maxsize=10)
    cache[False] = 'false'
    cache[True] = 'true'
    codeflash_output = cache.pop(False) # 1.41μs -> 1.02μs (37.6% faster)
    codeflash_output = cache.pop(True) # 692ns -> 528ns (31.1% faster)

def test_pop_with_custom_object_key():
    # Edge case: custom object as key
    class MyKey:
        def __init__(self, val): self.val = val
        def __hash__(self): return hash(self.val)
        def __eq__(self, other): return isinstance(other, MyKey) and self.val == other.val

    cache = Cache(maxsize=10)
    key = MyKey(42)
    cache[key] = 'obj'
    codeflash_output = cache.pop(key) # 1.67μs -> 1.13μs (47.4% faster)

def test_pop_with_mutable_default():
    # Edge case: mutable default value
    cache = Cache(maxsize=10)
    default = []
    codeflash_output = cache.pop('missing', default=default); result = codeflash_output # 1.02μs -> 1.18μs (13.6% slower)

def test_pop_with_multiple_types_of_keys():
    # Edge case: keys of different types
    cache = Cache(maxsize=10)
    cache['str'] = 1
    cache[100] = 2
    cache[(1,2)] = 3
    codeflash_output = cache.pop('str') # 1.46μs -> 977ns (48.9% faster)
    codeflash_output = cache.pop(100) # 708ns -> 499ns (41.9% faster)
    codeflash_output = cache.pop((1,2)) # 548ns -> 489ns (12.1% faster)

def test_pop_does_not_affect_other_keys():
    # Edge case: pop only affects the specified key
    cache = Cache(maxsize=10)
    cache['a'] = 1
    cache['b'] = 2
    cache['c'] = 3
    cache.pop('b') # 1.33μs -> 940ns (41.5% faster)

def test_pop_with_key_that_was_evicted():
    # Edge case: pop a key that was evicted due to maxsize
    cache = Cache(maxsize=2)
    cache['x'] = 1
    cache['y'] = 2
    cache['z'] = 3  # Should evict 'x'
    with pytest.raises(KeyError):
        cache.pop('x') # 1.21μs -> 1.27μs (4.95% slower)

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

def test_pop_many_keys():
    # Large scale: pop many keys from a cache
    cache = Cache(maxsize=1000)
    for i in range(500):
        cache[i] = i
    # Pop all keys and check correctness
    for i in range(500):
        codeflash_output = cache.pop(i) # 223μs -> 180μs (23.9% faster)

def test_pop_with_large_default():
    # Large scale: pop missing key with large default object
    cache = Cache(maxsize=1000)
    big_default = list(range(1000))
    codeflash_output = cache.pop('missing', default=big_default); result = codeflash_output # 1.17μs -> 1.23μs (5.05% slower)

def test_pop_performance_under_load():
    # Large scale: pop performance under load (not timing, but correctness)
    cache = Cache(maxsize=1000)
    # Fill cache with 1000 keys
    for i in range(1000):
        cache[i] = i
    # Remove 500 keys
    for i in range(500):
        codeflash_output = cache.pop(i); val = codeflash_output # 224μs -> 179μs (24.9% faster)
    # Remaining keys
    for i in range(500, 1000):
        pass

def test_pop_with_large_string_keys():
    # Large scale: pop with large string keys
    cache = Cache(maxsize=1000)
    for i in range(500):
        key = 'key_' + str(i)
        cache[key] = i
    for i in range(500):
        key = 'key_' + str(i)
        codeflash_output = cache.pop(key) # 227μs -> 183μs (24.5% faster)

def test_pop_with_large_tuple_keys():
    # Large scale: pop with large tuple keys
    cache = Cache(maxsize=1000)
    for i in range(500):
        key = (i, i+1, i+2)
        cache[key] = i
    for i in range(500):
        key = (i, i+1, i+2)
        codeflash_output = cache.pop(key) # 257μs -> 202μs (27.1% faster)

def test_pop_with_large_custom_object_keys():
    # Large scale: pop with custom object keys
    class KeyObj:
        def __init__(self, x): self.x = x
        def __hash__(self): return hash(self.x)
        def __eq__(self, other): return isinstance(other, KeyObj) and self.x == other.x
    cache = Cache(maxsize=1000)
    keys = [KeyObj(i) for i in range(500)]
    for i, k in enumerate(keys):
        cache[k] = i
    for i, k in enumerate(keys):
        codeflash_output = cache.pop(k) # 306μs -> 239μs (28.0% faster)
# 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
from electrum.lrucache import Cache

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

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

# unit tests

# --- Basic Test Cases ---

def test_pop_existing_key_removes_and_returns_value():
    # Test popping an existing key returns its value and removes it from cache
    cache = Cache(maxsize=10)
    cache['a'] = 1
    codeflash_output = cache.pop('a'); result = codeflash_output # 1.70μs -> 1.01μs (67.6% faster)

def test_pop_multiple_keys():
    # Test popping several keys in sequence
    cache = Cache(maxsize=10)
    cache['x'] = 100
    cache['y'] = 200
    codeflash_output = cache.pop('x') # 1.33μs -> 899ns (48.4% faster)
    codeflash_output = cache.pop('y') # 785ns -> 536ns (46.5% faster)

def test_pop_returns_default_when_key_missing():
    # Test popping a missing key with a default returns the default value
    cache = Cache(maxsize=10)
    cache['a'] = 1
    codeflash_output = cache.pop('b', default=42); result = codeflash_output # 1.00μs -> 1.14μs (12.5% slower)

def test_pop_raises_keyerror_when_key_missing_and_no_default():
    # Test popping a missing key without a default raises KeyError
    cache = Cache(maxsize=10)
    cache['a'] = 1
    with pytest.raises(KeyError):
        cache.pop('b') # 1.21μs -> 1.24μs (2.50% slower)

def test_pop_with_none_default_returns_none():
    # Test popping a missing key with None as default returns None
    cache = Cache(maxsize=10)
    codeflash_output = cache.pop('missing', default=None); result = codeflash_output # 1.03μs -> 1.09μs (6.03% slower)

def test_pop_with_falsey_default_returns_falsey():
    # Test popping a missing key with a falsey default (0, False, '') returns that value
    cache = Cache(maxsize=10)
    codeflash_output = cache.pop('missing', default=0) # 886ns -> 931ns (4.83% slower)
    codeflash_output = cache.pop('missing2', default=False) # 404ns -> 390ns (3.59% faster)
    codeflash_output = cache.pop('missing3', default='') # 277ns -> 310ns (10.6% slower)

def test_pop_and_cache_size_update():
    # Test that pop updates the cache size correctly
    cache = Cache(maxsize=10)
    cache['a'] = 1
    cache['b'] = 2
    size_before = len(cache)
    cache.pop('a') # 1.53μs -> 1.15μs (32.4% faster)

# --- Edge Test Cases ---

def test_pop_on_empty_cache_raises_keyerror():
    # Test popping from an empty cache raises KeyError
    cache = Cache(maxsize=10)
    with pytest.raises(KeyError):
        cache.pop('anykey') # 1.17μs -> 1.20μs (2.33% slower)

def test_pop_on_empty_cache_with_default_returns_default():
    # Test popping from an empty cache with a default returns the default
    cache = Cache(maxsize=10)
    codeflash_output = cache.pop('anykey', default='default') # 983ns -> 1.06μs (7.09% slower)

def test_pop_key_with_mutable_value():
    # Test popping a key with a mutable value (list)
    cache = Cache(maxsize=10)
    cache['list'] = [1,2,3]
    codeflash_output = cache.pop('list'); val = codeflash_output # 1.52μs -> 1.11μs (37.3% faster)

def test_pop_key_with_tuple_key():
    # Test popping a key that is a tuple
    cache = Cache(maxsize=10)
    key = (1,2)
    cache[key] = 'tuple'
    codeflash_output = cache.pop(key) # 1.50μs -> 1.06μs (40.6% faster)

def test_pop_key_with_none_as_key():
    # Test popping a key where key is None
    cache = Cache(maxsize=10)
    cache[None] = 'none'
    codeflash_output = cache.pop(None) # 1.37μs -> 1.04μs (31.3% faster)

def test_pop_key_with_object_key():
    # Test popping a key that is a custom object
    class MyKey:
        pass
    k = MyKey()
    cache = Cache(maxsize=10)
    cache[k] = 'val'
    codeflash_output = cache.pop(k) # 1.41μs -> 1.00μs (40.5% faster)

def test_pop_after_cache_eviction():
    # Test popping a key that was evicted due to maxsize
    cache = Cache(maxsize=2)
    cache['a'] = 1
    cache['b'] = 2
    cache['c'] = 3  # This should evict 'a'
    with pytest.raises(KeyError):
        cache.pop('a') # 1.17μs -> 1.17μs (0.000% faster)

def test_pop_with_custom_getsizeof():
    # Test pop with custom getsizeof function
    def getsizeof(val):
        return len(str(val))
    cache = Cache(maxsize=10, getsizeof=getsizeof)
    cache['a'] = '123'
    cache['b'] = '4567'
    codeflash_output = cache.pop('a') # 1.52μs -> 1.03μs (47.8% faster)

def test_pop_key_with_int_key():
    # Test popping a key that is an integer
    cache = Cache(maxsize=10)
    cache[42] = 'answer'
    codeflash_output = cache.pop(42) # 1.43μs -> 1.09μs (31.1% faster)

def test_pop_key_with_float_key():
    # Test popping a key that is a float
    cache = Cache(maxsize=10)
    cache[3.14] = 'pi'
    codeflash_output = cache.pop(3.14) # 1.48μs -> 1.04μs (42.1% faster)

def test_pop_key_with_bool_key():
    # Test popping a key that is a boolean
    cache = Cache(maxsize=10)
    cache[True] = 'yes'
    codeflash_output = cache.pop(True) # 1.36μs -> 1.03μs (32.9% faster)

def test_pop_key_with_large_value_object():
    # Test popping a key with a large value (simulate with getsizeof)
    def getsizeof(val):
        return 5
    cache = Cache(maxsize=10, getsizeof=getsizeof)
    cache['big'] = 'xxxxx'
    codeflash_output = cache.pop('big') # 1.42μs -> 997ns (42.6% faster)

def test_pop_key_with_value_too_large():
    # Test that inserting a value too large raises ValueError, so pop never sees it
    def getsizeof(val):
        return 20
    cache = Cache(maxsize=10, getsizeof=getsizeof)
    with pytest.raises(ValueError):
        cache['huge'] = 'this is too big'
    # Now pop should not find the key
    codeflash_output = cache.pop('huge', default='not found') # 1.02μs -> 1.09μs (6.42% slower)

# --- Large Scale Test Cases ---

def test_pop_many_keys():
    # Test popping many keys in a cache with many items
    cache = Cache(maxsize=1000)
    for i in range(500):
        cache[i] = i*2
    # Pop half the keys and check
    for i in range(250):
        codeflash_output = cache.pop(i); val = codeflash_output # 111μs -> 91.6μs (22.2% faster)
    # Remaining keys should still be present
    for i in range(250, 500):
        pass

def test_pop_all_keys_until_empty():
    # Test popping all keys until cache is empty
    cache = Cache(maxsize=1000)
    for i in range(100):
        cache[i] = i
    for i in range(100):
        codeflash_output = cache.pop(i); val = codeflash_output # 44.9μs -> 36.6μs (22.7% faster)

def test_pop_on_large_cache_with_missing_key():
    # Test popping a missing key from a large cache
    cache = Cache(maxsize=1000)
    for i in range(900):
        cache[i] = i
    with pytest.raises(KeyError):
        cache.pop(9999) # 1.29μs -> 1.34μs (3.87% slower)

def test_pop_on_large_cache_with_default():
    # Test popping a missing key from a large cache with default
    cache = Cache(maxsize=1000)
    for i in range(900):
        cache[i] = i
    codeflash_output = cache.pop(9999, default='missing') # 1.08μs -> 1.17μs (7.53% slower)

def test_pop_performance_large_cache():
    # Test pop performance on a cache with many elements (not a timing test, just functional)
    cache = Cache(maxsize=1000)
    for i in range(1000):
        cache[i] = i
    # Pop 100 random keys
    for i in range(0, 1000, 10):
        codeflash_output = cache.pop(i); val = codeflash_output # 48.0μs -> 37.7μs (27.4% faster)

def test_pop_after_eviction_large_cache():
    # Test pop after some keys were evicted in a large cache
    cache = Cache(maxsize=500)
    for i in range(500):
        cache[i] = i
    # Add more to force eviction
    for i in range(500, 600):
        cache[i] = i
    # Old keys should be evicted
    for i in range(100):
        codeflash_output = cache.pop(i, default='evicted') # 29.4μs -> 33.1μs (11.3% slower)
    # New keys should be present
    for i in range(500, 600):
        codeflash_output = cache.pop(i) # 45.6μs -> 36.3μs (25.6% faster)
# 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-Cache.pop-mhx88bds and push.