⚡️ Speed up function apply_diff by 4,799%

[codeflash-ai]

📄 4,799% (47.99x) speedup for apply_diff in openhands/resolver/patching/apply.py

⏱️ Runtime : 1.07 millisecond → 21.9 microseconds (best of 112 runs)

📝 Explanation and details

To make this Python program faster, we will focus on a few key optimizations.

1. Minimize File I/O: Reading and writing files can be slow, so attempts to reduce the need for file operations should be prioritized. We can use more efficient ways of handling temporary files.

2. Efficient String Handling: Use efficient string operations, such as str.join() and str.splitlines(), which handle large and small string operations quicker than manually looping and concatenating strings.

3. Optimize Import Statements: Import only the necessary functions or classes instead of the entire module.

Here is the optimized version of the provided code.

Key Improvements:

• Use of NamedTemporaryFile: This avoids the manual cleanup of file paths and makes file handling more robust and clean. The delete=False option is used to handle file removal manually, maintaining the same logic as before while using temporary files more effectively.

• Efficient List Comprehension: Leveraging list comprehensions and in-built string operations for efficiency in _reverse and apply_diff functions.

• Simplified Error Messages: Using formatted string literals (f'...') for more readable and concise error messages.

These changes are aimed at boosting the performance of the program by focusing on efficient data handling and reducing unnecessary file operations.

✅ Correctness verification report:

Test	Status
⚙️ Existing Unit Tests	✅ 3 Passed
🌀 Generated Regression Tests	✅ 5 Passed
⏪ Replay Tests	🔘 None Found
🔎 Concolic Coverage Tests	✅ 2 Passed
📊 Tests Coverage	92.6%

⚙️ Existing Unit Tests Details

- codeflash_concolic_ft4x35va/tmpd4u_rl3k/test_concolic_coverage.py
- unit/resolver/test_patch_apply.py
- unit/test_patch_whitespace.py

🌀 Generated Regression Tests Details

import os
import os.path
import subprocess
import tempfile
from shutil import rmtree

# imports
import pytest  # used for our unit tests
from openhands.resolver.patching.apply import apply_diff
from openhands.resolver.patching.exceptions import (HunkApplyException,
                                                    SubprocessException)
from openhands.resolver.patching.patch import Change, diffobj
from openhands.resolver.patching.snippets import remove, which

# unit tests

# Mock classes to simulate diffobj and Change
class MockChange:
    def __init__(self, old, new, line, hunk):
        self.old = old
        self.new = new
        self.line = line
        self.hunk = hunk

    def _replace(self, old, new):
        return MockChange(old, new, self.line, self.hunk)

class MockDiffObj:
    def __init__(self, changes, text='', header=''):
        self.changes = changes
        self.text = text
        self.header = header

# Basic Test Cases




def test_empty_diff():
    # Test applying empty diff
    original = ["line 1"]
    changes = []
    diff = MockDiffObj(changes)
    codeflash_output = apply_diff(diff, original); result = codeflash_output








import os
import os.path
import subprocess
import tempfile
from shutil import rmtree

# imports
import pytest  # used for our unit tests
from openhands.resolver.patching.apply import apply_diff
from openhands.resolver.patching.exceptions import (HunkApplyException,
                                                    SubprocessException)
from openhands.resolver.patching.patch import Change, diffobj
from openhands.resolver.patching.snippets import remove, which

# unit tests

class MockDiffObj:
    def __init__(self, changes, text='', header=''):
        self.changes = changes
        self.text = text
        self.header = header

@pytest.fixture
def simple_addition_diff():
    changes = [(None, 1, "Added line", None)]
    return MockDiffObj(changes)

@pytest.fixture
def simple_deletion_diff():
    changes = [(1, None, "Line to delete", None)]
    return MockDiffObj(changes)

@pytest.fixture
def simple_modification_diff():
    changes = [(1, 1, "Modified line", None)]
    return MockDiffObj(changes)

def test_apply_diff_addition(simple_addition_diff):
    original_text = ""
    expected_result = ["Added line"]
    codeflash_output = apply_diff(simple_addition_diff, original_text); result = codeflash_output

def test_apply_diff_deletion(simple_deletion_diff):
    original_text = "Line to delete"
    expected_result = []
    codeflash_output = apply_diff(simple_deletion_diff, original_text); result = codeflash_output


def test_apply_diff_empty_input():
    empty_diff = MockDiffObj([])
    original_text = ""
    expected_result = []
    codeflash_output = apply_diff(empty_diff, original_text); result = codeflash_output



def test_apply_diff_subprocess_error():
    with pytest.raises(SubprocessException):
        apply_diff(MockDiffObj([], text='invalid'), "", use_patch=True)

def test_apply_diff_whitespace_handling():
    changes = [(1, 1, "Line with    spaces", None)]
    diff = MockDiffObj(changes)
    original_text = "Line with spaces"
    expected_result = ["Line with    spaces"]
    codeflash_output = apply_diff(diff, original_text); result = codeflash_output



from openhands.resolver.patching.apply import apply_diff
from openhands.resolver.patching.patch import diffobj
import pytest

def test_apply_diff():
    apply_diff(diffobj('', '', 0), '\u202a', reverse=True, use_patch=False)

def test_apply_diff_2():
    with pytest.raises(SideEffectDetected, match='We\'ve\\ blocked\\ a\\ file\\ writing\\ operation\\ on\\ "/tmp/mutqrxrw"\\.\\ CrossHair\\ should\\ not\\ be\\ run\\ on\\ code\\ with\\ side\\ effects'):
        apply_diff(diffobj('', 0, ''), [], reverse=False, use_patch=True)

def test_apply_diff_3():
    with pytest.raises(ValueError, match='not\\ enough\\ values\\ to\\ unpack\\ \\(expected\\ 4,\\ got\\ 1\\)'):
        apply_diff(diffobj('', '\x00', ''), [], reverse=False, use_patch=False)

To edit these changes git checkout codeflash/optimize-apply_diff-m8wteqt9 and push.