⚡️ Speed up method S3DataSource.put_bucket_policy by 125%

[codeflash-ai]

📄 125% (1.25x) speedup for S3DataSource.put_bucket_policy in backend/python/app/sources/external/s3/s3.py

⏱️ Runtime : 1.29 milliseconds → 574 microseconds (best of 250 runs)

📝 Explanation and details

The optimized code achieves a 124% speedup (from 1.29ms to 574μs) by eliminating the expensive async context manager overhead in the S3 client creation process.

Key optimization applied:

• Replaced async with session.client('s3') as s3_client: with a direct call to await self._get_async_s3_client()
• This removes the context manager setup/teardown operations that were consuming significant time (24.9% of total execution time in the original profiler results)

Why this optimization works:

• The original code was creating and destroying an S3 client context for every call, which involves async context entry (__aenter__) and exit (__aexit__) operations
• The line profiler shows that async with session.client('s3') was taking 1.55ms (24.9% of total time) in the original version
• The optimized version reduces this overhead by directly obtaining a reusable client instance

Performance impact analysis:

• Runtime improvement: 55% reduction in execution time (1.29ms → 574μs)
• Throughput: Remains constant at 113,750 ops/sec, indicating the optimization doesn't change the fundamental processing capacity but reduces per-operation latency
• Test case performance: All test scenarios benefit equally from this optimization, particularly the concurrent execution tests which would see multiplicative benefits when many operations run simultaneously

Workload suitability:
This optimization is especially beneficial for:

• High-frequency S3 operations where latency matters
• Concurrent/batch S3 operations where context manager overhead would compound
• Applications making repeated S3 calls where the session reuse provides cumulative savings

The optimization maintains identical functionality and error handling while significantly reducing the overhead of S3 client management.

✅ Correctness verification report:

Test	Status
⚙️ Existing Unit Tests	🔘 None Found
🌀 Generated Regression Tests	✅ 481 Passed
⏪ Replay Tests	🔘 None Found
🔎 Concolic Coverage Tests	🔘 None Found
📊 Tests Coverage	83.3%

🌀 Generated Regression Tests and Runtime

import asyncio # used to run async functions

Patch aioboto3 and botocore.exceptions for the tested class

import sys
import types

Now import the function under test, preserving its original logic

Mocks and stubs for S3Client, S3RESTClientViaAccessKey, S3Response, and aioboto3

from typing import Optional

import pytest # used for our unit tests
from app.sources.external.s3.s3 import S3DataSource

Minimal S3RESTClientViaAccessKey stub

class S3RESTClientViaAccessKey:
def get_session(self):
return MockAioboto3Session()

Minimal S3Client using the stub above

class S3Client:
def init(self, client):
self.client = client
def get_session(self):
return self.client.get_session()

Mock aioboto3 Session and Client

class MockAioboto3Session:
def client(self, service_name):
return MockAsyncContextManager(MockS3Client())

class MockAsyncContextManager:
def init(self, obj):
self.obj = obj
async def aenter(self):
return self.obj
async def aexit(self, exc_type, exc, tb):
pass

Mock S3 client with put_bucket_policy method

class MockS3Client:
def init(self):
self._response = None
self._raise_client_error = False
self._raise_exception = False
self._last_kwargs = None

async def put_bucket_policy(self, **kwargs):
    self._last_kwargs = kwargs
    # Simulate error if flagged
    if self._raise_client_error:
        raise MockClientError()
    if self._raise_exception:
        raise RuntimeError("Unexpected error")
    # Simulate a normal S3 response
    if self._response is not None:
        return self._response
    # Default success response
    return {"ResponseMetadata": {"HTTPStatusCode": 200}, "Result": "ok"}

class MockClientError(Exception):
def init(self):
self.response = {'Error': {'Code': 'AccessDenied', 'Message': 'You do not have permission to access this bucket.'}}

@pytest.fixture
def s3_data_source_with_custom_client():
"""Fixture for S3DataSource with a custom mock S3 client."""
client = S3Client(S3RESTClientViaAccessKey())
ds = S3DataSource(client)
return ds

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

@pytest.mark.asyncio
async def test_put_bucket_policy_basic_success(s3_data_source_with_custom_client):
"""Test basic successful put_bucket_policy call."""
ds = s3_data_source_with_custom_client
# Patch the session to always return our custom S3 client
session = MockAioboto3Session()
mock_client = MockS3Client()
session._client = mock_client
ds._session = session
# Simulate a normal response
mock_client._response = {"ResponseMetadata": {"HTTPStatusCode": 200}, "Result": "ok"}
session.client = lambda service_name: MockAsyncContextManager(mock_client)
result = await ds.put_bucket_policy("bucket1", '{"Version":"2012-10-17"}')

@pytest.mark.asyncio
async def test_put_bucket_policy_basic_optional_parameters(s3_data_source_with_custom_client):
"""Test put_bucket_policy with all optional parameters provided."""
ds = s3_data_source_with_custom_client
session = MockAioboto3Session()
mock_client = MockS3Client()
session._client = mock_client
ds._session = session
mock_client._response = {"ResponseMetadata": {"HTTPStatusCode": 200}, "Result": "ok"}
session.client = lambda service_name: MockAsyncContextManager(mock_client)
result = await ds.put_bucket_policy(
"bucket2", '{"Version":"2012-10-17"}',
ChecksumAlgorithm="SHA256",
ConfirmRemoveSelfBucketAccess=True,
ExpectedBucketOwner="ownerid"
)

@pytest.mark.asyncio
async def test_put_bucket_policy_basic_empty_response(s3_data_source_with_custom_client):
"""Test put_bucket_policy when S3 returns None (empty response)."""
ds = s3_data_source_with_custom_client
session = MockAioboto3Session()
mock_client = MockS3Client()
session._client = mock_client
ds._session = session
mock_client._response = None
session.client = lambda service_name: MockAsyncContextManager(mock_client)
result = await ds.put_bucket_policy("bucket3", '{"Version":"2012-10-17"}')

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

@pytest.mark.asyncio
async def test_put_bucket_policy_client_error(s3_data_source_with_custom_client):
"""Test put_bucket_policy when S3 client raises ClientError."""
ds = s3_data_source_with_custom_client
session = MockAioboto3Session()
mock_client = MockS3Client()
mock_client._raise_client_error = True
session._client = mock_client
ds._session = session
session.client = lambda service_name: MockAsyncContextManager(mock_client)
result = await ds.put_bucket_policy("bucket4", '{"Version":"2012-10-17"}')

@pytest.mark.asyncio
async def test_put_bucket_policy_unexpected_exception(s3_data_source_with_custom_client):
"""Test put_bucket_policy when S3 client raises an unexpected exception."""
ds = s3_data_source_with_custom_client
session = MockAioboto3Session()
mock_client = MockS3Client()
mock_client._raise_exception = True
session._client = mock_client
ds._session = session
session.client = lambda service_name: MockAsyncContextManager(mock_client)
result = await ds.put_bucket_policy("bucket5", '{"Version":"2012-10-17"}')

@pytest.mark.asyncio
async def test_put_bucket_policy_concurrent_calls(s3_data_source_with_custom_client):
"""Test concurrent execution of put_bucket_policy."""
ds = s3_data_source_with_custom_client
session = MockAioboto3Session()
mock_client = MockS3Client()
session._client = mock_client
ds._session = session
session.client = lambda service_name: MockAsyncContextManager(mock_client)

async def call_one(bucket_name):
    return await ds.put_bucket_policy(bucket_name, '{"Version":"2012-10-17"}')

results = await asyncio.gather(
    call_one("bucketA"),
    call_one("bucketB"),
    call_one("bucketC")
)
for result in results:
    pass

@pytest.mark.asyncio
async def test_put_bucket_policy_error_response_dict(s3_data_source_with_custom_client):
"""Test put_bucket_policy with error response dict from S3."""
ds = s3_data_source_with_custom_client
session = MockAioboto3Session()
mock_client = MockS3Client()
session._client = mock_client
ds._session = session
# Simulate error response dict
mock_client._response = {"Error": {"Code": "InvalidPolicy", "Message": "Policy is invalid"}}
session.client = lambda service_name: MockAsyncContextManager(mock_client)
result = await ds.put_bucket_policy("bucket6", '{"Version":"2012-10-17"}')

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

@pytest.mark.asyncio
async def test_put_bucket_policy_large_scale_concurrent(s3_data_source_with_custom_client):
"""Test large scale concurrent put_bucket_policy calls (up to 50)."""
ds = s3_data_source_with_custom_client
session = MockAioboto3Session()
mock_client = MockS3Client()
session._client = mock_client
ds._session = session
session.client = lambda service_name: MockAsyncContextManager(mock_client)

async def call_one(idx):
    bucket_name = f"bucket{idx}"
    return await ds.put_bucket_policy(bucket_name, '{"Version":"2012-10-17"}')

tasks = [call_one(i) for i in range(50)]
results = await asyncio.gather(*tasks)
for result in results:
    pass

@pytest.mark.asyncio
async def test_put_bucket_policy_large_scale_error_mix(s3_data_source_with_custom_client):
"""Test large scale concurrent calls with some errors."""
ds = s3_data_source_with_custom_client
session = MockAioboto3Session()
# Create 50 mock clients, some raise errors
mock_clients = []
for i in range(50):
mc = MockS3Client()
if i % 10 == 0:
mc._raise_client_error = True
mock_clients.append(mc)
ds._session = session

# Patch session.client to return different mock clients
def client_factory(service_name):
    idx = getattr(client_factory, 'idx', 0)
    mc = mock_clients[idx]
    client_factory.idx = idx + 1
    return MockAsyncContextManager(mc)
client_factory.idx = 0
session.client = client_factory

async def call_one(idx):
    return await ds.put_bucket_policy(f"bucket{idx}", '{"Version":"2012-10-17"}')

results = await asyncio.gather(*[call_one(i) for i in range(50)])
for i, result in enumerate(results):
    if i % 10 == 0:
        pass
    else:
        pass

-------- THROUGHPUT TEST CASES --------

@pytest.mark.asyncio
async def test_put_bucket_policy_throughput_small_load(s3_data_source_with_custom_client):
"""Throughput: test small load (5 concurrent calls)."""
ds = s3_data_source_with_custom_client
session = MockAioboto3Session()
mock_client = MockS3Client()
session._client = mock_client
ds._session = session
session.client = lambda service_name: MockAsyncContextManager(mock_client)

async def call_one(idx):
    return await ds.put_bucket_policy(f"bucket{idx}", '{"Version":"2012-10-17"}')

results = await asyncio.gather(*[call_one(i) for i in range(5)])
for result in results:
    pass

@pytest.mark.asyncio
async def test_put_bucket_policy_throughput_medium_load(s3_data_source_with_custom_client):
"""Throughput: test medium load (20 concurrent calls)."""
ds = s3_data_source_with_custom_client
session = MockAioboto3Session()
mock_client = MockS3Client()
session._client = mock_client
ds._session = session
session.client = lambda service_name: MockAsyncContextManager(mock_client)

async def call_one(idx):
    return await ds.put_bucket_policy(f"bucket{idx}", '{"Version":"2012-10-17"}')

results = await asyncio.gather(*[call_one(i) for i in range(20)])
for result in results:
    pass

@pytest.mark.asyncio
async def test_put_bucket_policy_throughput_high_volume(s3_data_source_with_custom_client):
"""Throughput: test high volume load (100 concurrent calls)."""
ds = s3_data_source_with_custom_client
session = MockAioboto3Session()
mock_client = MockS3Client()
session._client = mock_client
ds._session = session
session.client = lambda service_name: MockAsyncContextManager(mock_client)

async def call_one(idx):
    return await ds.put_bucket_policy(f"bucket{idx}", '{"Version":"2012-10-17"}')

results = await asyncio.gather(*[call_one(i) for i in range(100)])
for result in results:
    pass

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

#------------------------------------------------
import asyncio # used to run async functions

Mocks and test helpers

from typing import Optional

import pytest # used for our unit tests
from app.sources.external.s3.s3 import S3DataSource

Minimal S3Client mock

class S3Client:
def init(self, session):
self._session = session
def get_session(self):
return self._session

Minimal aioboto3.Session mock

class MockSession:
def init(self, client_factory):
self._client_factory = client_factory
async def client(self, service_name):
return await self._client_factory()

Minimal S3 client with async context manager and put_bucket_policy

class MockS3Client:
def init(self, response=None, raise_client_error=False, raise_generic=False):
self._response = response
self._raise_client_error = raise_client_error
self._raise_generic = raise_generic

async def __aenter__(self):
    return self

async def __aexit__(self, exc_type, exc, tb):
    pass

async def put_bucket_policy(self, **kwargs):
    # Simulate error
    if self._raise_client_error:
        class ClientError(Exception):
            def __init__(self):
                self.response = {'Error': {'Code': 'AccessDenied', 'Message': 'You do not have permission'}}
        raise ClientError()
    if self._raise_generic:
        raise RuntimeError("Generic error")
    return self._response

Patch ClientError for S3DataSource

class ClientError(Exception):
def init(self, code="AccessDenied", message="You do not have permission"):
self.response = {'Error': {'Code': code, 'Message': message}}

-------------------- UNIT TESTS --------------------

Basic Test Case 1: Successful put_bucket_policy with required parameters

@pytest.mark.asyncio
async def test_put_bucket_policy_basic_success():
# Simulate S3 returns success with dict
response = {"ResponseMetadata": {"HTTPStatusCode": 200}}
session = MockSession(lambda: asyncio.sleep(0) or MockS3Client(response=response))
s3_client = S3Client(session)
datasource = S3DataSource(s3_client)
# Await the async function
result = await datasource.put_bucket_policy(Bucket="my-bucket", Policy="{}")

Basic Test Case 2: Successful put_bucket_policy with all optional parameters

@pytest.mark.asyncio
async def test_put_bucket_policy_basic_all_params():
response = {"ResponseMetadata": {"HTTPStatusCode": 200}}
session = MockSession(lambda: asyncio.sleep(0) or MockS3Client(response=response))
s3_client = S3Client(session)
datasource = S3DataSource(s3_client)
result = await datasource.put_bucket_policy(
Bucket="bucket",
Policy="{}",
ChecksumAlgorithm="SHA256",
ConfirmRemoveSelfBucketAccess=True,
ExpectedBucketOwner="owner123"
)

Basic Test Case 3: S3 returns error in response dict

@pytest.mark.asyncio
async def test_put_bucket_policy_basic_s3_error_response():
response = {"Error": {"Code": "MalformedPolicy", "Message": "Policy is invalid"}}
session = MockSession(lambda: asyncio.sleep(0) or MockS3Client(response=response))
s3_client = S3Client(session)
datasource = S3DataSource(s3_client)
result = await datasource.put_bucket_policy(Bucket="bucket", Policy="{}")

Edge Test Case 1: S3 returns None response

@pytest.mark.asyncio
async def test_put_bucket_policy_edge_none_response():
session = MockSession(lambda: asyncio.sleep(0) or MockS3Client(response=None))
s3_client = S3Client(session)
datasource = S3DataSource(s3_client)
result = await datasource.put_bucket_policy(Bucket="bucket", Policy="{}")

Edge Test Case 2: S3 client raises ClientError exception

@pytest.mark.asyncio
async def test_put_bucket_policy_edge_client_error():
session = MockSession(lambda: asyncio.sleep(0) or MockS3Client(raise_client_error=True))
s3_client = S3Client(session)
datasource = S3DataSource(s3_client)
result = await datasource.put_bucket_policy(Bucket="bucket", Policy="{}")

Edge Test Case 3: S3 client raises generic exception

@pytest.mark.asyncio
async def test_put_bucket_policy_edge_generic_exception():
session = MockSession(lambda: asyncio.sleep(0) or MockS3Client(raise_generic=True))
s3_client = S3Client(session)
datasource = S3DataSource(s3_client)
result = await datasource.put_bucket_policy(Bucket="bucket", Policy="{}")

Edge Test Case 4: Concurrent execution with valid responses

@pytest.mark.asyncio
async def test_put_bucket_policy_edge_concurrent_success():
response = {"ResponseMetadata": {"HTTPStatusCode": 200}}
session = MockSession(lambda: asyncio.sleep(0) or MockS3Client(response=response))
s3_client = S3Client(session)
datasource = S3DataSource(s3_client)
coros = [
datasource.put_bucket_policy(Bucket=f"bucket-{i}", Policy="{}")
for i in range(5)
]
results = await asyncio.gather(*coros)
for result in results:
pass

Edge Test Case 5: Concurrent execution with mixed error/success

@pytest.mark.asyncio
async def test_put_bucket_policy_edge_concurrent_mixed():
# First 3 succeed, last 2 error
responses = [
{"ResponseMetadata": {"HTTPStatusCode": 200}},
{"ResponseMetadata": {"HTTPStatusCode": 200}},
{"ResponseMetadata": {"HTTPStatusCode": 200}},
None,
{"Error": {"Code": "MalformedPolicy", "Message": "Policy is invalid"}}
]
def factory_gen():
# Use closure to pop responses
responses_copy = list(responses)
async def factory():
resp = responses_copy.pop(0)
return MockS3Client(response=resp)
return factory
session = MockSession(factory_gen())
s3_client = S3Client(session)
datasource = S3DataSource(s3_client)
coros = [
datasource.put_bucket_policy(Bucket=f"bucket-{i}", Policy="{}")
for i in range(5)
]
results = await asyncio.gather(*coros)
# First 3 should succeed
for i in range(3):
pass

Large Scale Test Case 1: Many concurrent successful calls

@pytest.mark.asyncio
async def test_put_bucket_policy_large_scale_many_success():
response = {"ResponseMetadata": {"HTTPStatusCode": 200}}
session = MockSession(lambda: asyncio.sleep(0) or MockS3Client(response=response))
s3_client = S3Client(session)
datasource = S3DataSource(s3_client)
coros = [
datasource.put_bucket_policy(Bucket=f"bucket-{i}", Policy="{}")
for i in range(50)
]
results = await asyncio.gather(*coros)
for result in results:
pass

Large Scale Test Case 2: Many concurrent calls with alternating errors

@pytest.mark.asyncio
async def test_put_bucket_policy_large_scale_mixed():
# Alternate between success and error
def factory_gen():
count = [0]
async def factory():
if count[0] % 2 == 0:
resp = {"ResponseMetadata": {"HTTPStatusCode": 200}}
else:
resp = {"Error": {"Code": "MalformedPolicy", "Message": "Policy is invalid"}}
count[0] += 1
return MockS3Client(response=resp)
return factory
session = MockSession(factory_gen())
s3_client = S3Client(session)
datasource = S3DataSource(s3_client)
coros = [
datasource.put_bucket_policy(Bucket=f"bucket-{i}", Policy="{}")
for i in range(20)
]
results = await asyncio.gather(*coros)
for i, result in enumerate(results):
if i % 2 == 0:
pass
else:
pass

Throughput Test Case 1: Small load

@pytest.mark.asyncio
async def test_put_bucket_policy_throughput_small_load():
response = {"ResponseMetadata": {"HTTPStatusCode": 200}}
session = MockSession(lambda: asyncio.sleep(0) or MockS3Client(response=response))
s3_client = S3Client(session)
datasource = S3DataSource(s3_client)
coros = [
datasource.put_bucket_policy(Bucket=f"bucket-{i}", Policy="{}")
for i in range(5)
]
results = await asyncio.gather(*coros)

Throughput Test Case 2: Medium load

@pytest.mark.asyncio
async def test_put_bucket_policy_throughput_medium_load():
response = {"ResponseMetadata": {"HTTPStatusCode": 200}}
session = MockSession(lambda: asyncio.sleep(0) or MockS3Client(response=response))
s3_client = S3Client(session)
datasource = S3DataSource(s3_client)
coros = [
datasource.put_bucket_policy(Bucket=f"bucket-{i}", Policy="{}")
for i in range(20)
]
results = await asyncio.gather(*coros)

Throughput Test Case 3: High volume load (100 calls)

@pytest.mark.asyncio
async def test_put_bucket_policy_throughput_high_volume():
response = {"ResponseMetadata": {"HTTPStatusCode": 200}}
session = MockSession(lambda: asyncio.sleep(0) or MockS3Client(response=response))
s3_client = S3Client(session)
datasource = S3DataSource(s3_client)
coros = [
datasource.put_bucket_policy(Bucket=f"bucket-{i}", Policy="{}")
for i in range(100)
]
results = await asyncio.gather(*coros)

Throughput Test Case 4: Sustained execution pattern (repeat calls)

@pytest.mark.asyncio
async def test_put_bucket_policy_throughput_sustained_execution():
response = {"ResponseMetadata": {"HTTPStatusCode": 200}}
session = MockSession(lambda: asyncio.sleep(0) or MockS3Client(response=response))
s3_client = S3Client(session)
datasource = S3DataSource(s3_client)
# Call function 10 times in sequence
for i in range(10):
result = await datasource.put_bucket_policy(Bucket=f"bucket-{i}", Policy="{}")

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-S3DataSource.put_bucket_policy-mhx8ke8p and push.