use ctypes.string_at for faster copying bytes

[trunglebka]

I've done some profiling and found that bytes(data_ptr[: int(data_len)]) is an expensive operation and can be done by ctypes.string_at instead.

The benchmark result:

Correctness: Pass
Method 1 (slicing) avg time: 0.016509 seconds
Method 2 (string_at) avg time: 0.000130 seconds

The benchmarking code:

import ctypes
import random
import time


def create_cdata():
    test_data = bytes(
        random.getrandbits(8) for _ in range(10**6)
    )  # 1 MB of random data
    data_len = len(test_data)

    # Create a ctypes pointer to the test data
    c_array = (ctypes.c_uint8 * data_len)(*test_data)
    data_ptr = ctypes.cast(c_array, ctypes.POINTER(ctypes.c_uint8))
    return data_ptr, data_len


def benchmark_and_validate(iterations=100):
    # Generate random test data
    # Variables to accumulate time
    total_time1 = 0.0
    total_time2 = 0.0
    is_correct = True

    for _ in range(iterations):
        data_ptr, data_len=create_cdata()
        # Method 2: Using ctypes.string_at
        start_time = time.perf_counter()
        event_data2 = ctypes.string_at(data_ptr, data_len)
        total_time2 += time.perf_counter() - start_time

        # Method 1: Using slicing
        start_time = time.perf_counter()
        event_data1 = bytes(data_ptr[:data_len])
        total_time1 += time.perf_counter() - start_time

        # Check correctness
        if event_data1 != event_data2:
            is_correct = False
            break

    # Average times
    avg_time1 = total_time1 / iterations
    avg_time2 = total_time2 / iterations

    # Print results
    print(f"Correctness: {'Pass' if is_correct else 'Fail'}")
    print(f"Method 1 (slicing) avg time: {avg_time1:.6f} seconds")
    print(f"Method 2 (string_at) avg time: {avg_time2:.6f} seconds")

    return avg_time1, avg_time2, is_correct


if __name__ == "__main__":
    benchmark_and_validate(iterations=1000)

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.

---

Charlie seems not to be a GitHub user. You need a GitHub account to be able to sign the CLA. If you have already a GitHub account, please add the email address used for this commit to your account.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

[theomonnom]

Hey, this lg! Can you sign the CLA?

[trunglebka]

Hi @theomonnom,
I signed the CLA, but it seems like it got messed up with my profile, and there's another location to modify. I will create another PR