Fix: 修复 aiohttp 流式响应分块大小不固定问题

[KeepingRunning]

环境配置

python版本：python3.12.12
操作系统: macOS 26.2 25C56 arm64

问题复现

代码拉下来跑了一下pytest

test failed，说是返回的块大小不一定等于chunk_size

原因分析

原来的代码是：

response_headers = response.headers.copy()
async for chunk in response.content.iter_chunked(chunk_size):
    yield Response(
        response.status,
        headers=response_headers,
        content=chunk,
        request=setup,
    )

而iter_chunked底层调用的是_read_nowait，注解里写的是“Read not more than n bytes”，所以chunk大小可能小于chunk_size

def _read_nowait(self, n: int) -> bytes:
    """Read not more than n bytes, or whole buffer if n == -1"""
    self._timer.assert_timeout()

    chunks = []
    while self._buffer:
        chunk = self._read_nowait_chunk(n)
        chunks.append(chunk)
        if n != -1:
            n -= len(chunk)
            if n == 0:
                break

    return b"".join(chunks) if chunks else b""

解决方案

现在改成，手动写一个buffer，池子里chunk的大小大于等于要求的chunk_size的时候就截断并yield出去，结束后再把buffer里的yield出去

async for chunk in response.content.iter_chunked(chunk_size):
    if not chunk:
        continue
    buffer.extend(chunk)
    while len(buffer) >= chunk_size:
        out = bytes(buffer[:chunk_size])
        del buffer[:chunk_size]
        yield Response(
            response.status,
            headers=response_headers,
            content=out,
            request=setup,
        )
if buffer:
    yield Response(
        response.status,
        headers=response_headers,
        content=bytes(buffer),
        request=setup,
    )

最后一块chunked可能小于chunk_size的情况我并未处理，如果需要的话我可以补到chunk_size大小

测试

已通过全部测试

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.78%. Comparing base (4f1c590) to head (1df3a1b).
⚠️ Report is 1 commits behind head on master.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3919      +/-   ##
==========================================
+ Coverage   93.77%   93.78%   +0.01%     
==========================================
  Files          48       48              
  Lines        4351     4360       +9     
==========================================
+ Hits         4080     4089       +9     
  Misses        271      271              

Flag	Coverage Δ
unittests	93.78% <100.00%> (+0.01%)	⬆️

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[github-actions]

🚀 Deployed to https://deploy-preview-3919--nonebot2.netlify.app

[NCBM]

个人认为大概率是测试代码的问题，分包大小只保证不超过最大值是普遍符合预期的行为

[KeepingRunning]

那我把test改成小于等于？

[NCBM]

应该不用，这么修也不是不行