test(triple): add concurrent send/close guards for duplexHTTPCall

[chaojixinren]

Description

Investigate whether connect-go v1.19.2's fix for the concurrent Send +
CloseAndReceive nil-pointer dereference (connectrpc/connect-go#919) applies to
Dubbo-go's forked Triple runtime under protocol/triple/triple_protocol.

Conclusion: duplexHTTPCall is not affected. newDuplexHTTPCall allocates
the request-body io.Pipe at construction and never reassigns
requestBodyWriter, so it is always non-nil and concurrent Write/CloseWrite
are safe in any order. The upstream race — where the pipe was created lazily on
the first Send and a racing CloseWrite could leave it nil — is structurally
impossible here, so no synchronization change is ported.

What this PR does:

• adds TestDuplexHTTPCallConcurrentWriteAndCloseWrite and
  TestDuplexHTTPCallConcurrentWriteCloseRace as regression guards (pass under
  go test -race) that pin the construction-time pipe invariant
• documents the invariant on requestBodyWriter to keep the allocation out of a
  lazy/first-send path

This is intentionally not a broad connect-go upgrade; it only checks and guards
the runtime safety property called out in the issue.

Fixes #3458

Checklist

• I confirm the target branch is develop
• Code has passed local testing
• I have added tests that prove my fix is effective or that my feature works

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 53.90%. Comparing base (8b5bbcf) to head (4183de5).
⚠️ Report is 3 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #3462      +/-   ##
===========================================
+ Coverage    53.57%   53.90%   +0.33%     
===========================================
  Files          460      461       +1     
  Lines        35182    35478     +296     
===========================================
+ Hits         18847    19125     +278     
+ Misses       14857    14848       -9     
- Partials      1478     1505      +27     

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[AlexStocks]

Review Summary

结论: ✅ 可 Merge

变更范围很小且精准：仅在 duplexHTTPCall 结构体上补充了 requestBodyWriter 构建时赋值不可变的注释不变量，并新增两个并发 guard test 作为回归保护。

核心判断：

1. newDuplexHTTPCall 中 io.Pipe() 在构造时一次性分配，requestBodyWriter 永不被重新赋值 — 从代码结构上杜绝了 connect-go#919 的 nil-pointer dereference 场景。
2. d.response 的写入发生在 makeRequest() 中 close(d.responseReady) 之前，所有读取方通过 BlockUntilResponseReady() 等待 channel 关闭后才访问 — channel close 提供了 Go memory model 的 happens-before 保证，无数据竞争。
3. 两个测试明确定位为 guard（非 reproducer），在正确代码上永远通过；但如果 pipe 创建被移到 lazy path，assert.NotNil 会立即失败 — 回归保护设计合理。
4. 测试在 -race 下运行可有效检测潜在 data race。

仅有一个 P2 建议，见 inline comment。

[AlexStocks]

[P2] 新文件的 copyright 年份为 2021-2023，建议更新为 2021-2025（或至少 2025）。仓库内部分旧文件沿用旧年份可以理解，但新增文件建议使用当前年份。

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud