feat: Add executor timing stats with thread config support

[qzhhhi]

• Add optional thread_config support for the executor update thread
• Log cumulative and 5s window timing stats for start lateness, update duration, skipped cycles, and top component costs
• Vendor a local TDigest utility for percentile reporting
• Switch affected packages to C++23 for std::format and std::expected
• Allow starting the executor with an empty components list for testing

主要变更

• 为执行器更新线程新增可选 thread_config 支持：可通过配置解析并应用线程名、CPU 亲和性、调度策略（policy）、优先级（priority）与 nice（nice），并在配置校验与应用失败时返回错误结果。
• 彻底改造更新线程的调度与统计框架：根据“计划开始时间/实际结束时间”推导下一次计划迭代，落后时自动计算并跳过周期，同时累计跳过次数；对每次迭代记录计划迟到与更新耗时的分布（用 TDigest 做 p50/p99/最大值等），并在每个 5 秒窗口到点输出累计与窗口统计（含启动迟到/更新持续时间、跳过占比，以及 5 秒内组件耗时 top3/占比）。
• 新增本地 TDigest 实现，用于分位数（quantile）与累计分布统计。
• 将相关包切换到 C++23：使用 CMake 标准变量强制 CMAKE_CXX_STANDARD 23，以便使用 std::format、std::expected 等能力。
• 允许在测试场景下以空 components 列表启动执行器；同时调整 main() 对 components 参数读取逻辑的处理方式（不再基于布尔返回值抛出显式异常）。

其他

• 新增公开接口：rmcs_utility::ThreadConfig（线程配置解析与应用）、rmcs_utility::TDigest（分位数统计）。

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: b4fc8ad7-d6ad-479c-98f4-6dd7d0064b3b

📥 Commits

Reviewing files that changed from the base of the PR and between 4ab6585 and 5f341fc.

📒 Files selected for processing (2)

• rmcs_ws/src/rmcs_executor/src/executor.hpp
• rmcs_ws/src/rmcs_utility/include/rmcs_utility/tdigest.hpp

🚧 Files skipped from review as they are similar to previous changes (2)

• rmcs_ws/src/rmcs_executor/src/executor.hpp
• rmcs_ws/src/rmcs_utility/include/rmcs_utility/tdigest.hpp

---

Walkthrough

本次改动将 rmcs_executor 与 rmcs_utility 的 C++ 标准升级至 23，重写了 Executor 更新线程实现，简化了 main.cpp 中 components 参数读取的错误处理，并新增了 TDigest 与 ThreadConfig 两个工具类。

Changes

Executor 线程调度与统计

Layer / File(s)	Summary
C++ 标准升级配置 rmcs_executor/CMakeLists.txt, rmcs_utility/CMakeLists.txt	两个包均改为通过 CMAKE_CXX_STANDARD 23 并启用 CMAKE_CXX_STANDARD_REQUIRED，替代原先追加 -std=c++20 的方式。
头文件依赖与线程配置接入 rmcs_executor/src/executor.hpp	新增标准库头及 tdigest/thread_config 依赖；start() 读取 thread_config 参数并在工作线程中构造、移动并应用该配置。
统计数据结构定义 rmcs_executor/src/executor.hpp	新增累计与窗口维度的统计结构、线程状态结构，以及窗口级组件耗时聚合结构。
线程主循环与迭代调度 rmcs_executor/src/executor.hpp	新增 thread_main、execute_update_iteration、record_start_lateness、record_update_duration 与 calculate_next_iteration_time，实现按计划时间推导下一迭代、跳过周期计数与迟到/耗时记录。
周期性统计日志输出 rmcs_executor/src/executor.hpp	新增 log_due_reports、log_cumulative_stats、log_window_stats、collect_top_component_stats、format_top_component_stats 及格式化辅助函数，用于每 5 秒输出累计与窗口统计并重置窗口计数。
components 参数读取简化 rmcs_executor/src/main.cpp	移除参数获取失败时抛出异常的分支，改为忽略返回值。

TDigest 与 ThreadConfig 工具类新增

Layer / File(s)	Summary
TDigest 类型与接口声明 rmcs_utility/include/rmcs_utility/tdigest.hpp	新增 Centroid 结构体、比较运算符，以及 TDigest 模板类的接口声明与内部数据结构。
构造、插入与合并实现 rmcs_utility/include/rmcs_utility/tdigest.hpp	实现 TDigest 的构造/移动/赋值、insert(const TDigest&)、reset()、get()，以及缩放函数与 merge() 压缩逻辑。
分位数与累计分布计算 rmcs_utility/include/rmcs_utility/tdigest.hpp	实现 quantile(p) 与 cumulative_distribution(x)，处理空/单 centroid 及边界插值情况。
ThreadConfig 构造与访问器 rmcs_utility/include/rmcs_utility/thread_config.hpp	新增两个构造函数解析 spec，及 name/cpus/policy/priority/nice 只读访问器。
应用到当前线程 rmcs_utility/include/rmcs_utility/thread_config.hpp	实现 apply_to_current_thread()，依次设置调度策略、nice、CPU 亲和性与线程名。
字段解析与跨字段校验 rmcs_utility/include/rmcs_utility/thread_config.hpp	新增解析工具函数、parse_fields/assign_field 字段分派、policy/cpus 解析，以及 validate 跨字段约束校验。

Estimated code review effort: 4 (Complex) | ~60 minutes

Suggested reviewers:creeper5820

Poem

兔子跳进代码林，标准升到二十三，
线程戴上新帽子，节拍跑得更整齐。
五秒一报小铃响，分位数里看高低，
🥕 耗时排行排前三，轻快更新向前提。

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	标题准确概括了本次变更的核心：执行器时序统计与线程配置支持。
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch dev/rt

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}

[coderabbitai]

Actionable comments posted: 5

🧹 Nitpick comments (1)

rmcs_ws/src/rmcs_utility/include/rmcs_utility/thread_config.hpp (1)

83-112: 🩺 Stability & Availability | 🔵 Trivial | ⚡ Quick win

改用线程安全的错误信息格式化

这 4 处都在用 std::strerror，并发时可能串用同一个静态缓冲区；建议统一改成 std::system_category().message(error_code)，errno 分支也改用同样的方式（可补 #include <system_error>）。

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.
In `@rmcs_ws/src/rmcs_utility/include/rmcs_utility/thread_config.hpp` around lines
83 - 112, The error formatting in ThreadConfig::apply uses std::strerror in
multiple failure paths, which is not thread-safe and can return mixed messages
under concurrency. Update the scheduling, nice, affinity, and name error
branches in thread_config.hpp to format messages via
std::system_category().message(error_code) instead of std::strerror, and apply
the same approach to the errno-based setpriority path; add the needed
system_error include if it is not already present.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.
Inline comments:
In `@rmcs_ws/src/rmcs_executor/src/executor.hpp`:
- Around line 125-126: The update_rate to period conversion in executor.hpp is
not validated, so non-finite, non-positive, or too-large values can produce an
invalid or zero period and break later logic. In start() of executor::Executor,
validate update_rate with std::isfinite(update_rate) and update_rate > 0.0
before computing the period, then verify the derived std::chrono::nanoseconds
period has a count greater than zero before using it; apply the check around the
existing period calculation and any code that relies on period.count().
In `@rmcs_ws/src/rmcs_utility/include/rmcs_utility/tdigest.hpp`:
- Around line 158-168: `TDigest::insert` only updates `buffer` until `merge()`
is triggered, but the read paths (`quantile`, `cumulative_distribution`, `get`,
`size`, and the executor’s `maybe_quantile` call site) appear to read only from
`active`, so pending samples can be invisible. Update the `TDigest` read API to
include buffered samples, either by flushing a snapshot before queries or by
merging/considering `buffer` inside the query methods, and make the `executor`
path use the corrected `TDigest::quantile` behavior so `sample_count > 0` never
reports stale or empty results.
- Around line 256-264: Reject zero-sized TDigest construction in
TDigest::TDigest(size_t size) by validating size at the start of the constructor
and preventing creation when size == 0. The issue is that one/two and the active
digest end up with zero capacity, which later breaks merge normalization in
merge() via normalizer_fn on inactive.values.capacity(). Add an upfront guard in
the TDigest constructor to fail fast with a clear error or exception so callers
cannot instantiate TDigest(0).
- Around line 305-318: The TDigest::insert(const TDigest& src) implementation
only copies src.active->values and ignores any pending samples still sitting in
src.buffer, so merge the source digest state first (on a local copy) before
inserting its centroids into this digest. Update TDigest::insert to work from a
merged copy of src, then feed that copy’s active values through the existing
buffer/merge flow so max_val/min_val and the actual data stay consistent.
- Around line 41-47: The tdigest.hpp header uses std::pair and std::make_pair
without explicitly including the required <utility> header, relying on indirect
includes. Update the header’s include list to add <utility> so the template code
in tdigest.hpp remains self-contained and compiles independently.
---
Nitpick comments:
In `@rmcs_ws/src/rmcs_utility/include/rmcs_utility/thread_config.hpp`:
- Around line 83-112: The error formatting in ThreadConfig::apply uses
std::strerror in multiple failure paths, which is not thread-safe and can return
mixed messages under concurrency. Update the scheduling, nice, affinity, and
name error branches in thread_config.hpp to format messages via
std::system_category().message(error_code) instead of std::strerror, and apply
the same approach to the errno-based setpriority path; add the needed
system_error include if it is not already present.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 794a3821-8ac4-4416-b7e2-018af9763e6c

📥 Commits

Reviewing files that changed from the base of the PR and between 2c63c7d and 4ab6585.

📒 Files selected for processing (6)

• rmcs_ws/src/rmcs_executor/CMakeLists.txt
• rmcs_ws/src/rmcs_executor/src/executor.hpp
• rmcs_ws/src/rmcs_executor/src/main.cpp
• rmcs_ws/src/rmcs_utility/CMakeLists.txt
• rmcs_ws/src/rmcs_utility/include/rmcs_utility/tdigest.hpp
• rmcs_ws/src/rmcs_utility/include/rmcs_utility/thread_config.hpp

[creeper5820]

AC