fix: eliminate flaky OnetimeConfigUpdateUnittest via injectable clock

[Copilot]

OnetimeConfigUpdateUnittest::OnCollectionConfigUpdate was intermittently off by 1 second in CI because the production code and the test assertion each called time(nullptr) independently, and a second boundary could tick between them.

Changes

• common/TimeUtil.h — Under APSARA_UNIT_TEST_MAIN, adds:

  • thread_local std::function<uint64_t()> gCurrentTimeNs — injectable clock returning nanoseconds since epoch, thread_local so background threads spawned by pipelines always use the real clock while the test thread can safely override without data races
  • ScopedClockOverride — RAII guard that accepts a std::chrono::system_clock::time_point, pins the test thread's clock to a fixed nanosecond value for the duration of a test, and restores it on destruction; copy/assign deleted

• common/TimeUtil.cpp — Defines the thread_local gCurrentTimeNs default (real system_clock::now()). All four GetCurrentTimeIn*() functions derive from it in UT builds by dividing to the appropriate precision.

• PipelineConfig.cpp — Both time(nullptr) calls in GetExpireTimeIfOneTime() replaced with GetCurrentTimeInSeconds(), routing through the injectable clock in test builds.

• PipelineConfig.h — Retains only friend class PipelineConfigUnittest (removed unnecessary friend class OnetimeConfigUpdateUnittest, which never accesses protected/private members).

• OnetimeConfigUpdateUnittest.cpp — Captures system_clock::now() before each UpdatePipelines() call, wraps the call in ScopedClockOverride, and asserts using duration_cast<seconds> of the captured value — making the expected value identical to what the production code computes.

• PipelineConfigUnittest.cpp — Same pattern applied to all mOnetimeExpireTime assertions (including the previously missed "new config" scenario) that formerly compared against an independent time(nullptr) call.

// Before (flaky — two independent time(nullptr) calls)
CollectionPipelineManager::GetInstance()->UpdatePipelines(diff.first);
APSARA_TEST_EQUAL(time(nullptr) + 1200U, item.mExpireTime);  // may differ by 1 s

// After (deterministic)
auto updateNow = std::chrono::system_clock::now();
{
    ScopedClockOverride clockGuard(updateNow);
    CollectionPipelineManager::GetInstance()->UpdatePipelines(diff.first);
}
APSARA_TEST_EQUAL(
    static_cast<uint32_t>(
        std::chrono::duration_cast<std::chrono::seconds>(updateNow.time_since_epoch()).count()) + 1200U,
    item.mExpireTime);

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Pull request overview

该 PR 旨在消除 onetime 配置相关单测在 CI 中因跨秒导致的偶现失败，通过在 UT 构建下提供可控“当前时间”，并让过期时间计算与断言使用同一时间源，从而使断言确定化。

Changes:

• 在 common/TimeUtil 中增加 UT 可注入时钟（gCurrentTimeNs）及 RAII 覆盖器 ScopedClockOverride，并让 GetCurrentTimeIn*() 在 UT 下走该注入点。
• PipelineConfig::GetExpireTimeIfOneTime() 使用 GetCurrentTimeInSeconds() 替代 time(nullptr)，避免生产代码与测试各自取时导致 off-by-1。
• 更新 OnetimeConfigUpdateUnittest / PipelineConfigUnittest 的部分断言：在调用更新逻辑时固定 now，并用固定值计算期望过期时间。

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
core/common/TimeUtil.h	UT 下引入可注入时钟声明与 ScopedClockOverride
core/common/TimeUtil.cpp	UT 下实现 gCurrentTimeNs，并让 GetCurrentTimeIn*() 可被覆盖
core/config/PipelineConfig.cpp	onetime 过期时间计算改用 GetCurrentTimeInSeconds()
core/config/PipelineConfig.h	新增 OnetimeConfigUpdateUnittest friend 声明
core/unittest/config/OnetimeConfigUpdateUnittest.cpp	用 ScopedClockOverride 固定更新时刻，断言使用固定 now
core/unittest/config/PipelineConfigUnittest.cpp	用 ScopedClockOverride 固定部分场景 now，断言使用固定 now

[yyuuttaaoo]

@copilot apply changes based on the comments in this thread

[Copilot]

@copilot apply changes based on the comments in this thread

已在 c32a7a4 中应用了以下修改：

1. gCurrentTimeNs 改为 thread_local（TimeUtil.h + TimeUtil.cpp）：后台线程各自持有独立副本并始终使用真实时钟，测试线程的覆盖操作不会跨线程传播，从根本上消除了对全局 std::function 的并发读写竞争。

2. 移除 friend class OnetimeConfigUpdateUnittest（PipelineConfig.h）：确认该测试类未访问 PipelineConfig 的任何受保护/私有成员，friend 声明多余。

3. 修复 PipelineConfigUnittest.cpp 中剩余的 flaky 断言（"new config" 场景，原第 163 行）：用 ScopedClockOverride + chrono 替换 time(nullptr) + 3600U，使该处断言与其他场景一致。

[messixukejia]

UT为什么要增加特殊分支？

[yyuuttaaoo]

UT为什么要增加特殊分支？

因为UT要用override的time函数，可能不是system_clock::now()，非UT不允许override time函数。
这可以完全解决

1. 两个system_clock::now()差了几十毫秒导致差值多了一秒或少了一秒，导致UT失败的问题
2. 其他依赖sleep的UT，可以利用这个util改造成不依赖sleep的，减少UT运行时间