Bugfix: bthread_worker_usage could exceed bthread_worker_count

[chenBright]

What problem does this PR solve?

Issue Number: resolve #1231 , resolve #2640 , resolve #2972

Problem Summary:

What is changed and the side effects?

Changed:

bthread_worker_usage should consist of _cumulated_cputime_ns and the CPU time of the task currently run by the worker.

Side effects:

• Performance effects:

• Breaking backward compatibility:

---

Check List:

• Please make sure your changes are compilable.
• When providing us with a new feature, it is best to add related tests.
• Please follow Contributor Covenant Code of Conduct.

[chenBright]

@wwbmmm @yanglimingcn Please take a look.

[chenBright]

@wwbmmm @yanglimingcn Friendly ping!

[chenBright]

void* test(void*) {
    while (!brpc::IsAskedToQuit()) {
        sleep(2);
        bthread_yield();
    }
}

for (int i = 0; i < 3; ++i) {
    bthread_t tid;
    bthread_start_background(&tid, NULL, test, NULL);
}

Start 3 bthreads and loop sleep for 2s. The value of bthread_worker_usage is correct, and the extra 1 comes from the epoll bthread.

[Copilot]

Pull Request Overview

This PR fixes a bug where bthread_worker_usage could exceed bthread_worker_count by refactoring how CPU time statistics are tracked for bthread workers. The fix ensures that worker usage calculations properly account for both cumulated CPU time and the current running task's elapsed time.

• Introduces atomic 128-bit operations for thread-safe CPU time tracking
• Refactors CPU time statistics to include both scheduling time and task type information
• Consolidates prime offset generation into a shared utility function

Reviewed Changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
src/bthread/task_group.h	Adds AtomicInteger128 and CPUTimeStat classes, refactors TaskGroup member variables with default initialization
src/bthread/task_group.cpp	Implements atomic operations and updates CPU time tracking logic in scheduling functions
src/bthread/task_control.h	Renames method from get_cumulated_worker_time_with_tag to get_cumulated_worker_time
src/bthread/task_control.cpp	Updates method calls and simplifies cumulated time calculation logic
src/bthread/prime_offset.h	New utility header providing centralized prime offset generation functions
Load balancer files	Updates to use the new centralized prime_offset() function instead of GenRandomStride()
src/brpc/load_balancer.h	Removes deprecated GenRandomStride() function

Comments suppressed due to low confidence (1)

src/bthread/task_group.h:91

• Misspelled word: 'Supress' should be 'Suppress'.

                                bthread_t* __restrict tid,

[wwbmmm]

LGTM