Method ending_sched

src/bthread/task_group.cpp:673–719

}

void TaskGroup::ending_sched(TaskGroup** pg) {
    TaskGroup* g = *pg;
    bthread_t next_tid = 0;
    // Find next task to run, if none, switch to idle thread of the group.
#ifndef BTHREAD_FAIR_WSQ
    // When BTHREAD_FAIR_WSQ is defined, profiling shows that cpu cost of
    // WSQ::steal() in example/multi_threaded_echo_c++ changes from 1.9%
    // to 2.9%
    const bool popped = g->_rq.pop(&next_tid);
#else
    const bool popped = g->_rq.steal(&next_tid);
#endif
    if (!popped && !g->steal_task(&next_tid)) {
        // Jump to main task if there's no task to run.
        next_tid = g->_main_tid;
    }

    TaskMeta* const cur_meta = g->_cur_meta;
    TaskMeta* next_meta = address_meta(next_tid);
    if (next_meta->stack == NULL) {
        if (next_meta->stack_type() == cur_meta->stack_type()) {
            // Reuse the stack of the current ending task.
            //
            // also works with pthread_task scheduling to pthread_task, the
            // transfered stack is just _main_stack.
            next_meta->set_stack(cur_meta->release_stack());
        } else {
#ifdef BUTIL_USE_ASAN
            ContextualStack* stk = get_stack(
                next_meta->stack_type(), asan_task_runner);
#else
            ContextualStack* stk = get_stack(next_meta->stack_type(), task_runner);
#endif // BUTIL_USE_ASAN
            if (stk) {
                next_meta->set_stack(stk);
            } else {
                // stack_type is BTHREAD_STACKTYPE_PTHREAD or out of memory,
                // In latter case, attr is forced to be BTHREAD_STACKTYPE_PTHREAD.
                // This basically means that if we can't allocate stack, run
                // the task in pthread directly.
                next_meta->attr.stack_type = BTHREAD_STACKTYPE_PTHREAD;
                next_meta->set_stack(g->_main_stack);
            }
        }
    }
    sched_to(pg, next_meta);
}

void TaskGroup::sched(TaskGroup** pg) {
    TaskGroup* g = *pg;