debugserver all-stop thread coordination

llvm-project/lldb/tools/debugserver/source/MacOSX/MachThreadList.cpp · 576 lines · browse source

ProcessWillResume applies a resume plan across the task’s threads, keeping non-selected threads suspended and preparing the selected stepping or running thread.

MachThreadList::ProcessWillResume source

void MachThreadList::ProcessWillResume(
    MachProcess *process, const DNBThreadResumeActions &thread_actions) {
  std::lock_guard<std::recursive_mutex> guard(m_threads_mutex);

  // Update our thread list, because sometimes libdispatch or the kernel
  // will spawn threads while a task is suspended.
  MachThreadList::collection new_threads;

  // First figure out if we were planning on running only one thread, and if so
  // force that thread to resume.
  bool run_one_thread;
  nub_thread_t solo_thread = INVALID_NUB_THREAD;
  if (thread_actions.GetSize() > 0 &&
      thread_actions.NumActionsWithState(eStateStepping) +
              thread_actions.NumActionsWithState(eStateRunning) ==
          1) {
    run_one_thread = true;
    const DNBThreadResumeAction *action_ptr = thread_actions.GetFirst();
    size_t num_actions = thread_actions.GetSize();
    for (size_t i = 0; i < num_actions; i++, action_ptr++) {
      if (action_ptr->state == eStateStepping ||
          action_ptr->state == eStateRunning) {
        solo_thread = action_ptr->tid;
        break;
      }
    }
  } else
    run_one_thread = false;

  UpdateThreadList(process, true, &new_threads);
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