composite_thread_registry_backend.hpp

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#pragma once
 
#include "thread_registry_backend.hpp"
 
#include <mutex>
#include <utility>
#include <vector>
 
namespace threadschedule
{
namespace detail
{
 
class composite_thread_registry_backend : public query_facade_mixin<composite_thread_registry_backend>
{
public:
  void
  attach(thread_registry_backend* reg)
  {
    if (reg == nullptr)
      return;
    std::lock_guard<std::mutex> lock(mutex_);
    registries_.push_back(reg);
  }
 
  [[nodiscard]] auto
  query() const -> thread_registry_backend::query_view
  {
    std::vector<registered_thread_info_backend> merged;
    std::vector<thread_registry_backend*> regs;
    {
      std::lock_guard<std::mutex> lock(mutex_);
      regs = registries_;
    }
    for (auto* r : regs)
      {
        auto view = r->query();
        auto const& entries = view.entries();
        merged.insert(merged.end(), entries.begin(), entries.end());
      }
    return thread_registry_backend::query_view(std::move(merged));
  }
 
private:
  mutable std::mutex mutex_;
  std::vector<thread_registry_backend*> registries_;
};
 
} // namespace detail
} // namespace threadschedule