boost::asio序列4: execution_contex

1. execution_context

execution_context_service_base	execution_context::service： 內部類
service_id	execution_context::id： 內部類
service_already_exists	std::logic_error
invalid_service_owner	std::logic_error

在execution_context中包含私有變量

boost::asio::detail::service_registry* service_registry_

實現Sevice註冊，每一個service_registry包含execution_context對象，表示註冊的service關聯的execution_context。

 

boost::asio::detail::service_registry，採用單向鏈表保存全部的execution_context::service

  // Mutex to protect access to internal data.
  mutable boost::asio::detail::mutex mutex_;

  // The owner of this service registry and the services it contains.
  execution_context& owner_;

  // The first service in the list of contained services.
  execution_context::service* first_service_;