io_service.hpp

这是国外的resip协议栈

   * This function must be called prior to any second or later set of
   * invocations of the run(), run_one(), poll() or poll_one() functions when a
   * previous invocation of these functions returned due to the io_service
   * being stopped or running out of work. This function allows the io_service
   * to reset any internal state, such as a "stopped" flag.
   *
   * This function must not be called while there are any unfinished calls to
   * the run(), run_one(), poll() or poll_one() functions.
   */
  void reset();

  /// Request the io_service to invoke the given handler.
  /**
   * This function is used to ask the io_service to execute the given handler.
   *
   * The io_service guarantees that the handler will only be called in a thread
   * in which the run(), run_one(), poll() or poll_one() member functions is
   * currently being invoked. The handler may be executed inside this function
   * if the guarantee can be met.
   *
   * @param handler The handler to be called. The io_service will make
   * a copy of the handler object as required. The function signature of the
   * handler must be: @code void handler(); @endcode
   */
  template <typename CompletionHandler>
  void dispatch(CompletionHandler handler);

  /// Request the io_service to invoke the given handler and return immediately.
  /**
   * This function is used to ask the io_service to execute the given handler,
   * but without allowing the io_service to call the handler from inside this
   * function.
   *
   * The io_service guarantees that the handler will only be called in a thread
   * in which the run(), run_one(), poll() or poll_one() member functions is
   * currently being invoked.
   *
   * @param handler The handler to be called. The io_service will make
   * a copy of the handler object as required. The function signature of the
   * handler must be: @code void handler(); @endcode
   */
  template <typename CompletionHandler>
  void post(CompletionHandler handler);

  /// Create a new handler that automatically dispatches the wrapped handler
  /// on the io_service.
  /**
   * This function is used to create a new handler function object that, when
   * invoked, will automatically pass the wrapped handler to the io_service's
   * dispatch function.
   *
   * @param handler The handler to be wrapped. The io_service will make a copy
   * of the handler object as required. The function signature of the handler
   * must be: @code void handler(A1 a1, ... An an); @endcode
   *
   * @return A function object that, when invoked, passes the wrapped handler to
   * the io_service's dispatch function. Given a function object with the
   * signature:
   * @code R f(A1 a1, ... An an); @endcode
   * If this function object is passed to the wrap function like so:
   * @code io_service.wrap(f); @endcode
   * then the return value is a function object with the signature
   * @code void g(A1 a1, ... An an); @endcode
   * that, when invoked, executes code equivalent to:
   * @code io_service.dispatch(boost::bind(f, a1, ... an)); @endcode
   */
  template <typename Handler>
#if defined(GENERATING_DOCUMENTATION)
  unspecified
#else
  detail::wrapped_handler<io_service&, Handler>
#endif
  wrap(Handler handler);

  /// Obtain the service object corresponding to the given type.
  /**
   * This function is used to locate a service object that corresponds to
   * the given service type. If there is no existing implementation of the
   * service, then the io_service will create a new instance of the service.
   *
   * @param ios The io_service object that owns the service.
   *
   * @return The service interface implementing the specified service type.
   * Ownership of the service interface is not transferred to the caller.
   */
  template <typename Service>
  friend Service& use_service(io_service& ios);

  /// Add a service object to the io_service.
  /**
   * This function is used to add a service to the io_service.
   *
   * @param ios The io_service object that owns the service.
   *
   * @param svc The service object. On success, ownership of the service object
   * is transferred to the io_service. When the io_service object is destroyed,
   * it will destroy the service object by performing:
   * @code delete static_cast<io_service::service*>(svc) @endcode
   *
   * @throws asio::service_already_exists Thrown if a service of the
   * given type is already present in the io_service.
   *
   * @throws asio::invalid_service_owner Thrown if the service's owning
   * io_service is not the io_service object specified by the ios parameter.
   */
  template <typename Service>
  friend void add_service(io_service& ios, Service* svc);

  /// Determine if an io_service contains a specified service type.
  /**
   * This function is used to determine whether the io_service contains a
   * service object corresponding to the given service type.
   *
   * @param ios The io_service object that owns the service.
   *
   * @return A boolean indicating whether the io_service contains the service.
   */
  template <typename Service>
  friend bool has_service(io_service& ios);

private:
#if defined(BOOST_WINDOWS) || defined(__CYGWIN__)
  detail::winsock_init<> init_;
#elif defined(__sun) || defined(__QNX__) || defined(__hpux) || defined(_AIX) \
  || defined(__osf__)
  detail::signal_init<> init_;
#endif

  // The service registry.
  asio::detail::service_registry* service_registry_;

  // The implementation.
  impl_type& impl_;
};

/// Class to inform the io_service when it has work to do.
/**
 * The work class is used to inform the io_service when work starts and
 * finishes. This ensures that the io_service's run() function will not exit
 * while work is underway, and that it does exit when there is no unfinished
 * work remaining.
 *
 * The work class is copy-constructible so that it may be used as a data member
 * in a handler class. It is not assignable.
 */
class io_service::work
{
public:
  /// Constructor notifies the io_service that work is starting.
  /**
   * The constructor is used to inform the io_service that some work has begun.
   * This ensures that the io_service's run() function will not exit while the
   * work is underway.
   */
  explicit work(asio::io_service& io_service);

  /// Copy constructor notifies the io_service that work is starting.
  /**
   * The constructor is used to inform the io_service that some work has begun.
   * This ensures that the io_service's run() function will not exit while the
   * work is underway.
   */
  work(const work& other);

  /// Destructor notifies the io_service that the work is complete.
  /**
   * The destructor is used to inform the io_service that some work has
   * finished. Once the count of unfinished work reaches zero, the io_service's
   * run() function is permitted to exit.
   */
  ~work();

  /// (Deprecated: use get_io_service().) Get the io_service associated with the
  /// work.
  asio::io_service& io_service();

  /// Get the io_service associated with the work.
  asio::io_service& get_io_service();

private:
  // Prevent assignment.
  void operator=(const work& other);

  // The io_service.
  asio::io_service& io_service_;
};

/// Class used to uniquely identify a service.
class io_service::id
  : private noncopyable
{
public:
  /// Constructor.
  id() {}
};

/// Base class for all io_service services.
class io_service::service
  : private noncopyable
{
public:
  /// (Deprecated: use get_io_service().) Get the io_service object that owns
  /// the service.
  asio::io_service& io_service();

  /// Get the io_service object that owns the service.
  asio::io_service& get_io_service();

protected:
  /// Constructor.
  /**
   * @param owner The io_service object that owns the service.
   */
  service(asio::io_service& owner);

  /// Destructor.
  virtual ~service();

private:
  /// Destroy all user-defined handler objects owned by the service.
  virtual void shutdown_service() = 0;

  friend class asio::detail::service_registry;
  asio::io_service& owner_;
  const std::type_info* type_info_;
  const asio::io_service::id* id_;
  service* next_;
};

/// Exception thrown when trying to add a duplicate service to an io_service.
class service_already_exists
  : public std::logic_error
{
public:
  service_already_exists()
    : std::logic_error("Service already exists.")
  {
  }
};

/// Exception thrown when trying to add a service object to an io_service where
/// the service has a different owner.
class invalid_service_owner
  : public std::logic_error
{
public:
  invalid_service_owner()
    : std::logic_error("Invalid service owner.")
  {
  }
};

} // namespace asio

#include "asio/impl/io_service.ipp"

#include "asio/detail/pop_options.hpp"

#endif // ASIO_IO_SERVICE_HPP