Chris@16: //
Chris@16: // io_service.hpp
Chris@16: // ~~~~~~~~~~~~~~
Chris@16: //
Chris@101: // Copyright (c) 2003-2015 Christopher M. Kohlhoff (chris at kohlhoff dot com)
Chris@16: //
Chris@16: // Distributed under the Boost Software License, Version 1.0. (See accompanying
Chris@16: // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@16: //
Chris@16: 
Chris@16: #ifndef BOOST_ASIO_IO_SERVICE_HPP
Chris@16: #define BOOST_ASIO_IO_SERVICE_HPP
Chris@16: 
Chris@16: #if defined(_MSC_VER) && (_MSC_VER >= 1200)
Chris@16: # pragma once
Chris@16: #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
Chris@16: 
Chris@16: #include <boost/asio/detail/config.hpp>
Chris@16: #include <cstddef>
Chris@16: #include <stdexcept>
Chris@16: #include <typeinfo>
Chris@16: #include <boost/asio/async_result.hpp>
Chris@16: #include <boost/asio/detail/noncopyable.hpp>
Chris@16: #include <boost/asio/detail/wrapped_handler.hpp>
Chris@16: #include <boost/system/error_code.hpp>
Chris@16: 
Chris@16: #if defined(BOOST_ASIO_WINDOWS) || defined(__CYGWIN__)
Chris@16: # include <boost/asio/detail/winsock_init.hpp>
Chris@16: #elif defined(__sun) || defined(__QNX__) || defined(__hpux) || defined(_AIX) \
Chris@16:   || defined(__osf__)
Chris@16: # include <boost/asio/detail/signal_init.hpp>
Chris@16: #endif
Chris@16: 
Chris@16: #include <boost/asio/detail/push_options.hpp>
Chris@16: 
Chris@16: namespace boost {
Chris@16: namespace asio {
Chris@16: 
Chris@16: class io_service;
Chris@16: template <typename Service> Service& use_service(io_service& ios);
Chris@16: template <typename Service> void add_service(io_service& ios, Service* svc);
Chris@16: template <typename Service> bool has_service(io_service& ios);
Chris@16: 
Chris@16: namespace detail {
Chris@16: #if defined(BOOST_ASIO_HAS_IOCP)
Chris@16:   typedef class win_iocp_io_service io_service_impl;
Chris@16:   class win_iocp_overlapped_ptr;
Chris@16: #else
Chris@16:   typedef class task_io_service io_service_impl;
Chris@16: #endif
Chris@16:   class service_registry;
Chris@16: } // namespace detail
Chris@16: 
Chris@16: /// Provides core I/O functionality.
Chris@16: /**
Chris@16:  * The io_service class provides the core I/O functionality for users of the
Chris@16:  * asynchronous I/O objects, including:
Chris@16:  *
Chris@16:  * @li boost::asio::ip::tcp::socket
Chris@16:  * @li boost::asio::ip::tcp::acceptor
Chris@16:  * @li boost::asio::ip::udp::socket
Chris@16:  * @li boost::asio::deadline_timer.
Chris@16:  *
Chris@16:  * The io_service class also includes facilities intended for developers of
Chris@16:  * custom asynchronous services.
Chris@16:  *
Chris@16:  * @par Thread Safety
Chris@16:  * @e Distinct @e objects: Safe.@n
Chris@16:  * @e Shared @e objects: Safe, with the specific exceptions of the reset() and
Chris@16:  * notify_fork() functions. Calling reset() while there are unfinished run(),
Chris@16:  * run_one(), poll() or poll_one() calls results in undefined behaviour. The
Chris@16:  * notify_fork() function should not be called while any io_service function,
Chris@16:  * or any function on an I/O object that is associated with the io_service, is
Chris@16:  * being called in another thread.
Chris@16:  *
Chris@16:  * @par Concepts:
Chris@16:  * Dispatcher.
Chris@16:  *
Chris@16:  * @par Synchronous and asynchronous operations
Chris@16:  *
Chris@16:  * Synchronous operations on I/O objects implicitly run the io_service object
Chris@16:  * for an individual operation. The io_service functions run(), run_one(),
Chris@16:  * poll() or poll_one() must be called for the io_service to perform
Chris@16:  * asynchronous operations on behalf of a C++ program. Notification that an
Chris@16:  * asynchronous operation has completed is delivered by invocation of the
Chris@16:  * associated handler. Handlers are invoked only by a thread that is currently
Chris@16:  * calling any overload of run(), run_one(), poll() or poll_one() for the
Chris@16:  * io_service.
Chris@16:  *
Chris@16:  * @par Effect of exceptions thrown from handlers
Chris@16:  *
Chris@16:  * If an exception is thrown from a handler, the exception is allowed to
Chris@16:  * propagate through the throwing thread's invocation of run(), run_one(),
Chris@16:  * poll() or poll_one(). No other threads that are calling any of these
Chris@16:  * functions are affected. It is then the responsibility of the application to
Chris@16:  * catch the exception.
Chris@16:  *
Chris@16:  * After the exception has been caught, the run(), run_one(), poll() or
Chris@16:  * poll_one() call may be restarted @em without the need for an intervening
Chris@16:  * call to reset(). This allows the thread to rejoin the io_service object's
Chris@16:  * thread pool without impacting any other threads in the pool.
Chris@16:  *
Chris@16:  * For example:
Chris@16:  *
Chris@16:  * @code
Chris@16:  * boost::asio::io_service io_service;
Chris@16:  * ...
Chris@16:  * for (;;)
Chris@16:  * {
Chris@16:  *   try
Chris@16:  *   {
Chris@16:  *     io_service.run();
Chris@16:  *     break; // run() exited normally
Chris@16:  *   }
Chris@16:  *   catch (my_exception& e)
Chris@16:  *   {
Chris@16:  *     // Deal with exception as appropriate.
Chris@16:  *   }
Chris@16:  * }
Chris@16:  * @endcode
Chris@16:  *
Chris@16:  * @par Stopping the io_service from running out of work
Chris@16:  *
Chris@16:  * Some applications may need to prevent an io_service object's run() call from
Chris@16:  * returning when there is no more work to do. For example, the io_service may
Chris@16:  * be being run in a background thread that is launched prior to the
Chris@16:  * application's asynchronous operations. The run() call may be kept running by
Chris@16:  * creating an object of type boost::asio::io_service::work:
Chris@16:  *
Chris@16:  * @code boost::asio::io_service io_service;
Chris@16:  * boost::asio::io_service::work work(io_service);
Chris@16:  * ... @endcode
Chris@16:  *
Chris@16:  * To effect a shutdown, the application will then need to call the io_service
Chris@16:  * object's stop() member function. This will cause the io_service run() call
Chris@16:  * to return as soon as possible, abandoning unfinished operations and without
Chris@16:  * permitting ready handlers to be dispatched.
Chris@16:  *
Chris@16:  * Alternatively, if the application requires that all operations and handlers
Chris@16:  * be allowed to finish normally, the work object may be explicitly destroyed.
Chris@16:  *
Chris@16:  * @code boost::asio::io_service io_service;
Chris@16:  * auto_ptr<boost::asio::io_service::work> work(
Chris@16:  *     new boost::asio::io_service::work(io_service));
Chris@16:  * ...
Chris@16:  * work.reset(); // Allow run() to exit. @endcode
Chris@16:  *
Chris@16:  * @par The io_service class and I/O services
Chris@16:  *
Chris@16:  * Class io_service implements an extensible, type-safe, polymorphic set of I/O
Chris@16:  * services, indexed by service type. An object of class io_service must be
Chris@16:  * initialised before I/O objects such as sockets, resolvers and timers can be
Chris@16:  * used. These I/O objects are distinguished by having constructors that accept
Chris@16:  * an @c io_service& parameter.
Chris@16:  *
Chris@16:  * I/O services exist to manage the logical interface to the operating system on
Chris@16:  * behalf of the I/O objects. In particular, there are resources that are shared
Chris@16:  * across a class of I/O objects. For example, timers may be implemented in
Chris@16:  * terms of a single timer queue. The I/O services manage these shared
Chris@16:  * resources.
Chris@16:  *
Chris@16:  * Access to the services of an io_service is via three function templates,
Chris@16:  * use_service(), add_service() and has_service().
Chris@16:  *
Chris@16:  * In a call to @c use_service<Service>(), the type argument chooses a service,
Chris@16:  * making available all members of the named type. If @c Service is not present
Chris@16:  * in an io_service, an object of type @c Service is created and added to the
Chris@16:  * io_service. A C++ program can check if an io_service implements a
Chris@16:  * particular service with the function template @c has_service<Service>().
Chris@16:  *
Chris@16:  * Service objects may be explicitly added to an io_service using the function
Chris@16:  * template @c add_service<Service>(). If the @c Service is already present, the
Chris@16:  * service_already_exists exception is thrown. If the owner of the service is
Chris@16:  * not the same object as the io_service parameter, the invalid_service_owner
Chris@16:  * exception is thrown.
Chris@16:  *
Chris@16:  * Once a service reference is obtained from an io_service object by calling
Chris@16:  * use_service(), that reference remains usable as long as the owning io_service
Chris@16:  * object exists.
Chris@16:  *
Chris@16:  * All I/O service implementations have io_service::service as a public base
Chris@16:  * class. Custom I/O services may be implemented by deriving from this class and
Chris@16:  * then added to an io_service using the facilities described above.
Chris@16:  */
Chris@16: class io_service
Chris@16:   : private noncopyable
Chris@16: {
Chris@16: private:
Chris@16:   typedef detail::io_service_impl impl_type;
Chris@16: #if defined(BOOST_ASIO_HAS_IOCP)
Chris@16:   friend class detail::win_iocp_overlapped_ptr;
Chris@16: #endif
Chris@16: 
Chris@16: public:
Chris@16:   class work;
Chris@16:   friend class work;
Chris@16: 
Chris@16:   class id;
Chris@16: 
Chris@16:   class service;
Chris@16: 
Chris@16:   class strand;
Chris@16: 
Chris@16:   /// Constructor.
Chris@16:   BOOST_ASIO_DECL io_service();
Chris@16: 
Chris@16:   /// Constructor.
Chris@16:   /**
Chris@16:    * Construct with a hint about the required level of concurrency.
Chris@16:    *
Chris@16:    * @param concurrency_hint A suggestion to the implementation on how many
Chris@16:    * threads it should allow to run simultaneously.
Chris@16:    */
Chris@16:   BOOST_ASIO_DECL explicit io_service(std::size_t concurrency_hint);
Chris@16: 
Chris@16:   /// Destructor.
Chris@16:   /**
Chris@16:    * On destruction, the io_service performs the following sequence of
Chris@16:    * operations:
Chris@16:    *
Chris@16:    * @li For each service object @c svc in the io_service set, in reverse order
Chris@16:    * of the beginning of service object lifetime, performs
Chris@16:    * @c svc->shutdown_service().
Chris@16:    *
Chris@16:    * @li Uninvoked handler objects that were scheduled for deferred invocation
Chris@16:    * on the io_service, or any associated strand, are destroyed.
Chris@16:    *
Chris@16:    * @li For each service object @c svc in the io_service set, in reverse order
Chris@16:    * of the beginning of service object lifetime, performs
Chris@16:    * <tt>delete static_cast<io_service::service*>(svc)</tt>.
Chris@16:    *
Chris@16:    * @note The destruction sequence described above permits programs to
Chris@16:    * simplify their resource management by using @c shared_ptr<>. Where an
Chris@16:    * object's lifetime is tied to the lifetime of a connection (or some other
Chris@16:    * sequence of asynchronous operations), a @c shared_ptr to the object would
Chris@16:    * be bound into the handlers for all asynchronous operations associated with
Chris@16:    * it. This works as follows:
Chris@16:    *
Chris@16:    * @li When a single connection ends, all associated asynchronous operations
Chris@16:    * complete. The corresponding handler objects are destroyed, and all
Chris@16:    * @c shared_ptr references to the objects are destroyed.
Chris@16:    *
Chris@16:    * @li To shut down the whole program, the io_service function stop() is
Chris@16:    * called to terminate any run() calls as soon as possible. The io_service
Chris@16:    * destructor defined above destroys all handlers, causing all @c shared_ptr
Chris@16:    * references to all connection objects to be destroyed.
Chris@16:    */
Chris@16:   BOOST_ASIO_DECL ~io_service();
Chris@16: 
Chris@16:   /// Run the io_service object's event processing loop.
Chris@16:   /**
Chris@16:    * The run() function blocks until all work has finished and there are no
Chris@16:    * more handlers to be dispatched, or until the io_service has been stopped.
Chris@16:    *
Chris@16:    * Multiple threads may call the run() function to set up a pool of threads
Chris@16:    * from which the io_service may execute handlers. All threads that are
Chris@16:    * waiting in the pool are equivalent and the io_service may choose any one
Chris@16:    * of them to invoke a handler.
Chris@16:    *
Chris@16:    * A normal exit from the run() function implies that the io_service object
Chris@16:    * is stopped (the stopped() function returns @c true). Subsequent calls to
Chris@16:    * run(), run_one(), poll() or poll_one() will return immediately unless there
Chris@16:    * is a prior call to reset().
Chris@16:    *
Chris@16:    * @return The number of handlers that were executed.
Chris@16:    *
Chris@16:    * @throws boost::system::system_error Thrown on failure.
Chris@16:    *
Chris@16:    * @note The run() function must not be called from a thread that is currently
Chris@16:    * calling one of run(), run_one(), poll() or poll_one() on the same
Chris@16:    * io_service object.
Chris@16:    *
Chris@16:    * The poll() function may also be used to dispatch ready handlers, but
Chris@16:    * without blocking.
Chris@16:    */
Chris@16:   BOOST_ASIO_DECL std::size_t run();
Chris@16: 
Chris@16:   /// Run the io_service object's event processing loop.
Chris@16:   /**
Chris@16:    * The run() function blocks until all work has finished and there are no
Chris@16:    * more handlers to be dispatched, or until the io_service has been stopped.
Chris@16:    *
Chris@16:    * Multiple threads may call the run() function to set up a pool of threads
Chris@16:    * from which the io_service may execute handlers. All threads that are
Chris@16:    * waiting in the pool are equivalent and the io_service may choose any one
Chris@16:    * of them to invoke a handler.
Chris@16:    *
Chris@16:    * A normal exit from the run() function implies that the io_service object
Chris@16:    * is stopped (the stopped() function returns @c true). Subsequent calls to
Chris@16:    * run(), run_one(), poll() or poll_one() will return immediately unless there
Chris@16:    * is a prior call to reset().
Chris@16:    *
Chris@16:    * @param ec Set to indicate what error occurred, if any.
Chris@16:    *
Chris@16:    * @return The number of handlers that were executed.
Chris@16:    *
Chris@16:    * @note The run() function must not be called from a thread that is currently
Chris@16:    * calling one of run(), run_one(), poll() or poll_one() on the same
Chris@16:    * io_service object.
Chris@16:    *
Chris@16:    * The poll() function may also be used to dispatch ready handlers, but
Chris@16:    * without blocking.
Chris@16:    */
Chris@16:   BOOST_ASIO_DECL std::size_t run(boost::system::error_code& ec);
Chris@16: 
Chris@16:   /// Run the io_service object's event processing loop to execute at most one
Chris@16:   /// handler.
Chris@16:   /**
Chris@16:    * The run_one() function blocks until one handler has been dispatched, or
Chris@16:    * until the io_service has been stopped.
Chris@16:    *
Chris@16:    * @return The number of handlers that were executed. A zero return value
Chris@16:    * implies that the io_service object is stopped (the stopped() function
Chris@16:    * returns @c true). Subsequent calls to run(), run_one(), poll() or
Chris@16:    * poll_one() will return immediately unless there is a prior call to
Chris@16:    * reset().
Chris@16:    *
Chris@16:    * @throws boost::system::system_error Thrown on failure.
Chris@16:    */
Chris@16:   BOOST_ASIO_DECL std::size_t run_one();
Chris@16: 
Chris@16:   /// Run the io_service object's event processing loop to execute at most one
Chris@16:   /// handler.
Chris@16:   /**
Chris@16:    * The run_one() function blocks until one handler has been dispatched, or
Chris@16:    * until the io_service has been stopped.
Chris@16:    *
Chris@16:    * @return The number of handlers that were executed. A zero return value
Chris@16:    * implies that the io_service object is stopped (the stopped() function
Chris@16:    * returns @c true). Subsequent calls to run(), run_one(), poll() or
Chris@16:    * poll_one() will return immediately unless there is a prior call to
Chris@16:    * reset().
Chris@16:    *
Chris@16:    * @return The number of handlers that were executed.
Chris@16:    */
Chris@16:   BOOST_ASIO_DECL std::size_t run_one(boost::system::error_code& ec);
Chris@16: 
Chris@16:   /// Run the io_service object's event processing loop to execute ready
Chris@16:   /// handlers.
Chris@16:   /**
Chris@16:    * The poll() function runs handlers that are ready to run, without blocking,
Chris@16:    * until the io_service has been stopped or there are no more ready handlers.
Chris@16:    *
Chris@16:    * @return The number of handlers that were executed.
Chris@16:    *
Chris@16:    * @throws boost::system::system_error Thrown on failure.
Chris@16:    */
Chris@16:   BOOST_ASIO_DECL std::size_t poll();
Chris@16: 
Chris@16:   /// Run the io_service object's event processing loop to execute ready
Chris@16:   /// handlers.
Chris@16:   /**
Chris@16:    * The poll() function runs handlers that are ready to run, without blocking,
Chris@16:    * until the io_service has been stopped or there are no more ready handlers.
Chris@16:    *
Chris@16:    * @param ec Set to indicate what error occurred, if any.
Chris@16:    *
Chris@16:    * @return The number of handlers that were executed.
Chris@16:    */
Chris@16:   BOOST_ASIO_DECL std::size_t poll(boost::system::error_code& ec);
Chris@16: 
Chris@16:   /// Run the io_service object's event processing loop to execute one ready
Chris@16:   /// handler.
Chris@16:   /**
Chris@16:    * The poll_one() function runs at most one handler that is ready to run,
Chris@16:    * without blocking.
Chris@16:    *
Chris@16:    * @return The number of handlers that were executed.
Chris@16:    *
Chris@16:    * @throws boost::system::system_error Thrown on failure.
Chris@16:    */
Chris@16:   BOOST_ASIO_DECL std::size_t poll_one();
Chris@16: 
Chris@16:   /// Run the io_service object's event processing loop to execute one ready
Chris@16:   /// handler.
Chris@16:   /**
Chris@16:    * The poll_one() function runs at most one handler that is ready to run,
Chris@16:    * without blocking.
Chris@16:    *
Chris@16:    * @param ec Set to indicate what error occurred, if any.
Chris@16:    *
Chris@16:    * @return The number of handlers that were executed.
Chris@16:    */
Chris@16:   BOOST_ASIO_DECL std::size_t poll_one(boost::system::error_code& ec);
Chris@16: 
Chris@16:   /// Stop the io_service object's event processing loop.
Chris@16:   /**
Chris@16:    * This function does not block, but instead simply signals the io_service to
Chris@16:    * stop. All invocations of its run() or run_one() member functions should
Chris@16:    * return as soon as possible. Subsequent calls to run(), run_one(), poll()
Chris@16:    * or poll_one() will return immediately until reset() is called.
Chris@16:    */
Chris@16:   BOOST_ASIO_DECL void stop();
Chris@16: 
Chris@16:   /// Determine whether the io_service object has been stopped.
Chris@16:   /**
Chris@16:    * This function is used to determine whether an io_service object has been
Chris@16:    * stopped, either through an explicit call to stop(), or due to running out
Chris@16:    * of work. When an io_service object is stopped, calls to run(), run_one(),
Chris@16:    * poll() or poll_one() will return immediately without invoking any
Chris@16:    * handlers.
Chris@16:    *
Chris@16:    * @return @c true if the io_service object is stopped, otherwise @c false.
Chris@16:    */
Chris@16:   BOOST_ASIO_DECL bool stopped() const;
Chris@16: 
Chris@16:   /// Reset the io_service in preparation for a subsequent run() invocation.
Chris@16:   /**
Chris@16:    * This function must be called prior to any second or later set of
Chris@16:    * invocations of the run(), run_one(), poll() or poll_one() functions when a
Chris@16:    * previous invocation of these functions returned due to the io_service
Chris@16:    * being stopped or running out of work. After a call to reset(), the
Chris@16:    * io_service object's stopped() function will return @c false.
Chris@16:    *
Chris@16:    * This function must not be called while there are any unfinished calls to
Chris@16:    * the run(), run_one(), poll() or poll_one() functions.
Chris@16:    */
Chris@16:   BOOST_ASIO_DECL void reset();
Chris@16: 
Chris@16:   /// Request the io_service to invoke the given handler.
Chris@16:   /**
Chris@16:    * This function is used to ask the io_service to execute the given handler.
Chris@16:    *
Chris@16:    * The io_service guarantees that the handler will only be called in a thread
Chris@16:    * in which the run(), run_one(), poll() or poll_one() member functions is
Chris@16:    * currently being invoked. The handler may be executed inside this function
Chris@16:    * if the guarantee can be met.
Chris@16:    *
Chris@16:    * @param handler The handler to be called. The io_service will make
Chris@16:    * a copy of the handler object as required. The function signature of the
Chris@16:    * handler must be: @code void handler(); @endcode
Chris@16:    *
Chris@16:    * @note This function throws an exception only if:
Chris@16:    *
Chris@16:    * @li the handler's @c asio_handler_allocate function; or
Chris@16:    *
Chris@16:    * @li the handler's copy constructor
Chris@16:    *
Chris@16:    * throws an exception.
Chris@16:    */
Chris@16:   template <typename CompletionHandler>
Chris@16:   BOOST_ASIO_INITFN_RESULT_TYPE(CompletionHandler, void ())
Chris@16:   dispatch(BOOST_ASIO_MOVE_ARG(CompletionHandler) handler);
Chris@16: 
Chris@16:   /// Request the io_service to invoke the given handler and return immediately.
Chris@16:   /**
Chris@16:    * This function is used to ask the io_service to execute the given handler,
Chris@16:    * but without allowing the io_service to call the handler from inside this
Chris@16:    * function.
Chris@16:    *
Chris@16:    * The io_service guarantees that the handler will only be called in a thread
Chris@16:    * in which the run(), run_one(), poll() or poll_one() member functions is
Chris@16:    * currently being invoked.
Chris@16:    *
Chris@16:    * @param handler The handler to be called. The io_service will make
Chris@16:    * a copy of the handler object as required. The function signature of the
Chris@16:    * handler must be: @code void handler(); @endcode
Chris@16:    *
Chris@16:    * @note This function throws an exception only if:
Chris@16:    *
Chris@16:    * @li the handler's @c asio_handler_allocate function; or
Chris@16:    *
Chris@16:    * @li the handler's copy constructor
Chris@16:    *
Chris@16:    * throws an exception.
Chris@16:    */
Chris@16:   template <typename CompletionHandler>
Chris@16:   BOOST_ASIO_INITFN_RESULT_TYPE(CompletionHandler, void ())
Chris@16:   post(BOOST_ASIO_MOVE_ARG(CompletionHandler) handler);
Chris@16: 
Chris@16:   /// Create a new handler that automatically dispatches the wrapped handler
Chris@16:   /// on the io_service.
Chris@16:   /**
Chris@16:    * This function is used to create a new handler function object that, when
Chris@16:    * invoked, will automatically pass the wrapped handler to the io_service
Chris@16:    * object's dispatch function.
Chris@16:    *
Chris@16:    * @param handler The handler to be wrapped. The io_service will make a copy
Chris@16:    * of the handler object as required. The function signature of the handler
Chris@16:    * must be: @code void handler(A1 a1, ... An an); @endcode
Chris@16:    *
Chris@16:    * @return A function object that, when invoked, passes the wrapped handler to
Chris@16:    * the io_service object's dispatch function. Given a function object with the
Chris@16:    * signature:
Chris@16:    * @code R f(A1 a1, ... An an); @endcode
Chris@16:    * If this function object is passed to the wrap function like so:
Chris@16:    * @code io_service.wrap(f); @endcode
Chris@16:    * then the return value is a function object with the signature
Chris@16:    * @code void g(A1 a1, ... An an); @endcode
Chris@16:    * that, when invoked, executes code equivalent to:
Chris@16:    * @code io_service.dispatch(boost::bind(f, a1, ... an)); @endcode
Chris@16:    */
Chris@16:   template <typename Handler>
Chris@16: #if defined(GENERATING_DOCUMENTATION)
Chris@16:   unspecified
Chris@16: #else
Chris@16:   detail::wrapped_handler<io_service&, Handler>
Chris@16: #endif
Chris@16:   wrap(Handler handler);
Chris@16: 
Chris@16:   /// Fork-related event notifications.
Chris@16:   enum fork_event
Chris@16:   {
Chris@16:     /// Notify the io_service that the process is about to fork.
Chris@16:     fork_prepare,
Chris@16: 
Chris@16:     /// Notify the io_service that the process has forked and is the parent.
Chris@16:     fork_parent,
Chris@16: 
Chris@16:     /// Notify the io_service that the process has forked and is the child.
Chris@16:     fork_child
Chris@16:   };
Chris@16: 
Chris@16:   /// Notify the io_service of a fork-related event.
Chris@16:   /**
Chris@16:    * This function is used to inform the io_service that the process is about
Chris@16:    * to fork, or has just forked. This allows the io_service, and the services
Chris@16:    * it contains, to perform any necessary housekeeping to ensure correct
Chris@16:    * operation following a fork.
Chris@16:    *
Chris@16:    * This function must not be called while any other io_service function, or
Chris@16:    * any function on an I/O object associated with the io_service, is being
Chris@16:    * called in another thread. It is, however, safe to call this function from
Chris@16:    * within a completion handler, provided no other thread is accessing the
Chris@16:    * io_service.
Chris@16:    *
Chris@16:    * @param event A fork-related event.
Chris@16:    *
Chris@16:    * @throws boost::system::system_error Thrown on failure. If the notification
Chris@16:    * fails the io_service object should no longer be used and should be
Chris@16:    * destroyed.
Chris@16:    *
Chris@16:    * @par Example
Chris@16:    * The following code illustrates how to incorporate the notify_fork()
Chris@16:    * function:
Chris@16:    * @code my_io_service.notify_fork(boost::asio::io_service::fork_prepare);
Chris@16:    * if (fork() == 0)
Chris@16:    * {
Chris@16:    *   // This is the child process.
Chris@16:    *   my_io_service.notify_fork(boost::asio::io_service::fork_child);
Chris@16:    * }
Chris@16:    * else
Chris@16:    * {
Chris@16:    *   // This is the parent process.
Chris@16:    *   my_io_service.notify_fork(boost::asio::io_service::fork_parent);
Chris@16:    * } @endcode
Chris@16:    *
Chris@16:    * @note For each service object @c svc in the io_service set, performs
Chris@16:    * <tt>svc->fork_service();</tt>. When processing the fork_prepare event,
Chris@16:    * services are visited in reverse order of the beginning of service object
Chris@16:    * lifetime. Otherwise, services are visited in order of the beginning of
Chris@16:    * service object lifetime.
Chris@16:    */
Chris@16:   BOOST_ASIO_DECL void notify_fork(boost::asio::io_service::fork_event event);
Chris@16: 
Chris@16:   /// Obtain the service object corresponding to the given type.
Chris@16:   /**
Chris@16:    * This function is used to locate a service object that corresponds to
Chris@16:    * the given service type. If there is no existing implementation of the
Chris@16:    * service, then the io_service will create a new instance of the service.
Chris@16:    *
Chris@16:    * @param ios The io_service object that owns the service.
Chris@16:    *
Chris@16:    * @return The service interface implementing the specified service type.
Chris@16:    * Ownership of the service interface is not transferred to the caller.
Chris@16:    */
Chris@16:   template <typename Service>
Chris@16:   friend Service& use_service(io_service& ios);
Chris@16: 
Chris@16:   /// Add a service object to the io_service.
Chris@16:   /**
Chris@16:    * This function is used to add a service to the io_service.
Chris@16:    *
Chris@16:    * @param ios The io_service object that owns the service.
Chris@16:    *
Chris@16:    * @param svc The service object. On success, ownership of the service object
Chris@16:    * is transferred to the io_service. When the io_service object is destroyed,
Chris@16:    * it will destroy the service object by performing:
Chris@16:    * @code delete static_cast<io_service::service*>(svc) @endcode
Chris@16:    *
Chris@16:    * @throws boost::asio::service_already_exists Thrown if a service of the
Chris@16:    * given type is already present in the io_service.
Chris@16:    *
Chris@16:    * @throws boost::asio::invalid_service_owner Thrown if the service's owning
Chris@16:    * io_service is not the io_service object specified by the ios parameter.
Chris@16:    */
Chris@16:   template <typename Service>
Chris@16:   friend void add_service(io_service& ios, Service* svc);
Chris@16: 
Chris@16:   /// Determine if an io_service contains a specified service type.
Chris@16:   /**
Chris@16:    * This function is used to determine whether the io_service contains a
Chris@16:    * service object corresponding to the given service type.
Chris@16:    *
Chris@16:    * @param ios The io_service object that owns the service.
Chris@16:    *
Chris@16:    * @return A boolean indicating whether the io_service contains the service.
Chris@16:    */
Chris@16:   template <typename Service>
Chris@16:   friend bool has_service(io_service& ios);
Chris@16: 
Chris@16: private:
Chris@16: #if defined(BOOST_ASIO_WINDOWS) || defined(__CYGWIN__)
Chris@16:   detail::winsock_init<> init_;
Chris@16: #elif defined(__sun) || defined(__QNX__) || defined(__hpux) || defined(_AIX) \
Chris@16:   || defined(__osf__)
Chris@16:   detail::signal_init<> init_;
Chris@16: #endif
Chris@16: 
Chris@16:   // The service registry.
Chris@16:   boost::asio::detail::service_registry* service_registry_;
Chris@16: 
Chris@16:   // The implementation.
Chris@16:   impl_type& impl_;
Chris@16: };
Chris@16: 
Chris@16: /// Class to inform the io_service when it has work to do.
Chris@16: /**
Chris@16:  * The work class is used to inform the io_service when work starts and
Chris@16:  * finishes. This ensures that the io_service object's run() function will not
Chris@16:  * exit while work is underway, and that it does exit when there is no
Chris@16:  * unfinished work remaining.
Chris@16:  *
Chris@16:  * The work class is copy-constructible so that it may be used as a data member
Chris@16:  * in a handler class. It is not assignable.
Chris@16:  */
Chris@16: class io_service::work
Chris@16: {
Chris@16: public:
Chris@16:   /// Constructor notifies the io_service that work is starting.
Chris@16:   /**
Chris@16:    * The constructor is used to inform the io_service that some work has begun.
Chris@16:    * This ensures that the io_service object's run() function will not exit
Chris@16:    * while the work is underway.
Chris@16:    */
Chris@16:   explicit work(boost::asio::io_service& io_service);
Chris@16: 
Chris@16:   /// Copy constructor notifies the io_service that work is starting.
Chris@16:   /**
Chris@16:    * The constructor is used to inform the io_service that some work has begun.
Chris@16:    * This ensures that the io_service object's run() function will not exit
Chris@16:    * while the work is underway.
Chris@16:    */
Chris@16:   work(const work& other);
Chris@16: 
Chris@16:   /// Destructor notifies the io_service that the work is complete.
Chris@16:   /**
Chris@16:    * The destructor is used to inform the io_service that some work has
Chris@16:    * finished. Once the count of unfinished work reaches zero, the io_service
Chris@16:    * object's run() function is permitted to exit.
Chris@16:    */
Chris@16:   ~work();
Chris@16: 
Chris@16:   /// Get the io_service associated with the work.
Chris@16:   boost::asio::io_service& get_io_service();
Chris@16: 
Chris@16: private:
Chris@16:   // Prevent assignment.
Chris@16:   void operator=(const work& other);
Chris@16: 
Chris@16:   // The io_service implementation.
Chris@16:   detail::io_service_impl& io_service_impl_;
Chris@16: };
Chris@16: 
Chris@16: /// Class used to uniquely identify a service.
Chris@16: class io_service::id
Chris@16:   : private noncopyable
Chris@16: {
Chris@16: public:
Chris@16:   /// Constructor.
Chris@16:   id() {}
Chris@16: };
Chris@16: 
Chris@16: /// Base class for all io_service services.
Chris@16: class io_service::service
Chris@16:   : private noncopyable
Chris@16: {
Chris@16: public:
Chris@16:   /// Get the io_service object that owns the service.
Chris@16:   boost::asio::io_service& get_io_service();
Chris@16: 
Chris@16: protected:
Chris@16:   /// Constructor.
Chris@16:   /**
Chris@16:    * @param owner The io_service object that owns the service.
Chris@16:    */
Chris@16:   BOOST_ASIO_DECL service(boost::asio::io_service& owner);
Chris@16: 
Chris@16:   /// Destructor.
Chris@16:   BOOST_ASIO_DECL virtual ~service();
Chris@16: 
Chris@16: private:
Chris@16:   /// Destroy all user-defined handler objects owned by the service.
Chris@16:   virtual void shutdown_service() = 0;
Chris@16: 
Chris@16:   /// Handle notification of a fork-related event to perform any necessary
Chris@16:   /// housekeeping.
Chris@16:   /**
Chris@16:    * This function is not a pure virtual so that services only have to
Chris@16:    * implement it if necessary. The default implementation does nothing.
Chris@16:    */
Chris@16:   BOOST_ASIO_DECL virtual void fork_service(
Chris@16:       boost::asio::io_service::fork_event event);
Chris@16: 
Chris@16:   friend class boost::asio::detail::service_registry;
Chris@16:   struct key
Chris@16:   {
Chris@16:     key() : type_info_(0), id_(0) {}
Chris@16:     const std::type_info* type_info_;
Chris@16:     const boost::asio::io_service::id* id_;
Chris@16:   } key_;
Chris@16: 
Chris@16:   boost::asio::io_service& owner_;
Chris@16:   service* next_;
Chris@16: };
Chris@16: 
Chris@16: /// Exception thrown when trying to add a duplicate service to an io_service.
Chris@16: class service_already_exists
Chris@16:   : public std::logic_error
Chris@16: {
Chris@16: public:
Chris@16:   BOOST_ASIO_DECL service_already_exists();
Chris@16: };
Chris@16: 
Chris@16: /// Exception thrown when trying to add a service object to an io_service where
Chris@16: /// the service has a different owner.
Chris@16: class invalid_service_owner
Chris@16:   : public std::logic_error
Chris@16: {
Chris@16: public:
Chris@16:   BOOST_ASIO_DECL invalid_service_owner();
Chris@16: };
Chris@16: 
Chris@16: namespace detail {
Chris@16: 
Chris@16: // Special derived service id type to keep classes header-file only.
Chris@16: template <typename Type>
Chris@16: class service_id
Chris@16:   : public boost::asio::io_service::id
Chris@16: {
Chris@16: };
Chris@16: 
Chris@16: // Special service base class to keep classes header-file only.
Chris@16: template <typename Type>
Chris@16: class service_base
Chris@16:   : public boost::asio::io_service::service
Chris@16: {
Chris@16: public:
Chris@16:   static boost::asio::detail::service_id<Type> id;
Chris@16: 
Chris@16:   // Constructor.
Chris@16:   service_base(boost::asio::io_service& io_service)
Chris@16:     : boost::asio::io_service::service(io_service)
Chris@16:   {
Chris@16:   }
Chris@16: };
Chris@16: 
Chris@16: template <typename Type>
Chris@16: boost::asio::detail::service_id<Type> service_base<Type>::id;
Chris@16: 
Chris@16: } // namespace detail
Chris@16: } // namespace asio
Chris@16: } // namespace boost
Chris@16: 
Chris@16: #include <boost/asio/detail/pop_options.hpp>
Chris@16: 
Chris@16: #include <boost/asio/impl/io_service.hpp>
Chris@16: #if defined(BOOST_ASIO_HEADER_ONLY)
Chris@16: # include <boost/asio/impl/io_service.ipp>
Chris@16: #endif // defined(BOOST_ASIO_HEADER_ONLY)
Chris@16: 
Chris@16: #endif // BOOST_ASIO_IO_SERVICE_HPP