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0001 //
0002 // detail/epoll_reactor.hpp
0003 // ~~~~~~~~~~~~~~~~~~~~~~~~
0004 //
0005 // Copyright (c) 2003-2023 Christopher M. Kohlhoff (chris at kohlhoff dot com)
0006 //
0007 // Distributed under the Boost Software License, Version 1.0. (See accompanying
0008 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0009 //
0010 
0011 #ifndef BOOST_ASIO_DETAIL_EPOLL_REACTOR_HPP
0012 #define BOOST_ASIO_DETAIL_EPOLL_REACTOR_HPP
0013 
0014 #if defined(_MSC_VER) && (_MSC_VER >= 1200)
0015 # pragma once
0016 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
0017 
0018 #include <boost/asio/detail/config.hpp>
0019 
0020 #if defined(BOOST_ASIO_HAS_EPOLL)
0021 
0022 #include <boost/asio/detail/atomic_count.hpp>
0023 #include <boost/asio/detail/conditionally_enabled_mutex.hpp>
0024 #include <boost/asio/detail/limits.hpp>
0025 #include <boost/asio/detail/object_pool.hpp>
0026 #include <boost/asio/detail/op_queue.hpp>
0027 #include <boost/asio/detail/reactor_op.hpp>
0028 #include <boost/asio/detail/scheduler_task.hpp>
0029 #include <boost/asio/detail/select_interrupter.hpp>
0030 #include <boost/asio/detail/socket_types.hpp>
0031 #include <boost/asio/detail/timer_queue_base.hpp>
0032 #include <boost/asio/detail/timer_queue_set.hpp>
0033 #include <boost/asio/detail/wait_op.hpp>
0034 #include <boost/asio/execution_context.hpp>
0035 
0036 #if defined(BOOST_ASIO_HAS_TIMERFD)
0037 # include <sys/timerfd.h>
0038 #endif // defined(BOOST_ASIO_HAS_TIMERFD)
0039 
0040 #include <boost/asio/detail/push_options.hpp>
0041 
0042 namespace boost {
0043 namespace asio {
0044 namespace detail {
0045 
0046 class epoll_reactor
0047   : public execution_context_service_base<epoll_reactor>,
0048     public scheduler_task
0049 {
0050 private:
0051   // The mutex type used by this reactor.
0052   typedef conditionally_enabled_mutex mutex;
0053 
0054 public:
0055   enum op_types { read_op = 0, write_op = 1,
0056     connect_op = 1, except_op = 2, max_ops = 3 };
0057 
0058   // Per-descriptor queues.
0059   class descriptor_state : operation
0060   {
0061     friend class epoll_reactor;
0062     friend class object_pool_access;
0063 
0064     descriptor_state* next_;
0065     descriptor_state* prev_;
0066 
0067     mutex mutex_;
0068     epoll_reactor* reactor_;
0069     int descriptor_;
0070     uint32_t registered_events_;
0071     op_queue<reactor_op> op_queue_[max_ops];
0072     bool try_speculative_[max_ops];
0073     bool shutdown_;
0074 
0075     BOOST_ASIO_DECL descriptor_state(bool locking);
0076     void set_ready_events(uint32_t events) { task_result_ = events; }
0077     void add_ready_events(uint32_t events) { task_result_ |= events; }
0078     BOOST_ASIO_DECL operation* perform_io(uint32_t events);
0079     BOOST_ASIO_DECL static void do_complete(
0080         void* owner, operation* base,
0081         const boost::system::error_code& ec, std::size_t bytes_transferred);
0082   };
0083 
0084   // Per-descriptor data.
0085   typedef descriptor_state* per_descriptor_data;
0086 
0087   // Constructor.
0088   BOOST_ASIO_DECL epoll_reactor(boost::asio::execution_context& ctx);
0089 
0090   // Destructor.
0091   BOOST_ASIO_DECL ~epoll_reactor();
0092 
0093   // Destroy all user-defined handler objects owned by the service.
0094   BOOST_ASIO_DECL void shutdown();
0095 
0096   // Recreate internal descriptors following a fork.
0097   BOOST_ASIO_DECL void notify_fork(
0098       boost::asio::execution_context::fork_event fork_ev);
0099 
0100   // Initialise the task.
0101   BOOST_ASIO_DECL void init_task();
0102 
0103   // Register a socket with the reactor. Returns 0 on success, system error
0104   // code on failure.
0105   BOOST_ASIO_DECL int register_descriptor(socket_type descriptor,
0106       per_descriptor_data& descriptor_data);
0107 
0108   // Register a descriptor with an associated single operation. Returns 0 on
0109   // success, system error code on failure.
0110   BOOST_ASIO_DECL int register_internal_descriptor(
0111       int op_type, socket_type descriptor,
0112       per_descriptor_data& descriptor_data, reactor_op* op);
0113 
0114   // Move descriptor registration from one descriptor_data object to another.
0115   BOOST_ASIO_DECL void move_descriptor(socket_type descriptor,
0116       per_descriptor_data& target_descriptor_data,
0117       per_descriptor_data& source_descriptor_data);
0118 
0119   // Post a reactor operation for immediate completion.
0120   void post_immediate_completion(operation* op, bool is_continuation) const;
0121 
0122   // Post a reactor operation for immediate completion.
0123   BOOST_ASIO_DECL static void call_post_immediate_completion(
0124       operation* op, bool is_continuation, const void* self);
0125 
0126   // Start a new operation. The reactor operation will be performed when the
0127   // given descriptor is flagged as ready, or an error has occurred.
0128   BOOST_ASIO_DECL void start_op(int op_type, socket_type descriptor,
0129       per_descriptor_data& descriptor_data, reactor_op* op,
0130       bool is_continuation, bool allow_speculative,
0131       void (*on_immediate)(operation*, bool, const void*),
0132       const void* immediate_arg);
0133 
0134   // Start a new operation. The reactor operation will be performed when the
0135   // given descriptor is flagged as ready, or an error has occurred.
0136   void start_op(int op_type, socket_type descriptor,
0137       per_descriptor_data& descriptor_data, reactor_op* op,
0138       bool is_continuation, bool allow_speculative)
0139   {
0140     start_op(op_type, descriptor, descriptor_data,
0141         op, is_continuation, allow_speculative,
0142         &epoll_reactor::call_post_immediate_completion, this);
0143   }
0144 
0145   // Cancel all operations associated with the given descriptor. The
0146   // handlers associated with the descriptor will be invoked with the
0147   // operation_aborted error.
0148   BOOST_ASIO_DECL void cancel_ops(socket_type descriptor,
0149       per_descriptor_data& descriptor_data);
0150 
0151   // Cancel all operations associated with the given descriptor and key. The
0152   // handlers associated with the descriptor will be invoked with the
0153   // operation_aborted error.
0154   BOOST_ASIO_DECL void cancel_ops_by_key(socket_type descriptor,
0155       per_descriptor_data& descriptor_data,
0156       int op_type, void* cancellation_key);
0157 
0158   // Cancel any operations that are running against the descriptor and remove
0159   // its registration from the reactor. The reactor resources associated with
0160   // the descriptor must be released by calling cleanup_descriptor_data.
0161   BOOST_ASIO_DECL void deregister_descriptor(socket_type descriptor,
0162       per_descriptor_data& descriptor_data, bool closing);
0163 
0164   // Remove the descriptor's registration from the reactor. The reactor
0165   // resources associated with the descriptor must be released by calling
0166   // cleanup_descriptor_data.
0167   BOOST_ASIO_DECL void deregister_internal_descriptor(
0168       socket_type descriptor, per_descriptor_data& descriptor_data);
0169 
0170   // Perform any post-deregistration cleanup tasks associated with the
0171   // descriptor data.
0172   BOOST_ASIO_DECL void cleanup_descriptor_data(
0173       per_descriptor_data& descriptor_data);
0174 
0175   // Add a new timer queue to the reactor.
0176   template <typename Time_Traits>
0177   void add_timer_queue(timer_queue<Time_Traits>& timer_queue);
0178 
0179   // Remove a timer queue from the reactor.
0180   template <typename Time_Traits>
0181   void remove_timer_queue(timer_queue<Time_Traits>& timer_queue);
0182 
0183   // Schedule a new operation in the given timer queue to expire at the
0184   // specified absolute time.
0185   template <typename Time_Traits>
0186   void schedule_timer(timer_queue<Time_Traits>& queue,
0187       const typename Time_Traits::time_type& time,
0188       typename timer_queue<Time_Traits>::per_timer_data& timer, wait_op* op);
0189 
0190   // Cancel the timer operations associated with the given token. Returns the
0191   // number of operations that have been posted or dispatched.
0192   template <typename Time_Traits>
0193   std::size_t cancel_timer(timer_queue<Time_Traits>& queue,
0194       typename timer_queue<Time_Traits>::per_timer_data& timer,
0195       std::size_t max_cancelled = (std::numeric_limits<std::size_t>::max)());
0196 
0197   // Cancel the timer operations associated with the given key.
0198   template <typename Time_Traits>
0199   void cancel_timer_by_key(timer_queue<Time_Traits>& queue,
0200       typename timer_queue<Time_Traits>::per_timer_data* timer,
0201       void* cancellation_key);
0202 
0203   // Move the timer operations associated with the given timer.
0204   template <typename Time_Traits>
0205   void move_timer(timer_queue<Time_Traits>& queue,
0206       typename timer_queue<Time_Traits>::per_timer_data& target,
0207       typename timer_queue<Time_Traits>::per_timer_data& source);
0208 
0209   // Run epoll once until interrupted or events are ready to be dispatched.
0210   BOOST_ASIO_DECL void run(long usec, op_queue<operation>& ops);
0211 
0212   // Interrupt the select loop.
0213   BOOST_ASIO_DECL void interrupt();
0214 
0215 private:
0216   // The hint to pass to epoll_create to size its data structures.
0217   enum { epoll_size = 20000 };
0218 
0219   // Create the epoll file descriptor. Throws an exception if the descriptor
0220   // cannot be created.
0221   BOOST_ASIO_DECL static int do_epoll_create();
0222 
0223   // Create the timerfd file descriptor. Does not throw.
0224   BOOST_ASIO_DECL static int do_timerfd_create();
0225 
0226   // Allocate a new descriptor state object.
0227   BOOST_ASIO_DECL descriptor_state* allocate_descriptor_state();
0228 
0229   // Free an existing descriptor state object.
0230   BOOST_ASIO_DECL void free_descriptor_state(descriptor_state* s);
0231 
0232   // Helper function to add a new timer queue.
0233   BOOST_ASIO_DECL void do_add_timer_queue(timer_queue_base& queue);
0234 
0235   // Helper function to remove a timer queue.
0236   BOOST_ASIO_DECL void do_remove_timer_queue(timer_queue_base& queue);
0237 
0238   // Called to recalculate and update the timeout.
0239   BOOST_ASIO_DECL void update_timeout();
0240 
0241   // Get the timeout value for the epoll_wait call. The timeout value is
0242   // returned as a number of milliseconds. A return value of -1 indicates
0243   // that epoll_wait should block indefinitely.
0244   BOOST_ASIO_DECL int get_timeout(int msec);
0245 
0246 #if defined(BOOST_ASIO_HAS_TIMERFD)
0247   // Get the timeout value for the timer descriptor. The return value is the
0248   // flag argument to be used when calling timerfd_settime.
0249   BOOST_ASIO_DECL int get_timeout(itimerspec& ts);
0250 #endif // defined(BOOST_ASIO_HAS_TIMERFD)
0251 
0252   // The scheduler implementation used to post completions.
0253   scheduler& scheduler_;
0254 
0255   // Mutex to protect access to internal data.
0256   mutex mutex_;
0257 
0258   // The interrupter is used to break a blocking epoll_wait call.
0259   select_interrupter interrupter_;
0260 
0261   // The epoll file descriptor.
0262   int epoll_fd_;
0263 
0264   // The timer file descriptor.
0265   int timer_fd_;
0266 
0267   // The timer queues.
0268   timer_queue_set timer_queues_;
0269 
0270   // Whether the service has been shut down.
0271   bool shutdown_;
0272 
0273   // Mutex to protect access to the registered descriptors.
0274   mutex registered_descriptors_mutex_;
0275 
0276   // Keep track of all registered descriptors.
0277   object_pool<descriptor_state> registered_descriptors_;
0278 
0279   // Helper class to do post-perform_io cleanup.
0280   struct perform_io_cleanup_on_block_exit;
0281   friend struct perform_io_cleanup_on_block_exit;
0282 };
0283 
0284 } // namespace detail
0285 } // namespace asio
0286 } // namespace boost
0287 
0288 #include <boost/asio/detail/pop_options.hpp>
0289 
0290 #include <boost/asio/detail/impl/epoll_reactor.hpp>
0291 #if defined(BOOST_ASIO_HEADER_ONLY)
0292 # include <boost/asio/detail/impl/epoll_reactor.ipp>
0293 #endif // defined(BOOST_ASIO_HEADER_ONLY)
0294 
0295 #endif // defined(BOOST_ASIO_HAS_EPOLL)
0296 
0297 #endif // BOOST_ASIO_DETAIL_EPOLL_REACTOR_HPP