boost/asio/detail/epoll_reactor.hpp
//
// detail/epoll_reactor.hpp
// ~~~~~~~~~~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2024 Christopher M. Kohlhoff (chris at kohlhoff dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
#ifndef BOOST_ASIO_DETAIL_EPOLL_REACTOR_HPP
#define BOOST_ASIO_DETAIL_EPOLL_REACTOR_HPP
#if defined(_MSC_VER) && (_MSC_VER >= 1200)
# pragma once
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
#include <boost/asio/detail/config.hpp>
#if defined(BOOST_ASIO_HAS_EPOLL)
#include <boost/asio/detail/atomic_count.hpp>
#include <boost/asio/detail/conditionally_enabled_mutex.hpp>
#include <boost/asio/detail/limits.hpp>
#include <boost/asio/detail/object_pool.hpp>
#include <boost/asio/detail/op_queue.hpp>
#include <boost/asio/detail/reactor_op.hpp>
#include <boost/asio/detail/scheduler_task.hpp>
#include <boost/asio/detail/select_interrupter.hpp>
#include <boost/asio/detail/socket_types.hpp>
#include <boost/asio/detail/timer_queue_base.hpp>
#include <boost/asio/detail/timer_queue_set.hpp>
#include <boost/asio/detail/wait_op.hpp>
#include <boost/asio/execution_context.hpp>
#if defined(BOOST_ASIO_HAS_TIMERFD)
# include <sys/timerfd.h>
#endif // defined(BOOST_ASIO_HAS_TIMERFD)
#include <boost/asio/detail/push_options.hpp>
namespace boost {
namespace asio {
namespace detail {
class epoll_reactor
: public execution_context_service_base<epoll_reactor>,
public scheduler_task
{
private:
// The mutex type used by this reactor.
typedef conditionally_enabled_mutex mutex;
public:
enum op_types { read_op = 0, write_op = 1,
connect_op = 1, except_op = 2, max_ops = 3 };
// Per-descriptor queues.
class descriptor_state : operation
{
friend class epoll_reactor;
friend class object_pool_access;
descriptor_state* next_;
descriptor_state* prev_;
mutex mutex_;
epoll_reactor* reactor_;
int descriptor_;
uint32_t registered_events_;
op_queue<reactor_op> op_queue_[max_ops];
bool try_speculative_[max_ops];
bool shutdown_;
BOOST_ASIO_DECL descriptor_state(bool locking, int spin_count);
void set_ready_events(uint32_t events) { task_result_ = events; }
void add_ready_events(uint32_t events) { task_result_ |= events; }
BOOST_ASIO_DECL operation* perform_io(uint32_t events);
BOOST_ASIO_DECL static void do_complete(
void* owner, operation* base,
const boost::system::error_code& ec, std::size_t bytes_transferred);
};
// Per-descriptor data.
typedef descriptor_state* per_descriptor_data;
// Constructor.
BOOST_ASIO_DECL epoll_reactor(boost::asio::execution_context& ctx);
// Destructor.
BOOST_ASIO_DECL ~epoll_reactor();
// Destroy all user-defined handler objects owned by the service.
BOOST_ASIO_DECL void shutdown();
// Recreate internal descriptors following a fork.
BOOST_ASIO_DECL void notify_fork(
boost::asio::execution_context::fork_event fork_ev);
// Initialise the task.
BOOST_ASIO_DECL void init_task();
// Register a socket with the reactor. Returns 0 on success, system error
// code on failure.
BOOST_ASIO_DECL int register_descriptor(socket_type descriptor,
per_descriptor_data& descriptor_data);
// Register a descriptor with an associated single operation. Returns 0 on
// success, system error code on failure.
BOOST_ASIO_DECL int register_internal_descriptor(
int op_type, socket_type descriptor,
per_descriptor_data& descriptor_data, reactor_op* op);
// Move descriptor registration from one descriptor_data object to another.
BOOST_ASIO_DECL void move_descriptor(socket_type descriptor,
per_descriptor_data& target_descriptor_data,
per_descriptor_data& source_descriptor_data);
// Post a reactor operation for immediate completion.
void post_immediate_completion(operation* op, bool is_continuation) const;
// Post a reactor operation for immediate completion.
BOOST_ASIO_DECL static void call_post_immediate_completion(
operation* op, bool is_continuation, const void* self);
// Start a new operation. The reactor operation will be performed when the
// given descriptor is flagged as ready, or an error has occurred.
BOOST_ASIO_DECL void start_op(int op_type, socket_type descriptor,
per_descriptor_data& descriptor_data, reactor_op* op,
bool is_continuation, bool allow_speculative,
void (*on_immediate)(operation*, bool, const void*),
const void* immediate_arg);
// Start a new operation. The reactor operation will be performed when the
// given descriptor is flagged as ready, or an error has occurred.
void start_op(int op_type, socket_type descriptor,
per_descriptor_data& descriptor_data, reactor_op* op,
bool is_continuation, bool allow_speculative)
{
start_op(op_type, descriptor, descriptor_data,
op, is_continuation, allow_speculative,
&epoll_reactor::call_post_immediate_completion, this);
}
// Cancel all operations associated with the given descriptor. The
// handlers associated with the descriptor will be invoked with the
// operation_aborted error.
BOOST_ASIO_DECL void cancel_ops(socket_type descriptor,
per_descriptor_data& descriptor_data);
// Cancel all operations associated with the given descriptor and key. The
// handlers associated with the descriptor will be invoked with the
// operation_aborted error.
BOOST_ASIO_DECL void cancel_ops_by_key(socket_type descriptor,
per_descriptor_data& descriptor_data,
int op_type, void* cancellation_key);
// Cancel any operations that are running against the descriptor and remove
// its registration from the reactor. The reactor resources associated with
// the descriptor must be released by calling cleanup_descriptor_data.
BOOST_ASIO_DECL void deregister_descriptor(socket_type descriptor,
per_descriptor_data& descriptor_data, bool closing);
// Remove the descriptor's registration from the reactor. The reactor
// resources associated with the descriptor must be released by calling
// cleanup_descriptor_data.
BOOST_ASIO_DECL void deregister_internal_descriptor(
socket_type descriptor, per_descriptor_data& descriptor_data);
// Perform any post-deregistration cleanup tasks associated with the
// descriptor data.
BOOST_ASIO_DECL void cleanup_descriptor_data(
per_descriptor_data& descriptor_data);
// Add a new timer queue to the reactor.
template <typename Time_Traits>
void add_timer_queue(timer_queue<Time_Traits>& timer_queue);
// Remove a timer queue from the reactor.
template <typename Time_Traits>
void remove_timer_queue(timer_queue<Time_Traits>& timer_queue);
// Schedule a new operation in the given timer queue to expire at the
// specified absolute time.
template <typename Time_Traits>
void schedule_timer(timer_queue<Time_Traits>& queue,
const typename Time_Traits::time_type& time,
typename timer_queue<Time_Traits>::per_timer_data& timer, wait_op* op);
// Cancel the timer operations associated with the given token. Returns the
// number of operations that have been posted or dispatched.
template <typename Time_Traits>
std::size_t cancel_timer(timer_queue<Time_Traits>& queue,
typename timer_queue<Time_Traits>::per_timer_data& timer,
std::size_t max_cancelled = (std::numeric_limits<std::size_t>::max)());
// Cancel the timer operations associated with the given key.
template <typename Time_Traits>
void cancel_timer_by_key(timer_queue<Time_Traits>& queue,
typename timer_queue<Time_Traits>::per_timer_data* timer,
void* cancellation_key);
// Move the timer operations associated with the given timer.
template <typename Time_Traits>
void move_timer(timer_queue<Time_Traits>& queue,
typename timer_queue<Time_Traits>::per_timer_data& target,
typename timer_queue<Time_Traits>::per_timer_data& source);
// Run epoll once until interrupted or events are ready to be dispatched.
BOOST_ASIO_DECL void run(long usec, op_queue<operation>& ops);
// Interrupt the select loop.
BOOST_ASIO_DECL void interrupt();
private:
// The hint to pass to epoll_create to size its data structures.
enum { epoll_size = 20000 };
// Create the epoll file descriptor. Throws an exception if the descriptor
// cannot be created.
BOOST_ASIO_DECL static int do_epoll_create();
// Create the timerfd file descriptor. Does not throw.
BOOST_ASIO_DECL static int do_timerfd_create();
// Allocate a new descriptor state object.
BOOST_ASIO_DECL descriptor_state* allocate_descriptor_state();
// Free an existing descriptor state object.
BOOST_ASIO_DECL void free_descriptor_state(descriptor_state* s);
// Helper function to add a new timer queue.
BOOST_ASIO_DECL void do_add_timer_queue(timer_queue_base& queue);
// Helper function to remove a timer queue.
BOOST_ASIO_DECL void do_remove_timer_queue(timer_queue_base& queue);
// Called to recalculate and update the timeout.
BOOST_ASIO_DECL void update_timeout();
// Get the timeout value for the epoll_wait call. The timeout value is
// returned as a number of milliseconds. A return value of -1 indicates
// that epoll_wait should block indefinitely.
BOOST_ASIO_DECL int get_timeout(int msec);
#if defined(BOOST_ASIO_HAS_TIMERFD)
// Get the timeout value for the timer descriptor. The return value is the
// flag argument to be used when calling timerfd_settime.
BOOST_ASIO_DECL int get_timeout(itimerspec& ts);
#endif // defined(BOOST_ASIO_HAS_TIMERFD)
// The scheduler implementation used to post completions.
scheduler& scheduler_;
// Mutex to protect access to internal data.
mutex mutex_;
// The interrupter is used to break a blocking epoll_wait call.
select_interrupter interrupter_;
// The epoll file descriptor.
int epoll_fd_;
// The timer file descriptor.
int timer_fd_;
// The timer queues.
timer_queue_set timer_queues_;
// Whether the service has been shut down.
bool shutdown_;
// Whether I/O locking is enabled.
const bool io_locking_;
// How any times to spin waiting for the I/O mutex.
const int io_locking_spin_count_;
// Mutex to protect access to the registered descriptors.
mutex registered_descriptors_mutex_;
// Keep track of all registered descriptors.
object_pool<descriptor_state> registered_descriptors_;
// Helper class to do post-perform_io cleanup.
struct perform_io_cleanup_on_block_exit;
friend struct perform_io_cleanup_on_block_exit;
};
} // namespace detail
} // namespace asio
} // namespace boost
#include <boost/asio/detail/pop_options.hpp>
#include <boost/asio/detail/impl/epoll_reactor.hpp>
#if defined(BOOST_ASIO_HEADER_ONLY)
# include <boost/asio/detail/impl/epoll_reactor.ipp>
#endif // defined(BOOST_ASIO_HEADER_ONLY)
#endif // defined(BOOST_ASIO_HAS_EPOLL)
#endif // BOOST_ASIO_DETAIL_EPOLL_REACTOR_HPP