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//
// detail/impl/dev_poll_reactor.ipp
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2017 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 ASIO_DETAIL_IMPL_DEV_POLL_REACTOR_IPP
#define ASIO_DETAIL_IMPL_DEV_POLL_REACTOR_IPP
#if defined(_MSC_VER) && (_MSC_VER >= 1200)
# pragma once
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
#include "asio/detail/config.hpp"
#if defined(ASIO_HAS_DEV_POLL)
#include "asio/detail/dev_poll_reactor.hpp"
#include "asio/detail/assert.hpp"
#include "asio/detail/throw_error.hpp"
#include "asio/error.hpp"
#include "asio/detail/push_options.hpp"
namespace asio {
namespace detail {
dev_poll_reactor::dev_poll_reactor(asio::execution_context& ctx)
: asio::detail::execution_context_service_base<dev_poll_reactor>(ctx),
scheduler_(use_service<scheduler>(ctx)),
mutex_(),
dev_poll_fd_(do_dev_poll_create()),
interrupter_(),
shutdown_(false)
{
// Add the interrupter's descriptor to /dev/poll.
::pollfd ev = { 0, 0, 0 };
ev.fd = interrupter_.read_descriptor();
ev.events = POLLIN | POLLERR;
ev.revents = 0;
::write(dev_poll_fd_, &ev, sizeof(ev));
}
dev_poll_reactor::~dev_poll_reactor()
{
shutdown();
::close(dev_poll_fd_);
}
void dev_poll_reactor::shutdown()
{
asio::detail::mutex::scoped_lock lock(mutex_);
shutdown_ = true;
lock.unlock();
op_queue<operation> ops;
for (int i = 0; i < max_ops; ++i)
op_queue_[i].get_all_operations(ops);
timer_queues_.get_all_timers(ops);
scheduler_.abandon_operations(ops);
}
void dev_poll_reactor::notify_fork(
asio::execution_context::fork_event fork_ev)
{
if (fork_ev == asio::execution_context::fork_child)
{
detail::mutex::scoped_lock lock(mutex_);
if (dev_poll_fd_ != -1)
::close(dev_poll_fd_);
dev_poll_fd_ = -1;
dev_poll_fd_ = do_dev_poll_create();
interrupter_.recreate();
// Add the interrupter's descriptor to /dev/poll.
::pollfd ev = { 0, 0, 0 };
ev.fd = interrupter_.read_descriptor();
ev.events = POLLIN | POLLERR;
ev.revents = 0;
::write(dev_poll_fd_, &ev, sizeof(ev));
// Re-register all descriptors with /dev/poll. The changes will be written
// to the /dev/poll descriptor the next time the reactor is run.
for (int i = 0; i < max_ops; ++i)
{
reactor_op_queue<socket_type>::iterator iter = op_queue_[i].begin();
reactor_op_queue<socket_type>::iterator end = op_queue_[i].end();
for (; iter != end; ++iter)
{
::pollfd& pending_ev = add_pending_event_change(iter->first);
pending_ev.events |= POLLERR | POLLHUP;
switch (i)
{
case read_op: pending_ev.events |= POLLIN; break;
case write_op: pending_ev.events |= POLLOUT; break;
case except_op: pending_ev.events |= POLLPRI; break;
default: break;
}
}
}
interrupter_.interrupt();
}
}
void dev_poll_reactor::init_task()
{
scheduler_.init_task();
}
int dev_poll_reactor::register_descriptor(socket_type, per_descriptor_data&)
{
return 0;
}
int dev_poll_reactor::register_internal_descriptor(int op_type,
socket_type descriptor, per_descriptor_data&, reactor_op* op)
{
asio::detail::mutex::scoped_lock lock(mutex_);
op_queue_[op_type].enqueue_operation(descriptor, op);
::pollfd& ev = add_pending_event_change(descriptor);
ev.events = POLLERR | POLLHUP;
switch (op_type)
{
case read_op: ev.events |= POLLIN; break;
case write_op: ev.events |= POLLOUT; break;
case except_op: ev.events |= POLLPRI; break;
default: break;
}
interrupter_.interrupt();
return 0;
}
void dev_poll_reactor::move_descriptor(socket_type,
dev_poll_reactor::per_descriptor_data&,
dev_poll_reactor::per_descriptor_data&)
{
}
void dev_poll_reactor::start_op(int op_type, socket_type descriptor,
dev_poll_reactor::per_descriptor_data&, reactor_op* op,
bool is_continuation, bool allow_speculative)
{
asio::detail::mutex::scoped_lock lock(mutex_);
if (shutdown_)
{
post_immediate_completion(op, is_continuation);
return;
}
if (allow_speculative)
{
if (op_type != read_op || !op_queue_[except_op].has_operation(descriptor))
{
if (!op_queue_[op_type].has_operation(descriptor))
{
if (op->perform())
{
lock.unlock();
scheduler_.post_immediate_completion(op, is_continuation);
return;
}
}
}
}
bool first = op_queue_[op_type].enqueue_operation(descriptor, op);
scheduler_.work_started();
if (first)
{
::pollfd& ev = add_pending_event_change(descriptor);
ev.events = POLLERR | POLLHUP;
if (op_type == read_op
|| op_queue_[read_op].has_operation(descriptor))
ev.events |= POLLIN;
if (op_type == write_op
|| op_queue_[write_op].has_operation(descriptor))
ev.events |= POLLOUT;
if (op_type == except_op
|| op_queue_[except_op].has_operation(descriptor))
ev.events |= POLLPRI;
interrupter_.interrupt();
}
}
void dev_poll_reactor::cancel_ops(socket_type descriptor,
dev_poll_reactor::per_descriptor_data&)
{
asio::detail::mutex::scoped_lock lock(mutex_);
cancel_ops_unlocked(descriptor, asio::error::operation_aborted);
}
void dev_poll_reactor::deregister_descriptor(socket_type descriptor,
dev_poll_reactor::per_descriptor_data&, bool)
{
asio::detail::mutex::scoped_lock lock(mutex_);
// Remove the descriptor from /dev/poll.
::pollfd& ev = add_pending_event_change(descriptor);
ev.events = POLLREMOVE;
interrupter_.interrupt();
// Cancel any outstanding operations associated with the descriptor.
cancel_ops_unlocked(descriptor, asio::error::operation_aborted);
}
void dev_poll_reactor::deregister_internal_descriptor(
socket_type descriptor, dev_poll_reactor::per_descriptor_data&)
{
asio::detail::mutex::scoped_lock lock(mutex_);
// Remove the descriptor from /dev/poll. Since this function is only called
// during a fork, we can apply the change immediately.
::pollfd ev = { 0, 0, 0 };
ev.fd = descriptor;
ev.events = POLLREMOVE;
ev.revents = 0;
::write(dev_poll_fd_, &ev, sizeof(ev));
// Destroy all operations associated with the descriptor.
op_queue<operation> ops;
asio::error_code ec;
for (int i = 0; i < max_ops; ++i)
op_queue_[i].cancel_operations(descriptor, ops, ec);
}
void dev_poll_reactor::cleanup_descriptor_data(
dev_poll_reactor::per_descriptor_data&)
{
}
void dev_poll_reactor::run(long usec, op_queue<operation>& ops)
{
asio::detail::mutex::scoped_lock lock(mutex_);
// We can return immediately if there's no work to do and the reactor is
// not supposed to block.
if (usec == 0 && op_queue_[read_op].empty() && op_queue_[write_op].empty()
&& op_queue_[except_op].empty() && timer_queues_.all_empty())
return;
// Write the pending event registration changes to the /dev/poll descriptor.
std::size_t events_size = sizeof(::pollfd) * pending_event_changes_.size();
if (events_size > 0)
{
errno = 0;
int result = ::write(dev_poll_fd_,
&pending_event_changes_[0], events_size);
if (result != static_cast<int>(events_size))
{
asio::error_code ec = asio::error_code(
errno, asio::error::get_system_category());
for (std::size_t i = 0; i < pending_event_changes_.size(); ++i)
{
int descriptor = pending_event_changes_[i].fd;
for (int j = 0; j < max_ops; ++j)
op_queue_[j].cancel_operations(descriptor, ops, ec);
}
}
pending_event_changes_.clear();
pending_event_change_index_.clear();
}
// Calculate timeout.
int timeout;
if (usec == 0)
timeout = 0;
else
{
timeout = (usec < 0) ? -1 : ((usec - 1) / 1000 + 1);
timeout = get_timeout(timeout);
}
lock.unlock();
// Block on the /dev/poll descriptor.
::pollfd events[128] = { { 0, 0, 0 } };
::dvpoll dp = { 0, 0, 0 };
dp.dp_fds = events;
dp.dp_nfds = 128;
dp.dp_timeout = timeout;
int num_events = ::ioctl(dev_poll_fd_, DP_POLL, &dp);
lock.lock();
// Dispatch the waiting events.
for (int i = 0; i < num_events; ++i)
{
int descriptor = events[i].fd;
if (descriptor == interrupter_.read_descriptor())
{
interrupter_.reset();
}
else
{
bool more_reads = false;
bool more_writes = false;
bool more_except = false;
// Exception operations must be processed first to ensure that any
// out-of-band data is read before normal data.
if (events[i].events & (POLLPRI | POLLERR | POLLHUP))
more_except =
op_queue_[except_op].perform_operations(descriptor, ops);
else
more_except = op_queue_[except_op].has_operation(descriptor);
if (events[i].events & (POLLIN | POLLERR | POLLHUP))
more_reads = op_queue_[read_op].perform_operations(descriptor, ops);
else
more_reads = op_queue_[read_op].has_operation(descriptor);
if (events[i].events & (POLLOUT | POLLERR | POLLHUP))
more_writes = op_queue_[write_op].perform_operations(descriptor, ops);
else
more_writes = op_queue_[write_op].has_operation(descriptor);
if ((events[i].events & (POLLERR | POLLHUP)) != 0
&& !more_except && !more_reads && !more_writes)
{
// If we have an event and no operations associated with the
// descriptor then we need to delete the descriptor from /dev/poll.
// The poll operation can produce POLLHUP or POLLERR events when there
// is no operation pending, so if we do not remove the descriptor we
// can end up in a tight polling loop.
::pollfd ev = { 0, 0, 0 };
ev.fd = descriptor;
ev.events = POLLREMOVE;
ev.revents = 0;
::write(dev_poll_fd_, &ev, sizeof(ev));
}
else
{
::pollfd ev = { 0, 0, 0 };
ev.fd = descriptor;
ev.events = POLLERR | POLLHUP;
if (more_reads)
ev.events |= POLLIN;
if (more_writes)
ev.events |= POLLOUT;
if (more_except)
ev.events |= POLLPRI;
ev.revents = 0;
int result = ::write(dev_poll_fd_, &ev, sizeof(ev));
if (result != sizeof(ev))
{
asio::error_code ec(errno,
asio::error::get_system_category());
for (int j = 0; j < max_ops; ++j)
op_queue_[j].cancel_operations(descriptor, ops, ec);
}
}
}
}
timer_queues_.get_ready_timers(ops);
}
void dev_poll_reactor::interrupt()
{
interrupter_.interrupt();
}
int dev_poll_reactor::do_dev_poll_create()
{
int fd = ::open("/dev/poll", O_RDWR);
if (fd == -1)
{
asio::error_code ec(errno,
asio::error::get_system_category());
asio::detail::throw_error(ec, "/dev/poll");
}
return fd;
}
void dev_poll_reactor::do_add_timer_queue(timer_queue_base& queue)
{
mutex::scoped_lock lock(mutex_);
timer_queues_.insert(&queue);
}
void dev_poll_reactor::do_remove_timer_queue(timer_queue_base& queue)
{
mutex::scoped_lock lock(mutex_);
timer_queues_.erase(&queue);
}
int dev_poll_reactor::get_timeout(int msec)
{
// By default we will wait no longer than 5 minutes. This will ensure that
// any changes to the system clock are detected after no longer than this.
const int max_msec = 5 * 60 * 1000;
return timer_queues_.wait_duration_msec(
(msec < 0 || max_msec < msec) ? max_msec : msec);
}
void dev_poll_reactor::cancel_ops_unlocked(socket_type descriptor,
const asio::error_code& ec)
{
bool need_interrupt = false;
op_queue<operation> ops;
for (int i = 0; i < max_ops; ++i)
need_interrupt = op_queue_[i].cancel_operations(
descriptor, ops, ec) || need_interrupt;
scheduler_.post_deferred_completions(ops);
if (need_interrupt)
interrupter_.interrupt();
}
::pollfd& dev_poll_reactor::add_pending_event_change(int descriptor)
{
hash_map<int, std::size_t>::iterator iter
= pending_event_change_index_.find(descriptor);
if (iter == pending_event_change_index_.end())
{
std::size_t index = pending_event_changes_.size();
pending_event_changes_.reserve(pending_event_changes_.size() + 1);
pending_event_change_index_.insert(std::make_pair(descriptor, index));
pending_event_changes_.push_back(::pollfd());
pending_event_changes_[index].fd = descriptor;
pending_event_changes_[index].revents = 0;
return pending_event_changes_[index];
}
else
{
return pending_event_changes_[iter->second];
}
}
} // namespace detail
} // namespace asio
#include "asio/detail/pop_options.hpp"
#endif // defined(ASIO_HAS_DEV_POLL)
#endif // ASIO_DETAIL_IMPL_DEV_POLL_REACTOR_IPP
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