Replace boost by the standalone asio library

1 files changed, 787 insertions, 0 deletions

diff --git a/lib/asio/detail/impl/epoll_reactor.ipp b/lib/asio/detail/impl/epoll_reactor.ipp
new file mode 100644
index 0000000..65584a4
--- /dev/null
+++ b/lib/asio/detail/impl/epoll_reactor.ipp
@@ -0,0 +1,787 @@
+//
+// detail/impl/epoll_reactor.ipp
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2018 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_EPOLL_REACTOR_IPP
+#define ASIO_DETAIL_IMPL_EPOLL_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_EPOLL)
+
+#include <cstddef>
+#include <sys/epoll.h>
+#include "asio/detail/epoll_reactor.hpp"
+#include "asio/detail/throw_error.hpp"
+#include "asio/error.hpp"
+
+#if defined(ASIO_HAS_TIMERFD)
+# include <sys/timerfd.h>
+#endif // defined(ASIO_HAS_TIMERFD)
+
+#include "asio/detail/push_options.hpp"
+
+namespace asio {
+namespace detail {
+
+epoll_reactor::epoll_reactor(asio::execution_context& ctx)
+  : execution_context_service_base<epoll_reactor>(ctx),
+    scheduler_(use_service<scheduler>(ctx)),
+    mutex_(ASIO_CONCURRENCY_HINT_IS_LOCKING(
+          REACTOR_REGISTRATION, scheduler_.concurrency_hint())),
+    interrupter_(),
+    epoll_fd_(do_epoll_create()),
+    timer_fd_(do_timerfd_create()),
+    shutdown_(false),
+    registered_descriptors_mutex_(mutex_.enabled())
+{
+  // Add the interrupter's descriptor to epoll.
+  epoll_event ev = { 0, { 0 } };
+  ev.events = EPOLLIN | EPOLLERR | EPOLLET;
+  ev.data.ptr = &interrupter_;
+  epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, interrupter_.read_descriptor(), &ev);
+  interrupter_.interrupt();
+
+  // Add the timer descriptor to epoll.
+  if (timer_fd_ != -1)
+  {
+    ev.events = EPOLLIN | EPOLLERR;
+    ev.data.ptr = &timer_fd_;
+    epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, timer_fd_, &ev);
+  }
+}
+
+epoll_reactor::~epoll_reactor()
+{
+  if (epoll_fd_ != -1)
+    close(epoll_fd_);
+  if (timer_fd_ != -1)
+    close(timer_fd_);
+}
+
+void epoll_reactor::shutdown()
+{
+  mutex::scoped_lock lock(mutex_);
+  shutdown_ = true;
+  lock.unlock();
+
+  op_queue<operation> ops;
+
+  while (descriptor_state* state = registered_descriptors_.first())
+  {
+    for (int i = 0; i < max_ops; ++i)
+      ops.push(state->op_queue_[i]);
+    state->shutdown_ = true;
+    registered_descriptors_.free(state);
+  }
+
+  timer_queues_.get_all_timers(ops);
+
+  scheduler_.abandon_operations(ops);
+}
+
+void epoll_reactor::notify_fork(
+    asio::execution_context::fork_event fork_ev)
+{
+  if (fork_ev == asio::execution_context::fork_child)
+  {
+    if (epoll_fd_ != -1)
+      ::close(epoll_fd_);
+    epoll_fd_ = -1;
+    epoll_fd_ = do_epoll_create();
+
+    if (timer_fd_ != -1)
+      ::close(timer_fd_);
+    timer_fd_ = -1;
+    timer_fd_ = do_timerfd_create();
+
+    interrupter_.recreate();
+
+    // Add the interrupter's descriptor to epoll.
+    epoll_event ev = { 0, { 0 } };
+    ev.events = EPOLLIN | EPOLLERR | EPOLLET;
+    ev.data.ptr = &interrupter_;
+    epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, interrupter_.read_descriptor(), &ev);
+    interrupter_.interrupt();
+
+    // Add the timer descriptor to epoll.
+    if (timer_fd_ != -1)
+    {
+      ev.events = EPOLLIN | EPOLLERR;
+      ev.data.ptr = &timer_fd_;
+      epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, timer_fd_, &ev);
+    }
+
+    update_timeout();
+
+    // Re-register all descriptors with epoll.
+    mutex::scoped_lock descriptors_lock(registered_descriptors_mutex_);
+    for (descriptor_state* state = registered_descriptors_.first();
+        state != 0; state = state->next_)
+    {
+      ev.events = state->registered_events_;
+      ev.data.ptr = state;
+      int result = epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, state->descriptor_, &ev);
+      if (result != 0)
+      {
+        asio::error_code ec(errno,
+            asio::error::get_system_category());
+        asio::detail::throw_error(ec, "epoll re-registration");
+      }
+    }
+  }
+}
+
+void epoll_reactor::init_task()
+{
+  scheduler_.init_task();
+}
+
+int epoll_reactor::register_descriptor(socket_type descriptor,
+    epoll_reactor::per_descriptor_data& descriptor_data)
+{
+  descriptor_data = allocate_descriptor_state();
+
+  ASIO_HANDLER_REACTOR_REGISTRATION((
+        context(), static_cast<uintmax_t>(descriptor),
+        reinterpret_cast<uintmax_t>(descriptor_data)));
+
+  {
+    mutex::scoped_lock descriptor_lock(descriptor_data->mutex_);
+
+    descriptor_data->reactor_ = this;
+    descriptor_data->descriptor_ = descriptor;
+    descriptor_data->shutdown_ = false;
+    for (int i = 0; i < max_ops; ++i)
+      descriptor_data->try_speculative_[i] = true;
+  }
+
+  epoll_event ev = { 0, { 0 } };
+  ev.events = EPOLLIN | EPOLLERR | EPOLLHUP | EPOLLPRI | EPOLLET;
+  descriptor_data->registered_events_ = ev.events;
+  ev.data.ptr = descriptor_data;
+  int result = epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, descriptor, &ev);
+  if (result != 0)
+  {
+    if (errno == EPERM)
+    {
+      // This file descriptor type is not supported by epoll. However, if it is
+      // a regular file then operations on it will not block. We will allow
+      // this descriptor to be used and fail later if an operation on it would
+      // otherwise require a trip through the reactor.
+      descriptor_data->registered_events_ = 0;
+      return 0;
+    }
+    return errno;
+  }
+
+  return 0;
+}
+
+int epoll_reactor::register_internal_descriptor(
+    int op_type, socket_type descriptor,
+    epoll_reactor::per_descriptor_data& descriptor_data, reactor_op* op)
+{
+  descriptor_data = allocate_descriptor_state();
+
+  ASIO_HANDLER_REACTOR_REGISTRATION((
+        context(), static_cast<uintmax_t>(descriptor),
+        reinterpret_cast<uintmax_t>(descriptor_data)));
+
+  {
+    mutex::scoped_lock descriptor_lock(descriptor_data->mutex_);
+
+    descriptor_data->reactor_ = this;
+    descriptor_data->descriptor_ = descriptor;
+    descriptor_data->shutdown_ = false;
+    descriptor_data->op_queue_[op_type].push(op);
+    for (int i = 0; i < max_ops; ++i)
+      descriptor_data->try_speculative_[i] = true;
+  }
+
+  epoll_event ev = { 0, { 0 } };
+  ev.events = EPOLLIN | EPOLLERR | EPOLLHUP | EPOLLPRI | EPOLLET;
+  descriptor_data->registered_events_ = ev.events;
+  ev.data.ptr = descriptor_data;
+  int result = epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, descriptor, &ev);
+  if (result != 0)
+    return errno;
+
+  return 0;
+}
+
+void epoll_reactor::move_descriptor(socket_type,
+    epoll_reactor::per_descriptor_data& target_descriptor_data,
+    epoll_reactor::per_descriptor_data& source_descriptor_data)
+{
+  target_descriptor_data = source_descriptor_data;
+  source_descriptor_data = 0;
+}
+
+void epoll_reactor::start_op(int op_type, socket_type descriptor,
+    epoll_reactor::per_descriptor_data& descriptor_data, reactor_op* op,
+    bool is_continuation, bool allow_speculative)
+{
+  if (!descriptor_data)
+  {
+    op->ec_ = asio::error::bad_descriptor;
+    post_immediate_completion(op, is_continuation);
+    return;
+  }
+
+  mutex::scoped_lock descriptor_lock(descriptor_data->mutex_);
+
+  if (descriptor_data->shutdown_)
+  {
+    post_immediate_completion(op, is_continuation);
+    return;
+  }
+
+  if (descriptor_data->op_queue_[op_type].empty())
+  {
+    if (allow_speculative
+        && (op_type != read_op
+          || descriptor_data->op_queue_[except_op].empty()))
+    {
+      if (descriptor_data->try_speculative_[op_type])
+      {
+        if (reactor_op::status status = op->perform())
+        {
+          if (status == reactor_op::done_and_exhausted)
+            if (descriptor_data->registered_events_ != 0)
+              descriptor_data->try_speculative_[op_type] = false;
+          descriptor_lock.unlock();
+          scheduler_.post_immediate_completion(op, is_continuation);
+          return;
+        }
+      }
+
+      if (descriptor_data->registered_events_ == 0)
+      {
+        op->ec_ = asio::error::operation_not_supported;
+        scheduler_.post_immediate_completion(op, is_continuation);
+        return;
+      }
+
+      if (op_type == write_op)
+      {
+        if ((descriptor_data->registered_events_ & EPOLLOUT) == 0)
+        {
+          epoll_event ev = { 0, { 0 } };
+          ev.events = descriptor_data->registered_events_ | EPOLLOUT;
+          ev.data.ptr = descriptor_data;
+          if (epoll_ctl(epoll_fd_, EPOLL_CTL_MOD, descriptor, &ev) == 0)
+          {
+            descriptor_data->registered_events_ |= ev.events;
+          }
+          else
+          {
+            op->ec_ = asio::error_code(errno,
+                asio::error::get_system_category());
+            scheduler_.post_immediate_completion(op, is_continuation);
+            return;
+          }
+        }
+      }
+    }
+    else if (descriptor_data->registered_events_ == 0)
+    {
+      op->ec_ = asio::error::operation_not_supported;
+      scheduler_.post_immediate_completion(op, is_continuation);
+      return;
+    }
+    else
+    {
+      if (op_type == write_op)
+      {
+        descriptor_data->registered_events_ |= EPOLLOUT;
+      }
+
+      epoll_event ev = { 0, { 0 } };
+      ev.events = descriptor_data->registered_events_;
+      ev.data.ptr = descriptor_data;
+      epoll_ctl(epoll_fd_, EPOLL_CTL_MOD, descriptor, &ev);
+    }
+  }
+
+  descriptor_data->op_queue_[op_type].push(op);
+  scheduler_.work_started();
+}
+
+void epoll_reactor::cancel_ops(socket_type,
+    epoll_reactor::per_descriptor_data& descriptor_data)
+{
+  if (!descriptor_data)
+    return;
+
+  mutex::scoped_lock descriptor_lock(descriptor_data->mutex_);
+
+  op_queue<operation> ops;
+  for (int i = 0; i < max_ops; ++i)
+  {
+    while (reactor_op* op = descriptor_data->op_queue_[i].front())
+    {
+      op->ec_ = asio::error::operation_aborted;
+      descriptor_data->op_queue_[i].pop();
+      ops.push(op);
+    }
+  }
+
+  descriptor_lock.unlock();
+
+  scheduler_.post_deferred_completions(ops);
+}
+
+void epoll_reactor::deregister_descriptor(socket_type descriptor,
+    epoll_reactor::per_descriptor_data& descriptor_data, bool closing)
+{
+  if (!descriptor_data)
+    return;
+
+  mutex::scoped_lock descriptor_lock(descriptor_data->mutex_);
+
+  if (!descriptor_data->shutdown_)
+  {
+    if (closing)
+    {
+      // The descriptor will be automatically removed from the epoll set when
+      // it is closed.
+    }
+    else if (descriptor_data->registered_events_ != 0)
+    {
+      epoll_event ev = { 0, { 0 } };
+      epoll_ctl(epoll_fd_, EPOLL_CTL_DEL, descriptor, &ev);
+    }
+
+    op_queue<operation> ops;
+    for (int i = 0; i < max_ops; ++i)
+    {
+      while (reactor_op* op = descriptor_data->op_queue_[i].front())
+      {
+        op->ec_ = asio::error::operation_aborted;
+        descriptor_data->op_queue_[i].pop();
+        ops.push(op);
+      }
+    }
+
+    descriptor_data->descriptor_ = -1;
+    descriptor_data->shutdown_ = true;
+
+    descriptor_lock.unlock();
+
+    ASIO_HANDLER_REACTOR_DEREGISTRATION((
+          context(), static_cast<uintmax_t>(descriptor),
+          reinterpret_cast<uintmax_t>(descriptor_data)));
+
+    scheduler_.post_deferred_completions(ops);
+
+    // Leave descriptor_data set so that it will be freed by the subsequent
+    // call to cleanup_descriptor_data.
+  }
+  else
+  {
+    // We are shutting down, so prevent cleanup_descriptor_data from freeing
+    // the descriptor_data object and let the destructor free it instead.
+    descriptor_data = 0;
+  }
+}
+
+void epoll_reactor::deregister_internal_descriptor(socket_type descriptor,
+    epoll_reactor::per_descriptor_data& descriptor_data)
+{
+  if (!descriptor_data)
+    return;
+
+  mutex::scoped_lock descriptor_lock(descriptor_data->mutex_);
+
+  if (!descriptor_data->shutdown_)
+  {
+    epoll_event ev = { 0, { 0 } };
+    epoll_ctl(epoll_fd_, EPOLL_CTL_DEL, descriptor, &ev);
+
+    op_queue<operation> ops;
+    for (int i = 0; i < max_ops; ++i)
+      ops.push(descriptor_data->op_queue_[i]);
+
+    descriptor_data->descriptor_ = -1;
+    descriptor_data->shutdown_ = true;
+
+    descriptor_lock.unlock();
+
+    ASIO_HANDLER_REACTOR_DEREGISTRATION((
+          context(), static_cast<uintmax_t>(descriptor),
+          reinterpret_cast<uintmax_t>(descriptor_data)));
+
+    // Leave descriptor_data set so that it will be freed by the subsequent
+    // call to cleanup_descriptor_data.
+  }
+  else
+  {
+    // We are shutting down, so prevent cleanup_descriptor_data from freeing
+    // the descriptor_data object and let the destructor free it instead.
+    descriptor_data = 0;
+  }
+}
+
+void epoll_reactor::cleanup_descriptor_data(
+    per_descriptor_data& descriptor_data)
+{
+  if (descriptor_data)
+  {
+    free_descriptor_state(descriptor_data);
+    descriptor_data = 0;
+  }
+}
+
+void epoll_reactor::run(long usec, op_queue<operation>& ops)
+{
+  // This code relies on the fact that the scheduler queues the reactor task
+  // behind all descriptor operations generated by this function. This means,
+  // that by the time we reach this point, any previously returned descriptor
+  // operations have already been dequeued. Therefore it is now safe for us to
+  // reuse and return them for the scheduler to queue again.
+
+  // Calculate timeout. Check the timer queues only if timerfd is not in use.
+  int timeout;
+  if (usec == 0)
+    timeout = 0;
+  else
+  {
+    timeout = (usec < 0) ? -1 : ((usec - 1) / 1000 + 1);
+    if (timer_fd_ == -1)
+    {
+      mutex::scoped_lock lock(mutex_);
+      timeout = get_timeout(timeout);
+    }
+  }
+
+  // Block on the epoll descriptor.
+  epoll_event events[128];
+  int num_events = epoll_wait(epoll_fd_, events, 128, timeout);
+
+#if defined(ASIO_ENABLE_HANDLER_TRACKING)
+  // Trace the waiting events.
+  for (int i = 0; i < num_events; ++i)
+  {
+    void* ptr = events[i].data.ptr;
+    if (ptr == &interrupter_)
+    {
+      // Ignore.
+    }
+# if defined(ASIO_HAS_TIMERFD)
+    else if (ptr == &timer_fd_)
+    {
+      // Ignore.
+    }
+# endif // defined(ASIO_HAS_TIMERFD)
+    else
+    {
+      unsigned event_mask = 0;
+      if ((events[i].events & EPOLLIN) != 0)
+        event_mask |= ASIO_HANDLER_REACTOR_READ_EVENT;
+      if ((events[i].events & EPOLLOUT))
+        event_mask |= ASIO_HANDLER_REACTOR_WRITE_EVENT;
+      if ((events[i].events & (EPOLLERR | EPOLLHUP)) != 0)
+        event_mask |= ASIO_HANDLER_REACTOR_ERROR_EVENT;
+      ASIO_HANDLER_REACTOR_EVENTS((context(),
+            reinterpret_cast<uintmax_t>(ptr), event_mask));
+    }
+  }
+#endif // defined(ASIO_ENABLE_HANDLER_TRACKING)
+
+#if defined(ASIO_HAS_TIMERFD)
+  bool check_timers = (timer_fd_ == -1);
+#else // defined(ASIO_HAS_TIMERFD)
+  bool check_timers = true;
+#endif // defined(ASIO_HAS_TIMERFD)
+
+  // Dispatch the waiting events.
+  for (int i = 0; i < num_events; ++i)
+  {
+    void* ptr = events[i].data.ptr;
+    if (ptr == &interrupter_)
+    {
+      // No need to reset the interrupter since we're leaving the descriptor
+      // in a ready-to-read state and relying on edge-triggered notifications
+      // to make it so that we only get woken up when the descriptor's epoll
+      // registration is updated.
+
+#if defined(ASIO_HAS_TIMERFD)
+      if (timer_fd_ == -1)
+        check_timers = true;
+#else // defined(ASIO_HAS_TIMERFD)
+      check_timers = true;
+#endif // defined(ASIO_HAS_TIMERFD)
+    }
+#if defined(ASIO_HAS_TIMERFD)
+    else if (ptr == &timer_fd_)
+    {
+      check_timers = true;
+    }
+#endif // defined(ASIO_HAS_TIMERFD)
+    else
+    {
+      // The descriptor operation doesn't count as work in and of itself, so we
+      // don't call work_started() here. This still allows the scheduler to
+      // stop if the only remaining operations are descriptor operations.
+      descriptor_state* descriptor_data = static_cast<descriptor_state*>(ptr);
+      if (!ops.is_enqueued(descriptor_data))
+      {
+        descriptor_data->set_ready_events(events[i].events);
+        ops.push(descriptor_data);
+      }
+      else
+      {
+        descriptor_data->add_ready_events(events[i].events);
+      }
+    }
+  }
+
+  if (check_timers)
+  {
+    mutex::scoped_lock common_lock(mutex_);
+    timer_queues_.get_ready_timers(ops);
+
+#if defined(ASIO_HAS_TIMERFD)
+    if (timer_fd_ != -1)
+    {
+      itimerspec new_timeout;
+      itimerspec old_timeout;
+      int flags = get_timeout(new_timeout);
+      timerfd_settime(timer_fd_, flags, &new_timeout, &old_timeout);
+    }
+#endif // defined(ASIO_HAS_TIMERFD)
+  }
+}
+
+void epoll_reactor::interrupt()
+{
+  epoll_event ev = { 0, { 0 } };
+  ev.events = EPOLLIN | EPOLLERR | EPOLLET;
+  ev.data.ptr = &interrupter_;
+  epoll_ctl(epoll_fd_, EPOLL_CTL_MOD, interrupter_.read_descriptor(), &ev);
+}
+
+int epoll_reactor::do_epoll_create()
+{
+#if defined(EPOLL_CLOEXEC)
+  int fd = epoll_create1(EPOLL_CLOEXEC);
+#else // defined(EPOLL_CLOEXEC)
+  int fd = -1;
+  errno = EINVAL;
+#endif // defined(EPOLL_CLOEXEC)
+
+  if (fd == -1 && (errno == EINVAL || errno == ENOSYS))
+  {
+    fd = epoll_create(epoll_size);
+    if (fd != -1)
+      ::fcntl(fd, F_SETFD, FD_CLOEXEC);
+  }
+
+  if (fd == -1)
+  {
+    asio::error_code ec(errno,
+        asio::error::get_system_category());
+    asio::detail::throw_error(ec, "epoll");
+  }
+
+  return fd;
+}
+
+int epoll_reactor::do_timerfd_create()
+{
+#if defined(ASIO_HAS_TIMERFD)
+# if defined(TFD_CLOEXEC)
+  int fd = timerfd_create(CLOCK_MONOTONIC, TFD_CLOEXEC);
+# else // defined(TFD_CLOEXEC)
+  int fd = -1;
+  errno = EINVAL;
+# endif // defined(TFD_CLOEXEC)
+
+  if (fd == -1 && errno == EINVAL)
+  {
+    fd = timerfd_create(CLOCK_MONOTONIC, 0);
+    if (fd != -1)
+      ::fcntl(fd, F_SETFD, FD_CLOEXEC);
+  }
+
+  return fd;
+#else // defined(ASIO_HAS_TIMERFD)
+  return -1;
+#endif // defined(ASIO_HAS_TIMERFD)
+}
+
+epoll_reactor::descriptor_state* epoll_reactor::allocate_descriptor_state()
+{
+  mutex::scoped_lock descriptors_lock(registered_descriptors_mutex_);
+  return registered_descriptors_.alloc(ASIO_CONCURRENCY_HINT_IS_LOCKING(
+        REACTOR_IO, scheduler_.concurrency_hint()));
+}
+
+void epoll_reactor::free_descriptor_state(epoll_reactor::descriptor_state* s)
+{
+  mutex::scoped_lock descriptors_lock(registered_descriptors_mutex_);
+  registered_descriptors_.free(s);
+}
+
+void epoll_reactor::do_add_timer_queue(timer_queue_base& queue)
+{
+  mutex::scoped_lock lock(mutex_);
+  timer_queues_.insert(&queue);
+}
+
+void epoll_reactor::do_remove_timer_queue(timer_queue_base& queue)
+{
+  mutex::scoped_lock lock(mutex_);
+  timer_queues_.erase(&queue);
+}
+
+void epoll_reactor::update_timeout()
+{
+#if defined(ASIO_HAS_TIMERFD)
+  if (timer_fd_ != -1)
+  {
+    itimerspec new_timeout;
+    itimerspec old_timeout;
+    int flags = get_timeout(new_timeout);
+    timerfd_settime(timer_fd_, flags, &new_timeout, &old_timeout);
+    return;
+  }
+#endif // defined(ASIO_HAS_TIMERFD)
+  interrupt();
+}
+
+int epoll_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);
+}
+
+#if defined(ASIO_HAS_TIMERFD)
+int epoll_reactor::get_timeout(itimerspec& ts)
+{
+  ts.it_interval.tv_sec = 0;
+  ts.it_interval.tv_nsec = 0;
+
+  long usec = timer_queues_.wait_duration_usec(5 * 60 * 1000 * 1000);
+  ts.it_value.tv_sec = usec / 1000000;
+  ts.it_value.tv_nsec = usec ? (usec % 1000000) * 1000 : 1;
+
+  return usec ? 0 : TFD_TIMER_ABSTIME;
+}
+#endif // defined(ASIO_HAS_TIMERFD)
+
+struct epoll_reactor::perform_io_cleanup_on_block_exit
+{
+  explicit perform_io_cleanup_on_block_exit(epoll_reactor* r)
+    : reactor_(r), first_op_(0)
+  {
+  }
+
+  ~perform_io_cleanup_on_block_exit()
+  {
+    if (first_op_)
+    {
+      // Post the remaining completed operations for invocation.
+      if (!ops_.empty())
+        reactor_->scheduler_.post_deferred_completions(ops_);
+
+      // A user-initiated operation has completed, but there's no need to
+      // explicitly call work_finished() here. Instead, we'll take advantage of
+      // the fact that the scheduler will call work_finished() once we return.
+    }
+    else
+    {
+      // No user-initiated operations have completed, so we need to compensate
+      // for the work_finished() call that the scheduler will make once this
+      // operation returns.
+      reactor_->scheduler_.compensating_work_started();
+    }
+  }
+
+  epoll_reactor* reactor_;
+  op_queue<operation> ops_;
+  operation* first_op_;
+};
+
+epoll_reactor::descriptor_state::descriptor_state(bool locking)
+  : operation(&epoll_reactor::descriptor_state::do_complete),
+    mutex_(locking)
+{
+}
+
+operation* epoll_reactor::descriptor_state::perform_io(uint32_t events)
+{
+  mutex_.lock();
+  perform_io_cleanup_on_block_exit io_cleanup(reactor_);
+  mutex::scoped_lock descriptor_lock(mutex_, mutex::scoped_lock::adopt_lock);
+
+  // Exception operations must be processed first to ensure that any
+  // out-of-band data is read before normal data.
+  static const int flag[max_ops] = { EPOLLIN, EPOLLOUT, EPOLLPRI };
+  for (int j = max_ops - 1; j >= 0; --j)
+  {
+    if (events & (flag[j] | EPOLLERR | EPOLLHUP))
+    {
+      try_speculative_[j] = true;
+      while (reactor_op* op = op_queue_[j].front())
+      {
+        if (reactor_op::status status = op->perform())
+        {
+          op_queue_[j].pop();
+          io_cleanup.ops_.push(op);
+          if (status == reactor_op::done_and_exhausted)
+          {
+            try_speculative_[j] = false;
+            break;
+          }
+        }
+        else
+          break;
+      }
+    }
+  }
+
+  // The first operation will be returned for completion now. The others will
+  // be posted for later by the io_cleanup object's destructor.
+  io_cleanup.first_op_ = io_cleanup.ops_.front();
+  io_cleanup.ops_.pop();
+  return io_cleanup.first_op_;
+}
+
+void epoll_reactor::descriptor_state::do_complete(
+    void* owner, operation* base,
+    const asio::error_code& ec, std::size_t bytes_transferred)
+{
+  if (owner)
+  {
+    descriptor_state* descriptor_data = static_cast<descriptor_state*>(base);
+    uint32_t events = static_cast<uint32_t>(bytes_transferred);
+    if (operation* op = descriptor_data->perform_io(events))
+    {
+      op->complete(owner, ec, 0);
+    }
+  }
+}
+
+} // namespace detail
+} // namespace asio
+
+#include "asio/detail/pop_options.hpp"
+
+#endif // defined(ASIO_HAS_EPOLL)
+
+#endif // ASIO_DETAIL_IMPL_EPOLL_REACTOR_IPP