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+//
+// detail/impl/scheduler.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_SCHEDULER_IPP
+#define ASIO_DETAIL_IMPL_SCHEDULER_IPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include "asio/detail/config.hpp"
+
+#include "asio/detail/concurrency_hint.hpp"
+#include "asio/detail/event.hpp"
+#include "asio/detail/limits.hpp"
+#include "asio/detail/reactor.hpp"
+#include "asio/detail/scheduler.hpp"
+#include "asio/detail/scheduler_thread_info.hpp"
+
+#include "asio/detail/push_options.hpp"
+
+namespace asio {
+namespace detail {
+
+struct scheduler::task_cleanup
+{
+ ~task_cleanup()
+ {
+ if (this_thread_->private_outstanding_work > 0)
+ {
+ asio::detail::increment(
+ scheduler_->outstanding_work_,
+ this_thread_->private_outstanding_work);
+ }
+ this_thread_->private_outstanding_work = 0;
+
+ // Enqueue the completed operations and reinsert the task at the end of
+ // the operation queue.
+ lock_->lock();
+ scheduler_->task_interrupted_ = true;
+ scheduler_->op_queue_.push(this_thread_->private_op_queue);
+ scheduler_->op_queue_.push(&scheduler_->task_operation_);
+ }
+
+ scheduler* scheduler_;
+ mutex::scoped_lock* lock_;
+ thread_info* this_thread_;
+};
+
+struct scheduler::work_cleanup
+{
+ ~work_cleanup()
+ {
+ if (this_thread_->private_outstanding_work > 1)
+ {
+ asio::detail::increment(
+ scheduler_->outstanding_work_,
+ this_thread_->private_outstanding_work - 1);
+ }
+ else if (this_thread_->private_outstanding_work < 1)
+ {
+ scheduler_->work_finished();
+ }
+ this_thread_->private_outstanding_work = 0;
+
+#if defined(ASIO_HAS_THREADS)
+ if (!this_thread_->private_op_queue.empty())
+ {
+ lock_->lock();
+ scheduler_->op_queue_.push(this_thread_->private_op_queue);
+ }
+#endif // defined(ASIO_HAS_THREADS)
+ }
+
+ scheduler* scheduler_;
+ mutex::scoped_lock* lock_;
+ thread_info* this_thread_;
+};
+
+scheduler::scheduler(
+ asio::execution_context& ctx, int concurrency_hint)
+ : asio::detail::execution_context_service_base<scheduler>(ctx),
+ one_thread_(concurrency_hint == 1
+ || !ASIO_CONCURRENCY_HINT_IS_LOCKING(
+ SCHEDULER, concurrency_hint)
+ || !ASIO_CONCURRENCY_HINT_IS_LOCKING(
+ REACTOR_IO, concurrency_hint)),
+ mutex_(ASIO_CONCURRENCY_HINT_IS_LOCKING(
+ SCHEDULER, concurrency_hint)),
+ task_(0),
+ task_interrupted_(true),
+ outstanding_work_(0),
+ stopped_(false),
+ shutdown_(false),
+ concurrency_hint_(concurrency_hint)
+{
+ ASIO_HANDLER_TRACKING_INIT;
+}
+
+void scheduler::shutdown()
+{
+ mutex::scoped_lock lock(mutex_);
+ shutdown_ = true;
+ lock.unlock();
+
+ // Destroy handler objects.
+ while (!op_queue_.empty())
+ {
+ operation* o = op_queue_.front();
+ op_queue_.pop();
+ if (o != &task_operation_)
+ o->destroy();
+ }
+
+ // Reset to initial state.
+ task_ = 0;
+}
+
+void scheduler::init_task()
+{
+ mutex::scoped_lock lock(mutex_);
+ if (!shutdown_ && !task_)
+ {
+ task_ = &use_service<reactor>(this->context());
+ op_queue_.push(&task_operation_);
+ wake_one_thread_and_unlock(lock);
+ }
+}
+
+std::size_t scheduler::run(asio::error_code& ec)
+{
+ ec = asio::error_code();
+ if (outstanding_work_ == 0)
+ {
+ stop();
+ return 0;
+ }
+
+ thread_info this_thread;
+ this_thread.private_outstanding_work = 0;
+ thread_call_stack::context ctx(this, this_thread);
+
+ mutex::scoped_lock lock(mutex_);
+
+ std::size_t n = 0;
+ for (; do_run_one(lock, this_thread, ec); lock.lock())
+ if (n != (std::numeric_limits<std::size_t>::max)())
+ ++n;
+ return n;
+}
+
+std::size_t scheduler::run_one(asio::error_code& ec)
+{
+ ec = asio::error_code();
+ if (outstanding_work_ == 0)
+ {
+ stop();
+ return 0;
+ }
+
+ thread_info this_thread;
+ this_thread.private_outstanding_work = 0;
+ thread_call_stack::context ctx(this, this_thread);
+
+ mutex::scoped_lock lock(mutex_);
+
+ return do_run_one(lock, this_thread, ec);
+}
+
+std::size_t scheduler::wait_one(long usec, asio::error_code& ec)
+{
+ ec = asio::error_code();
+ if (outstanding_work_ == 0)
+ {
+ stop();
+ return 0;
+ }
+
+ thread_info this_thread;
+ this_thread.private_outstanding_work = 0;
+ thread_call_stack::context ctx(this, this_thread);
+
+ mutex::scoped_lock lock(mutex_);
+
+ return do_wait_one(lock, this_thread, usec, ec);
+}
+
+std::size_t scheduler::poll(asio::error_code& ec)
+{
+ ec = asio::error_code();
+ if (outstanding_work_ == 0)
+ {
+ stop();
+ return 0;
+ }
+
+ thread_info this_thread;
+ this_thread.private_outstanding_work = 0;
+ thread_call_stack::context ctx(this, this_thread);
+
+ mutex::scoped_lock lock(mutex_);
+
+#if defined(ASIO_HAS_THREADS)
+ // We want to support nested calls to poll() and poll_one(), so any handlers
+ // that are already on a thread-private queue need to be put on to the main
+ // queue now.
+ if (one_thread_)
+ if (thread_info* outer_info = static_cast<thread_info*>(ctx.next_by_key()))
+ op_queue_.push(outer_info->private_op_queue);
+#endif // defined(ASIO_HAS_THREADS)
+
+ std::size_t n = 0;
+ for (; do_poll_one(lock, this_thread, ec); lock.lock())
+ if (n != (std::numeric_limits<std::size_t>::max)())
+ ++n;
+ return n;
+}
+
+std::size_t scheduler::poll_one(asio::error_code& ec)
+{
+ ec = asio::error_code();
+ if (outstanding_work_ == 0)
+ {
+ stop();
+ return 0;
+ }
+
+ thread_info this_thread;
+ this_thread.private_outstanding_work = 0;
+ thread_call_stack::context ctx(this, this_thread);
+
+ mutex::scoped_lock lock(mutex_);
+
+#if defined(ASIO_HAS_THREADS)
+ // We want to support nested calls to poll() and poll_one(), so any handlers
+ // that are already on a thread-private queue need to be put on to the main
+ // queue now.
+ if (one_thread_)
+ if (thread_info* outer_info = static_cast<thread_info*>(ctx.next_by_key()))
+ op_queue_.push(outer_info->private_op_queue);
+#endif // defined(ASIO_HAS_THREADS)
+
+ return do_poll_one(lock, this_thread, ec);
+}
+
+void scheduler::stop()
+{
+ mutex::scoped_lock lock(mutex_);
+ stop_all_threads(lock);
+}
+
+bool scheduler::stopped() const
+{
+ mutex::scoped_lock lock(mutex_);
+ return stopped_;
+}
+
+void scheduler::restart()
+{
+ mutex::scoped_lock lock(mutex_);
+ stopped_ = false;
+}
+
+void scheduler::compensating_work_started()
+{
+ thread_info_base* this_thread = thread_call_stack::contains(this);
+ ++static_cast<thread_info*>(this_thread)->private_outstanding_work;
+}
+
+void scheduler::post_immediate_completion(
+ scheduler::operation* op, bool is_continuation)
+{
+#if defined(ASIO_HAS_THREADS)
+ if (one_thread_ || is_continuation)
+ {
+ if (thread_info_base* this_thread = thread_call_stack::contains(this))
+ {
+ ++static_cast<thread_info*>(this_thread)->private_outstanding_work;
+ static_cast<thread_info*>(this_thread)->private_op_queue.push(op);
+ return;
+ }
+ }
+#else // defined(ASIO_HAS_THREADS)
+ (void)is_continuation;
+#endif // defined(ASIO_HAS_THREADS)
+
+ work_started();
+ mutex::scoped_lock lock(mutex_);
+ op_queue_.push(op);
+ wake_one_thread_and_unlock(lock);
+}
+
+void scheduler::post_deferred_completion(scheduler::operation* op)
+{
+#if defined(ASIO_HAS_THREADS)
+ if (one_thread_)
+ {
+ if (thread_info_base* this_thread = thread_call_stack::contains(this))
+ {
+ static_cast<thread_info*>(this_thread)->private_op_queue.push(op);
+ return;
+ }
+ }
+#endif // defined(ASIO_HAS_THREADS)
+
+ mutex::scoped_lock lock(mutex_);
+ op_queue_.push(op);
+ wake_one_thread_and_unlock(lock);
+}
+
+void scheduler::post_deferred_completions(
+ op_queue<scheduler::operation>& ops)
+{
+ if (!ops.empty())
+ {
+#if defined(ASIO_HAS_THREADS)
+ if (one_thread_)
+ {
+ if (thread_info_base* this_thread = thread_call_stack::contains(this))
+ {
+ static_cast<thread_info*>(this_thread)->private_op_queue.push(ops);
+ return;
+ }
+ }
+#endif // defined(ASIO_HAS_THREADS)
+
+ mutex::scoped_lock lock(mutex_);
+ op_queue_.push(ops);
+ wake_one_thread_and_unlock(lock);
+ }
+}
+
+void scheduler::do_dispatch(
+ scheduler::operation* op)
+{
+ work_started();
+ mutex::scoped_lock lock(mutex_);
+ op_queue_.push(op);
+ wake_one_thread_and_unlock(lock);
+}
+
+void scheduler::abandon_operations(
+ op_queue<scheduler::operation>& ops)
+{
+ op_queue<scheduler::operation> ops2;
+ ops2.push(ops);
+}
+
+std::size_t scheduler::do_run_one(mutex::scoped_lock& lock,
+ scheduler::thread_info& this_thread,
+ const asio::error_code& ec)
+{
+ while (!stopped_)
+ {
+ if (!op_queue_.empty())
+ {
+ // Prepare to execute first handler from queue.
+ operation* o = op_queue_.front();
+ op_queue_.pop();
+ bool more_handlers = (!op_queue_.empty());
+
+ if (o == &task_operation_)
+ {
+ task_interrupted_ = more_handlers;
+
+ if (more_handlers && !one_thread_)
+ wakeup_event_.unlock_and_signal_one(lock);
+ else
+ lock.unlock();
+
+ task_cleanup on_exit = { this, &lock, &this_thread };
+ (void)on_exit;
+
+ // Run the task. May throw an exception. Only block if the operation
+ // queue is empty and we're not polling, otherwise we want to return
+ // as soon as possible.
+ task_->run(more_handlers ? 0 : -1, this_thread.private_op_queue);
+ }
+ else
+ {
+ std::size_t task_result = o->task_result_;
+
+ if (more_handlers && !one_thread_)
+ wake_one_thread_and_unlock(lock);
+ else
+ lock.unlock();
+
+ // Ensure the count of outstanding work is decremented on block exit.
+ work_cleanup on_exit = { this, &lock, &this_thread };
+ (void)on_exit;
+
+ // Complete the operation. May throw an exception. Deletes the object.
+ o->complete(this, ec, task_result);
+
+ return 1;
+ }
+ }
+ else
+ {
+ wakeup_event_.clear(lock);
+ wakeup_event_.wait(lock);
+ }
+ }
+
+ return 0;
+}
+
+std::size_t scheduler::do_wait_one(mutex::scoped_lock& lock,
+ scheduler::thread_info& this_thread, long usec,
+ const asio::error_code& ec)
+{
+ if (stopped_)
+ return 0;
+
+ operation* o = op_queue_.front();
+ if (o == 0)
+ {
+ wakeup_event_.clear(lock);
+ wakeup_event_.wait_for_usec(lock, usec);
+ usec = 0; // Wait at most once.
+ o = op_queue_.front();
+ }
+
+ if (o == &task_operation_)
+ {
+ op_queue_.pop();
+ bool more_handlers = (!op_queue_.empty());
+
+ task_interrupted_ = more_handlers;
+
+ if (more_handlers && !one_thread_)
+ wakeup_event_.unlock_and_signal_one(lock);
+ else
+ lock.unlock();
+
+ {
+ task_cleanup on_exit = { this, &lock, &this_thread };
+ (void)on_exit;
+
+ // Run the task. May throw an exception. Only block if the operation
+ // queue is empty and we're not polling, otherwise we want to return
+ // as soon as possible.
+ task_->run(more_handlers ? 0 : usec, this_thread.private_op_queue);
+ }
+
+ o = op_queue_.front();
+ if (o == &task_operation_)
+ {
+ if (!one_thread_)
+ wakeup_event_.maybe_unlock_and_signal_one(lock);
+ return 0;
+ }
+ }
+
+ if (o == 0)
+ return 0;
+
+ op_queue_.pop();
+ bool more_handlers = (!op_queue_.empty());
+
+ std::size_t task_result = o->task_result_;
+
+ if (more_handlers && !one_thread_)
+ wake_one_thread_and_unlock(lock);
+ else
+ lock.unlock();
+
+ // Ensure the count of outstanding work is decremented on block exit.
+ work_cleanup on_exit = { this, &lock, &this_thread };
+ (void)on_exit;
+
+ // Complete the operation. May throw an exception. Deletes the object.
+ o->complete(this, ec, task_result);
+
+ return 1;
+}
+
+std::size_t scheduler::do_poll_one(mutex::scoped_lock& lock,
+ scheduler::thread_info& this_thread,
+ const asio::error_code& ec)
+{
+ if (stopped_)
+ return 0;
+
+ operation* o = op_queue_.front();
+ if (o == &task_operation_)
+ {
+ op_queue_.pop();
+ lock.unlock();
+
+ {
+ task_cleanup c = { this, &lock, &this_thread };
+ (void)c;
+
+ // Run the task. May throw an exception. Only block if the operation
+ // queue is empty and we're not polling, otherwise we want to return
+ // as soon as possible.
+ task_->run(0, this_thread.private_op_queue);
+ }
+
+ o = op_queue_.front();
+ if (o == &task_operation_)
+ {
+ wakeup_event_.maybe_unlock_and_signal_one(lock);
+ return 0;
+ }
+ }
+
+ if (o == 0)
+ return 0;
+
+ op_queue_.pop();
+ bool more_handlers = (!op_queue_.empty());
+
+ std::size_t task_result = o->task_result_;
+
+ if (more_handlers && !one_thread_)
+ wake_one_thread_and_unlock(lock);
+ else
+ lock.unlock();
+
+ // Ensure the count of outstanding work is decremented on block exit.
+ work_cleanup on_exit = { this, &lock, &this_thread };
+ (void)on_exit;
+
+ // Complete the operation. May throw an exception. Deletes the object.
+ o->complete(this, ec, task_result);
+
+ return 1;
+}
+
+void scheduler::stop_all_threads(
+ mutex::scoped_lock& lock)
+{
+ stopped_ = true;
+ wakeup_event_.signal_all(lock);
+
+ if (!task_interrupted_ && task_)
+ {
+ task_interrupted_ = true;
+ task_->interrupt();
+ }
+}
+
+void scheduler::wake_one_thread_and_unlock(
+ mutex::scoped_lock& lock)
+{
+ if (!wakeup_event_.maybe_unlock_and_signal_one(lock))
+ {
+ if (!task_interrupted_ && task_)
+ {
+ task_interrupted_ = true;
+ task_->interrupt();
+ }
+ lock.unlock();
+ }
+}
+
+} // namespace detail
+} // namespace asio
+
+#include "asio/detail/pop_options.hpp"
+
+#endif // ASIO_DETAIL_IMPL_SCHEDULER_IPP