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//
// detail/impl/strand_executor_service.ipp
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2019 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_IMPL_STRAND_EXECUTOR_SERVICE_IPP
#define BOOST_ASIO_DETAIL_IMPL_STRAND_EXECUTOR_SERVICE_IPP
#if defined(_MSC_VER) && (_MSC_VER >= 1200)
# pragma once
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
#include <boost/asio/detail/config.hpp>
#include <boost/asio/detail/strand_executor_service.hpp>
#include <boost/asio/detail/push_options.hpp>
namespace boost {
namespace asio {
namespace detail {
strand_executor_service::strand_executor_service(execution_context& ctx)
: execution_context_service_base<strand_executor_service>(ctx),
mutex_(),
salt_(0),
impl_list_(0)
{
}
void strand_executor_service::shutdown()
{
op_queue<scheduler_operation> ops;
boost::asio::detail::mutex::scoped_lock lock(mutex_);
strand_impl* impl = impl_list_;
while (impl)
{
impl->mutex_->lock();
impl->shutdown_ = true;
ops.push(impl->waiting_queue_);
ops.push(impl->ready_queue_);
impl->mutex_->unlock();
impl = impl->next_;
}
}
strand_executor_service::implementation_type
strand_executor_service::create_implementation()
{
implementation_type new_impl(new strand_impl);
new_impl->locked_ = false;
new_impl->shutdown_ = false;
boost::asio::detail::mutex::scoped_lock lock(mutex_);
// Select a mutex from the pool of shared mutexes.
std::size_t salt = salt_++;
std::size_t mutex_index = reinterpret_cast<std::size_t>(new_impl.get());
mutex_index += (reinterpret_cast<std::size_t>(new_impl.get()) >> 3);
mutex_index ^= salt + 0x9e3779b9 + (mutex_index << 6) + (mutex_index >> 2);
mutex_index = mutex_index % num_mutexes;
if (!mutexes_[mutex_index].get())
mutexes_[mutex_index].reset(new mutex);
new_impl->mutex_ = mutexes_[mutex_index].get();
// Insert implementation into linked list of all implementations.
new_impl->next_ = impl_list_;
new_impl->prev_ = 0;
if (impl_list_)
impl_list_->prev_ = new_impl.get();
impl_list_ = new_impl.get();
new_impl->service_ = this;
return new_impl;
}
strand_executor_service::strand_impl::~strand_impl()
{
boost::asio::detail::mutex::scoped_lock lock(service_->mutex_);
// Remove implementation from linked list of all implementations.
if (service_->impl_list_ == this)
service_->impl_list_ = next_;
if (prev_)
prev_->next_ = next_;
if (next_)
next_->prev_= prev_;
}
bool strand_executor_service::enqueue(const implementation_type& impl,
scheduler_operation* op)
{
impl->mutex_->lock();
if (impl->shutdown_)
{
impl->mutex_->unlock();
op->destroy();
return false;
}
else if (impl->locked_)
{
// Some other function already holds the strand lock. Enqueue for later.
impl->waiting_queue_.push(op);
impl->mutex_->unlock();
return false;
}
else
{
// The function is acquiring the strand lock and so is responsible for
// scheduling the strand.
impl->locked_ = true;
impl->mutex_->unlock();
impl->ready_queue_.push(op);
return true;
}
}
bool strand_executor_service::running_in_this_thread(
const implementation_type& impl)
{
return !!call_stack<strand_impl>::contains(impl.get());
}
} // namespace detail
} // namespace asio
} // namespace boost
#include <boost/asio/detail/pop_options.hpp>
#endif // BOOST_ASIO_DETAIL_IMPL_STRAND_EXECUTOR_SERVICE_IPP
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