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//
// detail/resolve_query_op.hpp
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~
//
// 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_RESOLVE_QUERY_OP_HPP
#define ASIO_DETAIL_RESOLVE_QUERY_OP_HPP
#if defined(_MSC_VER) && (_MSC_VER >= 1200)
# pragma once
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
#include "asio/detail/config.hpp"
#include "asio/error.hpp"
#include "asio/io_context.hpp"
#include "asio/ip/basic_resolver_query.hpp"
#include "asio/ip/basic_resolver_results.hpp"
#include "asio/detail/bind_handler.hpp"
#include "asio/detail/fenced_block.hpp"
#include "asio/detail/handler_alloc_helpers.hpp"
#include "asio/detail/handler_invoke_helpers.hpp"
#include "asio/detail/memory.hpp"
#include "asio/detail/resolve_op.hpp"
#include "asio/detail/socket_ops.hpp"
#include "asio/detail/push_options.hpp"
namespace asio {
namespace detail {
template <typename Protocol, typename Handler>
class resolve_query_op : public resolve_op
{
public:
ASIO_DEFINE_HANDLER_PTR(resolve_query_op);
typedef asio::ip::basic_resolver_query<Protocol> query_type;
typedef asio::ip::basic_resolver_results<Protocol> results_type;
resolve_query_op(socket_ops::weak_cancel_token_type cancel_token,
const query_type& query, io_context_impl& ioc, Handler& handler)
: resolve_op(&resolve_query_op::do_complete),
cancel_token_(cancel_token),
query_(query),
io_context_impl_(ioc),
handler_(ASIO_MOVE_CAST(Handler)(handler)),
addrinfo_(0)
{
handler_work<Handler>::start(handler_);
}
~resolve_query_op()
{
if (addrinfo_)
socket_ops::freeaddrinfo(addrinfo_);
}
static void do_complete(void* owner, operation* base,
const asio::error_code& /*ec*/,
std::size_t /*bytes_transferred*/)
{
// Take ownership of the operation object.
resolve_query_op* o(static_cast<resolve_query_op*>(base));
ptr p = { asio::detail::addressof(o->handler_), o, o };
if (owner && owner != &o->io_context_impl_)
{
// The operation is being run on the worker io_context. Time to perform
// the resolver operation.
// Perform the blocking host resolution operation.
socket_ops::background_getaddrinfo(o->cancel_token_,
o->query_.host_name().c_str(), o->query_.service_name().c_str(),
o->query_.hints(), &o->addrinfo_, o->ec_);
// Pass operation back to main io_context for completion.
o->io_context_impl_.post_deferred_completion(o);
p.v = p.p = 0;
}
else
{
// The operation has been returned to the main io_context. The completion
// handler is ready to be delivered.
// Take ownership of the operation's outstanding work.
handler_work<Handler> w(o->handler_);
ASIO_HANDLER_COMPLETION((*o));
// Make a copy of the handler so that the memory can be deallocated
// before the upcall is made. Even if we're not about to make an upcall,
// a sub-object of the handler may be the true owner of the memory
// associated with the handler. Consequently, a local copy of the handler
// is required to ensure that any owning sub-object remains valid until
// after we have deallocated the memory here.
detail::binder2<Handler, asio::error_code, results_type>
handler(o->handler_, o->ec_, results_type());
p.h = asio::detail::addressof(handler.handler_);
if (o->addrinfo_)
{
handler.arg2_ = results_type::create(o->addrinfo_,
o->query_.host_name(), o->query_.service_name());
}
p.reset();
if (owner)
{
fenced_block b(fenced_block::half);
ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_, "..."));
w.complete(handler, handler.handler_);
ASIO_HANDLER_INVOCATION_END;
}
}
}
private:
socket_ops::weak_cancel_token_type cancel_token_;
query_type query_;
io_context_impl& io_context_impl_;
Handler handler_;
asio::detail::addrinfo_type* addrinfo_;
};
} // namespace detail
} // namespace asio
#include "asio/detail/pop_options.hpp"
#endif // ASIO_DETAIL_RESOLVE_QUERY_OP_HPP
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