Resolver.hpp

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// The Reactive C++ Toolbox.
// Copyright (C) 2013-2019 Swirly Cloud Limited
// Copyright (C) 2021 Reactive Markets Limited
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
 
#ifndef TOOLBOX_NET_RESOLVER_HPP
#define TOOLBOX_NET_RESOLVER_HPP
 
#include <toolbox/net/Socket.hpp>
#include <toolbox/sys/Time.hpp>
#include <toolbox/util/TaskQueue.hpp>
 
#include <cassert>
#include <future>
 
namespace toolbox {
inline namespace net {
 
using AddrInfoFuture = std::future<AddrInfoPtr>;
 
class TOOLBOX_API Resolver {
    using Task = std::packaged_task<AddrInfoPtr()>;
 
  public:
    Resolver() = default;
    ~Resolver() = default;
 
    // Copy.
    Resolver(const Resolver& rhs) = delete;
    Resolver& operator=(const Resolver& rhs) = delete;
 
    // Move.
    Resolver(Resolver&&) = delete;
    Resolver& operator=(Resolver&&) = delete;
 
    bool run();
 
    void stop();
 
    void clear();
 
    AddrInfoFuture resolve(std::string uri, int type);
 
  private:
    TaskQueue<Task> tq_;
};
 
template <typename EndpointT>
EndpointT get_endpoint(AddrInfoFuture& future)
{
    const auto ai = future.get();
    assert(!future.valid());
    return {ai->ai_addr, ai->ai_addrlen, ai->ai_protocol};
}
 
template <typename ResultT>
bool is_ready(std::future<ResultT>& future)
{
    switch (future.wait_for(Seconds{0})) {
    case std::future_status::ready:
        return true;
    case std::future_status::deferred:
    case std::future_status::timeout:
        break;
    }
    return false;
}
 
} // namespace net
} // namespace toolbox
 
#endif // TOOLBOX_NET_RESOLVER_HPP