zircon/system/ulib/fidl-async/include/lib/fidl-async/cpp/channel_transaction.h

// Copyright 2019 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef LIB_FIDL_ASYNC_CPP_CHANNEL_TRANSACTION_H_
#define LIB_FIDL_ASYNC_CPP_CHANNEL_TRANSACTION_H_

#include <lib/fidl/llcpp/transaction.h>
#include <lib/zx/channel.h>
#include <zircon/fidl.h>

#include <utility>

namespace fidl {

namespace internal {

class SimpleBinding;

// A basic implementation of |fidl::Transaction|. Designed to work with |fidl::Bind|, which pauses
// message dispatching when an asynchronous transaction is in-flight.
// The channel is owned by |SimpleBinding|.
// |SimpleBinding| ownership ping-pongs between this transaction and the async dispatcher.
class ChannelTransaction final : public Transaction {
public:
    ChannelTransaction(zx_txid_t txid, std::unique_ptr<SimpleBinding> binding)
        : Transaction(), txid_(txid), binding_(std::move(binding)) {}

    ~ChannelTransaction() final;

    ChannelTransaction(ChannelTransaction&& other) noexcept : Transaction(std::move(other)) {
        if (this != &other) {
            MoveImpl(std::move(other));
        }
    }

    ChannelTransaction& operator=(ChannelTransaction&& other) noexcept {
        if (this != &other) {
            MoveImpl(std::move(other));
        }
        return *this;
    }

protected:
    void Reply(fidl::Message msg) final;

    void Close(zx_status_t epitaph) final;

    std::unique_ptr<Transaction> TakeOwnership() final;

private:
    friend fidl::internal::SimpleBinding;

    void Dispatch(fidl_msg_t msg);

    std::unique_ptr<SimpleBinding> TakeBinding() { return std::move(binding_); }

    void MoveImpl(ChannelTransaction&& other) noexcept {
        txid_ = other.txid_;
        other.txid_ = 0;
        binding_ = std::move(other.binding_);
    }

    zx_txid_t txid_ = 0;
    std::unique_ptr<SimpleBinding> binding_ = {};
};

} // namespace internal

} // namespace fidl

#endif // LIB_FIDL_ASYNC_CPP_CHANNEL_TRANSACTION_H_