RemoteProcedure.h

/*
  Copyright (C) 2009-2026 by Marc Duerner
 
  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.
 
  As a special exception, you may use this file as part of a free
  software library without restriction. Specifically, if other files
  instantiate templates or use macros or inline functions from this
  file, or you compile this file and link it with other files to
  produce an executable, this file does not by itself cause the
  resulting executable to be covered by the GNU General Public
  License. This exception does not however invalidate any other
  reasons why the executable file might be covered by the GNU Library
  General Public License.
 
  This library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  Lesser General Public License for more details.
 
  You should have received a copy of the GNU Lesser General Public
  License along with this library; if not, write to the:
  Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  Boston, MA 02110-1301 USA
*/
 
#ifndef PT_REMOTING_REMOTEPROCEDURE_H
#define PT_REMOTING_REMOTEPROCEDURE_H
 
#include <Pt/Remoting/Api.h>
#include <Pt/Remoting/Client.h>
#include <Pt/SerializationContext.h>
#include <Pt/Composer.h>
#include <Pt/Decomposer.h>
#include <Pt/NonCopyable.h>
#include <Pt/Signal.h>
#include <Pt/String.h>
#include <cstddef>
#include <string>
 
namespace Pt {
 
namespace Remoting {

class PT_REMOTING_API RemoteCall : private Pt::NonCopyable
{
    public:
        RemoteCall(Client& client, const String& name);
 
        RemoteCall(Client& client, const std::string& name);
 
        RemoteCall(Client& client, const char* name);
 
        virtual ~RemoteCall();

        Client& client()
        { return *_client; }

        const String& name() const
        { return _name; }

        bool isFailed() const
        { return _client->isFailed(); }

        void cancel();

        void setReady();

        void endCall();
 
    protected:
        virtual void onReady() = 0;

        virtual void onReset() = 0;

        virtual void onClear() = 0;
 
    private:
        Client* _client;
        String _name;
};
 

template <typename R>
class Result : private Pt::NonCopyable
{
    public:
        explicit Result(RemoteCall* call = 0)
        : _call(call)
        , _result(0)
        {
            _result = new (_mem) R;
        }
 
        ~Result()
        {
            _result->~R();
        }
 
        void init(RemoteCall* call)
        { _call = call; }

        bool isFailed() const
        {
            return _call->isFailed();
        }

        R& value()
        { return *_result; }

        const R& get() const
        {
            _call->endCall();
            return *_result;
        }
 
        void clear()
        {
            _result->~R();
            _result = new (_mem) R;
        }
 
    private:
        RemoteCall* _call;
        char _mem[ sizeof(R) ];
        R* _result;
};
 

template <typename R>
class RemoteProcedureBase : public RemoteCall
{
    public:
        RemoteProcedureBase(Client& client, const std::string& name)
        : RemoteCall(client, name)
        , _result(0)
        , _r(0)
        {
            _result.init(this);
        }
 
        ~RemoteProcedureBase()
        {
            if(_r)
                _r->~BasicComposer<R>();
        }

        Result<R>& result()
        {
            return _result;
        }

        const Result<R>& result() const
        {
            return _result;
        }

        Signal< const Result<R>& >& finished()
        { return _finished; }
 
    protected:
        void onReady()
        { _finished.send(_result); }
 
        BasicComposer<R>& beginResult()
        {
            if(_r)
            {
                _r->~BasicComposer<R>();
                _r = 0;
            }
 
            _r = new (_mem) BasicComposer<R>( &client().context() );
            _r->begin( result().value() );
            return *_r;
        }
 
        virtual void onReset()
        {
            if(_r)
            {
                _r->~BasicComposer<R>();
                _r = 0;
            }
        }
 
        virtual void onClear()
        {
            this->onReset();
            _result.clear();
        }
 
    private:
        Signal< const Result<R>& > _finished;
        Result<R> _result;
        char _mem[ sizeof(BasicComposer<R>) ];
        BasicComposer<R>* _r;
};
 
 
template <typename A>
class RemoteArgument : private Pt::NonCopyable
{
    public:
        RemoteArgument(SerializationContext* )
        : _decomposer(0)
        { }
 
        ~RemoteArgument()
        {
            if(_decomposer)
                _decomposer->~BasicDecomposer<A>();
        }
 
        void begin(const A& a, const char* name, SerializationContext& ctx)
        {
            if(_decomposer)
            {
                _decomposer->~BasicDecomposer<A>();
                _decomposer = 0;
            }
 
            _decomposer = new (_mem) BasicDecomposer<A>(&ctx);
            _decomposer->begin(a, name);
        }
 
        void clear(SerializationContext* )
        {
            if(_decomposer)
            {
                _decomposer->~BasicDecomposer<A>();
                _decomposer = 0;
            }
        }
 
        // TODO: return decomposer pointer from begin
        BasicDecomposer<A>* decomposer()
        { return reinterpret_cast<BasicDecomposer<A>*>(_mem); }
 
    private:
        char _mem[ sizeof(BasicDecomposer<A>) ];
        BasicDecomposer<A>* _decomposer;
};
 
 
template <typename... Ts>
class RemoteArguments;
 
 
template <>
class RemoteArguments<>
{
    public:
        explicit RemoteArguments(SerializationContext* /*ctx*/)
        { }
 
        void begin(SerializationContext& /*ctx*/)
        { }
 
        void fill(std::size_t i, Decomposer** args)
        {
            args[i] = 0;
        }
 
        void clear(SerializationContext* /*ctx*/)
        { }
};
 
 
template <typename T, typename... Ts>
class RemoteArguments<T, Ts...>
{
    public:
        explicit RemoteArguments(SerializationContext* ctx)
        : _head(ctx)
        , _tail(ctx)
        { }
 
        void begin(SerializationContext& ctx, const T& a, const Ts&... as)
        {
            _head.begin(a, "", ctx);
            _tail.begin(ctx, as...);
        }
 
        void fill(std::size_t i, Decomposer** args)
        {
            args[i] = _head.decomposer();
            _tail.fill(i + 1, args);
        }
 
        void clear(SerializationContext* ctx)
        {
            _head.clear(ctx);
            _tail.clear(ctx);
        }
 
    private:
        RemoteArgument<T> _head;
        RemoteArguments<Ts...> _tail;
};
 

template <typename R, typename... As>
class RemoteProcedure : public RemoteProcedureBase<R>
{
    public:
        RemoteProcedure(Client& client, const std::string& name)
        : RemoteProcedureBase<R>(client, name)
        , _argv( &client.context() )
        {
            _argv.fill(0, _args);
        }

        virtual ~RemoteProcedure()
        { }

        void begin(const As&... args)
        {
            try
            {
                _argv.begin(this->client().context(), args...);
                BasicComposer<R>& r = this->beginResult();
 
                this->client().beginCall(r, *this, _args, sizeof...(As));
            }
            catch(...)
            {
                this->onClear();
                throw;
            }
        }

        const R& call(const As&... args)
        {
            try
            {
                _argv.begin(this->client().context(), args...);
                BasicComposer<R>& r = this->beginResult();
 
                this->client().call(r, *this, _args, sizeof...(As));
                this->onReset();
            }
            catch(...)
            {
                this->onClear();
                throw;
            }
 
            return this->result().value();
        }

        const R& operator()(const As&... args)
        {
            return this->call(args...);
        }
 
    protected:
        void onReset()
        {
            RemoteProcedureBase<R>::onReset();
            _argv.clear( &this->client().context() );
        }
 
    private:
        RemoteArguments<As...> _argv;
        Decomposer* _args[sizeof...(As) + 1];
};
 
} // namespace Remoting
 
} // namespace Pt
 
#endif // PT_REMOTING_REMOTEPROCEDURE_H