transmission/qt/RpcQueue.h

149 lines
4.5 KiB
C++

/*
* This file Copyright (C) 2016 Mnemosyne LLC
*
* It may be used under the GNU GPL versions 2 or 3
* or any future license endorsed by Mnemosyne LLC.
*
*/
#pragma once
#include <functional>
#include <type_traits>
#include <QFutureInterface>
#include <QFutureWatcher>
#include <QObject>
#include <QPair>
#include <QQueue>
#include "RpcClient.h"
class RpcQueue : public QObject
{
Q_OBJECT
public:
explicit RpcQueue(QObject* parent = nullptr);
void setTolerateErrors(bool tolerateErrors = true)
{
myTolerateErrors = tolerateErrors;
}
template<typename Func>
void add(Func func)
{
myQueue.enqueue(qMakePair(normalizeFunc(func), ErrorHandlerFunction()));
}
template<typename Func, typename ErrorHandler>
void add(Func func, ErrorHandler errorHandler)
{
myQueue.enqueue(qMakePair(normalizeFunc(func), normalizeErrorHandler(errorHandler)));
}
RpcResponseFuture future();
// The first function in queue is ran synchronously
// (hence it may be e. g. a lambda capturing local variables by reference).
void run();
private:
// Internally queued function. Takes the last response future, makes a
// request and returns a new response future.
typedef std::function<RpcResponseFuture(RpcResponseFuture const&)> QueuedFunction;
// Internally stored error handler function. Takes the last response future and returns nothing.
typedef std::function<void (RpcResponseFuture const&)> ErrorHandlerFunction;
private slots:
void stepFinished();
private:
void runNext(RpcResponseFuture const& response);
// These overloads convert various forms of input closures to what we store internally.
// normal closure, takes response and returns new future
template<typename Func, typename std::enable_if<
std::is_same<typename std::result_of<Func(RpcResponse const&)>::type, RpcResponseFuture>::value
>::type* = nullptr>
QueuedFunction normalizeFunc(Func const& func)
{
return [func](RpcResponseFuture const& r)
{
return func(r.result());
};
}
// closure without argument (first step), takes nothing and returns new future
template<typename Func, typename std::enable_if<
std::is_same<typename std::result_of<Func()>::type, RpcResponseFuture>::value
>::type* = nullptr>
QueuedFunction normalizeFunc(Func const& func)
{
return [func](RpcResponseFuture const&)
{
return func();
};
}
// closure without return value ("auxiliary"), takes response and returns nothing -- internally we reuse the last future
template<typename Func, typename std::enable_if<
std::is_same<typename std::result_of<Func(RpcResponse const&)>::type, void>::value
>::type* = nullptr>
QueuedFunction normalizeFunc(Func const& func)
{
return [func](RpcResponseFuture const& r)
{
func(r.result());
return r;
};
}
// closure without argument and return value, takes nothing and returns nothing -- next function will also get nothing
template<typename Func, typename std::enable_if<
std::is_same<typename std::result_of<Func()>::type, void>::value
>::type* = nullptr>
QueuedFunction normalizeFunc(Func const& func)
{
return [func](RpcResponseFuture const& r)
{
func();
return r;
};
}
// normal error handler, takes last response
template<typename Func, typename std::enable_if<
std::is_same<typename std::result_of<Func(RpcResponse const&)>::type, void>::value
>::type* = nullptr>
ErrorHandlerFunction normalizeErrorHandler(Func const& func)
{
return [func](RpcResponseFuture const& r)
{
func(r.result());
};
}
// error handler without an argument, takes nothing
template<typename Func, typename std::enable_if<
std::is_same<typename std::result_of<Func()>::type, void>::value
>::type* = nullptr>
ErrorHandlerFunction normalizeErrorHandler(Func const& func)
{
return [func](RpcResponseFuture const&)
{
func();
};
}
private:
bool myTolerateErrors;
QFutureInterface<RpcResponse> myPromise;
QQueue<QPair<QueuedFunction, ErrorHandlerFunction>> myQueue;
ErrorHandlerFunction myNextErrorHandler;
QFutureWatcher<RpcResponse> myFutureWatcher;
};