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/*
* Copyright 2014 Daniel Vrátil <dvratil@redhat.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public License as
* published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
*
* 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 Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public License
* along with this library. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef FUTURE_H
#define FUTURE_H
class QEventLoop;
#include <type_traits>
#include <QSharedDataPointer>
#include <QPointer>
#include <QVector>
#include <QEventLoop>
namespace Async {
namespace Private {
class Execution;
class ExecutorBase;
typedef QSharedPointer<Execution> ExecutionPtr;
}
class FutureBase
{
friend class Async::Private::Execution;
public:
virtual ~FutureBase();
virtual void setFinished() = 0;
virtual bool isFinished() const = 0;
virtual void setError(int code = 1, const QString &message = QString()) = 0;
protected:
virtual void releaseExecution() = 0;
class PrivateBase : public QSharedData
{
public:
PrivateBase(const Async::Private::ExecutionPtr &execution);
virtual ~PrivateBase();
void releaseExecution();
private:
QWeakPointer<Async::Private::Execution> mExecution;
};
FutureBase();
FutureBase(const FutureBase &other);
};
template<typename T>
class FutureWatcher;
template<typename T>
class Future;
template<typename T>
class FutureGeneric : public FutureBase
{
friend class FutureWatcher<T>;
public:
void setFinished()
{
if (d->finished) {
return;
}
d->finished = true;
for (auto watcher : d->watchers) {
if (watcher) {
watcher->futureReadyCallback();
}
}
}
bool isFinished() const
{
return d->finished;
}
void setError(int errorCode, const QString &message)
{
d->errorCode = errorCode;
d->errorMessage = message;
setFinished();
}
int errorCode() const
{
return d->errorCode;
}
QString errorMessage() const
{
return d->errorMessage;
}
void waitForFinished()
{
if (isFinished()) {
return;
}
FutureWatcher<T> watcher;
QEventLoop eventLoop;
QObject::connect(&watcher, &Async::FutureWatcher<T>::futureReady,
&eventLoop, &QEventLoop::quit);
watcher.setFuture(*static_cast<Async::Future<T>*>(this));
eventLoop.exec();
}
protected:
FutureGeneric(const Async::Private::ExecutionPtr &execution)
: FutureBase()
, d(new Private(execution))
{}
FutureGeneric(const FutureGeneric<T> &other)
: FutureBase(other)
, d(other.d)
{}
class Private : public FutureBase::PrivateBase
{
public:
Private(const Async::Private::ExecutionPtr &execution)
: FutureBase::PrivateBase(execution)
, finished(false)
, errorCode(0)
{}
typename std::conditional<std::is_void<T>::value, int /* dummy */, T>::type
value;
QVector<QPointer<FutureWatcher<T>>> watchers;
bool finished;
int errorCode;
QString errorMessage;
};
QExplicitlySharedDataPointer<Private> d;
void releaseExecution()
{
d->releaseExecution();
}
void addWatcher(FutureWatcher<T> *watcher)
{
d->watchers.append(QPointer<FutureWatcher<T>>(watcher));
}
};
template<typename T>
class Future : public FutureGeneric<T>
{
friend class Async::Private::ExecutorBase;
template<typename T_>
friend class Async::FutureWatcher;
public:
Future()
: FutureGeneric<T>(Async::Private::ExecutionPtr())
{}
Future(const Future<T> &other)
: FutureGeneric<T>(other)
{}
void setValue(const T &value)
{
this->d->value = value;
}
T value() const
{
return this->d->value;
}
protected:
Future(const Async::Private::ExecutionPtr &execution)
: FutureGeneric<T>(execution)
{}
};
template<>
class Future<void> : public FutureGeneric<void>
{
friend class Async::Private::ExecutorBase;
template<typename T_>
friend class Async::FutureWatcher;
public:
Future()
: FutureGeneric<void>(Async::Private::ExecutionPtr())
{}
Future(const Future<void> &other)
: FutureGeneric<void>(other)
{}
protected:
Future(const Async::Private::ExecutionPtr &execution)
: FutureGeneric<void>(execution)
{}
};
class FutureWatcherBase : public QObject
{
Q_OBJECT
protected:
FutureWatcherBase(QObject *parent = nullptr);
virtual ~FutureWatcherBase();
Q_SIGNALS:
void futureReady();
};
template<typename T>
class FutureWatcher : public FutureWatcherBase
{
friend class Async::FutureGeneric<T>;
public:
FutureWatcher(QObject *parent = nullptr)
: FutureWatcherBase(parent)
{}
~FutureWatcher()
{}
void setFuture(const Async::Future<T> &future)
{
mFuture = future;
mFuture.addWatcher(this);
if (future.isFinished()) {
futureReadyCallback();
}
}
Async::Future<T> future() const
{
return mFuture;
}
private:
void futureReadyCallback()
{
Q_EMIT futureReady();
}
Async::Future<T> mFuture;
};
} // namespace Async
#endif // FUTURE_H
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