YiFuture.h

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// © You i Labs Inc. 2000-2017. All rights reserved.
#ifndef _YI_FUTURE_H_
#define _YI_FUTURE_H_

#include "signal/YiSignal.h"
#include "thread/YiAutoMutex.h"

class CYITaskBase;
class CYIMutex;
class CYIWaitCondition;

class CYIAbstractFuture
{
    friend class CYITaskBase;
    template<typename T> friend class CYIFuture;
    
public:
    virtual ~CYIAbstractFuture();

    bool IsCancelled() const;
    
    bool IsCompleted() const;
    
    bool Cancel();
    
    bool CancelOrWait();
    
    bool Wait() const;
    
    bool Wait(uint64_t uTimeoutMs) const;

    CYISignal<> ExecutionStarted; 
    CYISignal<> Cancelled; 
    
protected:
    void ExclusiveLock() const; 
    void ExclusiveUnlock() const; 
    void NotifyStateChanged() const; 
    bool SetTask(CYITaskBase *pTask); 
    void DisconnectFromTask(); 
    bool SetCancelledNonLocking(); 
    bool WaitNonLocking() const; 
    bool WaitNonLocking(uint64_t uTimeoutMs) const; 
    bool CancelInternal(bool bWait);
    
private:
    CYIAbstractFuture();

    // Hiding copy constructor and assignment operator
    CYIAbstractFuture(const CYIAbstractFuture &);
    CYIAbstractFuture &operator=(const CYIAbstractFuture &);

    bool                     m_bCancelled;
    bool                     m_bCompleted;
    mutable CYIMutex            m_mutex;
    mutable CYIWaitCondition    m_stateChange;
    CYITaskBase                *m_pTask;
};



template <typename ResultType = void>
class CYIFuture : public CYIAbstractFuture
{
    template<typename T> friend class CYITask;
    
public:
    CYIFuture();
    virtual ~CYIFuture();
    
    bool Get(ResultType *pValue) const;
    
    const ResultType &Get() const;
    
    bool Get(ResultType *pValue, uint32_t uTimeoutMs) const;

    const ResultType &Get(uint32_t uTimeoutMs) const;

    bool Set(const ResultType &rValue);
    
public: // signals
    CYISignal<const ResultType&> Completed; 
    
protected:
    bool SetCompleted(const ResultType &rValue); 
    
private:
    ResultType m_result;
};



template <>
class CYIFuture<> : public CYIAbstractFuture
{
    template<typename T> friend class CYITask;
    
public:
    CYIFuture();
    virtual ~CYIFuture();
    
    bool Set();
    
public: // signals
    CYISignal<> Completed; 
    
protected:
    bool SetCompleted(); 
};



template <typename ResultType>
class CYIFuture<ResultType*> : public CYIAbstractFuture
{
    template<typename T> friend class CYITask;
    
public:
    CYIFuture();
    virtual ~CYIFuture();
    
    bool Get(ResultType **pValue) const;
    
    const ResultType *Get() const;
    
    bool Get(ResultType **pValue, uint32_t uTimeoutMs) const;

    const ResultType *Get(uint32_t uTimeoutMs) const;

    ResultType* Take();
    
    ResultType *Take(uint32_t uTimeoutMs);

    bool Set(ResultType *pValue);
    
public: // signals
    CYISignal<> Completed; 
    
protected:
    bool SetCompleted(ResultType *pValue); 
    
private:
    ResultType *m_pResult;
    bool     m_bHasOwnershipOfResult;
};



// Use of array types in CYIFuture objects is not supported.
template <typename ResultType>
class CYIFuture<ResultType[]> : public CYIAbstractFuture
{    
private:
    CYIFuture();
};


#include "YiFuture.inl"

#endif /* _YI_FUTURE_H_ */