core/sql/refresh/RuEmpCheckTask.h

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#ifndef _RU_EMP_CHECK_TASK_H_
#define _RU_EMP_CHECK_TASK_H_

/* -*-C++-*-
******************************************************************************
*
* File:         RuEmpCheckTask.h
* Description:  Definition of class CRUEmpCheckTask.
*
*
* Created:      04/06/2000
* Language:     C++
*
*
******************************************************************************
*/

#include "refresh.h"

#include "RuLogProcessingTask.h"

//--------------------------------------------------------------------------//
//	CRUEmpCheckTask
//	
//	The EmpCheck task (works on a single table) checks whether the delta(s) 
//	of the table towards the using MV(s) are empty. The emptiness check's 
//	results are recorded in the *emptiness check vector*. For each MV on T,
//	the vector's element V[MV.EPOCH[T]] contains two flags (a bitmap):
//	(1) Are there single-row records in the log starting from epoch MV.EPOCH[T]?
//	(2) Are there range records in the log starting from epoch MV.EPOCH[T]?
//
//	The task's executor applies the EmpCheck algorithm as a generic unit.
//
//--------------------------------------------------------------------------//

class REFRESH_LIB_CLASS CRUEmpCheckTask : public CRULogProcessingTask {

private:
	typedef CRULogProcessingTask inherited;

	//---------------------------------------//
	//	PUBLIC AREA
	//---------------------------------------//
public:
	CRUEmpCheckTask(Lng32 id, CRUTbl &table);
	virtual ~CRUEmpCheckTask();

	//-----------------------------------//
	// Accessors
	//-----------------------------------//
public:
	//-- Implementation of pure virtuals
	virtual CRUTask::Type GetType() const 
	{ 
		return CRUTask::EMP_CHECK; 
	}

	//---------------------------------------//
	//	PRIVATE AND PROTECTED AREA
	//---------------------------------------//
protected:
	
	virtual CDSString GetTaskName() const;

	// Refinement of the parent's method
	virtual void PullDataFromExecutor();

	// Create the concrete task executor
	virtual CRUTaskExecutor *CreateExecutorInstance();

	virtual TInt32 GetComputedCost() const
	{
		return 0;
	}

	virtual BOOL IsImmediate() const
	{
		return FALSE;
	}

private:
	//-- Prevent copying
	CRUEmpCheckTask(const CRUEmpCheckTask &other);
	CRUEmpCheckTask& operator= (const CRUEmpCheckTask &other);
};

#endif