core/sql/refresh/RuEmpCheck.h

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#ifndef _RU_EMP_CHECK_H_
#define _RU_EMP_CHECK_H_

/* -*-C++-*-
******************************************************************************
*
* File:         RuEmpCheck.h
* Description:  Definition of class CRUEmpCheck
*
*
* Created:      10/15/2000
* Language:     C++
*
*
******************************************************************************
*/

#include "refresh.h"
#include "dsstring.h"

#include "RuEmpCheckVector.h"

class CRUSQLDynamicStatementContainer;
class CRUTbl;
class CUOFsIpcMessageTranslator;

//--------------------------------------------------------------------------//
//	CRUEmpCheck
//
//	This class implements the delta emptiness check algorithm, which checks 
//	whether the table-delta	is empty starting from epoch1, epoch2, ...
//
//	Emptiness check is required by various task	executors: 
//	EmpCheckTask, MultiTxn Refresh, LogCleanup.
//
//	The algorithm must take into account that the logging of ranges 
//	and single-row records is separated into negative and positive
//	epochs, and apply different queries, respectively.
//
//	The emptiness check's results are recorded in an emptiness check vector, 
//	which is constructed outside the class, in accordance with the algorithm's
//	client's requirements. The class initializes a *local* vector based 
//	on the epochs in the external one, and populates it by the check's result.
//	Local storage makes the class transportable between processes.
//
//--------------------------------------------------------------------------//

class REFRESH_LIB_CLASS CRUEmpCheck {

public:
	CRUEmpCheck();
	CRUEmpCheck(CRUEmpCheckVector &vec);
	virtual ~CRUEmpCheck();

public:
	const CRUEmpCheckVector &GetVector() const
	{
		return *pVec_;
	}

public:
	// If upperBound=0, the WHERE predicate
	// does not limit the epoch from above.
	void ComposeSQL(CRUTbl &tbl, TInt32 upperBound=0);

	void PrepareSQL();

	void PerformCheck();

public:
	// IPC pack/unpack
	void LoadData(CUOFsIpcMessageTranslator &translator);
	void StoreData(CUOFsIpcMessageTranslator &translator);

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

private:
	enum StmtType {

		CHECK_NEG_EPOCHS         = 0,	// Range records
		CHECK_POS_EPOCHS_INSERTS = 1,	// Single-row insert records
		CHECK_POS_EPOCHS_DELETES = 2,	// Single row delete and update records

		NUM_STMTS
	};

	void ComposeSelectStmt(
		CRUTbl &tbl, CDSString &to, 
		StmtType stmtType, TInt32 upperBound);

	void PerformSingleCheck(
		CRUEmpCheckVector::Elem &elem,
		CRUTbl::IUDLogContentType ct,
		StmtType stmtType);

private:
	CRUEmpCheckVector *pVec_;

	CRUSQLDynamicStatementContainer *pSQLContainer_;

	// Which checks to perform?
	Lng32 checkMask_;
};

#endif