greenplumn CSearchStage 代码
文件路径：/src/backend/gporca/libgpopt/include/gpopt/search/CSearchStage.h
/---------------------------------------------------------------------------
/ Greenplum Database
/ Copyright (C) 2012 EMC Corp.
/
/ @filename:
/ CSearchStage.h
/
/ @doc:
/ Search stage
/---------------------------------------------------------------------------
#ifndef GPOPT_CSearchStage_H
#define GPOPT_CSearchStage_H
#include "gpos/base.h"
#include "gpos/common/CDynamicPtrArray.h"
#include "gpos/common/CTimerUser.h"
#include "gpopt/xforms/CXform.h"
namespace gpopt
{
using namespace gpos;
/ forward declarations
class CSearchStage;
class CExpression;
/ definition of array of search stages
using CSearchStageArray = CDynamicPtrArray<CSearchStage, CleanupDelete>;
/---------------------------------------------------------------------------
/ @class:
/ CSearchStage
/
/ @doc:
/ Search stage
/
/---------------------------------------------------------------------------
class CSearchStage : public DbgPrintMixin<CSearchStage>
{
private:
/ set of xforms to be applied during stage
CXformSet *m_xforms;
/ time threshold in milliseconds
ULONG m_time_threshold;
/ cost threshold
CCost m_cost_threshold;
/ best plan found at the end of search stage
CExpression *m_pexprBest;
/ cost of best plan found
CCost m_costBest;
/ elapsed time
CTimerUser m_timer;
public:
/ ctor
CSearchStage(CXformSet *xform_set, ULONG ulTimeThreshold = gpos::ulong_max,
CCost costThreshold = CCost(0.0));
/ dtor
virtual ~CSearchStage();
/ restart timer if time threshold is not default indicating don't timeout
/ Restart() is a costly method, so avoid calling unnecessarily
void
RestartTimer()
{
if (m_time_threshold != gpos::ulong_max)
{
m_timer.Restart();
}
}
/ is search stage timed-out?
/ if threshold is gpos::ulong_max, its the default and we need not time out
/ ElapsedMS() is a costly method, so avoid calling unnecesarily
BOOL
FTimedOut() const
{
if (m_time_threshold == gpos::ulong_max)
{
return false;
}
return m_timer.ElapsedMS() > m_time_threshold;
}
/ return elapsed time (in millseconds) since timer was last restarted
ULONG
UlElapsedTime() const
{
return m_timer.ElapsedMS();
}
BOOL
FAchievedReqdCost() const
{
return (nullptr != m_pexprBest && m_costBest <= m_cost_threshold);
}
/ xforms set accessor
CXformSet *
GetXformSet() const
{
return m_xforms;
}
/ time threshold accessor
ULONG
TimeThreshold() const
{
return m_time_threshold;
}
/ cost threshold accessor
CCost
CostThreshold() const
{
return m_cost_threshold;
}
/ set best plan found at the end of search stage
void SetBestExpr(CExpression *pexpr);
/ best plan found accessor
CExpression *
PexprBest() const
{
return m_pexprBest;
}
/ best plan cost accessor
CCost
CostBest() const
{
return m_costBest;
}
/ print function
IOstream &OsPrint(IOstream &) const;
/ generate default search strategy
static CSearchStageArray *PdrgpssDefault(CMemoryPool *mp);
};
/ shorthand for printing
inline IOstream &
operator<<(IOstream &os, CSearchStage &ss)
{
return ss.OsPrint(os);
}
} / namespace gpopt
#endif / !GPOPT_CSearchStage_H
/ EOF
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