greenplumn CSyncList 源码
greenplumn CSyncList 代码
文件路径：/src/backend/gporca/libgpos/include/gpos/common/CSyncList.h
//---------------------------------------------------------------------------
// Greenplum Database
// Copyright (C) 2011 EMC Corp.
//
// @filename:
// CSyncList.h
//
// @doc:
// Template-based synchronized list class - no longer thread-safe
//
// It requires that the elements are only inserted once, as their address
// is used for identification;
//
// In order to be useful for system programming the class must be
// allocation-less, i.e. manage elements without additional allocation,
// to work in exception or OOM situations;
//---------------------------------------------------------------------------
#ifndef GPOS_CSyncList_H
#define GPOS_CSyncList_H
#include "gpos/common/CList.h"
#include "gpos/types.h"
namespace gpos
{
//---------------------------------------------------------------------------
// @class:
// CSyncList<class T>
//
// @doc:
// Allocation-less list class; requires T to have a pointer to T embedded
// and N being the offset of this member;
//
//---------------------------------------------------------------------------
template <class T>
class CSyncList
{
private:
// underlying list
CList<T> m_list;
public:
CSyncList(const CSyncList &) = delete;
// ctor
CSyncList() = default;
// dtor
~CSyncList() = default;
// init function to facilitate arrays
void
Init(ULONG offset)
{
m_list.Init(offset);
}
// insert element at the head of the list;
void
Push(T *elem)
{
m_list.Prepend(elem);
}
// remove element from the head of the list;
T *
Pop()
{
if (!m_list.IsEmpty())
{
return m_list.RemoveHead();
}
return nullptr;
}
// get first element
T *
PtFirst() const
{
return m_list.First();
}
// get next element
T *
Next(T *elem) const
{
return m_list.Next(elem);
}
// check if list is empty
BOOL
IsEmpty() const
{
return NULL == m_list.First();
}
#ifdef GPOS_DEBUG
// lookup a given element in the stack
// this works only when no elements are removed
GPOS_RESULT
Find(T *elem) const
{
return m_list.Find(elem);
}
// debug print of element addresses
// this works only when no elements are removed
IOstream &
OsPrint(IOstream &os) const
{
return m_list.OsPrint(os);
}
#endif // GPOS_DEBUG
}; // class CSyncList
} // namespace gpos
#endif // !GPOS_CSyncList_H
// EOF
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