greenplumn CSyncHashtableAccessorBase 源码

greenplumn CSyncHashtableAccessorBase 代码

文件路径：/src/backend/gporca/libgpos/include/gpos/common/CSyncHashtableAccessorBase.h

//---------------------------------------------------------------------------
//	Greenplum Database
//	Copyright (C) 2011 EMC Corp.
//
//	@filename:
//		CSyncHashtableAccessorBase.h
//
//	@doc:
//		Base hashtable accessor class; provides primitives to operate
//		on a target bucket in the hashtable.
//
//---------------------------------------------------------------------------
#ifndef GPOS_CSyncHashtableAccessorBase_H_
#define GPOS_CSyncHashtableAccessorBase_H_

#include "gpos/base.h"
#include "gpos/common/CSyncHashtable.h"
#include "gpos/common/CSyncHashtableIter.h"


namespace gpos
{
//---------------------------------------------------------------------------
//	@class:
//		CSyncHashtableAccessorBase<T, K, S>
//
//	@doc:
//		Accessor class to encapsulate locking of a hashtable bucket;
//		has to know all template parameters of the hashtable class in order
//		to link to the target hashtable; see file doc for more details on the
//		rationale behind this class
//
//---------------------------------------------------------------------------
template <class T, class K>
class CSyncHashtableAccessorBase : public CStackObject
{
private:
	// shorthand for buckets
	using SBucket = typename gpos::CSyncHashtable<T, K>::SBucket;

	// target hashtable
	CSyncHashtable<T, K> &m_ht;

	// bucket to operate on
	SBucket &m_bucket;

protected:
	// ctor - protected to restrict instantiation to children
	CSyncHashtableAccessorBase<T, K>(CSyncHashtable<T, K> &ht, ULONG bucket_idx)
		: m_ht(ht), m_bucket(m_ht.GetBucket(bucket_idx))
	{
	}

	// dtor
	virtual ~CSyncHashtableAccessorBase<T, K>() = default;

	// accessor to hashtable
	CSyncHashtable<T, K> &
	GetHashTable() const
	{
		return m_ht;
	}

	// accessor to maintained bucket
	SBucket &
	GetBucket() const
	{
		return m_bucket;
	}

	// returns the first element in the hash chain
	T *
	First() const
	{
		return m_bucket.m_chain.First();
	}

	// finds the element next to the given one
	T *
	Next(T *value) const
	{
		GPOS_ASSERT(nullptr != value);

		// make sure element is in this hash chain
		GPOS_ASSERT(GPOS_OK == m_bucket.m_chain.Find(value));

		return m_bucket.m_chain.Next(value);
	}

	// inserts element at the head of hash chain
	void
	Prepend(T *value)
	{
		GPOS_ASSERT(nullptr != value);

		m_bucket.m_chain.Prepend(value);

		// increase number of entries
		m_ht.m_size++;
	}

	// adds first element before second element
	void
	Prepend(T *value, T *ptNext)
	{
		GPOS_ASSERT(nullptr != value);

		// make sure element is in this hash chain
		GPOS_ASSERT(GPOS_OK == m_bucket.m_chain.Find(ptNext));

		m_bucket.m_chain.Prepend(value, ptNext);

		// increase number of entries
		m_ht.m_size++;
	}

	// adds first element after second element
	void
	Append(T *value, T *ptPrev)
	{
		GPOS_ASSERT(nullptr != value);

		// make sure element is in this hash chain
		GPOS_ASSERT(GPOS_OK == m_bucket.m_chain.Find(ptPrev));

		m_bucket.m_chain.Append(value, ptPrev);

		// increase number of entries
		m_ht.m_size++;
	}

public:
	CSyncHashtableAccessorBase<T, K>(const CSyncHashtableAccessorBase<T, K> &) =
		delete;

	// unlinks element
	void
	Remove(T *value)
	{
		// not NULL and is-list-member checks are done in CList
		m_bucket.m_chain.Remove(value);

		// decrease number of entries
		m_ht.m_size--;
	}

};	// class CSyncHashtableAccessorBase

}  // namespace gpos

#endif	// GPOS_CSyncHashtableAccessorBase_H_

// EOF

相关信息

greenplumn 源码目录

相关文章

greenplumn CAutoP 源码

greenplumn CAutoRef 源码

greenplumn CAutoRg 源码

greenplumn CAutoTimer 源码

greenplumn CBitSet 源码

greenplumn CBitSetIter 源码

greenplumn CBitVector 源码

greenplumn CDebugCounter 源码

greenplumn CDouble 源码

greenplumn CDynamicPtrArray 源码