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