Class BCBHashTable

src/jrd/cch.cpp:241–283

class BCBHashTable
{
#ifdef HASH_USE_CDS_LIST
	using chain_type = BdbList;
#else
	using chain_type = que;
#endif

public:
	BCBHashTable(MemoryPool& pool, ULONG count) :
		m_pool(pool),
		m_count(0),
		m_chains(nullptr)
	{
		resize(count);
	}

	~BCBHashTable()
	{
		clear();
	}

	void resize(ULONG count);
	void clear();

	BufferDesc* find(const PageNumber& page) const;

	// tries to put bdb into hash slot by page
	// if succeed, removes bdb from old slot, if necessary, and returns NULL
	// else, returns BufferDesc that is currently occupies target slot
	BufferDesc* emplace(BufferDesc* bdb, const PageNumber& page, bool remove);

	void remove(BufferDesc* bdb);
private:
	ULONG hash(const PageNumber& pageno) const
	{
		return pageno.getPageNum() % m_count;
	}

	MemoryPool& m_pool;
	ULONG m_count;
	chain_type* m_chains;
};

}