Function TRA_get_inventory

src/jrd/tra.cpp:650–709

void TRA_get_inventory(thread_db* tdbb, UCHAR* bit_vector, TraNumber base, TraNumber top)
{
/**************************************
 *
 *	T R A _ g e t _ i n v e n t o r y
 *
 **************************************
 *
 * Functional description
 *	Get an inventory of the state of all transactions
 *	between the base and top (included) transactions passed.
 *	To get a consistent view of the transaction
 *	inventory (in case we ever implement sub-transactions),
 *	do handoffs to read the pages in order.
 *
 **************************************/
	SET_TDBB(tdbb);
	Database* dbb = tdbb->getDatabase();
	CHECK_DBB(dbb);

	// It does not make sence to call this function without bit_vector now
	fb_assert(bit_vector);

	const ULONG trans_per_tip = dbb->dbb_page_manager.transPerTIP;
	ULONG sequence = base / trans_per_tip;
	const ULONG last = top / trans_per_tip;

	// fetch the first inventory page

	WIN window(DB_PAGE_SPACE, -1);
	const tx_inv_page* tip = fetch_inventory_page(tdbb, &window, sequence++, LCK_read);

	// move the first page into the bit vector

	UCHAR* p = bit_vector;
	ULONG l = base % trans_per_tip;
	const UCHAR* q = tip->tip_transactions + TRANS_OFFSET(l);
	l = TRANS_OFFSET(MIN((top + TRA_MASK + 1 - base), trans_per_tip - l));
	memcpy(p, q, l);
	p += l;

	// move successive pages into the bit vector

	while (sequence <= last)
	{
		base = (TraNumber) sequence * trans_per_tip;

		// release the read lock as we go, so that some one else can
		// commit without having to signal all other transactions.

		tip = (tx_inv_page*) CCH_HANDOFF(tdbb, &window, inventory_page(tdbb, sequence++),
							  LCK_read, pag_transactions);

		l = TRANS_OFFSET(MIN((top + TRA_MASK + 1 - base), trans_per_tip));
		memcpy(p, tip->tip_transactions, l);
		p += l;
	}