Function prefetch_io

src/jrd/cch.cpp:4485–4526

static void prefetch_io(Prefetch* prefetch, FbStatusVector* status_vector)
{
/**************************************
 *
 *	p r e f e t c h _ i o
 *
 **************************************
 *
 * Functional description
 *	Queue an asynchronous I/O to read
 *	multiple pages into prefetch buffer.
 *
 **************************************/
	thread_db* tdbb = prefetch->prf_tdbb;
	Database* dbb = tdbb->getDatabase();

	if (!prefetch->prf_page_count)
		prefetch->prf_flags &= ~PRF_active;
	else
	{
		// Get the cache reader working on our behalf too

		if (!(dbb->dbb_bcb->bcb_flags & BCB_reader_active))
			dbb->dbb_reader_sem.post();

		const bool async_status =
			PIO_read_ahead(dbb, prefetch->prf_start_page, prefetch->prf_io_buffer,
						   prefetch->prf_page_count, &prefetch->prf_piob, status_vector);
		if (!async_status)
		{
			BufferDesc** next_bdb = prefetch->prf_bdbs;
			for (USHORT i = 0; i < prefetch->prf_max_prefetch; i++)
			{
				if (*next_bdb)
					release_bdb(tdbb, *next_bdb, true, false, false);

				next_bdb++;
			}
			prefetch->prf_flags &= ~PRF_active;
		}
	}
}


static void prefetch_prologue(Prefetch* prefetch, SLONG* start_page)