Function memory_init

src/jrd/cch.cpp:4222–4353

static ULONG memory_init(thread_db* tdbb, BufferControl* bcb, ULONG number)
{
/**************************************
 *
 *	m e m o r y _ i n i t
 *
 **************************************
 *
 * Functional description
 *	Initialize memory for the cache.
 *	Return number of buffers allocated.
 *
 **************************************/
	SET_TDBB(tdbb);
	Database* const dbb = tdbb->getDatabase();

	ULONG buffers = 0;
	const size_t page_size = dbb->dbb_page_size;
	UCHAR* memory = nullptr;
	UCHAR* lock_memory = nullptr;
	const UCHAR* memory_end = nullptr;
	BufferDesc* tail = nullptr;

	const size_t lock_key_extra = PageNumber::getLockLen() > Lock::KEY_STATIC_SIZE ?
		PageNumber::getLockLen() - Lock::KEY_STATIC_SIZE : 0;

	const size_t lock_size = (bcb->bcb_flags & BCB_exclusive) ? 0 :
		FB_ALIGN(sizeof(Lock) + lock_key_extra, alignof(Lock));

	while (number)
	{
		if (!memory)
		{
			// Allocate memory block big enough to accomodate BufferDesc's, Lock's and page buffers.

			ULONG to_alloc = number;

			while (true)
			{
				const size_t memory_size = (sizeof(BufferDesc) + lock_size + page_size) * (to_alloc + 1);

				fb_assert(memory_size > 0);
				if (memory_size < MIN_BUFFER_SEGMENT)
				{
					// Diminishing returns
					return buffers;
				}

				try
				{
					memory = (UCHAR*) bcb->bcb_bufferpool->allocate(memory_size ALLOC_ARGS);
					memory_end = memory + memory_size;
					break;
				}
				catch (Firebird::BadAlloc&)
				{
					// Either there's not enough virtual memory or there is
					// but it's not virtually contiguous. Let's find out by