Method compact

src/jrd/trace/TraceConfigStorage.cpp:462–561

void ConfigStorage::compact()
{
	SlotsByOffsetArray data(*getDefaultMemoryPool());

	TraceCSHeader* header = m_sharedMemory->getHeader();

	const ULONG pid = getpid();

	ULONG check_used, check_size;
	check_used = check_size = sizeof(TraceCSHeader);

	// Track undeleted slots from dead processes
	Firebird::SortedArray<ULONG, InlineStorage<ULONG, 16>> deadProcesses;

	// collect used slots, sort them by offset
	for (TraceCSHeader::Slot* slot = header->slots; slot < header->slots + header->slots_cnt; slot++)
	{
		if (slot->used && slot->ses_pid != pid &&
			((slot->ses_flags & trs_system) == 0) && // System sessions are shared for multiple connections so they may live without the original process
			!ISC_check_process_existence(slot->ses_pid))
		{
			// A SUPER server may shut down, but its Storage shared memory continues to live due to an embedded user session.
			// The process might allocate multiple slots, so count them carefully.
			deadProcesses.add(slot->ses_pid);

			markDeleted(slot);
		}

		SlotByOffset item;
		item.index = slot - header->slots;
		item.offset = slot->offset;

		check_used += slot->used;
		check_size += slot->size;
		data.add(item);
	}

	// Process that created storages disappeared, count it out
	fb_assert(header->cnt_uses > deadProcesses.getCount());
	header->cnt_uses -= deadProcesses.getCount();
	deadProcesses.clear();

	fb_assert(check_used == header->mem_used);
	fb_assert(check_size == header->mem_offset);

	// remove unused space between sessions data
	ULONG destOffset = sizeof(TraceCSHeader);
	for (SlotByOffset* item = data.begin(); item < data.end(); item++)
	{
		TraceCSHeader::Slot* slot = header->slots + item->index;
		if (slot->used == 0)
		{
			slot->size = 0;
			continue;
		}

		fb_assert(slot->offset >= destOffset);