Record SPSegment::inPlaceLookup(TID tid) {
// TODO assert(tid.getPage() is part of this segment);
BufferFrame frame = bm->fixPage(tid.getPage(), false);
SlottedPage* page = reinterpret_cast<SlottedPage*>(frame.getData());
Slot* slot = page->getSlot(tid.getSlot());
if (slot->isMoved() || slot->isEmpty()) {
// Slot is empty: Return empty record
bm->unfixPage(frame, false);
return Record(0, nullptr);
} else {
// Slot has content: Return record with content.
bm->unfixPage(frame, false);
return Record(slot->length(), slot->getRecord()->getData());
}
}
bool SPSegment::update(TID tid, const Record& r){
Record r_old = this->lookup(tid);
unsigned len_old = r_old.getLen();
unsigned len_new = r.getLen();
BufferFrame frame = bm->fixPage(tid.getPage(), true);
SlottedPage* page = reinterpret_cast<SlottedPage*>(frame.getData());
if(len_old == len_new){
// If size doesn't change, use memcpy
memcpy(page->getSlot(tid.getSlot())->getRecord(), &r, r.getLen());
} else if(len_old > len_new){
// Record has become smaller
memcpy(page->getSlot(tid.getSlot())->getRecord(), &r, r.getLen());
// TODO Update freeSpace of page
// TODO update FSI
} else {
// Record has become larger
unsigned freeSpaceOnPage = page->remove(tid.getSlot());
this->fsi[tid.getPage()] = freeSpaceOnPage;
if (freeSpaceOnPage >= len_new) {
// It fits on the page after removal
page->insert(r);
} else {
// Even after removal it is too large
// Get another page
uint64_t sndPageId = this->lastPage + 1;
for (auto it = this->fsi.rbegin(); it != this->fsi.rend(); it++) {
if (it->second >= r.getLen()) {
sndPageId = it->first;
break;
}
}
BufferFrame sndFrame = bm->fixPage(sndPageId, true);
// Create a new SlottedPage if necessary
SlottedPage* sndPage = reinterpret_cast<SlottedPage*>(sndFrame.getData());
if (sndPageId > this->lastPage) {
*sndPage = SlottedPage();
this->lastPage++;
if (lastPage > 1l << 48) throw "Max page number reached.";
}
Slot* fstSlot = page->getSlot(tid.getSlot());
assert(fstSlot->isEmpty());
// Insert into new page
unsigned sndSlotNum = sndPage->insert(r);
this->fsi[sndPageId] -= r.getLen() + (sndSlotNum == sndPage->getMaxSlot() ? sizeof(Slot) : 0);
// Update first slot to directo to second page.
*fstSlot = Slot(TID(sndPageId, sndSlotNum));
bm->unfixPage(sndFrame, true);
}
}
bm->unfixPage(frame, true);
return true;
}