mirror of
https://github.com/dragonflydb/dragonfly.git
synced 2025-05-11 10:25:47 +02:00
chore(denseset): Simplify DenseSet, remove empty links. (#339)
This commit is contained in:
Roman Gershman
GitHub
parent
7715ee06c6
commit
44f98de128
6 changed files with 287 additions and 235 deletions
|
|
@ -25,6 +25,35 @@ constexpr size_t kMinSizeShift = 2;
|
|||
constexpr size_t kMinSize = 1 << kMinSizeShift;
|
||||
constexpr bool kAllowDisplacements = true;
|
||||
|
||||
DenseSet::IteratorBase::IteratorBase(const DenseSet* owner, ChainVectorIterator begin_list)
|
||||
: owner_(*owner), curr_list_(begin_list) {
|
||||
if (begin_list != owner->entries_.end()) {
|
||||
curr_entry_ = *begin_list;
|
||||
// find the first non null entry
|
||||
if (curr_entry_.IsEmpty()) {
|
||||
Advance();
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
void DenseSet::IteratorBase::Advance() {
|
||||
if (curr_entry_.IsLink()) {
|
||||
curr_entry_ = curr_entry_.AsLink()->next;
|
||||
DCHECK(!curr_entry_.IsEmpty());
|
||||
} else {
|
||||
DCHECK(curr_list_ != owner_.entries_.end());
|
||||
do {
|
||||
++curr_list_;
|
||||
if (curr_list_ == owner_.entries_.end()) {
|
||||
curr_entry_.Reset();
|
||||
return;
|
||||
}
|
||||
} while (curr_list_->IsEmpty());
|
||||
DCHECK(curr_list_ != owner_.entries_.end());
|
||||
curr_entry_ = *curr_list_;
|
||||
}
|
||||
}
|
||||
|
||||
DenseSet::DenseSet(pmr::memory_resource* mr) : entries_(mr) {
|
||||
}
|
||||
|
||||
|
|
@ -36,27 +65,34 @@ size_t DenseSet::PushFront(DenseSet::ChainVectorIterator it, void* data) {
|
|||
// if this is an empty list assign the value to the empty placeholder pointer
|
||||
if (it->IsEmpty()) {
|
||||
it->SetObject(data);
|
||||
return ObjectAllocSize(data);
|
||||
} else {
|
||||
// otherwise make a new link and connect it to the front of the list
|
||||
it->SetLink(NewLink(data, *it));
|
||||
}
|
||||
|
||||
// otherwise make a new link and connect it to the front of the list
|
||||
it->SetLink(NewLink(data, *it));
|
||||
return ObjectAllocSize(data);
|
||||
}
|
||||
|
||||
void DenseSet::PushFront(DenseSet::ChainVectorIterator it, DenseSet::DensePtr ptr) {
|
||||
DVLOG(2) << "PushFront to " << distance(entries_.begin(), it) << ", "
|
||||
<< ObjectAllocSize(ptr.GetObject());
|
||||
|
||||
if (it->IsEmpty()) {
|
||||
it->SetObject(ptr.GetObject());
|
||||
if (ptr.IsLink()) {
|
||||
FreeLink(ptr);
|
||||
FreeLink(ptr.AsLink());
|
||||
}
|
||||
} else if (ptr.IsLink()) {
|
||||
// if the pointer is already a link then no allocation needed
|
||||
// if the pointer is already a link then no allocation needed.
|
||||
*ptr.Next() = *it;
|
||||
*it = ptr;
|
||||
DCHECK(!it->AsLink()->next.IsEmpty());
|
||||
} else {
|
||||
DCHECK(ptr.IsObject());
|
||||
|
||||
// allocate a new link if needed and copy the pointer to the new link
|
||||
it->SetLink(NewLink(ptr.GetObject(), *it));
|
||||
it->SetLink(NewLink(ptr.Raw(), *it));
|
||||
DCHECK(!it->AsLink()->next.IsEmpty());
|
||||
}
|
||||
}
|
||||
|
||||
|
|
@ -73,6 +109,7 @@ auto DenseSet::PopPtrFront(DenseSet::ChainVectorIterator it) -> DensePtr {
|
|||
it->Reset();
|
||||
} else {
|
||||
DCHECK(it->IsLink());
|
||||
|
||||
// since a DenseLinkKey could be at the end of a chain and have a nullptr for next
|
||||
// avoid dereferencing a nullptr and just reset the pointer to this DenseLinkKey
|
||||
if (it->Next() == nullptr) {
|
||||
|
|
@ -90,19 +127,7 @@ void* DenseSet::PopDataFront(DenseSet::ChainVectorIterator it) {
|
|||
void* ret = front.GetObject();
|
||||
|
||||
if (front.IsLink()) {
|
||||
FreeLink(front);
|
||||
}
|
||||
|
||||
return ret;
|
||||
}
|
||||
|
||||
// updates *node with the next item
|
||||
auto DenseSet::Unlink(DenseSet::DensePtr* node) -> DensePtr {
|
||||
DensePtr ret = *node;
|
||||
if (node->IsObject()) {
|
||||
node->Reset();
|
||||
} else {
|
||||
*node = *node->Next();
|
||||
FreeLink(front.AsLink());
|
||||
}
|
||||
|
||||
return ret;
|
||||
|
|
@ -111,19 +136,20 @@ auto DenseSet::Unlink(DenseSet::DensePtr* node) -> DensePtr {
|
|||
void DenseSet::ClearInternal() {
|
||||
for (auto it = entries_.begin(); it != entries_.end(); ++it) {
|
||||
while (!it->IsEmpty()) {
|
||||
PopDataFront(it);
|
||||
void* obj = PopDataFront(it);
|
||||
ObjDelete(obj);
|
||||
}
|
||||
}
|
||||
|
||||
entries_.clear();
|
||||
}
|
||||
|
||||
bool DenseSet::Equal(DensePtr dptr, const void* ptr) const {
|
||||
bool DenseSet::Equal(DensePtr dptr, const void* ptr, uint32_t cookie) const {
|
||||
if (dptr.IsEmpty()) {
|
||||
return false;
|
||||
}
|
||||
|
||||
return ObjEqual(dptr.GetObject(), ptr);
|
||||
return ObjEqual(dptr.GetObject(), ptr, cookie);
|
||||
}
|
||||
|
||||
auto DenseSet::FindEmptyAround(uint32_t bid) -> ChainVectorIterator {
|
||||
|
|
@ -135,12 +161,16 @@ auto DenseSet::FindEmptyAround(uint32_t bid) -> ChainVectorIterator {
|
|||
return entries_.end();
|
||||
}
|
||||
|
||||
if (bid + 1 < entries_.size() && entries_[bid + 1].IsEmpty()) {
|
||||
return entries_.begin() + bid + 1;
|
||||
if (bid + 1 < entries_.size()) {
|
||||
auto it = next(entries_.begin(), bid + 1);
|
||||
if (it->IsEmpty())
|
||||
return it;
|
||||
}
|
||||
|
||||
if (bid && entries_[bid - 1].IsEmpty()) {
|
||||
return entries_.begin() + bid - 1;
|
||||
if (bid) {
|
||||
auto it = next(entries_.begin(), bid - 1);
|
||||
if (it->IsEmpty())
|
||||
return it;
|
||||
}
|
||||
|
||||
return entries_.end();
|
||||
|
|
@ -162,32 +192,70 @@ void DenseSet::Grow() {
|
|||
// perform rehashing of items in the set
|
||||
for (long i = prev_size - 1; i >= 0; --i) {
|
||||
DensePtr* curr = &entries_[i];
|
||||
DensePtr* prev = nullptr;
|
||||
|
||||
// curr != nullptr checks if we have reached the end of a chain
|
||||
// while !curr->IsEmpty() checks that the current chain is not empty
|
||||
while (curr != nullptr && !curr->IsEmpty()) {
|
||||
while (true) {
|
||||
if (curr->IsEmpty())
|
||||
break;
|
||||
void* ptr = curr->GetObject();
|
||||
uint32_t bid = BucketId(ptr);
|
||||
|
||||
DCHECK(ptr != nullptr && ObjectAllocSize(ptr));
|
||||
|
||||
uint32_t bid = BucketId(ptr, 0);
|
||||
|
||||
// if the item does not move from the current chain, ensure
|
||||
// it is not marked as displaced and move to the next item in the chain
|
||||
if (bid == i) {
|
||||
curr->ClearDisplaced();
|
||||
prev = curr;
|
||||
curr = curr->Next();
|
||||
if (curr == nullptr)
|
||||
break;
|
||||
} else {
|
||||
// if the entry is in the wrong chain remove it and
|
||||
// add it to the correct chain. This will also correct
|
||||
// displaced entries
|
||||
DensePtr node = Unlink(curr);
|
||||
PushFront(entries_.begin() + bid, node);
|
||||
entries_[bid].ClearDisplaced();
|
||||
auto dest = entries_.begin() + bid;
|
||||
DensePtr dptr = *curr;
|
||||
|
||||
if (curr->IsObject()) {
|
||||
curr->Reset(); // reset the original placeholder (.next or root)
|
||||
|
||||
if (prev) {
|
||||
DCHECK(prev->IsLink());
|
||||
|
||||
DenseLinkKey* plink = prev->AsLink();
|
||||
DCHECK(&plink->next == curr);
|
||||
|
||||
// we want to make *prev a DensePtr instead of DenseLink and we
|
||||
// want to deallocate the link.
|
||||
DensePtr tmp = DensePtr::From(plink);
|
||||
DCHECK(ObjectAllocSize(tmp.GetObject()));
|
||||
|
||||
FreeLink(plink);
|
||||
*prev = tmp;
|
||||
}
|
||||
|
||||
DVLOG(2) << " Pushing to " << bid << " " << dptr.GetObject();
|
||||
PushFront(dest, dptr);
|
||||
|
||||
dest->ClearDisplaced();
|
||||
|
||||
break;
|
||||
} // if IsObject
|
||||
|
||||
*curr = *dptr.Next();
|
||||
DCHECK(!curr->IsEmpty());
|
||||
|
||||
PushFront(dest, dptr);
|
||||
dest->ClearDisplaced();
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
bool DenseSet::AddInternal(void* ptr) {
|
||||
uint64_t hc = Hash(ptr);
|
||||
uint64_t hc = Hash(ptr, 0);
|
||||
|
||||
if (entries_.empty()) {
|
||||
capacity_log_ = kMinSizeShift;
|
||||
|
|
@ -203,7 +271,7 @@ bool DenseSet::AddInternal(void* ptr) {
|
|||
|
||||
// if the value is already in the set exit early
|
||||
uint32_t bucket_id = BucketId(hc);
|
||||
if (Find(ptr, bucket_id) != nullptr) {
|
||||
if (Find(ptr, bucket_id, 0).second != nullptr) {
|
||||
return false;
|
||||
}
|
||||
|
||||
|
|
@ -265,42 +333,57 @@ bool DenseSet::AddInternal(void* ptr) {
|
|||
return true;
|
||||
}
|
||||
|
||||
auto DenseSet::Find(const void* ptr, uint32_t bid) const -> const DensePtr* {
|
||||
const DensePtr* curr = &entries_[bid];
|
||||
if (Equal(*curr, ptr)) {
|
||||
return curr;
|
||||
}
|
||||
auto DenseSet::Find(const void* ptr, uint32_t bid, uint32_t cookie) -> pair<DensePtr*, DensePtr*> {
|
||||
// could do it with zigzag decoding but this is clearer.
|
||||
int offset[] = {0, -1, 1};
|
||||
|
||||
// first look for displaced nodes since this is quicker than iterating a potential long chain
|
||||
if (bid && Equal(entries_[bid - 1], ptr)) {
|
||||
return &entries_[bid - 1];
|
||||
}
|
||||
for (int j = 0; j < 3; ++j) {
|
||||
if ((bid == 0 && j == 1) || (bid + 1 == entries_.size() && j == 2))
|
||||
continue;
|
||||
|
||||
if (bid + 1 < entries_.size() && Equal(entries_[bid + 1], ptr)) {
|
||||
return &entries_[bid + 1];
|
||||
DensePtr* curr = &entries_[bid + offset[j]];
|
||||
|
||||
if (Equal(*curr, ptr, cookie)) {
|
||||
return make_pair(nullptr, curr);
|
||||
}
|
||||
}
|
||||
|
||||
// if the node is not displaced, search the correct chain
|
||||
curr = curr->Next();
|
||||
DensePtr* prev = &entries_[bid];
|
||||
DensePtr* curr = prev->Next();
|
||||
while (curr != nullptr) {
|
||||
if (Equal(*curr, ptr)) {
|
||||
return curr;
|
||||
if (Equal(*curr, ptr, cookie)) {
|
||||
return make_pair(prev, curr);
|
||||
}
|
||||
|
||||
prev = curr;
|
||||
curr = curr->Next();
|
||||
}
|
||||
|
||||
// not in the Set
|
||||
return nullptr;
|
||||
return make_pair(nullptr, nullptr);
|
||||
}
|
||||
|
||||
void* DenseSet::Delete(DensePtr* ptr) {
|
||||
void* DenseSet::Delete(DensePtr* prev, DensePtr* ptr) {
|
||||
void* ret = nullptr;
|
||||
|
||||
if (ptr->IsObject()) {
|
||||
ret = ptr->Raw();
|
||||
ptr->Reset();
|
||||
--num_used_buckets_;
|
||||
if (prev == nullptr) {
|
||||
--num_used_buckets_;
|
||||
} else {
|
||||
DCHECK(prev->IsLink());
|
||||
|
||||
--num_chain_entries_;
|
||||
DenseLinkKey* plink = prev->AsLink();
|
||||
DensePtr tmp = DensePtr::From(plink);
|
||||
DCHECK(ObjectAllocSize(tmp.GetObject()));
|
||||
|
||||
FreeLink(plink);
|
||||
*prev = tmp;
|
||||
DCHECK(!prev->IsLink());
|
||||
}
|
||||
} else {
|
||||
DCHECK(ptr->IsLink());
|
||||
|
||||
|
|
@ -308,7 +391,7 @@ void* DenseSet::Delete(DensePtr* ptr) {
|
|||
ret = link->Raw();
|
||||
*ptr = link->next;
|
||||
--num_chain_entries_;
|
||||
mr()->deallocate(link, sizeof(DenseLinkKey), alignof(DenseLinkKey));
|
||||
FreeLink(link);
|
||||
}
|
||||
|
||||
obj_malloc_used_ -= ObjectAllocSize(ret);
|
||||
|
|
@ -373,7 +456,7 @@ uint32_t DenseSet::Scan(uint32_t cursor, const ItemCb& cb) const {
|
|||
++entries_idx;
|
||||
}
|
||||
|
||||
if (entries_idx >= entries_.size()) {
|
||||
if (entries_idx == entries_.size()) {
|
||||
return 0;
|
||||
}
|
||||
|
||||
|
|
|
|||
Loading…
Add table
Add a link
Reference in a new issue