bb5dcea98e
Summary: We want to sample the file I/O issued by RocksDB and report the function calls. This requires us to include the file paths otherwise it's hard to tell what has been going on. Pull Request resolved: https://github.com/facebook/rocksdb/pull/4039 Differential Revision: D8670178 Pulled By: riversand963 fbshipit-source-id: 97ee806d1c583a2983e28e213ee764dc6ac28f7a
623 lines
21 KiB
C++
623 lines
21 KiB
C++
// Copyright (c) 2016-present, Facebook, Inc. All rights reserved.
|
|
// This source code is licensed under both the GPLv2 (found in the
|
|
// COPYING file in the root directory) and Apache 2.0 License
|
|
// (found in the LICENSE.Apache file in the root directory).
|
|
|
|
#include "db/range_del_aggregator.h"
|
|
#include "util/heap.h"
|
|
|
|
#include <algorithm>
|
|
|
|
namespace rocksdb {
|
|
|
|
struct TombstoneStartKeyComparator {
|
|
TombstoneStartKeyComparator(const Comparator* c) : cmp(c) {}
|
|
|
|
bool operator()(const RangeTombstone& a, const RangeTombstone& b) const {
|
|
return cmp->Compare(a.start_key_, b.start_key_) < 0;
|
|
}
|
|
|
|
const Comparator* cmp;
|
|
};
|
|
|
|
// An UncollapsedRangeDelMap is quick to create but slow to answer ShouldDelete
|
|
// queries.
|
|
class UncollapsedRangeDelMap : public RangeDelMap {
|
|
typedef std::multiset<RangeTombstone, TombstoneStartKeyComparator> Rep;
|
|
|
|
class Iterator : public RangeDelIterator {
|
|
const Rep& rep_;
|
|
Rep::const_iterator iter_;
|
|
|
|
public:
|
|
Iterator(const Rep& rep) : rep_(rep), iter_(rep.begin()) {}
|
|
bool Valid() const override { return iter_ != rep_.end(); }
|
|
void Next() override { iter_++; }
|
|
|
|
void Seek(const Slice&) override {
|
|
fprintf(stderr, "UncollapsedRangeDelMap::Iterator::Seek unimplemented\n");
|
|
abort();
|
|
}
|
|
|
|
RangeTombstone Tombstone() const override { return *iter_; }
|
|
};
|
|
|
|
Rep rep_;
|
|
const Comparator* ucmp_;
|
|
|
|
public:
|
|
UncollapsedRangeDelMap(const Comparator* ucmp)
|
|
: rep_(TombstoneStartKeyComparator(ucmp)), ucmp_(ucmp) {}
|
|
|
|
bool ShouldDelete(const ParsedInternalKey& parsed,
|
|
RangeDelPositioningMode mode) override {
|
|
(void)mode;
|
|
assert(mode == RangeDelPositioningMode::kFullScan);
|
|
for (const auto& tombstone : rep_) {
|
|
if (ucmp_->Compare(parsed.user_key, tombstone.start_key_) < 0) {
|
|
break;
|
|
}
|
|
if (parsed.sequence < tombstone.seq_ &&
|
|
ucmp_->Compare(parsed.user_key, tombstone.end_key_) < 0) {
|
|
return true;
|
|
}
|
|
}
|
|
return false;
|
|
}
|
|
|
|
bool IsRangeOverlapped(const Slice& start, const Slice& end) override {
|
|
for (const auto& tombstone : rep_) {
|
|
if (ucmp_->Compare(start, tombstone.end_key_) < 0 &&
|
|
ucmp_->Compare(tombstone.start_key_, end) <= 0 &&
|
|
ucmp_->Compare(tombstone.start_key_, tombstone.end_key_) < 0) {
|
|
return true;
|
|
}
|
|
}
|
|
return false;
|
|
}
|
|
|
|
void AddTombstone(RangeTombstone tombstone) override {
|
|
rep_.emplace(tombstone);
|
|
}
|
|
|
|
size_t Size() const override { return rep_.size(); }
|
|
|
|
void InvalidatePosition() override {} // no-op
|
|
|
|
std::unique_ptr<RangeDelIterator> NewIterator() override {
|
|
return std::unique_ptr<RangeDelIterator>(new Iterator(this->rep_));
|
|
}
|
|
};
|
|
|
|
// A CollapsedRangeDelMap is slow to create but quick to answer ShouldDelete
|
|
// queries.
|
|
//
|
|
// An explanation of the design follows. Suppose we have tombstones [b, n) @ 1,
|
|
// [e, h) @ 2, [q, t) @ 2, and [g, k) @ 3. Visually, the tombstones look like
|
|
// this:
|
|
//
|
|
// 3: g---k
|
|
// 2: e---h q--t
|
|
// 1: b------------n
|
|
//
|
|
// The CollapsedRangeDelMap representation is based on the observation that
|
|
// wherever tombstones overlap, we need only store the tombstone with the
|
|
// largest seqno. From the perspective of a read at seqno 4 or greater, this set
|
|
// of tombstones is exactly equivalent:
|
|
//
|
|
// 3: g---k
|
|
// 2: e--g q--t
|
|
// 1: b--e k--n
|
|
//
|
|
// Because these tombstones do not overlap, they can be efficiently represented
|
|
// in an ordered map from keys to sequence numbers. Each entry should be thought
|
|
// of as a transition from one tombstone to the next. In this example, the
|
|
// CollapsedRangeDelMap would store the following entries, in order:
|
|
//
|
|
// b → 1, e → 2, g → 3, k → 1, n → 0, q → 2, t → 0
|
|
//
|
|
// If a tombstone ends before the next tombstone begins, a sentinel seqno of 0
|
|
// is installed to indicate that no tombstone exists. This occurs at keys n and
|
|
// t in the example above.
|
|
//
|
|
// To check whether a key K is covered by a tombstone, the map is binary
|
|
// searched for the last key less than K. K is covered iff the map entry has a
|
|
// larger seqno than K. As an example, consider the key h @ 4. It would be
|
|
// compared against the map entry g → 3 and determined to be uncovered. By
|
|
// contrast, the key h @ 2 would be determined to be covered.
|
|
class CollapsedRangeDelMap : public RangeDelMap {
|
|
typedef std::map<Slice, SequenceNumber, stl_wrappers::LessOfComparator> Rep;
|
|
|
|
class Iterator : public RangeDelIterator {
|
|
void MaybeSeekPastSentinel() {
|
|
if (Valid() && iter_->second == 0) {
|
|
iter_++;
|
|
}
|
|
}
|
|
|
|
const Rep& rep_;
|
|
Rep::const_iterator iter_;
|
|
|
|
public:
|
|
Iterator(const Rep& rep) : rep_(rep), iter_(rep.begin()) {}
|
|
|
|
bool Valid() const override { return iter_ != rep_.end(); }
|
|
|
|
void Next() override {
|
|
iter_++;
|
|
MaybeSeekPastSentinel();
|
|
}
|
|
|
|
void Seek(const Slice& target) override {
|
|
iter_ = rep_.upper_bound(target);
|
|
if (iter_ != rep_.begin()) {
|
|
iter_--;
|
|
}
|
|
MaybeSeekPastSentinel();
|
|
}
|
|
|
|
RangeTombstone Tombstone() const override {
|
|
assert(Valid());
|
|
assert(std::next(iter_) != rep_.end());
|
|
assert(iter_->second != 0);
|
|
RangeTombstone tombstone;
|
|
tombstone.start_key_ = iter_->first;
|
|
tombstone.end_key_ = std::next(iter_)->first;
|
|
tombstone.seq_ = iter_->second;
|
|
return tombstone;
|
|
}
|
|
};
|
|
|
|
Rep rep_;
|
|
Rep::iterator iter_;
|
|
const Comparator* ucmp_;
|
|
|
|
public:
|
|
CollapsedRangeDelMap(const Comparator* ucmp) : ucmp_(ucmp) {
|
|
InvalidatePosition();
|
|
}
|
|
|
|
bool ShouldDelete(const ParsedInternalKey& parsed,
|
|
RangeDelPositioningMode mode) override {
|
|
if (iter_ == rep_.end() &&
|
|
(mode == RangeDelPositioningMode::kForwardTraversal ||
|
|
mode == RangeDelPositioningMode::kBackwardTraversal)) {
|
|
// invalid (e.g., if AddTombstones() changed the deletions), so need to
|
|
// reseek
|
|
mode = RangeDelPositioningMode::kBinarySearch;
|
|
}
|
|
switch (mode) {
|
|
case RangeDelPositioningMode::kFullScan:
|
|
assert(false);
|
|
case RangeDelPositioningMode::kForwardTraversal:
|
|
assert(iter_ != rep_.end());
|
|
if (iter_ == rep_.begin() &&
|
|
ucmp_->Compare(parsed.user_key, iter_->first) < 0) {
|
|
// before start of deletion intervals
|
|
return false;
|
|
}
|
|
while (std::next(iter_) != rep_.end() &&
|
|
ucmp_->Compare(std::next(iter_)->first, parsed.user_key) <= 0) {
|
|
++iter_;
|
|
}
|
|
break;
|
|
case RangeDelPositioningMode::kBackwardTraversal:
|
|
assert(iter_ != rep_.end());
|
|
while (iter_ != rep_.begin() &&
|
|
ucmp_->Compare(parsed.user_key, iter_->first) < 0) {
|
|
--iter_;
|
|
}
|
|
if (iter_ == rep_.begin() &&
|
|
ucmp_->Compare(parsed.user_key, iter_->first) < 0) {
|
|
// before start of deletion intervals
|
|
return false;
|
|
}
|
|
break;
|
|
case RangeDelPositioningMode::kBinarySearch:
|
|
iter_ = rep_.upper_bound(parsed.user_key);
|
|
if (iter_ == rep_.begin()) {
|
|
// before start of deletion intervals
|
|
return false;
|
|
}
|
|
--iter_;
|
|
break;
|
|
}
|
|
assert(iter_ != rep_.end() &&
|
|
ucmp_->Compare(iter_->first, parsed.user_key) <= 0);
|
|
assert(std::next(iter_) == rep_.end() ||
|
|
ucmp_->Compare(parsed.user_key, std::next(iter_)->first) < 0);
|
|
return parsed.sequence < iter_->second;
|
|
}
|
|
|
|
bool IsRangeOverlapped(const Slice&, const Slice&) override {
|
|
// Unimplemented because the only client of this method, file ingestion,
|
|
// uses uncollapsed maps.
|
|
fprintf(stderr, "CollapsedRangeDelMap::IsRangeOverlapped unimplemented");
|
|
abort();
|
|
}
|
|
|
|
void AddTombstone(RangeTombstone t) override {
|
|
if (ucmp_->Compare(t.start_key_, t.end_key_) >= 0 || t.seq_ == 0) {
|
|
// The tombstone covers no keys. Nothing to do.
|
|
return;
|
|
}
|
|
|
|
auto it = rep_.upper_bound(t.start_key_);
|
|
auto prev_seq = [&]() {
|
|
return it == rep_.begin() ? 0 : std::prev(it)->second;
|
|
};
|
|
|
|
// end_seq stores the seqno of the last transition that the new tombstone
|
|
// covered. This is the seqno that we'll install if we need to insert a
|
|
// transition for the new tombstone's end key.
|
|
SequenceNumber end_seq = 0;
|
|
|
|
// In the diagrams below, the new tombstone is always [c, k) @ 2. The
|
|
// existing tombstones are varied to depict different scenarios. Uppercase
|
|
// letters are used to indicate points that exist in the map, while
|
|
// lowercase letters are used to indicate points that do not exist in the
|
|
// map. The location of the iterator is marked with a caret; it may point
|
|
// off the end of the diagram to indicate that it is positioned at a
|
|
// entry with a larger key whose specific key is irrelevant.
|
|
|
|
if (t.seq_ > prev_seq()) {
|
|
// The new tombstone's start point covers the existing tombstone:
|
|
//
|
|
// 3: 3: A--C 3: 3:
|
|
// 2: c--- OR 2: c--- OR 2: c--- OR 2: c------
|
|
// 1: A--C 1: 1: A------ 1: C------
|
|
// ^ ^ ^ ^
|
|
// Insert a new transition at the new tombstone's start point, or raise
|
|
// the existing transition at that point to the new tombstone's seqno.
|
|
end_seq = prev_seq();
|
|
rep_[t.start_key_] = t.seq_; // operator[] will overwrite existing entry
|
|
} else {
|
|
// The new tombstone's start point is covered by an existing tombstone:
|
|
//
|
|
// 3: A----- OR 3: C------
|
|
// 2: c--- 2: c------
|
|
// ^ ^
|
|
// Do nothing.
|
|
}
|
|
|
|
// Look at all the existing transitions that overlap the new tombstone.
|
|
while (it != rep_.end() && ucmp_->Compare(it->first, t.end_key_) < 0) {
|
|
if (t.seq_ > it->second) {
|
|
// The transition is to an existing tombstone that the new tombstone
|
|
// covers. Save the covered tombstone's seqno. We'll need to return to
|
|
// it if the new tombstone ends before the existing tombstone.
|
|
end_seq = it->second;
|
|
|
|
if (t.seq_ == prev_seq()) {
|
|
// The previous transition is to the seqno of the new tombstone:
|
|
//
|
|
// 3: 3: 3: --F
|
|
// 2: C------ OR 2: C------ OR 2: F----
|
|
// 1: F--- 1: ---F 1: H--
|
|
// ^ ^ ^
|
|
//
|
|
// Erase this transition. It's been superseded.
|
|
it = rep_.erase(it);
|
|
continue; // skip increment; erase positions iterator correctly
|
|
} else {
|
|
// The previous transition is to a tombstone that covers the new
|
|
// tombstone, but this transition is to a tombstone that is covered by
|
|
// the new tombstone. That is, this is the end of a run of existing
|
|
// tombstones that cover the new tombstone:
|
|
//
|
|
// 3: A---E OR 3: E-G
|
|
// 2: c---- 2: ------
|
|
// ^ ^
|
|
// Preserve this transition point, but raise it to the new tombstone's
|
|
// seqno.
|
|
it->second = t.seq_;
|
|
}
|
|
} else {
|
|
// The transition is to an existing tombstone that covers the new
|
|
// tombstone:
|
|
//
|
|
// 4: 4: --F
|
|
// 3: F-- OR 3: F--
|
|
// 2: ----- 2: -----
|
|
// ^ ^
|
|
// Do nothing.
|
|
}
|
|
++it;
|
|
}
|
|
|
|
if (t.seq_ == prev_seq()) {
|
|
// The new tombstone is unterminated in the map:
|
|
//
|
|
// 3: OR 3: --G OR 3: --G K--
|
|
// 2: C-------k 2: G---k 2: G---k
|
|
// ^ ^ ^
|
|
// End it now, returning to the last seqno we covered. Because end keys
|
|
// are exclusive, if there's an existing transition at t.end_key_, it
|
|
// takes precedence over the transition that we install here.
|
|
rep_.emplace(t.end_key_, end_seq); // emplace is a noop if existing entry
|
|
} else {
|
|
// The new tombstone is implicitly ended because its end point is covered
|
|
// by an existing tombstone with a higher seqno.
|
|
//
|
|
// 3: I---M OR 3: A-----------M
|
|
// 2: ----k 2: c-------k
|
|
// ^ ^
|
|
// Do nothing.
|
|
}
|
|
}
|
|
|
|
size_t Size() const override { return rep_.size() - 1; }
|
|
|
|
void InvalidatePosition() override { iter_ = rep_.end(); }
|
|
|
|
std::unique_ptr<RangeDelIterator> NewIterator() override {
|
|
return std::unique_ptr<RangeDelIterator>(new Iterator(this->rep_));
|
|
}
|
|
};
|
|
|
|
RangeDelAggregator::RangeDelAggregator(
|
|
const InternalKeyComparator& icmp,
|
|
const std::vector<SequenceNumber>& snapshots,
|
|
bool collapse_deletions /* = true */)
|
|
: upper_bound_(kMaxSequenceNumber),
|
|
icmp_(icmp),
|
|
collapse_deletions_(collapse_deletions) {
|
|
InitRep(snapshots);
|
|
}
|
|
|
|
RangeDelAggregator::RangeDelAggregator(const InternalKeyComparator& icmp,
|
|
SequenceNumber snapshot,
|
|
bool collapse_deletions /* = false */)
|
|
: upper_bound_(snapshot),
|
|
icmp_(icmp),
|
|
collapse_deletions_(collapse_deletions) {}
|
|
|
|
void RangeDelAggregator::InitRep(const std::vector<SequenceNumber>& snapshots) {
|
|
assert(rep_ == nullptr);
|
|
rep_.reset(new Rep());
|
|
for (auto snapshot : snapshots) {
|
|
rep_->stripe_map_.emplace(snapshot, NewRangeDelMap());
|
|
}
|
|
// Data newer than any snapshot falls in this catch-all stripe
|
|
rep_->stripe_map_.emplace(kMaxSequenceNumber, NewRangeDelMap());
|
|
rep_->pinned_iters_mgr_.StartPinning();
|
|
}
|
|
|
|
std::unique_ptr<RangeDelMap> RangeDelAggregator::NewRangeDelMap() {
|
|
RangeDelMap* tombstone_map;
|
|
if (collapse_deletions_) {
|
|
tombstone_map = new CollapsedRangeDelMap(icmp_.user_comparator());
|
|
} else {
|
|
tombstone_map = new UncollapsedRangeDelMap(icmp_.user_comparator());
|
|
}
|
|
return std::unique_ptr<RangeDelMap>(tombstone_map);
|
|
}
|
|
|
|
bool RangeDelAggregator::ShouldDeleteImpl(const Slice& internal_key,
|
|
RangeDelPositioningMode mode) {
|
|
assert(rep_ != nullptr);
|
|
ParsedInternalKey parsed;
|
|
if (!ParseInternalKey(internal_key, &parsed)) {
|
|
assert(false);
|
|
}
|
|
return ShouldDelete(parsed, mode);
|
|
}
|
|
|
|
bool RangeDelAggregator::ShouldDeleteImpl(const ParsedInternalKey& parsed,
|
|
RangeDelPositioningMode mode) {
|
|
assert(IsValueType(parsed.type));
|
|
assert(rep_ != nullptr);
|
|
auto& tombstone_map = GetRangeDelMap(parsed.sequence);
|
|
if (tombstone_map.IsEmpty()) {
|
|
return false;
|
|
}
|
|
return tombstone_map.ShouldDelete(parsed, mode);
|
|
}
|
|
|
|
bool RangeDelAggregator::IsRangeOverlapped(const Slice& start,
|
|
const Slice& end) {
|
|
// Unimplemented because the only client of this method, file ingestion,
|
|
// uses uncollapsed maps.
|
|
assert(!collapse_deletions_);
|
|
if (rep_ == nullptr) {
|
|
return false;
|
|
}
|
|
for (const auto& stripe : rep_->stripe_map_) {
|
|
if (stripe.second->IsRangeOverlapped(start, end)) {
|
|
return true;
|
|
}
|
|
}
|
|
return false;
|
|
}
|
|
|
|
Status RangeDelAggregator::AddTombstones(
|
|
std::unique_ptr<InternalIterator> input,
|
|
const InternalKey* smallest,
|
|
const InternalKey* largest) {
|
|
if (input == nullptr) {
|
|
return Status::OK();
|
|
}
|
|
input->SeekToFirst();
|
|
bool first_iter = true;
|
|
while (input->Valid()) {
|
|
if (first_iter) {
|
|
if (rep_ == nullptr) {
|
|
InitRep({upper_bound_});
|
|
} else {
|
|
InvalidateRangeDelMapPositions();
|
|
}
|
|
first_iter = false;
|
|
}
|
|
ParsedInternalKey parsed_key;
|
|
bool parsed;
|
|
if (input->IsKeyPinned()) {
|
|
parsed = ParseInternalKey(input->key(), &parsed_key);
|
|
} else {
|
|
// The tombstone map holds slices into the iterator's memory. Make a
|
|
// copy of the key if it is not pinned.
|
|
rep_->pinned_slices_.emplace_back(input->key().data(),
|
|
input->key().size());
|
|
parsed = ParseInternalKey(rep_->pinned_slices_.back(), &parsed_key);
|
|
}
|
|
if (!parsed) {
|
|
return Status::Corruption("Unable to parse range tombstone InternalKey");
|
|
}
|
|
RangeTombstone tombstone;
|
|
if (input->IsValuePinned()) {
|
|
tombstone = RangeTombstone(parsed_key, input->value());
|
|
} else {
|
|
// The tombstone map holds slices into the iterator's memory. Make a
|
|
// copy of the value if it is not pinned.
|
|
rep_->pinned_slices_.emplace_back(input->value().data(),
|
|
input->value().size());
|
|
tombstone = RangeTombstone(parsed_key, rep_->pinned_slices_.back());
|
|
}
|
|
// Truncate the tombstone to the range [smallest, largest].
|
|
if (smallest != nullptr) {
|
|
if (icmp_.user_comparator()->Compare(
|
|
tombstone.start_key_, smallest->user_key()) < 0) {
|
|
tombstone.start_key_ = smallest->user_key();
|
|
}
|
|
}
|
|
if (largest != nullptr) {
|
|
// This is subtly correct despite the discrepancy between
|
|
// FileMetaData::largest being inclusive while RangeTombstone::end_key_
|
|
// is exclusive. A tombstone will only extend past the bounds of an
|
|
// sstable if its end-key is the largest key in the table. If that
|
|
// occurs, the largest key for the table is set based on the smallest
|
|
// key in the next table in the level. In that case, largest->user_key()
|
|
// is not actually a key in the current table and thus we can use it as
|
|
// the exclusive end-key for the tombstone.
|
|
if (icmp_.user_comparator()->Compare(
|
|
tombstone.end_key_, largest->user_key()) > 0) {
|
|
// The largest key should be a tombstone sentinel key.
|
|
assert(GetInternalKeySeqno(largest->Encode()) == kMaxSequenceNumber);
|
|
tombstone.end_key_ = largest->user_key();
|
|
}
|
|
}
|
|
GetRangeDelMap(tombstone.seq_).AddTombstone(std::move(tombstone));
|
|
input->Next();
|
|
}
|
|
if (!first_iter) {
|
|
rep_->pinned_iters_mgr_.PinIterator(input.release(), false /* arena */);
|
|
}
|
|
return Status::OK();
|
|
}
|
|
|
|
void RangeDelAggregator::InvalidateRangeDelMapPositions() {
|
|
if (rep_ == nullptr) {
|
|
return;
|
|
}
|
|
for (auto& stripe : rep_->stripe_map_) {
|
|
stripe.second->InvalidatePosition();
|
|
}
|
|
}
|
|
|
|
RangeDelMap& RangeDelAggregator::GetRangeDelMap(SequenceNumber seq) {
|
|
assert(rep_ != nullptr);
|
|
// The stripe includes seqnum for the snapshot above and excludes seqnum for
|
|
// the snapshot below.
|
|
StripeMap::iterator iter;
|
|
if (seq > 0) {
|
|
// upper_bound() checks strict inequality so need to subtract one
|
|
iter = rep_->stripe_map_.upper_bound(seq - 1);
|
|
} else {
|
|
iter = rep_->stripe_map_.begin();
|
|
}
|
|
// catch-all stripe justifies this assertion in either of above cases
|
|
assert(iter != rep_->stripe_map_.end());
|
|
return *iter->second;
|
|
}
|
|
|
|
bool RangeDelAggregator::IsEmpty() {
|
|
if (rep_ == nullptr) {
|
|
return true;
|
|
}
|
|
for (const auto& stripe : rep_->stripe_map_) {
|
|
if (!stripe.second->IsEmpty()) {
|
|
return false;
|
|
}
|
|
}
|
|
return true;
|
|
}
|
|
|
|
bool RangeDelAggregator::AddFile(uint64_t file_number) {
|
|
if (rep_ == nullptr) {
|
|
return true;
|
|
}
|
|
return rep_->added_files_.emplace(file_number).second;
|
|
}
|
|
|
|
class MergingRangeDelIter : public RangeDelIterator {
|
|
public:
|
|
MergingRangeDelIter(const Comparator* c)
|
|
: heap_(IterMinHeap(IterComparator(c))), current_(nullptr) {}
|
|
|
|
void AddIterator(std::unique_ptr<RangeDelIterator> iter) {
|
|
if (iter->Valid()) {
|
|
heap_.push(iter.get());
|
|
iters_.push_back(std::move(iter));
|
|
current_ = heap_.top();
|
|
}
|
|
}
|
|
|
|
bool Valid() const override { return current_ != nullptr; }
|
|
|
|
void Next() override {
|
|
current_->Next();
|
|
if (current_->Valid()) {
|
|
heap_.replace_top(current_);
|
|
} else {
|
|
heap_.pop();
|
|
}
|
|
current_ = heap_.empty() ? nullptr : heap_.top();
|
|
}
|
|
|
|
void Seek(const Slice& target) override {
|
|
heap_.clear();
|
|
for (auto& iter : iters_) {
|
|
iter->Seek(target);
|
|
if (iter->Valid()) {
|
|
heap_.push(iter.get());
|
|
}
|
|
}
|
|
current_ = heap_.empty() ? nullptr : heap_.top();
|
|
}
|
|
|
|
RangeTombstone Tombstone() const override { return current_->Tombstone(); }
|
|
|
|
private:
|
|
struct IterComparator {
|
|
IterComparator(const Comparator* c) : cmp(c) {}
|
|
|
|
bool operator()(const RangeDelIterator* a,
|
|
const RangeDelIterator* b) const {
|
|
// Note: counterintuitively, returning the tombstone with the larger start
|
|
// key puts the tombstone with the smallest key at the top of the heap.
|
|
return cmp->Compare(a->Tombstone().start_key_,
|
|
b->Tombstone().start_key_) > 0;
|
|
}
|
|
|
|
const Comparator* cmp;
|
|
};
|
|
|
|
typedef BinaryHeap<RangeDelIterator*, IterComparator> IterMinHeap;
|
|
|
|
std::vector<std::unique_ptr<RangeDelIterator>> iters_;
|
|
IterMinHeap heap_;
|
|
RangeDelIterator* current_;
|
|
};
|
|
|
|
std::unique_ptr<RangeDelIterator> RangeDelAggregator::NewIterator() {
|
|
std::unique_ptr<MergingRangeDelIter> iter(
|
|
new MergingRangeDelIter(icmp_.user_comparator()));
|
|
if (rep_ != nullptr) {
|
|
for (const auto& stripe : rep_->stripe_map_) {
|
|
iter->AddIterator(stripe.second->NewIterator());
|
|
}
|
|
}
|
|
return std::move(iter);
|
|
}
|
|
|
|
} // namespace rocksdb
|