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rocksdb/db/range_del_aggregator.cc

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21 KiB

// 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 <algorithm>
namespace rocksdb {
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,
PositionalTombstoneMap(TombstoneMap(
stl_wrappers::LessOfComparator(icmp_.user_comparator()))));
}
// Data newer than any snapshot falls in this catch-all stripe
rep_->stripe_map_.emplace(
kMaxSequenceNumber,
PositionalTombstoneMap(TombstoneMap(
stl_wrappers::LessOfComparator(icmp_.user_comparator()))));
rep_->pinned_iters_mgr_.StartPinning();
}
bool RangeDelAggregator::ShouldDelete(
const Slice& internal_key, RangeDelAggregator::RangePositioningMode mode) {
if (rep_ == nullptr) {
return false;
}
ParsedInternalKey parsed;
if (!ParseInternalKey(internal_key, &parsed)) {
assert(false);
}
return ShouldDelete(parsed, mode);
}
bool RangeDelAggregator::ShouldDelete(
const ParsedInternalKey& parsed,
RangeDelAggregator::RangePositioningMode mode) {
assert(IsValueType(parsed.type));
if (rep_ == nullptr) {
return false;
}
auto& positional_tombstone_map = GetPositionalTombstoneMap(parsed.sequence);
const auto& tombstone_map = positional_tombstone_map.raw_map;
if (tombstone_map.empty()) {
return false;
}
auto& tombstone_map_iter = positional_tombstone_map.iter;
if (tombstone_map_iter == tombstone_map.end() &&
(mode == kForwardTraversal || mode == kBackwardTraversal)) {
// invalid (e.g., if AddTombstones() changed the deletions), so need to
// reseek
mode = kBinarySearch;
}
switch (mode) {
case kFullScan:
assert(!collapse_deletions_);
// The maintained state (PositionalTombstoneMap::iter) isn't useful when
// we linear scan from the beginning each time, but we maintain it anyways
// for consistency.
tombstone_map_iter = tombstone_map.begin();
while (tombstone_map_iter != tombstone_map.end()) {
const auto& tombstone = tombstone_map_iter->second;
if (icmp_.user_comparator()->Compare(parsed.user_key,
tombstone.start_key_) < 0) {
break;
}
if (parsed.sequence < tombstone.seq_ &&
icmp_.user_comparator()->Compare(parsed.user_key,
tombstone.end_key_) < 0) {
return true;
}
++tombstone_map_iter;
}
return false;
case kForwardTraversal:
assert(collapse_deletions_ && tombstone_map_iter != tombstone_map.end());
if (tombstone_map_iter == tombstone_map.begin() &&
icmp_.user_comparator()->Compare(parsed.user_key,
tombstone_map_iter->first) < 0) {
// before start of deletion intervals
return false;
}
while (std::next(tombstone_map_iter) != tombstone_map.end() &&
icmp_.user_comparator()->Compare(
std::next(tombstone_map_iter)->first, parsed.user_key) <= 0) {
++tombstone_map_iter;
}
break;
case kBackwardTraversal:
assert(collapse_deletions_ && tombstone_map_iter != tombstone_map.end());
while (tombstone_map_iter != tombstone_map.begin() &&
icmp_.user_comparator()->Compare(parsed.user_key,
tombstone_map_iter->first) < 0) {
--tombstone_map_iter;
}
if (tombstone_map_iter == tombstone_map.begin() &&
icmp_.user_comparator()->Compare(parsed.user_key,
tombstone_map_iter->first) < 0) {
// before start of deletion intervals
return false;
}
break;
case kBinarySearch:
assert(collapse_deletions_);
tombstone_map_iter =
tombstone_map.upper_bound(parsed.user_key);
if (tombstone_map_iter == tombstone_map.begin()) {
// before start of deletion intervals
return false;
}
--tombstone_map_iter;
break;
}
assert(mode != kFullScan);
assert(tombstone_map_iter != tombstone_map.end() &&
icmp_.user_comparator()->Compare(tombstone_map_iter->first,
parsed.user_key) <= 0);
assert(std::next(tombstone_map_iter) == tombstone_map.end() ||
icmp_.user_comparator()->Compare(
parsed.user_key, std::next(tombstone_map_iter)->first) < 0);
return parsed.sequence < tombstone_map_iter->second.seq_;
}
bool RangeDelAggregator::ShouldAddTombstones(
bool bottommost_level /* = false */) {
// TODO(andrewkr): can we just open a file and throw it away if it ends up
// empty after AddToBuilder()? This function doesn't take into subcompaction
// boundaries so isn't completely accurate.
if (rep_ == nullptr) {
return false;
}
auto stripe_map_iter = rep_->stripe_map_.begin();
assert(stripe_map_iter != rep_->stripe_map_.end());
if (bottommost_level) {
// For the bottommost level, keys covered by tombstones in the first
// (oldest) stripe have been compacted away, so the tombstones are obsolete.
++stripe_map_iter;
}
while (stripe_map_iter != rep_->stripe_map_.end()) {
if (!stripe_map_iter->second.raw_map.empty()) {
return true;
}
++stripe_map_iter;
}
return false;
}
Status RangeDelAggregator::AddTombstones(
std::unique_ptr<InternalIterator> input) {
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 {
InvalidateTombstoneMapPositions();
}
first_iter = false;
}
ParsedInternalKey parsed_key;
if (!ParseInternalKey(input->key(), &parsed_key)) {
return Status::Corruption("Unable to parse range tombstone InternalKey");
}
RangeTombstone tombstone(parsed_key, input->value());
AddTombstone(std::move(tombstone));
input->Next();
}
if (!first_iter) {
rep_->pinned_iters_mgr_.PinIterator(input.release(), false /* arena */);
}
return Status::OK();
}
void RangeDelAggregator::InvalidateTombstoneMapPositions() {
if (rep_ == nullptr) {
return;
}
for (auto stripe_map_iter = rep_->stripe_map_.begin();
stripe_map_iter != rep_->stripe_map_.end(); ++stripe_map_iter) {
stripe_map_iter->second.iter = stripe_map_iter->second.raw_map.end();
}
}
Status RangeDelAggregator::AddTombstone(RangeTombstone tombstone) {
auto& positional_tombstone_map = GetPositionalTombstoneMap(tombstone.seq_);
auto& tombstone_map = positional_tombstone_map.raw_map;
if (collapse_deletions_) {
// In collapsed mode, we only fill the seq_ field in the TombstoneMap's
// values. The end_key is unneeded because we assume the tombstone extends
// until the next tombstone starts. For gaps between real tombstones and
// for the last real tombstone, we denote end keys by inserting fake
// tombstones with sequence number zero.
std::vector<RangeTombstone> new_range_dels{
tombstone, RangeTombstone(tombstone.end_key_, Slice(), 0)};
auto new_range_dels_iter = new_range_dels.begin();
// Position at the first overlapping existing tombstone; if none exists,
// insert until we find an existing one overlapping a new point
const Slice* tombstone_map_begin = nullptr;
if (!tombstone_map.empty()) {
tombstone_map_begin = &tombstone_map.begin()->first;
}
auto last_range_dels_iter = new_range_dels_iter;
while (new_range_dels_iter != new_range_dels.end() &&
(tombstone_map_begin == nullptr ||
icmp_.user_comparator()->Compare(new_range_dels_iter->start_key_,
*tombstone_map_begin) < 0)) {
tombstone_map.emplace(
new_range_dels_iter->start_key_,
RangeTombstone(Slice(), Slice(), new_range_dels_iter->seq_));
last_range_dels_iter = new_range_dels_iter;
++new_range_dels_iter;
}
if (new_range_dels_iter == new_range_dels.end()) {
return Status::OK();
}
// above loop advances one too far
new_range_dels_iter = last_range_dels_iter;
auto tombstone_map_iter =
tombstone_map.upper_bound(new_range_dels_iter->start_key_);
// if nothing overlapped we would've already inserted all the new points
// and returned early
assert(tombstone_map_iter != tombstone_map.begin());
tombstone_map_iter--;
// untermed_seq is non-kMaxSequenceNumber when we covered an existing point
// but haven't seen its corresponding endpoint. It's used for (1) deciding
// whether to forcibly insert the new interval's endpoint; and (2) possibly
// raising the seqnum for the to-be-inserted element (we insert the max
// seqnum between the next new interval and the unterminated interval).
SequenceNumber untermed_seq = kMaxSequenceNumber;
while (tombstone_map_iter != tombstone_map.end() &&
new_range_dels_iter != new_range_dels.end()) {
const Slice *tombstone_map_iter_end = nullptr,
*new_range_dels_iter_end = nullptr;
if (tombstone_map_iter != tombstone_map.end()) {
auto next_tombstone_map_iter = std::next(tombstone_map_iter);
if (next_tombstone_map_iter != tombstone_map.end()) {
tombstone_map_iter_end = &next_tombstone_map_iter->first;
}
}
if (new_range_dels_iter != new_range_dels.end()) {
auto next_new_range_dels_iter = std::next(new_range_dels_iter);
if (next_new_range_dels_iter != new_range_dels.end()) {
new_range_dels_iter_end = &next_new_range_dels_iter->start_key_;
}
}
// our positions in existing/new tombstone collections should always
// overlap. The non-overlapping cases are handled above and below this
// loop.
assert(new_range_dels_iter_end == nullptr ||
icmp_.user_comparator()->Compare(tombstone_map_iter->first,
*new_range_dels_iter_end) < 0);
assert(tombstone_map_iter_end == nullptr ||
icmp_.user_comparator()->Compare(new_range_dels_iter->start_key_,
*tombstone_map_iter_end) < 0);
int new_to_old_start_cmp = icmp_.user_comparator()->Compare(
new_range_dels_iter->start_key_, tombstone_map_iter->first);
// nullptr end means extends infinitely rightwards, set new_to_old_end_cmp
// accordingly so we can use common code paths later.
int new_to_old_end_cmp;
if (new_range_dels_iter_end == nullptr &&
tombstone_map_iter_end == nullptr) {
new_to_old_end_cmp = 0;
} else if (new_range_dels_iter_end == nullptr) {
new_to_old_end_cmp = 1;
} else if (tombstone_map_iter_end == nullptr) {
new_to_old_end_cmp = -1;
} else {
new_to_old_end_cmp = icmp_.user_comparator()->Compare(
*new_range_dels_iter_end, *tombstone_map_iter_end);
}
if (new_to_old_start_cmp < 0) {
// the existing one's left endpoint comes after, so raise/delete it if
// it's covered.
if (tombstone_map_iter->second.seq_ < new_range_dels_iter->seq_) {
untermed_seq = tombstone_map_iter->second.seq_;
if (tombstone_map_iter != tombstone_map.begin() &&
std::prev(tombstone_map_iter)->second.seq_ ==
new_range_dels_iter->seq_) {
tombstone_map_iter = tombstone_map.erase(tombstone_map_iter);
--tombstone_map_iter;
} else {
tombstone_map_iter->second.seq_ = new_range_dels_iter->seq_;
}
}
} else if (new_to_old_start_cmp > 0) {
if (untermed_seq != kMaxSequenceNumber ||
tombstone_map_iter->second.seq_ < new_range_dels_iter->seq_) {
auto seq = tombstone_map_iter->second.seq_;
// need to adjust this element if not intended to span beyond the new
// element (i.e., was_tombstone_map_iter_raised == true), or if it
// can be raised
tombstone_map_iter = tombstone_map.emplace(
new_range_dels_iter->start_key_,
RangeTombstone(
Slice(), Slice(),
std::max(
untermed_seq == kMaxSequenceNumber ? 0 : untermed_seq,
new_range_dels_iter->seq_)));
untermed_seq = seq;
}
} else {
// their left endpoints coincide, so raise the existing one if needed
if (tombstone_map_iter->second.seq_ < new_range_dels_iter->seq_) {
untermed_seq = tombstone_map_iter->second.seq_;
tombstone_map_iter->second.seq_ = new_range_dels_iter->seq_;
}
}
// advance whichever one ends earlier, or both if their right endpoints
// coincide
if (new_to_old_end_cmp < 0) {
++new_range_dels_iter;
} else if (new_to_old_end_cmp > 0) {
++tombstone_map_iter;
untermed_seq = kMaxSequenceNumber;
} else {
++new_range_dels_iter;
++tombstone_map_iter;
untermed_seq = kMaxSequenceNumber;
}
}
while (new_range_dels_iter != new_range_dels.end()) {
tombstone_map.emplace(
new_range_dels_iter->start_key_,
RangeTombstone(Slice(), Slice(), new_range_dels_iter->seq_));
++new_range_dels_iter;
}
} else {
auto start_key = tombstone.start_key_;
tombstone_map.emplace(start_key, std::move(tombstone));
}
return Status::OK();
}
RangeDelAggregator::PositionalTombstoneMap&
RangeDelAggregator::GetPositionalTombstoneMap(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;
}
// TODO(andrewkr): We should implement an iterator over range tombstones in our
// map. It'd enable compaction to open tables on-demand, i.e., only once range
// tombstones are known to be available, without the code duplication we have
// in ShouldAddTombstones(). It'll also allow us to move the table-modifying
// code into more coherent places: CompactionJob and BuildTable().
void RangeDelAggregator::AddToBuilder(
TableBuilder* builder, const Slice* lower_bound, const Slice* upper_bound,
FileMetaData* meta,
CompactionIterationStats* range_del_out_stats /* = nullptr */,
bool bottommost_level /* = false */) {
if (rep_ == nullptr) {
return;
}
auto stripe_map_iter = rep_->stripe_map_.begin();
assert(stripe_map_iter != rep_->stripe_map_.end());
if (bottommost_level) {
// TODO(andrewkr): these are counted for each compaction output file, so
// lots of double-counting.
if (!stripe_map_iter->second.raw_map.empty()) {
range_del_out_stats->num_range_del_drop_obsolete +=
static_cast<int64_t>(stripe_map_iter->second.raw_map.size()) -
(collapse_deletions_ ? 1 : 0);
range_del_out_stats->num_record_drop_obsolete +=
static_cast<int64_t>(stripe_map_iter->second.raw_map.size()) -
(collapse_deletions_ ? 1 : 0);
}
// For the bottommost level, keys covered by tombstones in the first
// (oldest) stripe have been compacted away, so the tombstones are obsolete.
++stripe_map_iter;
}
// Note the order in which tombstones are stored is insignificant since we
// insert them into a std::map on the read path.
while (stripe_map_iter != rep_->stripe_map_.end()) {
bool first_added = false;
for (auto tombstone_map_iter = stripe_map_iter->second.raw_map.begin();
tombstone_map_iter != stripe_map_iter->second.raw_map.end();
++tombstone_map_iter) {
RangeTombstone tombstone;
if (collapse_deletions_) {
auto next_tombstone_map_iter = std::next(tombstone_map_iter);
if (next_tombstone_map_iter == stripe_map_iter->second.raw_map.end() ||
tombstone_map_iter->second.seq_ == 0) {
// it's a sentinel tombstone
continue;
}
tombstone.start_key_ = tombstone_map_iter->first;
tombstone.end_key_ = next_tombstone_map_iter->first;
tombstone.seq_ = tombstone_map_iter->second.seq_;
} else {
tombstone = tombstone_map_iter->second;
}
if (upper_bound != nullptr &&
icmp_.user_comparator()->Compare(*upper_bound,
tombstone.start_key_) <= 0) {
// Tombstones starting at upper_bound or later only need to be included
// in the next table. Break because subsequent tombstones will start
// even later.
break;
}
if (lower_bound != nullptr &&
icmp_.user_comparator()->Compare(tombstone.end_key_,
*lower_bound) <= 0) {
// Tombstones ending before or at lower_bound only need to be included
// in the prev table. Continue because subsequent tombstones may still
// overlap [lower_bound, upper_bound).
continue;
}
auto ikey_and_end_key = tombstone.Serialize();
builder->Add(ikey_and_end_key.first.Encode(), ikey_and_end_key.second);
if (!first_added) {
first_added = true;
InternalKey smallest_candidate = std::move(ikey_and_end_key.first);
if (lower_bound != nullptr &&
icmp_.user_comparator()->Compare(smallest_candidate.user_key(),
*lower_bound) <= 0) {
// Pretend the smallest key has the same user key as lower_bound
// (the max key in the previous table or subcompaction) in order for
// files to appear key-space partitioned.
//
// Choose lowest seqnum so this file's smallest internal key comes
// after the previous file's/subcompaction's largest. The fake seqnum
// is OK because the read path's file-picking code only considers user
// key.
smallest_candidate = InternalKey(*lower_bound, 0, kTypeRangeDeletion);
}
if (meta->smallest.size() == 0 ||
icmp_.Compare(smallest_candidate, meta->smallest) < 0) {
meta->smallest = std::move(smallest_candidate);
}
}
InternalKey largest_candidate = tombstone.SerializeEndKey();
if (upper_bound != nullptr &&
icmp_.user_comparator()->Compare(*upper_bound,
largest_candidate.user_key()) <= 0) {
// Pretend the largest key has the same user key as upper_bound (the
// min key in the following table or subcompaction) in order for files
// to appear key-space partitioned.
//
// Choose highest seqnum so this file's largest internal key comes
// before the next file's/subcompaction's smallest. The fake seqnum is
// OK because the read path's file-picking code only considers the user
// key portion.
//
// Note Seek() also creates InternalKey with (user_key,
// kMaxSequenceNumber), but with kTypeDeletion (0x7) instead of
// kTypeRangeDeletion (0xF), so the range tombstone comes before the
// Seek() key in InternalKey's ordering. So Seek() will look in the
// next file for the user key.
largest_candidate = InternalKey(*upper_bound, kMaxSequenceNumber,
kTypeRangeDeletion);
}
if (meta->largest.size() == 0 ||
icmp_.Compare(meta->largest, largest_candidate) < 0) {
meta->largest = std::move(largest_candidate);
}
meta->smallest_seqno = std::min(meta->smallest_seqno, tombstone.seq_);
meta->largest_seqno = std::max(meta->largest_seqno, tombstone.seq_);
}
++stripe_map_iter;
}
}
bool RangeDelAggregator::IsEmpty() {
if (rep_ == nullptr) {
return true;
}
for (auto stripe_map_iter = rep_->stripe_map_.begin();
stripe_map_iter != rep_->stripe_map_.end(); ++stripe_map_iter) {
if (!stripe_map_iter->second.raw_map.empty()) {
return false;
}
}
return true;
}
} // namespace rocksdb