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rocksdb/db/range_del_aggregator.cc

246 lines
9.1 KiB

// Copyright (c) 2016-present, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.
#include "db/range_del_aggregator.h"
#include <algorithm>
namespace rocksdb {
RangeDelAggregator::RangeDelAggregator(
const InternalKeyComparator& icmp,
const std::vector<SequenceNumber>& snapshots)
: upper_bound_(kMaxSequenceNumber), icmp_(icmp) {
InitRep(snapshots);
}
RangeDelAggregator::RangeDelAggregator(const InternalKeyComparator& icmp,
SequenceNumber snapshot)
: upper_bound_(snapshot), icmp_(icmp) {}
void RangeDelAggregator::InitRep(const std::vector<SequenceNumber>& snapshots) {
assert(rep_ == nullptr);
rep_.reset(new Rep());
for (auto snapshot : snapshots) {
rep_->stripe_map_.emplace(
snapshot, TombstoneMap(stl_wrappers::LessOfComparator(&icmp_)));
}
// Data newer than any snapshot falls in this catch-all stripe
rep_->stripe_map_.emplace(
kMaxSequenceNumber, TombstoneMap(stl_wrappers::LessOfComparator(&icmp_)));
rep_->pinned_iters_mgr_.StartPinning();
}
bool RangeDelAggregator::ShouldDelete(const Slice& internal_key) {
if (rep_ == nullptr) {
return false;
}
ParsedInternalKey parsed;
if (!ParseInternalKey(internal_key, &parsed)) {
assert(false);
}
return ShouldDelete(parsed);
}
bool RangeDelAggregator::ShouldDelete(const ParsedInternalKey& parsed) {
assert(IsValueType(parsed.type));
if (rep_ == nullptr) {
return false;
}
const auto& tombstone_map = GetTombstoneMap(parsed.sequence);
for (const auto& start_key_and_tombstone : tombstone_map) {
const auto& tombstone = start_key_and_tombstone.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;
}
}
return false;
}
bool RangeDelAggregator::ShouldAddTombstones(
bool bottommost_level /* = false */) {
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.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_});
}
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());
auto& tombstone_map = GetTombstoneMap(tombstone.seq_);
tombstone_map.emplace(input->key(), std::move(tombstone));
input->Next();
}
if (!first_iter) {
rep_->pinned_iters_mgr_.PinIterator(input.release(), false /* arena */);
}
return Status::OK();
}
RangeDelAggregator::TombstoneMap& RangeDelAggregator::GetTombstoneMap(
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,
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) {
// 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.
bool first_added = false;
while (stripe_map_iter != rep_->stripe_map_.end()) {
for (const auto& start_key_and_tombstone : stripe_map_iter->second) {
const auto& tombstone = start_key_and_tombstone.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.empty()) {
return false;
}
}
return true;
}
} // namespace rocksdb