Adding upstream version 18.2.2.upstream/18.2.2

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 357 insertions, 0 deletions

diff --git a/src/rocksdb/db/range_tombstone_fragmenter.h b/src/rocksdb/db/range_tombstone_fragmenter.h
new file mode 100644
index 000000000..df07fa894
--- /dev/null
+++ b/src/rocksdb/db/range_tombstone_fragmenter.h
@@ -0,0 +1,357 @@
+//  Copyright (c) 2018-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).
+
+#pragma once
+
+#include <list>
+#include <memory>
+#include <set>
+#include <string>
+#include <vector>
+
+#include "db/dbformat.h"
+#include "db/pinned_iterators_manager.h"
+#include "rocksdb/status.h"
+#include "table/internal_iterator.h"
+
+namespace ROCKSDB_NAMESPACE {
+struct FragmentedRangeTombstoneList;
+
+struct FragmentedRangeTombstoneListCache {
+  // ensure only the first reader needs to initialize l
+  std::mutex reader_mutex;
+  std::unique_ptr<FragmentedRangeTombstoneList> tombstones = nullptr;
+  // readers will first check this bool to avoid
+  std::atomic<bool> initialized = false;
+};
+
+struct FragmentedRangeTombstoneList {
+ public:
+  // A compact representation of a "stack" of range tombstone fragments, which
+  // start and end at the same user keys but have different sequence numbers.
+  // The members seq_start_idx and seq_end_idx are intended to be parameters to
+  // seq_iter().
+  // If user-defined timestamp is enabled, `start` and `end` should be user keys
+  // with timestamp, and the timestamps are set to max timestamp to be returned
+  // by parsed_start_key()/parsed_end_key(). seq_start_idx and seq_end_idx will
+  // also be used as parameters to ts_iter().
+  struct RangeTombstoneStack {
+    RangeTombstoneStack(const Slice& start, const Slice& end, size_t start_idx,
+                        size_t end_idx)
+        : start_key(start),
+          end_key(end),
+          seq_start_idx(start_idx),
+          seq_end_idx(end_idx) {}
+    Slice start_key;
+    Slice end_key;
+    size_t seq_start_idx;
+    size_t seq_end_idx;
+  };
+  // Assumes unfragmented_tombstones->key() and unfragmented_tombstones->value()
+  // both contain timestamp if enabled.
+  FragmentedRangeTombstoneList(
+      std::unique_ptr<InternalIterator> unfragmented_tombstones,
+      const InternalKeyComparator& icmp, bool for_compaction = false,
+      const std::vector<SequenceNumber>& snapshots = {});
+
+  std::vector<RangeTombstoneStack>::const_iterator begin() const {
+    return tombstones_.begin();
+  }
+
+  std::vector<RangeTombstoneStack>::const_iterator end() const {
+    return tombstones_.end();
+  }
+
+  std::vector<SequenceNumber>::const_iterator seq_iter(size_t idx) const {
+    return std::next(tombstone_seqs_.begin(), idx);
+  }
+
+  std::vector<Slice>::const_iterator ts_iter(size_t idx) const {
+    return std::next(tombstone_timestamps_.begin(), idx);
+  }
+
+  std::vector<SequenceNumber>::const_iterator seq_begin() const {
+    return tombstone_seqs_.begin();
+  }
+
+  std::vector<SequenceNumber>::const_iterator seq_end() const {
+    return tombstone_seqs_.end();
+  }
+
+  bool empty() const { return tombstones_.empty(); }
+
+  // Returns true if the stored tombstones contain with one with a sequence
+  // number in [lower, upper].
+  // This method is not const as it internally lazy initialize a set of
+  // sequence numbers (`seq_set_`).
+  bool ContainsRange(SequenceNumber lower, SequenceNumber upper);
+
+  uint64_t num_unfragmented_tombstones() const {
+    return num_unfragmented_tombstones_;
+  }
+
+  uint64_t total_tombstone_payload_bytes() const {
+    return total_tombstone_payload_bytes_;
+  }
+
+ private:
+  // Given an ordered range tombstone iterator unfragmented_tombstones,
+  // "fragment" the tombstones into non-overlapping pieces. Each
+  // "non-overlapping piece" is a RangeTombstoneStack in tombstones_, which
+  // contains start_key, end_key, and indices that points to sequence numbers
+  // (in tombstone_seqs_) and timestamps (in tombstone_timestamps_). If
+  // for_compaction is true, then `snapshots` should be provided. Range
+  // tombstone fragments are dropped if they are not visible in any snapshot and
+  // user-defined timestamp is not enabled. That is, for each snapshot stripe
+  // [lower, upper], the range tombstone fragment with largest seqno in [lower,
+  // upper] is preserved, and all the other range tombstones are dropped.
+  void FragmentTombstones(
+      std::unique_ptr<InternalIterator> unfragmented_tombstones,
+      const InternalKeyComparator& icmp, bool for_compaction,
+      const std::vector<SequenceNumber>& snapshots);
+
+  std::vector<RangeTombstoneStack> tombstones_;
+  std::vector<SequenceNumber> tombstone_seqs_;
+  std::vector<Slice> tombstone_timestamps_;
+  std::once_flag seq_set_init_once_flag_;
+  std::set<SequenceNumber> seq_set_;
+  std::list<std::string> pinned_slices_;
+  PinnedIteratorsManager pinned_iters_mgr_;
+  uint64_t num_unfragmented_tombstones_;
+  uint64_t total_tombstone_payload_bytes_;
+};
+
+// FragmentedRangeTombstoneIterator converts an InternalIterator of a range-del
+// meta block into an iterator over non-overlapping tombstone fragments. The
+// tombstone fragmentation process should be more efficient than the range
+// tombstone collapsing algorithm in RangeDelAggregator because this leverages
+// the internal key ordering already provided by the input iterator, if
+// applicable (when the iterator is unsorted, a new sorted iterator is created
+// before proceeding). If there are few overlaps, creating a
+// FragmentedRangeTombstoneIterator should be O(n), while the RangeDelAggregator
+// tombstone collapsing is always O(n log n).
+class FragmentedRangeTombstoneIterator : public InternalIterator {
+ public:
+  FragmentedRangeTombstoneIterator(FragmentedRangeTombstoneList* tombstones,
+                                   const InternalKeyComparator& icmp,
+                                   SequenceNumber upper_bound,
+                                   const Slice* ts_upper_bound = nullptr,
+                                   SequenceNumber lower_bound = 0);
+  FragmentedRangeTombstoneIterator(
+      const std::shared_ptr<FragmentedRangeTombstoneList>& tombstones,
+      const InternalKeyComparator& icmp, SequenceNumber upper_bound,
+      const Slice* ts_upper_bound = nullptr, SequenceNumber lower_bound = 0);
+  FragmentedRangeTombstoneIterator(
+      const std::shared_ptr<FragmentedRangeTombstoneListCache>& tombstones,
+      const InternalKeyComparator& icmp, SequenceNumber upper_bound,
+      const Slice* ts_upper_bound = nullptr, SequenceNumber lower_bound = 0);
+
+  void SeekToFirst() override;
+  void SeekToLast() override;
+
+  void SeekToTopFirst();
+  void SeekToTopLast();
+
+  // NOTE: Seek and SeekForPrev do not behave in the way InternalIterator
+  // seeking should behave. This is OK because they are not currently used, but
+  // eventually FragmentedRangeTombstoneIterator should no longer implement
+  // InternalIterator.
+  //
+  // Seeks to the range tombstone that covers target at a seqnum in the
+  // snapshot. If no such tombstone exists, seek to the earliest tombstone in
+  // the snapshot that ends after target.
+  void Seek(const Slice& target) override;
+  // Seeks to the range tombstone that covers target at a seqnum in the
+  // snapshot. If no such tombstone exists, seek to the latest tombstone in the
+  // snapshot that starts before target.
+  void SeekForPrev(const Slice& target) override;
+
+  void Next() override;
+  void Prev() override;
+
+  void TopNext();
+  void TopPrev();
+
+  bool Valid() const override;
+  // Note that key() and value() do not return correct timestamp.
+  // Caller should call timestamp() to get the current timestamp.
+  Slice key() const override {
+    MaybePinKey();
+    return current_start_key_.Encode();
+  }
+  Slice value() const override { return pos_->end_key; }
+  bool IsKeyPinned() const override { return false; }
+  bool IsValuePinned() const override { return true; }
+  Status status() const override { return Status::OK(); }
+
+  bool empty() const { return tombstones_->empty(); }
+  void Invalidate() {
+    pos_ = tombstones_->end();
+    seq_pos_ = tombstones_->seq_end();
+    pinned_pos_ = tombstones_->end();
+    pinned_seq_pos_ = tombstones_->seq_end();
+  }
+
+  RangeTombstone Tombstone() const {
+    assert(Valid());
+    if (icmp_->user_comparator()->timestamp_size()) {
+      return RangeTombstone(start_key(), end_key(), seq(), timestamp());
+    }
+    return RangeTombstone(start_key(), end_key(), seq());
+  }
+  // Note that start_key() and end_key() are not guaranteed to have the
+  // correct timestamp. User can call timestamp() to get the correct
+  // timestamp().
+  Slice start_key() const { return pos_->start_key; }
+  Slice end_key() const { return pos_->end_key; }
+  SequenceNumber seq() const { return *seq_pos_; }
+  Slice timestamp() const {
+    // seqno and timestamp are stored in the same order.
+    return *tombstones_->ts_iter(seq_pos_ - tombstones_->seq_begin());
+  }
+  // Current use case is by CompactionRangeDelAggregator to set
+  // full_history_ts_low_.
+  void SetTimestampUpperBound(const Slice* ts_upper_bound) {
+    ts_upper_bound_ = ts_upper_bound;
+  }
+
+  ParsedInternalKey parsed_start_key() const {
+    return ParsedInternalKey(pos_->start_key, kMaxSequenceNumber,
+                             kTypeRangeDeletion);
+  }
+  ParsedInternalKey parsed_end_key() const {
+    return ParsedInternalKey(pos_->end_key, kMaxSequenceNumber,
+                             kTypeRangeDeletion);
+  }
+
+  // Return the max sequence number of a range tombstone that covers
+  // the given user key.
+  // If there is no covering tombstone, then 0 is returned.
+  SequenceNumber MaxCoveringTombstoneSeqnum(const Slice& user_key);
+
+  // Splits the iterator into n+1 iterators (where n is the number of
+  // snapshots), each providing a view over a "stripe" of sequence numbers. The
+  // iterators are keyed by the upper bound of their ranges (the provided
+  // snapshots + kMaxSequenceNumber).
+  //
+  // NOTE: the iterators in the returned map are no longer valid if their
+  // parent iterator is deleted, since they do not modify the refcount of the
+  // underlying tombstone list. Therefore, this map should be deleted before
+  // the parent iterator.
+  std::map<SequenceNumber, std::unique_ptr<FragmentedRangeTombstoneIterator>>
+  SplitBySnapshot(const std::vector<SequenceNumber>& snapshots);
+
+  SequenceNumber upper_bound() const { return upper_bound_; }
+  SequenceNumber lower_bound() const { return lower_bound_; }
+
+  uint64_t num_unfragmented_tombstones() const {
+    return tombstones_->num_unfragmented_tombstones();
+  }
+  uint64_t total_tombstone_payload_bytes() const {
+    return tombstones_->total_tombstone_payload_bytes();
+  }
+
+ private:
+  using RangeTombstoneStack = FragmentedRangeTombstoneList::RangeTombstoneStack;
+
+  struct RangeTombstoneStackStartComparator {
+    explicit RangeTombstoneStackStartComparator(const Comparator* c) : cmp(c) {}
+
+    bool operator()(const RangeTombstoneStack& a,
+                    const RangeTombstoneStack& b) const {
+      return cmp->CompareWithoutTimestamp(a.start_key, b.start_key) < 0;
+    }
+
+    bool operator()(const RangeTombstoneStack& a, const Slice& b) const {
+      return cmp->CompareWithoutTimestamp(a.start_key, b) < 0;
+    }
+
+    bool operator()(const Slice& a, const RangeTombstoneStack& b) const {
+      return cmp->CompareWithoutTimestamp(a, b.start_key) < 0;
+    }
+
+    const Comparator* cmp;
+  };
+
+  struct RangeTombstoneStackEndComparator {
+    explicit RangeTombstoneStackEndComparator(const Comparator* c) : cmp(c) {}
+
+    bool operator()(const RangeTombstoneStack& a,
+                    const RangeTombstoneStack& b) const {
+      return cmp->CompareWithoutTimestamp(a.end_key, b.end_key) < 0;
+    }
+
+    bool operator()(const RangeTombstoneStack& a, const Slice& b) const {
+      return cmp->CompareWithoutTimestamp(a.end_key, b) < 0;
+    }
+
+    bool operator()(const Slice& a, const RangeTombstoneStack& b) const {
+      return cmp->CompareWithoutTimestamp(a, b.end_key) < 0;
+    }
+
+    const Comparator* cmp;
+  };
+
+  void MaybePinKey() const {
+    if (pos_ != tombstones_->end() && seq_pos_ != tombstones_->seq_end() &&
+        (pinned_pos_ != pos_ || pinned_seq_pos_ != seq_pos_)) {
+      current_start_key_.Set(pos_->start_key, *seq_pos_, kTypeRangeDeletion);
+      pinned_pos_ = pos_;
+      pinned_seq_pos_ = seq_pos_;
+    }
+  }
+
+  void SeekToCoveringTombstone(const Slice& key);
+  void SeekForPrevToCoveringTombstone(const Slice& key);
+  void ScanForwardToVisibleTombstone();
+  void ScanBackwardToVisibleTombstone();
+  bool ValidPos() const {
+    return Valid() && seq_pos_ != tombstones_->seq_iter(pos_->seq_end_idx);
+  }
+
+  const RangeTombstoneStackStartComparator tombstone_start_cmp_;
+  const RangeTombstoneStackEndComparator tombstone_end_cmp_;
+  const InternalKeyComparator* icmp_;
+  const Comparator* ucmp_;
+  std::shared_ptr<FragmentedRangeTombstoneList> tombstones_ref_;
+  std::shared_ptr<FragmentedRangeTombstoneListCache> tombstones_cache_ref_;
+  FragmentedRangeTombstoneList* tombstones_;
+  SequenceNumber upper_bound_;
+  SequenceNumber lower_bound_;
+  // Only consider timestamps <= ts_upper_bound_.
+  const Slice* ts_upper_bound_;
+  std::vector<RangeTombstoneStack>::const_iterator pos_;
+  std::vector<SequenceNumber>::const_iterator seq_pos_;
+  mutable std::vector<RangeTombstoneStack>::const_iterator pinned_pos_;
+  mutable std::vector<SequenceNumber>::const_iterator pinned_seq_pos_;
+  mutable InternalKey current_start_key_;
+
+  // Check the current RangeTombstoneStack `pos_` against timestamp
+  // upper bound `ts_upper_bound_` and sequence number upper bound
+  // `upper_bound_`. Update the sequence number (and timestamp) pointer
+  // `seq_pos_` to the first valid position satisfying both bounds.
+  void SetMaxVisibleSeqAndTimestamp() {
+    seq_pos_ = std::lower_bound(tombstones_->seq_iter(pos_->seq_start_idx),
+                                tombstones_->seq_iter(pos_->seq_end_idx),
+                                upper_bound_, std::greater<SequenceNumber>());
+    if (ts_upper_bound_ && !ts_upper_bound_->empty()) {
+      auto ts_pos = std::lower_bound(
+          tombstones_->ts_iter(pos_->seq_start_idx),
+          tombstones_->ts_iter(pos_->seq_end_idx), *ts_upper_bound_,
+          [this](const Slice& s1, const Slice& s2) {
+            return ucmp_->CompareTimestamp(s1, s2) > 0;
+          });
+      auto ts_idx = ts_pos - tombstones_->ts_iter(pos_->seq_start_idx);
+      auto seq_idx = seq_pos_ - tombstones_->seq_iter(pos_->seq_start_idx);
+      if (seq_idx < ts_idx) {
+        // seq and ts are ordered in non-increasing order. Only updates seq_pos_
+        // to a larger index for smaller sequence number and timestamp.
+        seq_pos_ = tombstones_->seq_iter(pos_->seq_start_idx + ts_idx);
+      }
+    }
+  }
+};
+
+}  // namespace ROCKSDB_NAMESPACE