Adding upstream version 18.2.2.upstream/18.2.2

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

1 files changed, 420 insertions, 0 deletions

diff --git a/src/rocksdb/db/db_iter.h b/src/rocksdb/db/db_iter.h
new file mode 100644
index 000000000..e87c2b4c9
--- /dev/null
+++ b/src/rocksdb/db/db_iter.h
@@ -0,0 +1,420 @@
+//  Copyright (c) 2011-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).
+//
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#pragma once
+#include <cstdint>
+#include <string>
+
+#include "db/db_impl/db_impl.h"
+#include "db/range_del_aggregator.h"
+#include "memory/arena.h"
+#include "options/cf_options.h"
+#include "rocksdb/db.h"
+#include "rocksdb/iterator.h"
+#include "rocksdb/wide_columns.h"
+#include "table/iterator_wrapper.h"
+#include "util/autovector.h"
+
+namespace ROCKSDB_NAMESPACE {
+class Version;
+
+// This file declares the factory functions of DBIter, in its original form
+// or a wrapped form with class ArenaWrappedDBIter, which is defined here.
+// Class DBIter, which is declared and implemented inside db_iter.cc, is
+// an iterator that converts internal keys (yielded by an InternalIterator)
+// that were live at the specified sequence number into appropriate user
+// keys.
+// Each internal key consists of a user key, a sequence number, and a value
+// type. DBIter deals with multiple key versions, tombstones, merge operands,
+// etc, and exposes an Iterator.
+// For example, DBIter may wrap following InternalIterator:
+//    user key: AAA  value: v3   seqno: 100    type: Put
+//    user key: AAA  value: v2   seqno: 97     type: Put
+//    user key: AAA  value: v1   seqno: 95     type: Put
+//    user key: BBB  value: v1   seqno: 90     type: Put
+//    user key: BBC  value: N/A  seqno: 98     type: Delete
+//    user key: BBC  value: v1   seqno: 95     type: Put
+// If the snapshot passed in is 102, then the DBIter is expected to
+// expose the following iterator:
+//    key: AAA  value: v3
+//    key: BBB  value: v1
+// If the snapshot passed in is 96, then it should expose:
+//    key: AAA  value: v1
+//    key: BBB  value: v1
+//    key: BBC  value: v1
+//
+
+// Memtables and sstables that make the DB representation contain
+// (userkey,seq,type) => uservalue entries.  DBIter
+// combines multiple entries for the same userkey found in the DB
+// representation into a single entry while accounting for sequence
+// numbers, deletion markers, overwrites, etc.
+class DBIter final : public Iterator {
+ public:
+  // The following is grossly complicated. TODO: clean it up
+  // Which direction is the iterator currently moving?
+  // (1) When moving forward:
+  //   (1a) if current_entry_is_merged_ = false, the internal iterator is
+  //        positioned at the exact entry that yields this->key(), this->value()
+  //   (1b) if current_entry_is_merged_ = true, the internal iterator is
+  //        positioned immediately after the last entry that contributed to the
+  //        current this->value(). That entry may or may not have key equal to
+  //        this->key().
+  // (2) When moving backwards, the internal iterator is positioned
+  //     just before all entries whose user key == this->key().
+  enum Direction : uint8_t { kForward, kReverse };
+
+  // LocalStatistics contain Statistics counters that will be aggregated per
+  // each iterator instance and then will be sent to the global statistics when
+  // the iterator is destroyed.
+  //
+  // The purpose of this approach is to avoid perf regression happening
+  // when multiple threads bump the atomic counters from a DBIter::Next().
+  struct LocalStatistics {
+    explicit LocalStatistics() { ResetCounters(); }
+
+    void ResetCounters() {
+      next_count_ = 0;
+      next_found_count_ = 0;
+      prev_count_ = 0;
+      prev_found_count_ = 0;
+      bytes_read_ = 0;
+      skip_count_ = 0;
+    }
+
+    void BumpGlobalStatistics(Statistics* global_statistics) {
+      RecordTick(global_statistics, NUMBER_DB_NEXT, next_count_);
+      RecordTick(global_statistics, NUMBER_DB_NEXT_FOUND, next_found_count_);
+      RecordTick(global_statistics, NUMBER_DB_PREV, prev_count_);
+      RecordTick(global_statistics, NUMBER_DB_PREV_FOUND, prev_found_count_);
+      RecordTick(global_statistics, ITER_BYTES_READ, bytes_read_);
+      RecordTick(global_statistics, NUMBER_ITER_SKIP, skip_count_);
+      PERF_COUNTER_ADD(iter_read_bytes, bytes_read_);
+      ResetCounters();
+    }
+
+    // Map to Tickers::NUMBER_DB_NEXT
+    uint64_t next_count_;
+    // Map to Tickers::NUMBER_DB_NEXT_FOUND
+    uint64_t next_found_count_;
+    // Map to Tickers::NUMBER_DB_PREV
+    uint64_t prev_count_;
+    // Map to Tickers::NUMBER_DB_PREV_FOUND
+    uint64_t prev_found_count_;
+    // Map to Tickers::ITER_BYTES_READ
+    uint64_t bytes_read_;
+    // Map to Tickers::NUMBER_ITER_SKIP
+    uint64_t skip_count_;
+  };
+
+  DBIter(Env* _env, const ReadOptions& read_options,
+         const ImmutableOptions& ioptions,
+         const MutableCFOptions& mutable_cf_options, const Comparator* cmp,
+         InternalIterator* iter, const Version* version, SequenceNumber s,
+         bool arena_mode, uint64_t max_sequential_skip_in_iterations,
+         ReadCallback* read_callback, DBImpl* db_impl, ColumnFamilyData* cfd,
+         bool expose_blob_index);
+
+  // No copying allowed
+  DBIter(const DBIter&) = delete;
+  void operator=(const DBIter&) = delete;
+
+  ~DBIter() override {
+    // Release pinned data if any
+    if (pinned_iters_mgr_.PinningEnabled()) {
+      pinned_iters_mgr_.ReleasePinnedData();
+    }
+    RecordTick(statistics_, NO_ITERATOR_DELETED);
+    ResetInternalKeysSkippedCounter();
+    local_stats_.BumpGlobalStatistics(statistics_);
+    iter_.DeleteIter(arena_mode_);
+  }
+  void SetIter(InternalIterator* iter) {
+    assert(iter_.iter() == nullptr);
+    iter_.Set(iter);
+    iter_.iter()->SetPinnedItersMgr(&pinned_iters_mgr_);
+  }
+
+  bool Valid() const override {
+#ifdef ROCKSDB_ASSERT_STATUS_CHECKED
+    if (valid_) {
+      status_.PermitUncheckedError();
+    }
+#endif  // ROCKSDB_ASSERT_STATUS_CHECKED
+    return valid_;
+  }
+  Slice key() const override {
+    assert(valid_);
+    if (timestamp_lb_) {
+      return saved_key_.GetInternalKey();
+    } else {
+      const Slice ukey_and_ts = saved_key_.GetUserKey();
+      return Slice(ukey_and_ts.data(), ukey_and_ts.size() - timestamp_size_);
+    }
+  }
+  Slice value() const override {
+    assert(valid_);
+
+    return value_;
+  }
+
+  const WideColumns& columns() const override {
+    assert(valid_);
+
+    return wide_columns_;
+  }
+
+  Status status() const override {
+    if (status_.ok()) {
+      return iter_.status();
+    } else {
+      assert(!valid_);
+      return status_;
+    }
+  }
+  Slice timestamp() const override {
+    assert(valid_);
+    assert(timestamp_size_ > 0);
+    if (direction_ == kReverse) {
+      return saved_timestamp_;
+    }
+    const Slice ukey_and_ts = saved_key_.GetUserKey();
+    assert(timestamp_size_ < ukey_and_ts.size());
+    return ExtractTimestampFromUserKey(ukey_and_ts, timestamp_size_);
+  }
+  bool IsBlob() const {
+    assert(valid_);
+    return is_blob_;
+  }
+
+  Status GetProperty(std::string prop_name, std::string* prop) override;
+
+  void Next() final override;
+  void Prev() final override;
+  // 'target' does not contain timestamp, even if user timestamp feature is
+  // enabled.
+  void Seek(const Slice& target) final override;
+  void SeekForPrev(const Slice& target) final override;
+  void SeekToFirst() final override;
+  void SeekToLast() final override;
+  Env* env() const { return env_; }
+  void set_sequence(uint64_t s) {
+    sequence_ = s;
+    if (read_callback_) {
+      read_callback_->Refresh(s);
+    }
+  }
+  void set_valid(bool v) { valid_ = v; }
+
+ private:
+  // For all methods in this block:
+  // PRE: iter_->Valid() && status_.ok()
+  // Return false if there was an error, and status() is non-ok, valid_ = false;
+  // in this case callers would usually stop what they were doing and return.
+  bool ReverseToForward();
+  bool ReverseToBackward();
+  // Set saved_key_ to the seek key to target, with proper sequence number set.
+  // It might get adjusted if the seek key is smaller than iterator lower bound.
+  // target does not have timestamp.
+  void SetSavedKeyToSeekTarget(const Slice& target);
+  // Set saved_key_ to the seek key to target, with proper sequence number set.
+  // It might get adjusted if the seek key is larger than iterator upper bound.
+  // target does not have timestamp.
+  void SetSavedKeyToSeekForPrevTarget(const Slice& target);
+  bool FindValueForCurrentKey();
+  bool FindValueForCurrentKeyUsingSeek();
+  bool FindUserKeyBeforeSavedKey();
+  // If `skipping_saved_key` is true, the function will keep iterating until it
+  // finds a user key that is larger than `saved_key_`.
+  // If `prefix` is not null, the iterator needs to stop when all keys for the
+  // prefix are exhausted and the iterator is set to invalid.
+  bool FindNextUserEntry(bool skipping_saved_key, const Slice* prefix);
+  // Internal implementation of FindNextUserEntry().
+  bool FindNextUserEntryInternal(bool skipping_saved_key, const Slice* prefix);
+  bool ParseKey(ParsedInternalKey* key);
+  bool MergeValuesNewToOld();
+
+  // If prefix is not null, we need to set the iterator to invalid if no more
+  // entry can be found within the prefix.
+  void PrevInternal(const Slice* prefix);
+  bool TooManyInternalKeysSkipped(bool increment = true);
+  bool IsVisible(SequenceNumber sequence, const Slice& ts,
+                 bool* more_recent = nullptr);
+
+  // Temporarily pin the blocks that we encounter until ReleaseTempPinnedData()
+  // is called
+  void TempPinData() {
+    if (!pin_thru_lifetime_) {
+      pinned_iters_mgr_.StartPinning();
+    }
+  }
+
+  // Release blocks pinned by TempPinData()
+  void ReleaseTempPinnedData() {
+    if (!pin_thru_lifetime_ && pinned_iters_mgr_.PinningEnabled()) {
+      pinned_iters_mgr_.ReleasePinnedData();
+    }
+  }
+
+  inline void ClearSavedValue() {
+    if (saved_value_.capacity() > 1048576) {
+      std::string empty;
+      swap(empty, saved_value_);
+    } else {
+      saved_value_.clear();
+    }
+  }
+
+  inline void ResetInternalKeysSkippedCounter() {
+    local_stats_.skip_count_ += num_internal_keys_skipped_;
+    if (valid_) {
+      local_stats_.skip_count_--;
+    }
+    num_internal_keys_skipped_ = 0;
+  }
+
+  bool expect_total_order_inner_iter() {
+    assert(expect_total_order_inner_iter_ || prefix_extractor_ != nullptr);
+    return expect_total_order_inner_iter_;
+  }
+
+  // If lower bound of timestamp is given by ReadOptions.iter_start_ts, we need
+  // to return versions of the same key. We cannot just skip if the key value
+  // is the same but timestamps are different but fall in timestamp range.
+  inline int CompareKeyForSkip(const Slice& a, const Slice& b) {
+    return timestamp_lb_ != nullptr
+               ? user_comparator_.Compare(a, b)
+               : user_comparator_.CompareWithoutTimestamp(a, b);
+  }
+
+  // Retrieves the blob value for the specified user key using the given blob
+  // index when using the integrated BlobDB implementation.
+  bool SetBlobValueIfNeeded(const Slice& user_key, const Slice& blob_index);
+
+  void ResetBlobValue() {
+    is_blob_ = false;
+    blob_value_.Reset();
+  }
+
+  void SetValueAndColumnsFromPlain(const Slice& slice) {
+    assert(value_.empty());
+    assert(wide_columns_.empty());
+
+    value_ = slice;
+    wide_columns_.emplace_back(kDefaultWideColumnName, slice);
+  }
+
+  bool SetValueAndColumnsFromEntity(Slice slice);
+
+  void ResetValueAndColumns() {
+    value_.clear();
+    wide_columns_.clear();
+  }
+
+  // If user-defined timestamp is enabled, `user_key` includes timestamp.
+  bool Merge(const Slice* val, const Slice& user_key);
+  bool MergeEntity(const Slice& entity, const Slice& user_key);
+
+  const SliceTransform* prefix_extractor_;
+  Env* const env_;
+  SystemClock* clock_;
+  Logger* logger_;
+  UserComparatorWrapper user_comparator_;
+  const MergeOperator* const merge_operator_;
+  IteratorWrapper iter_;
+  const Version* version_;
+  ReadCallback* read_callback_;
+  // Max visible sequence number. It is normally the snapshot seq unless we have
+  // uncommitted data in db as in WriteUnCommitted.
+  SequenceNumber sequence_;
+
+  IterKey saved_key_;
+  // Reusable internal key data structure. This is only used inside one function
+  // and should not be used across functions. Reusing this object can reduce
+  // overhead of calling construction of the function if creating it each time.
+  ParsedInternalKey ikey_;
+  std::string saved_value_;
+  Slice pinned_value_;
+  // for prefix seek mode to support prev()
+  PinnableSlice blob_value_;
+  // Value of the default column
+  Slice value_;
+  // All columns (i.e. name-value pairs)
+  WideColumns wide_columns_;
+  Statistics* statistics_;
+  uint64_t max_skip_;
+  uint64_t max_skippable_internal_keys_;
+  uint64_t num_internal_keys_skipped_;
+  const Slice* iterate_lower_bound_;
+  const Slice* iterate_upper_bound_;
+
+  // The prefix of the seek key. It is only used when prefix_same_as_start_
+  // is true and prefix extractor is not null. In Next() or Prev(), current keys
+  // will be checked against this prefix, so that the iterator can be
+  // invalidated if the keys in this prefix has been exhausted. Set it using
+  // SetUserKey() and use it using GetUserKey().
+  IterKey prefix_;
+
+  Status status_;
+  Direction direction_;
+  bool valid_;
+  bool current_entry_is_merged_;
+  // True if we know that the current entry's seqnum is 0.
+  // This information is used as that the next entry will be for another
+  // user key.
+  bool is_key_seqnum_zero_;
+  const bool prefix_same_as_start_;
+  // Means that we will pin all data blocks we read as long the Iterator
+  // is not deleted, will be true if ReadOptions::pin_data is true
+  const bool pin_thru_lifetime_;
+  // Expect the inner iterator to maintain a total order.
+  // prefix_extractor_ must be non-NULL if the value is false.
+  const bool expect_total_order_inner_iter_;
+  ReadTier read_tier_;
+  bool fill_cache_;
+  bool verify_checksums_;
+  // Whether the iterator is allowed to expose blob references. Set to true when
+  // the stacked BlobDB implementation is used, false otherwise.
+  bool expose_blob_index_;
+  bool is_blob_;
+  bool arena_mode_;
+  // List of operands for merge operator.
+  MergeContext merge_context_;
+  LocalStatistics local_stats_;
+  PinnedIteratorsManager pinned_iters_mgr_;
+#ifdef ROCKSDB_LITE
+  ROCKSDB_FIELD_UNUSED
+#endif
+  DBImpl* db_impl_;
+#ifdef ROCKSDB_LITE
+  ROCKSDB_FIELD_UNUSED
+#endif
+  ColumnFamilyData* cfd_;
+  const Slice* const timestamp_ub_;
+  const Slice* const timestamp_lb_;
+  const size_t timestamp_size_;
+  std::string saved_timestamp_;
+
+  // Used only if timestamp_lb_ is not nullptr.
+  std::string saved_ikey_;
+};
+
+// Return a new iterator that converts internal keys (yielded by
+// "*internal_iter") that were live at the specified `sequence` number
+// into appropriate user keys.
+extern Iterator* NewDBIterator(
+    Env* env, const ReadOptions& read_options, const ImmutableOptions& ioptions,
+    const MutableCFOptions& mutable_cf_options,
+    const Comparator* user_key_comparator, InternalIterator* internal_iter,
+    const Version* version, const SequenceNumber& sequence,
+    uint64_t max_sequential_skip_in_iterations, ReadCallback* read_callback,
+    DBImpl* db_impl = nullptr, ColumnFamilyData* cfd = nullptr,
+    bool expose_blob_index = false);
+
+}  // namespace ROCKSDB_NAMESPACE