Adding upstream version 18.2.2.upstream/18.2.2

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

1 files changed, 231 insertions, 0 deletions

diff --git a/src/rocksdb/table/get_context.h b/src/rocksdb/table/get_context.h
new file mode 100644
index 000000000..dcc7ab8d6
--- /dev/null
+++ b/src/rocksdb/table/get_context.h
@@ -0,0 +1,231 @@
+//  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).
+
+#pragma once
+#include <string>
+
+#include "db/read_callback.h"
+#include "rocksdb/types.h"
+
+namespace ROCKSDB_NAMESPACE {
+class BlobFetcher;
+class Comparator;
+class Logger;
+class MergeContext;
+class MergeOperator;
+class PinnableWideColumns;
+class PinnedIteratorsManager;
+class Statistics;
+class SystemClock;
+struct ParsedInternalKey;
+
+// Data structure for accumulating statistics during a point lookup. At the
+// end of the point lookup, the corresponding ticker stats are updated. This
+// avoids the overhead of frequent ticker stats updates
+struct GetContextStats {
+  uint64_t num_cache_hit = 0;
+  uint64_t num_cache_index_hit = 0;
+  uint64_t num_cache_data_hit = 0;
+  uint64_t num_cache_filter_hit = 0;
+  uint64_t num_cache_compression_dict_hit = 0;
+  uint64_t num_cache_index_miss = 0;
+  uint64_t num_cache_filter_miss = 0;
+  uint64_t num_cache_data_miss = 0;
+  uint64_t num_cache_compression_dict_miss = 0;
+  uint64_t num_cache_bytes_read = 0;
+  uint64_t num_cache_miss = 0;
+  uint64_t num_cache_add = 0;
+  uint64_t num_cache_add_redundant = 0;
+  uint64_t num_cache_bytes_write = 0;
+  uint64_t num_cache_index_add = 0;
+  uint64_t num_cache_index_add_redundant = 0;
+  uint64_t num_cache_index_bytes_insert = 0;
+  uint64_t num_cache_data_add = 0;
+  uint64_t num_cache_data_add_redundant = 0;
+  uint64_t num_cache_data_bytes_insert = 0;
+  uint64_t num_cache_filter_add = 0;
+  uint64_t num_cache_filter_add_redundant = 0;
+  uint64_t num_cache_filter_bytes_insert = 0;
+  uint64_t num_cache_compression_dict_add = 0;
+  uint64_t num_cache_compression_dict_add_redundant = 0;
+  uint64_t num_cache_compression_dict_bytes_insert = 0;
+  // MultiGet stats.
+  uint64_t num_filter_read = 0;
+  uint64_t num_index_read = 0;
+  uint64_t num_sst_read = 0;
+};
+
+// A class to hold context about a point lookup, such as pointer to value
+// slice, key, merge context etc, as well as the current state of the
+// lookup. Any user using GetContext to track the lookup result must call
+// SaveValue() whenever the internal key is found. This can happen
+// repeatedly in case of merge operands. In case the key may exist with
+// high probability, but IO is required to confirm and the user doesn't allow
+// it, MarkKeyMayExist() must be called instead of SaveValue().
+class GetContext {
+ public:
+  // Current state of the point lookup. All except kNotFound and kMerge are
+  // terminal states
+  enum GetState {
+    kNotFound,
+    kFound,
+    kDeleted,
+    kCorrupt,
+    kMerge,  // saver contains the current merge result (the operands)
+    kUnexpectedBlobIndex,
+  };
+  GetContextStats get_context_stats_;
+
+  // Constructor
+  // @param value Holds the value corresponding to user_key. If its nullptr
+  //              then return all merge operands corresponding to user_key
+  //              via merge_context
+  // @param value_found If non-nullptr, set to false if key may be present
+  //                    but we can't be certain because we cannot do IO
+  // @param max_covering_tombstone_seq Pointer to highest sequence number of
+  //                    range deletion covering the key. When an internal key
+  //                    is found with smaller sequence number, the lookup
+  //                    terminates
+  // @param seq If non-nullptr, the sequence number of the found key will be
+  //            saved here
+  // @param callback Pointer to ReadCallback to perform additional checks
+  //                 for visibility of a key
+  // @param is_blob_index If non-nullptr, will be used to indicate if a found
+  //                      key is of type blob index
+  // @param do_merge True if value associated with user_key has to be returned
+  // and false if all the merge operands associated with user_key has to be
+  // returned. Id do_merge=false then all the merge operands are stored in
+  // merge_context and they are never merged. The value pointer is untouched.
+  GetContext(const Comparator* ucmp, const MergeOperator* merge_operator,
+             Logger* logger, Statistics* statistics, GetState init_state,
+             const Slice& user_key, PinnableSlice* value,
+             PinnableWideColumns* columns, bool* value_found,
+             MergeContext* merge_context, bool do_merge,
+             SequenceNumber* max_covering_tombstone_seq, SystemClock* clock,
+             SequenceNumber* seq = nullptr,
+             PinnedIteratorsManager* _pinned_iters_mgr = nullptr,
+             ReadCallback* callback = nullptr, bool* is_blob_index = nullptr,
+             uint64_t tracing_get_id = 0, BlobFetcher* blob_fetcher = nullptr);
+  GetContext(const Comparator* ucmp, const MergeOperator* merge_operator,
+             Logger* logger, Statistics* statistics, GetState init_state,
+             const Slice& user_key, PinnableSlice* value,
+             PinnableWideColumns* columns, std::string* timestamp,
+             bool* value_found, MergeContext* merge_context, bool do_merge,
+             SequenceNumber* max_covering_tombstone_seq, SystemClock* clock,
+             SequenceNumber* seq = nullptr,
+             PinnedIteratorsManager* _pinned_iters_mgr = nullptr,
+             ReadCallback* callback = nullptr, bool* is_blob_index = nullptr,
+             uint64_t tracing_get_id = 0, BlobFetcher* blob_fetcher = nullptr);
+
+  GetContext() = delete;
+
+  // This can be called to indicate that a key may be present, but cannot be
+  // confirmed due to IO not allowed
+  void MarkKeyMayExist();
+
+  // Records this key, value, and any meta-data (such as sequence number and
+  // state) into this GetContext.
+  //
+  // If the parsed_key matches the user key that we are looking for, sets
+  // matched to true.
+  //
+  // Returns True if more keys need to be read (due to merges) or
+  //         False if the complete value has been found.
+  bool SaveValue(const ParsedInternalKey& parsed_key, const Slice& value,
+                 bool* matched, Cleanable* value_pinner = nullptr);
+
+  // Simplified version of the previous function. Should only be used when we
+  // know that the operation is a Put.
+  void SaveValue(const Slice& value, SequenceNumber seq);
+
+  GetState State() const { return state_; }
+
+  SequenceNumber* max_covering_tombstone_seq() {
+    return max_covering_tombstone_seq_;
+  }
+
+  bool NeedTimestamp() { return timestamp_ != nullptr; }
+
+  void SetTimestampFromRangeTombstone(const Slice& timestamp) {
+    assert(timestamp_);
+    timestamp_->assign(timestamp.data(), timestamp.size());
+    ts_from_rangetombstone_ = true;
+  }
+
+  PinnedIteratorsManager* pinned_iters_mgr() { return pinned_iters_mgr_; }
+
+  // If a non-null string is passed, all the SaveValue calls will be
+  // logged into the string. The operations can then be replayed on
+  // another GetContext with replayGetContextLog.
+  void SetReplayLog(std::string* replay_log) { replay_log_ = replay_log; }
+
+  // Do we need to fetch the SequenceNumber for this key?
+  bool NeedToReadSequence() const { return (seq_ != nullptr); }
+
+  bool sample() const { return sample_; }
+
+  bool CheckCallback(SequenceNumber seq) {
+    if (callback_) {
+      return callback_->IsVisible(seq);
+    }
+    return true;
+  }
+
+  void ReportCounters();
+
+  bool has_callback() const { return callback_ != nullptr; }
+
+  uint64_t get_tracing_get_id() const { return tracing_get_id_; }
+
+  void push_operand(const Slice& value, Cleanable* value_pinner);
+
+ private:
+  void Merge(const Slice* value);
+  void MergeWithEntity(Slice entity);
+  bool GetBlobValue(const Slice& blob_index, PinnableSlice* blob_value);
+
+  const Comparator* ucmp_;
+  const MergeOperator* merge_operator_;
+  // the merge operations encountered;
+  Logger* logger_;
+  Statistics* statistics_;
+
+  GetState state_;
+  Slice user_key_;
+  PinnableSlice* pinnable_val_;
+  PinnableWideColumns* columns_;
+  std::string* timestamp_;
+  bool ts_from_rangetombstone_{false};
+  bool* value_found_;  // Is value set correctly? Used by KeyMayExist
+  MergeContext* merge_context_;
+  SequenceNumber* max_covering_tombstone_seq_;
+  SystemClock* clock_;
+  // If a key is found, seq_ will be set to the SequenceNumber of most recent
+  // write to the key or kMaxSequenceNumber if unknown
+  SequenceNumber* seq_;
+  std::string* replay_log_;
+  // Used to temporarily pin blocks when state_ == GetContext::kMerge
+  PinnedIteratorsManager* pinned_iters_mgr_;
+  ReadCallback* callback_;
+  bool sample_;
+  // Value is true if it's called as part of DB Get API and false if it's
+  // called as part of DB GetMergeOperands API. When it's false merge operators
+  // are never merged.
+  bool do_merge_;
+  bool* is_blob_index_;
+  // Used for block cache tracing only. A tracing get id uniquely identifies a
+  // Get or a MultiGet.
+  const uint64_t tracing_get_id_;
+  BlobFetcher* blob_fetcher_;
+};
+
+// Call this to replay a log and bring the get_context up to date. The replay
+// log must have been created by another GetContext object, whose replay log
+// must have been set by calling GetContext::SetReplayLog().
+void replayGetContextLog(const Slice& replay_log, const Slice& user_key,
+                         GetContext* get_context,
+                         Cleanable* value_pinner = nullptr);
+
+}  // namespace ROCKSDB_NAMESPACE