update sources to ceph Nautilus 14.2.1

[ceph.git] / ceph / src / rocksdb / include / rocksdb / merge_operator.h

diff --git a/ceph/src/rocksdb/include/rocksdb/merge_operator.h b/ceph/src/rocksdb/include/rocksdb/merge_operator.h
index 6ec34fe3e45354944657933e104f2dbc23ad520b..b90f3d72f190ab4f6a99fc6318bbc4da3a4065ee 100644 (file)
--- a/ceph/src/rocksdb/include/rocksdb/merge_operator.h
+++ b/ceph/src/rocksdb/include/rocksdb/merge_operator.h
@@ -1,10 +1,9 @@
 // Copyright (c) 2011-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.
+//  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).
 
-#ifndef STORAGE_ROCKSDB_INCLUDE_MERGE_OPERATOR_H_
-#define STORAGE_ROCKSDB_INCLUDE_MERGE_OPERATOR_H_
+#pragma once
 
 #include <deque>
 #include <memory>
@@ -66,11 +65,9 @@ class MergeOperator {
   // internal corruption. This will be treated as an error by the library.
   //
   // Also make use of the *logger for error messages.
-  virtual bool FullMerge(const Slice& key,
-                         const Slice* existing_value,
-                         const std::deque<std::string>& operand_list,
-                         std::string* new_value,
-                         Logger* logger) const {
+  virtual bool FullMerge(const Slice& /*key*/, const Slice* /*existing_value*/,
+                         const std::deque<std::string>& /*operand_list*/,
+                         std::string* /*new_value*/, Logger* /*logger*/) const {
     // deprecated, please use FullMergeV2()
     assert(false);
     return false;
@@ -89,7 +86,7 @@ class MergeOperator {
     // The key associated with the merge operation.
     const Slice& key;
     // The existing value of the current key, nullptr means that the
-    // value dont exist.
+    // value doesn't exist.
     const Slice* existing_value;
     // A list of operands to apply.
     const std::vector<Slice>& operand_list;
@@ -145,9 +142,10 @@ class MergeOperator {
   // If there is corruption in the data, handle it in the FullMergeV2() function
   // and return false there.  The default implementation of PartialMerge will
   // always return false.
-  virtual bool PartialMerge(const Slice& key, const Slice& left_operand,
-                            const Slice& right_operand, std::string* new_value,
-                            Logger* logger) const {
+  virtual bool PartialMerge(const Slice& /*key*/, const Slice& /*left_operand*/,
+                            const Slice& /*right_operand*/,
+                            std::string* /*new_value*/,
+                            Logger* /*logger*/) const {
     return false;
   }
 
@@ -183,12 +181,33 @@ class MergeOperator {
   //       no checking is enforced. Client is responsible for providing
   //       consistent MergeOperator between DB opens.
   virtual const char* Name() const = 0;
+
+  // Determines whether the MergeOperator can be called with just a single
+  // merge operand.
+  // Override and return true for allowing a single operand. Both FullMergeV2
+  // and PartialMerge/PartialMergeMulti should be overridden and implemented
+  // correctly to handle a single operand.
+  virtual bool AllowSingleOperand() const { return false; }
+
+  // Allows to control when to invoke a full merge during Get.
+  // This could be used to limit the number of merge operands that are looked at
+  // during a point lookup, thereby helping in limiting the number of levels to
+  // read from.
+  // Doesn't help with iterators.
+  //
+  // Note: the merge operands are passed to this function in the reversed order
+  // relative to how they were merged (passed to FullMerge or FullMergeV2)
+  // for performance reasons, see also:
+  // https://github.com/facebook/rocksdb/issues/3865
+  virtual bool ShouldMerge(const std::vector<Slice>& /*operands*/) const {
+    return false;
+  }
 };
 
 // The simpler, associative merge operator.
 class AssociativeMergeOperator : public MergeOperator {
  public:
-  virtual ~AssociativeMergeOperator() {}
+  ~AssociativeMergeOperator() override {}
 
   // Gives the client a way to express the read -> modify -> write semantics
   // key:           (IN) The key that's associated with this merge operation.
@@ -212,16 +231,12 @@ class AssociativeMergeOperator : public MergeOperator {
 
  private:
   // Default implementations of the MergeOperator functions
-  virtual bool FullMergeV2(const MergeOperationInput& merge_in,
-                           MergeOperationOutput* merge_out) const override;
+  bool FullMergeV2(const MergeOperationInput& merge_in,
+                   MergeOperationOutput* merge_out) const override;
 
-  virtual bool PartialMerge(const Slice& key,
-                            const Slice& left_operand,
-                            const Slice& right_operand,
-                            std::string* new_value,
-                            Logger* logger) const override;
+  bool PartialMerge(const Slice& key, const Slice& left_operand,
+                    const Slice& right_operand, std::string* new_value,
+                    Logger* logger) const override;
 };
 
 }  // namespace rocksdb
-
-#endif  // STORAGE_ROCKSDB_INCLUDE_MERGE_OPERATOR_H_