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rocksdb/db/merge_operator.cc

51 lines
1.4 KiB

/**
* Back-end implementation details specific to the Merge Operator.
*
* @author Deon Nicholas (dnicholas@fb.com)
* Copyright 2013 Facebook
*/
#include "rocksdb/merge_operator.h"
namespace rocksdb {
// Given a "real" merge from the library, call the user's
// associative merge function one-by-one on each of the operands.
// NOTE: It is assumed that the client's merge-operator will handle any errors.
bool AssociativeMergeOperator::FullMerge(
const Slice& key,
const Slice* existing_value,
const std::deque<std::string>& operand_list,
std::string* new_value,
Logger* logger) const {
// Simply loop through the operands
Slice temp_existing;
std::string temp_value;
for (const auto& operand : operand_list) {
Slice value(operand);
if (!Merge(key, existing_value, value, &temp_value, logger)) {
return false;
}
swap(temp_value, *new_value);
temp_existing = Slice(*new_value);
existing_value = &temp_existing;
}
// The result will be in *new_value. All merges succeeded.
return true;
}
// Call the user defined simple merge on the operands;
// NOTE: It is assumed that the client's merge-operator will handle any errors.
bool AssociativeMergeOperator::PartialMerge(
const Slice& key,
const Slice& left_operand,
const Slice& right_operand,
std::string* new_value,
Logger* logger) const {
return Merge(key, &left_operand, right_operand, new_value, logger);
}
} // namespace rocksdb