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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-21 11:54:28 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-21 11:54:28 +0000 |
commit | e6918187568dbd01842d8d1d2c808ce16a894239 (patch) | |
tree | 64f88b554b444a49f656b6c656111a145cbbaa28 /src/rocksdb/db/merge_context.h | |
parent | Initial commit. (diff) | |
download | ceph-e6918187568dbd01842d8d1d2c808ce16a894239.tar.xz ceph-e6918187568dbd01842d8d1d2c808ce16a894239.zip |
Adding upstream version 18.2.2.upstream/18.2.2
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | src/rocksdb/db/merge_context.h | 147 |
1 files changed, 147 insertions, 0 deletions
diff --git a/src/rocksdb/db/merge_context.h b/src/rocksdb/db/merge_context.h new file mode 100644 index 000000000..8a7b07290 --- /dev/null +++ b/src/rocksdb/db/merge_context.h @@ -0,0 +1,147 @@ +// 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 <algorithm> +#include <memory> +#include <string> +#include <vector> + +#include "rocksdb/slice.h" + +namespace ROCKSDB_NAMESPACE { + +const std::vector<Slice> empty_operand_list; + +// The merge context for merging a user key. +// When doing a Get(), DB will create such a class and pass it when +// issuing Get() operation to memtables and version_set. The operands +// will be fetched from the context when issuing partial of full merge. +class MergeContext { + public: + // Clear all the operands + void Clear() { + if (operand_list_) { + operand_list_->clear(); + copied_operands_->clear(); + } + } + + // Push a merge operand + void PushOperand(const Slice& operand_slice, bool operand_pinned = false) { + Initialize(); + SetDirectionBackward(); + + if (operand_pinned) { + operand_list_->push_back(operand_slice); + } else { + // We need to have our own copy of the operand since it's not pinned + copied_operands_->emplace_back( + new std::string(operand_slice.data(), operand_slice.size())); + operand_list_->push_back(*copied_operands_->back()); + } + } + + // Push back a merge operand + void PushOperandBack(const Slice& operand_slice, + bool operand_pinned = false) { + Initialize(); + SetDirectionForward(); + + if (operand_pinned) { + operand_list_->push_back(operand_slice); + } else { + // We need to have our own copy of the operand since it's not pinned + copied_operands_->emplace_back( + new std::string(operand_slice.data(), operand_slice.size())); + operand_list_->push_back(*copied_operands_->back()); + } + } + + // return total number of operands in the list + size_t GetNumOperands() const { + if (!operand_list_) { + return 0; + } + return operand_list_->size(); + } + + // Get the operand at the index. + Slice GetOperand(int index) const { + assert(operand_list_); + + SetDirectionForward(); + return (*operand_list_)[index]; + } + + // Same as GetOperandsDirectionForward + // + // Note that the returned reference is only good until another call + // to this MergeContext. If the returned value is needed for longer, + // a copy must be made. + const std::vector<Slice>& GetOperands() const { + return GetOperandsDirectionForward(); + } + + // Return all the operands in the order as they were merged (passed to + // FullMerge or FullMergeV2) + // + // Note that the returned reference is only good until another call + // to this MergeContext. If the returned value is needed for longer, + // a copy must be made. + const std::vector<Slice>& GetOperandsDirectionForward() const { + if (!operand_list_) { + return empty_operand_list; + } + + SetDirectionForward(); + return *operand_list_; + } + + // Return all the operands in the reversed order relative to how they were + // merged (passed to FullMerge or FullMergeV2) + // + // Note that the returned reference is only good until another call + // to this MergeContext. If the returned value is needed for longer, + // a copy must be made. + const std::vector<Slice>& GetOperandsDirectionBackward() const { + if (!operand_list_) { + return empty_operand_list; + } + + SetDirectionBackward(); + return *operand_list_; + } + + private: + void Initialize() { + if (!operand_list_) { + operand_list_.reset(new std::vector<Slice>()); + copied_operands_.reset(new std::vector<std::unique_ptr<std::string>>()); + } + } + + void SetDirectionForward() const { + if (operands_reversed_ == true) { + std::reverse(operand_list_->begin(), operand_list_->end()); + operands_reversed_ = false; + } + } + + void SetDirectionBackward() const { + if (operands_reversed_ == false) { + std::reverse(operand_list_->begin(), operand_list_->end()); + operands_reversed_ = true; + } + } + + // List of operands + mutable std::unique_ptr<std::vector<Slice>> operand_list_; + // Copy of operands that are not pinned. + std::unique_ptr<std::vector<std::unique_ptr<std::string>>> copied_operands_; + mutable bool operands_reversed_ = true; +}; + +} // namespace ROCKSDB_NAMESPACE |