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https://github.com/dragonflydb/dragonfly.git
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46093e33ff
* chore: Fix errors/warnings in GCC13 * OpResult: Add non const overloads to */-> so we can std::move from the result * Run clang-format on file
62 lines
1.6 KiB
C++
62 lines
1.6 KiB
C++
// Copyright 2022, DragonflyDB authors. All rights reserved.
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// See LICENSE for licensing terms.
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//
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#pragma once
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#include <cstdint>
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#include <string_view>
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#include "core/core_types.h"
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namespace dfly {
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// blob strings of upto ~64KB. Small sizes are probably predominant
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// for in-memory workloads, especially for keys.
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// Please note that this class does not have automatic constructors and destructors, therefore
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// it requires explicit management.
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class SmallString {
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static constexpr unsigned kPrefLen = 10;
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public:
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static void InitThreadLocal(void* heap);
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static size_t UsedThreadLocal();
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void Reset() {
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size_ = 0;
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}
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// Returns malloc used.
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size_t Assign(std::string_view s);
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void Free();
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bool Equal(std::string_view o) const;
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bool Equal(const SmallString& mps) const;
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uint16_t size() const {
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return size_;
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}
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uint64_t HashCode() const;
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// I am lying here. we should use mi_malloc_usable size really.
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uint16_t MallocUsed() const;
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void Get(std::string* dest) const;
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// returns 1 or 2 slices representing this small string.
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// Guarantees zero copy, i.e. dest will not point to any of external buffers.
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// With current implementation, it will return 2 slices for a non-empty string.
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unsigned GetV(std::string_view dest[2]) const;
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bool DefragIfNeeded(float ratio);
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private:
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// prefix of the string that is broken down into 2 parts.
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char prefix_[kPrefLen];
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uint32_t small_ptr_; // 32GB capacity because we ignore 3 lsb bits (i.e. x8).
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uint16_t size_; // uint16_t - total size (including prefix)
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} __attribute__((packed));
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} // namespace dfly
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