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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#pragma once
#include <cstddef>
#include <cstdint>
namespace vespalib { class asciistream; }
namespace vespalib::datastore {
class EntryRef {
protected:
uint32_t _ref;
public:
EntryRef() noexcept : _ref(0u) { }
explicit EntryRef(uint32_t ref_) noexcept : _ref(ref_) { }
uint32_t ref() const noexcept { return _ref; }
uint32_t hash() const noexcept { return _ref; }
bool valid() const noexcept { return _ref != 0u; }
uint32_t buffer_id(uint32_t offset_bits) const noexcept { return _ref >> offset_bits; }
bool operator==(const EntryRef &rhs) const noexcept { return _ref == rhs._ref; }
bool operator!=(const EntryRef &rhs) const noexcept { return _ref != rhs._ref; }
bool operator <(const EntryRef &rhs) const noexcept { return _ref < rhs._ref; }
bool operator <=(const EntryRef &rhs) const noexcept { return _ref <= rhs._ref; }
};
/**
* Class for entry reference where we use OffsetBits bits for offset into buffer,
* and (32 - OffsetBits) bits for buffer id.
**/
template <uint32_t OffsetBits, uint32_t BufferBits = 32u - OffsetBits>
class EntryRefT : public EntryRef {
public:
static constexpr uint32_t offset_bits = OffsetBits;
EntryRefT() noexcept : EntryRef() {}
EntryRefT(size_t offset_, uint32_t bufferId_) noexcept;
EntryRefT(const EntryRef & ref_) noexcept : EntryRef(ref_.ref()) {}
size_t offset() const noexcept { return _ref & (offsetSize() - 1); }
uint32_t bufferId() const noexcept { return _ref >> OffsetBits; }
static constexpr size_t offsetSize() noexcept { return 1ul << OffsetBits; }
static constexpr uint32_t numBuffers() noexcept { return 1 << BufferBits; }
};
vespalib::asciistream& operator<<(vespalib::asciistream& os, const EntryRef& ref);
}
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