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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>
#include <iosfwd>
namespace vespalib {
class AddressSpace;
class MemoryUsage;
}
namespace vespalib::datastore {
class CompactionSpec;
/*
* Class describing compaction strategy for a compactable data structure.
*/
class CompactionStrategy
{
public:
static constexpr size_t DEAD_BYTES_SLACK = 0x10000u;
static constexpr size_t DEAD_ADDRESS_SPACE_SLACK = 0x10000u;
private:
float _maxDeadBytesRatio; // Max ratio of dead bytes before compaction
float _maxDeadAddressSpaceRatio; // Max ratio of dead address space before compaction
float _active_buffers_ratio; // Ratio of active buffers to compact for each reason (memory usage, address space usage)
uint32_t _max_buffers; // Max number of buffers to compact for each reason (memory usage, address space usage)
bool should_compact_memory(size_t used_bytes, size_t dead_bytes) const noexcept {
return ((dead_bytes >= DEAD_BYTES_SLACK) &&
(dead_bytes > used_bytes * getMaxDeadBytesRatio()));
}
bool should_compact_address_space(size_t used_address_space, size_t dead_address_space) const noexcept {
return ((dead_address_space >= DEAD_ADDRESS_SPACE_SLACK) &&
(dead_address_space > used_address_space * getMaxDeadAddressSpaceRatio()));
}
public:
CompactionStrategy() noexcept
: _maxDeadBytesRatio(0.05),
_maxDeadAddressSpaceRatio(0.2),
_active_buffers_ratio(0.1),
_max_buffers(1)
{ }
CompactionStrategy(float maxDeadBytesRatio, float maxDeadAddressSpaceRatio) noexcept
: _maxDeadBytesRatio(maxDeadBytesRatio),
_maxDeadAddressSpaceRatio(maxDeadAddressSpaceRatio),
_active_buffers_ratio(0.1),
_max_buffers(1)
{ }
CompactionStrategy(float maxDeadBytesRatio, float maxDeadAddressSpaceRatio, uint32_t max_buffers, float active_buffers_ratio) noexcept
: _maxDeadBytesRatio(maxDeadBytesRatio),
_maxDeadAddressSpaceRatio(maxDeadAddressSpaceRatio),
_active_buffers_ratio(active_buffers_ratio),
_max_buffers(max_buffers)
{ }
double getMaxDeadBytesRatio() const noexcept { return _maxDeadBytesRatio; }
double getMaxDeadAddressSpaceRatio() const noexcept { return _maxDeadAddressSpaceRatio; }
uint32_t get_max_buffers() const noexcept { return _max_buffers; }
double get_active_buffers_ratio() const noexcept { return _active_buffers_ratio; }
bool operator==(const CompactionStrategy & rhs) const noexcept {
return (_maxDeadBytesRatio == rhs._maxDeadBytesRatio) &&
(_maxDeadAddressSpaceRatio == rhs._maxDeadAddressSpaceRatio) &&
(_max_buffers == rhs._max_buffers) &&
(_active_buffers_ratio == rhs._active_buffers_ratio);
}
bool operator!=(const CompactionStrategy & rhs) const noexcept { return !(operator==(rhs)); }
bool should_compact_memory(const MemoryUsage& memory_usage) const noexcept;
bool should_compact_address_space(const AddressSpace& address_space) const noexcept;
CompactionSpec should_compact(const MemoryUsage& memory_usage, const AddressSpace& address_space) const noexcept;
static CompactionStrategy make_compact_all_active_buffers_strategy() noexcept;
};
std::ostream& operator<<(std::ostream& os, const CompactionStrategy& compaction_strategy);
}
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