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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 "memory_allocator.h"
#include "file_area_freelist.h"
#include <vespa/vespalib/io/fileutil.h>
#include <vespa/vespalib/stllike/hash_map.h>
#include <vespa/vespalib/stllike/string.h>
#include <vespa/vespalib/util/size_literals.h>
#include <map>
namespace vespalib::alloc {
/*
* Class handling memory allocations backed by one or more files.
* Not reentrant or thread safe. Should not be destructed before all allocations
* have been freed.
*
* Memory allocations smaller than _small_limit use portions of
* premmapped areas to reduce the total number of memory mappings.
*/
class MmapFileAllocator : public MemoryAllocator {
struct SizeAndOffset {
size_t size;
uint64_t offset;
SizeAndOffset()
: SizeAndOffset(0u, 0u)
{
}
SizeAndOffset(size_t size_in, uint64_t offset_in)
: size(size_in),
offset(offset_in)
{
}
};
using Allocations = hash_map<void *, SizeAndOffset>;
const vespalib::string _dir_name;
const uint32_t _small_limit;
const uint32_t _premmap_size;
mutable File _file;
mutable uint64_t _end_offset;
mutable Allocations _allocations;
mutable FileAreaFreeList _freelist;
mutable Allocations _small_allocations;
mutable FileAreaFreeList _small_freelist;
mutable std::map<uint64_t, void*> _premmapped_areas;
uint64_t alloc_area(size_t sz) const;
PtrAndSize alloc_large(size_t size) const;
PtrAndSize alloc_small(size_t size) const;
void free_large(PtrAndSize alloc) const noexcept;
void free_small(PtrAndSize alloc) const noexcept;
void* map_premapped_offset_to_ptr(uint64_t offset, size_t size) const;
uint64_t remove_allocation(PtrAndSize alloc, Allocations& allocations) const noexcept;
public:
static constexpr uint32_t default_small_limit = 128_Ki;
static constexpr uint32_t default_premmap_size = 1_Mi;
MmapFileAllocator(const vespalib::string& dir_name);
MmapFileAllocator(const vespalib::string& dir_name, uint32_t small_limit, uint32_t premmap_size);
~MmapFileAllocator();
PtrAndSize alloc(size_t sz) const override;
void free(PtrAndSize alloc) const noexcept override;
size_t resize_inplace(PtrAndSize, size_t) const override;
// For unit test
size_t get_end_offset() const noexcept { return _end_offset; }
};
}
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