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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 <vespa/vespalib/util/size_literals.h>
#include <utility>
#include <cstddef>
namespace vespalib::alloc {
class PtrAndSize {
public:
PtrAndSize() noexcept : _ptr(nullptr), _sz(0ul) {}
PtrAndSize(void * ptr, size_t sz) noexcept;
void * get() const noexcept { return _ptr; }
size_t size() const noexcept { return _sz; }
void reset() noexcept { _ptr = nullptr; _sz = 0ul; }
private:
void * _ptr;
size_t _sz;
};
/*
* Abstract base class for allocating memory at a low level.
*/
class MemoryAllocator {
public:
static constexpr size_t PAGE_SIZE = 4_Ki;
static constexpr size_t HUGEPAGE_SIZE = 2_Mi;
MemoryAllocator(const MemoryAllocator &) = delete;
MemoryAllocator & operator = (const MemoryAllocator &) = delete;
MemoryAllocator() noexcept = default;
virtual ~MemoryAllocator() = default;
virtual PtrAndSize alloc(size_t sz) const = 0;
virtual void free(PtrAndSize alloc) const noexcept = 0;
// Allow for freeing memory there size is the size requested, and not the size allocated.
virtual void free(void * ptr, size_t sz) const noexcept {
free(PtrAndSize(ptr, sz));
}
/*
* If possible the allocations will be resized. If it was possible it will return the real size,
* if not it shall return 0.
* Afterwards you have a buffer that can be accessed up to the new size.
* The old buffer is unmodified up to the new size.
* This is thread safe and at no point will data in the buffer be invalid.
* @param newSize The desired new size
* @return true if successful.
*/
virtual size_t resize_inplace(PtrAndSize current, size_t newSize) const = 0;
static size_t roundUpToHugePages(size_t sz) noexcept {
return (sz+(HUGEPAGE_SIZE-1)) & ~(HUGEPAGE_SIZE-1);
}
static const MemoryAllocator * select_allocator();
static const MemoryAllocator * select_allocator(size_t mmapLimit, size_t alignment);
};
}
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