libcruft-util/alloc/chunked.cpp

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2021-01-11 14:39:19 +11:00
/*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/.
*
* Copyright 2021, Danny Robson <danny@nerdcruft.net>
*/
#include "chunked.hpp"
#include "../log.hpp"
#include "../maths.hpp"
#include "../pointer.hpp"
2021-01-11 14:39:19 +11:00
using cruft::alloc::chunked;
///////////////////////////////////////////////////////////////////////////////
chunked::chunked (std::size_t initial_size)
: chunked (initial_size, DEFAULT_CHUNK_SIZE)
{ ; }
//-----------------------------------------------------------------------------
chunked::chunked (std::size_t initial_size, std::size_t _chunk_size)
: m_chunk (_chunk_size)
{
m_chunk = cruft::max (m_chunk, sizeof (node_t));
auto const initial_arenas = cruft::divup (initial_size, m_chunk);
m_data.resize (initial_arenas);
for (auto &i: m_data) {
i.data = new std::byte[m_chunk];
*i.node = {
.size = m_chunk,
.next = nullptr
};
}
}
///////////////////////////////////////////////////////////////////////////////
void*
chunked::do_allocate (std::size_t size, std::size_t alignment)
{
// Find a chunk that can service this allocation.
for (auto &i: m_data) {
if (i.node->size < size + alignment)
continue;
auto base = cruft::align::up (i.data, alignment);
std::byte* newbase = base + size;
if (newbase > i.data + i.node->size)
continue;
std::size_t newsize = i.data + i.node->size - newbase;
i.data = newbase;
i.node->size = newsize;
return base;
}
// No chunk was found. We need to allocate a new chunk of at least enough size.
std::size_t allocation_size = cruft::max (size + alignment, m_chunk);
std::unique_ptr<std::byte[]> ptr (new std::byte[allocation_size]);
m_data.push_back (arena { ptr.get () });
m_data.back ().node->size = allocation_size;
m_data.back ().node->next = m_data.back ().node;
ptr.release ();
return do_allocate (size, alignment);
}
//-----------------------------------------------------------------------------
void
chunked::do_deallocate (void *p, std::size_t bytes, std::size_t alignment)
{
(void)p;
(void)bytes;
(void)alignment;
LOG_WARNING ("chunked::do_deallocate is unimplemented");
}
//-----------------------------------------------------------------------------
bool
chunked::do_is_equal (memory_resource const &) const noexcept
{
warn ("chunked::do_is_equal is unimplemented");
return false;
}