shm/Project4/size_map.cc

#include "size_map.h"
#include "shm_helper.h"
#include "shm_manager.h"
#include "shm_config.h"
namespace bg
{
    namespace detail
    {

        bool SizeMap::Init()
        {
            // ·ÖÒ³
            size_t size = 8;
            size_t class_cnt = 0;
            size_t index_total = 1;
            size_t index = 0;
            do
            {
                size_t alig_size = bg::detail::SizeMap::CalcAlignment(size);
                if(size)
                {
                    class_cnt = CLASS_TOTAL_BYTES / size;
                    if(class_cnt)
                    {
                        class_cnt = std::min<size_t>(MAX_CLASSS, class_cnt);
                        class_cnt >>= 2;
                    }
                }
                size_t alig_page_byte = 0LL;
                do
                {
                    for(alig_page_byte += PAGE_BYTES; alig_page_byte % size > alig_page_byte >> 3; alig_page_byte += PAGE_BYTES);
                } while(alig_page_byte / size < class_cnt);

                size_t  page_cnt = BYTES_TO_PAGES(alig_page_byte);
                if(index_total > 1 && page_cnt == m_class_to_pages[index_total - 1]
                  && alig_page_byte / size == alig_page_byte / m_class_to_size[index_total - 1])
                {
                    m_class_to_size[index_total - 1] = size;
                }
                else
                {
                    m_class_to_pages[index_total] = page_cnt;
                    m_class_to_size[index_total] = size;
                    index_total++;
                }

                size += alig_size;

            } while(size <= CLASS_MAX_BYTES);


            if(index_total > CLASS_MAX_COUNT)
            {
                SHM_WARN("too many size classes, found: %u, max: %u", index_total, CLASS_MAX_COUNT);
            }
            else
            {
                if(index_total > 1u)
                {
                    size = 0;
                    for(char i = 1; i < index_total; ++i)
                    {
                        for(size_t j = m_class_to_size[i]; j >= size; size += SMALL_CALIGNMENT)
                        {
                            if(size <= BYTES_COMP_VALUE)
                            {
                                m_index_to_class[SMALL_BYTES_TO_INDEX(size)] = i;
                            }
                            else
                            {
                                m_index_to_class[BIG_BYTES_TO_INDEX(size)] = i;
                            }
                        }
                    }

                }

                size = 0;

                while(true)
                {
                    if(size <= BYTES_COMP_VALUE)
                    {
                        index = m_index_to_class[SMALL_BYTES_TO_INDEX(size)];
                    }
                    else
                    {
                        index = m_index_to_class[BIG_BYTES_TO_INDEX(size)];
                    }

                    if(index >= index_total)
                    {
                        goto FAIL;
                    }

                    size_t value = this->m_class_to_size[index];
                    if(index > 1)
                    {
                        if(m_class_to_size[index - 1] >= size)
                        {
                            SHM_WARN("size class too large, class: %zu, size: %zu", index, size);
                            return false;
                        }
                    }

                    if(!value)
                    {
                        SHM_WARN("bad class: %zu, size: %zu", index, size);
                        return false;
                    }

                    if(size > BYTES_COMP_VALUE)
                    {
                        size += SMALL_BYTES_TO_INDEX(BYTES_COMP_VALUE);
                        if(size <= CLASS_MAX_BYTES)
                        {
                            continue;
                        }
                        return true;
                    }
                    size += SMALL_CALIGNMENT;

                }
            }
FAIL:
            SHM_WARN("bad size class, class: %u, size: %lu", index, size);
            return false;
        }

        size_t SizeMap::CalcAlignment(size_t bytes)
        {
            size_t result; // rax

            char bit{};
            result = PAGE_BYTES;
            if(bytes < (PAGE_BYTES << 4))
            {
                if(bytes <= 0x7F)
                {
                    return  (-(int64_t)(bytes < 0x10) & 0xFFFFFFFFFFFFFFF8LL) + 16;
                }
                else
                {
                    for(int i = 16; i >= 1; i >>= 1)
                    {
                        size_t temp = bytes >> i;
                        if(temp)
                        {
                            bit += i;
                            bytes = temp;
                        }
                    }

                    result = (1ul << bit) >> 3;
                    return result;
                }
            }
            return result;
        }


    }
}