// Copyright (c) 2016, the SDSL Project Authors.  All rights reserved.
// Please see the AUTHORS file for details.  Use of this source code is governed
// by a BSD license that can be found in the LICENSE file.
/*!\file memory_management.hpp
 * \brief memory_management.hpp contains two function for allocating and deallocating memory
 * \author Simon Gog
 */
#ifndef INCLUDED_SDSL_MEMORY_MANAGEMENT
#define INCLUDED_SDSL_MEMORY_MANAGEMENT

#include <algorithm>
#include <chrono>

#include <sdsl/bits.hpp>
#include <sdsl/config.hpp>
#include <sdsl/memory_tracking.hpp>
#include <sdsl/ram_fs.hpp>
#include <sdsl/uintx_t.hpp>

namespace sdsl
{

inline void output_event_json(std::ostream & out, const mm_event & ev, const tracker_storage & m)
{
    using namespace std::chrono;
    out << "\t\t"
        << "\"name\" : "
        << "\"" << ev.name << "\",\n";
    out << "\t\t"
        << "\"usage\" : ["
        << "\n";
    for (size_t j = 0; j < ev.allocations.size(); j++)
    {
        out << "\t\t\t[" << duration_cast<milliseconds>(ev.allocations[j].timestamp - m.start_log).count() << ","
            << ev.allocations[j].usage << "]";
        if (j + 1 < ev.allocations.size()) { out << ",\n"; }
        else
        {
            out << "\n";
        }
    }
    out << "\t\t"
        << "]\n";
}

template <>
inline void write_mem_log<JSON_FORMAT>(std::ostream & out, const tracker_storage & m)
{
    auto events = m.completed_events;
    std::sort(events.begin(), events.end());

    // output
    out << "[\n";
    for (size_t i = 0; i < events.size(); i++)
    {
        out << "\t{\n";
        output_event_json(out, events[i], m);
        if (i < events.size() - 1) { out << "\t},\n"; }
        else
        {
            out << "\t}\n";
        }
    }
    out << "]\n";
}

inline std::string create_mem_html_header()
{
    std::stringstream jsonheader;
    jsonheader << "<html>\n"
               << "<head>\n"
               << "<meta charset=\"utf-8\">\n"
               << "<style>\n"
               << "    body { font: 11px sans-serif; }\n"
               << "    .rule { height: 90%; position: absolute; border-right: 1px dotted #000; "
                  "text-align: right; }\n"
               << "</style>\n"
               << "<title>sdsl memory usage visualization</title>\n"
               << "<script src=\"http://d3js.org/d3.v3.js\"></script>\n"
               << "</head>\n"
               << "<body marginwidth=\"0\" marginheight=\"0\">\n"
               << "<button><a id=\"download\">Save as SVG</a></button>\n"
               << "<div class=\"chart\"><div id=\"visualization\"></div></div><script>\n";
    return jsonheader.str();
}

inline std::string create_mem_js_body(const std::string & jsonObject)
{
    std::stringstream jsonbody;
    jsonbody << "var events = " << jsonObject << ";\n"
             << "var w = window,d = document,e = d.documentElement,g = d.getElementsByTagName('body')[0],\n"
             << "  xw = w.innerWidth || e.clientWidth || g.clientWidth,\n"
             << "  yh = w.innerHeight || e.clientHeight || g.clientHeight;\n\n"
             << "var margin = {top: 20,right: 80,bottom: 120,left: 120},\n"
             << "  width = xw - margin.left - margin.right,height = yh - margin.top - margin.bottom;\n"
             << "var x = d3.scale.linear().range([0, width]);\n"
             << "var y = d3.scale.linear().range([height, 0]);\n"
             << "var xAxis = d3.svg.axis().scale(x).orient(\"bottom\");\n"
             << "var yAxis = d3.svg.axis().scale(y).orient(\"left\").ticks(5);\n"
             << "var color = d3.scale.category10();\n"
             << "var x_max = d3.max(events, function (d) { return d3.max(d.usage, function (u) { return u[0] / "
                "1000;})})\n"
             << "var y_max = d3.max(events, function (d) { return d3.max(d.usage, function (u) { return 1.1 * u[1] / "
                "(1024 * 1024);})})\n"
             << "var peak = d3.max(events, function (d) { return d3.max(d.usage, function (u) { return u[1]; })})\n"
             << "var data = []\nevents.forEach(function (d) { data = data.concat(d.usage); });\n"
             << "var peakelem = data.filter(function (a) { return a[1] == peak; });\n"
             << "var peakelem = peakelem.splice(0,1);\n"
             << "x.domain([0, x_max]);\n y.domain([0, y_max]);\n"
             << "var svg = d3.select(\"#visualization\").append(\"svg\")\n"
             << "  .attr(\"width\", width + margin.left + margin.right)\n"
             << "  .attr(\"height\", height + margin.top + margin.bottom)\n"
             << "  .attr(\"xmlns\", \"http://www.w3.org/2000/svg\")\n"
             << "  .append(\"g\").attr(\"transform\",\"translate(\" + margin.left + \",\" + margin.top + \")\");\n\n"
             << "  svg.append(\"g\").attr(\"class\", \"xaxis\").attr(\"transform\", \"translate(0,\" + height + "
                "\")\")\n"
             << "  .call(xAxis).append(\"text\").attr(\"text-anchor\", \"end\")\n"
             << "  .attr(\"shape-rendering\", \"crispEdges\").attr(\"x\", width / 2 + 50).attr(\"y\", "
                "70).attr(\"shape-rendering\", \"crispEdges\")\n"
             << "  .attr(\"font-family\", \"sans-serif\").attr(\"font-size\", \"20px\").text(\"Time (seconds)\");\n\n"
             << "svg.append(\"g\").attr(\"class\", \"yaxis\").call(yAxis).append(\"text\").attr(\"transform\", "
                "\"rotate(-90)\").attr(\"x\", -height / 2 + 50)\n"
             << "  .attr(\"y\", -80).attr(\"shape-rendering\", \"crispEdges\").attr(\"font-family\", "
                "\"sans-serif\").attr(\"font-size\", \"20px\").style(\"text-anchor\", \"end\")\n"
             << "  .text(\"Memory Usage (MiB)\");\n\n"
             << "svg.selectAll(\".tick text\").style(\"font-size\", \"20px\");\n"
             << "svg.selectAll(\".xaxis .tick text\").attr(\"dy\", 23);\nsvg.selectAll(\".yaxis .tick "
                "text\").attr(\"dx\", -10);\n"
             << "svg.selectAll(\"line\").attr(\"fill\", \"none\").attr(\"stroke\", "
                "\"black\")\nsvg.selectAll(\"path\").attr(\"fill\", \"none\").attr(\"stroke\", \"black\")\n\n"
             << "svg.selectAll(\"line.horizontalGrid\").data(y.ticks(5)).enter().append(\"line\")\n"
             << "  .attr({\"class\": \"horizontalGrid\",\"x1\": 0,\"x2\": width,\"y1\": function (d) { return y(d);},\n"
             << "     \"y2\": function (d) { return y(d); }, \"fill\": \"none\", \"shape-rendering\": \"crispEdges\",\n"
             << "     \"stroke\": \"lightgrey\",\"stroke-dasharray\": \"10,10\",\"stroke-width\": \"1.5px\"});\n\n"
             << "var area = d3.svg.area().x(function (d) { return x(d[0] / 1000);}).y0(height).y1(function (d) { "
                "return y(d[1] / (1024 * 1024))});\n\n"
             << "var ev = svg.selectAll(\".event\").data(events).enter().append(\"svg:path\").attr(\"class\", "
                "\"area\")\n"
             << "  .attr(\"fill\", function (d) { return d3.rgb(color(d.name)); })\n"
             << "  .attr(\"d\", function (d) { return area(d.usage) })\n"
             << "  .style(\"stroke\", function (d) { return d3.rgb(color(d.name)).darker(2);}).style(\"stroke-width\", "
                "\"2px\")\n\n"
             << "svg.selectAll(\".dot\").data(peakelem).enter().append(\"circle\").attr(\"r\", 3).attr(\"fill\", "
                "\"red\")\n"
             << "  .attr(\"cx\", function (d) {return x(d[0] / 1000)})\n"
             << "  .attr(\"cy\", function (d) {return y(d[1] / (1024 * 1024))})\n"
             << "  .attr(\"fill\", \"red\").attr(\"stroke-width\", 2).attr(\"stroke\", \"#cc0000\")\n\n"
             << "svg.selectAll(\".dot\").data(peakelem).enter().append(\"svg:text\")\n"
             << "  .attr(\"x\", function (d) {return x(d[0] / 1000)}).attr(\"y\", function (d) {return y(d[1] / (1024 "
                "* 1024) * 1.025)})\n"
             << "  .text(function (d) {return \"Peak Usage: \" + Math.round(d[1] / (1024 * 1024)) + \" MB\"})\n"
             << "  .attr(\"font-size\", 12).attr(\"fill\", \"red\");\n\n"
             << "svg.selectAll(\".dot\").data(peakelem).enter().append(\"circle\")\n"
             << "  .attr(\"r\", 5).attr(\"fill\", \"red\")\n"
             << "  .attr(\"cx\", function (d) {return x(d[0] / 1000)})\n"
             << "  .attr(\"cy\", function (d) {return y(d[1] / (1024 * 1024))})\n"
             << "  .attr(\"fill\", \"none\").attr(\"stroke-width\", 2).attr(\"stroke\", "
                "\"#cc0000\").each(pulsepeak());\n\n"
             << "function pulsepeak() { return function (d, i, j) {\n"
             << "  d3.select(this).attr(\"r\", 5).style(\"stroke-opacity\", 1.0).transition()\n"
             << "    .ease(\"linear\").duration(1000).attr(\"r\", 10).style(\"stroke-opacity\", 0.0).each(\"end\", "
                "pulsepeak());};}\n\n"
             << "var vertical = d3.select(\".chart\").append(\"div\").attr(\"class\", \"remove\")\n"
             << "  .style(\"position\", \"absolute\").style(\"z-index\", \"19\").style(\"width\", \"1px\")\n"
             << "  .style(\"height\", height - margin).style(\"top\", \"30px\").style(\"bottom\", \"50px\")\n"
             << "  .style(\"left\", \"0px\").style(\"opacity\", \"0.4\").style(\"background\", \"black\");\n\n"
             << "var tooltip = d3.select(\".chart\").append(\"div\").attr(\"class\", \"remove\")\n"
             << "  .style(\"position\", \"absolute\").style(\"z-index\", \"20\").style(\"visibility\", "
                "\"hidden\").style(\"top\", \"10px\");\n\n"
             << "var circle = svg.append(\"circle\").attr(\"cx\", 100).attr(\"cy\", 350).attr(\"r\", 3).attr(\"fill\", "
                "\"black\").style(\"opacity\", \"0\")\n\n"
             << "d3.select(\"svg\").on(\"mousemove\", function () {\n"
             << "  mousex = d3.mouse(this);\n"
             << "  if (mousex[0] < margin.left + 3 || mousex[0] >= xw - margin.right) {\n"
             << "    vertical.style(\"opacity\", \"0\"); tooltip.style(\"opacity\", \"0\"); circle.style(\"opacity\", "
                "\"0\")\n"
             << "  } else {\n"
             << "    var xvalue = x.invert(mousex[0] - margin.left); var pos = findPosition(xvalue)\n"
             << "    vertical.style(\"opacity\", \"0.4\"); tooltip.style(\"opacity\", \"1\"); "
                "circle.style(\"opacity\", \"1\")\n"
             << "    circle.attr(\"cx\", pos.x).attr(\"cy\", pos.y); vertical.style(\"left\", mousex[0] + "
                "\"px\");tooltip.style(\"left\", mousex[0] + 15 + \"px\")\n"
             << "    tooltip.html(\"<p>\" + xvalue.toFixed(2) + \" Seconds <br>\" + Math.round(pos.mem) + \" MiB <br> "
                "\" + pos.name + "
             << "  \"<br> Phase Time: \" + pos.ptime + \" Seconds </p>\").style(\"visibility\", \"visible\");\n"
             << "  }\n})"
             << ".on(\"mouseover\", function () {\n"
             << "  mousex = d3.mouse(this);\n  if (mousex[0] < margin.left + 3 || mousex[0] > xw - margin.right) {\n"
             << "    vertical.style(\"opacity\", \"0\")\n  } else {\n    vertical.style(\"opacity\", "
                "\"0.4\");vertical.style(\"left\", mousex[0] + 7 + \"px\")\n}})\n"
             << "d3.select(\"#download\").on(\"click\", function () {\n"
             << "d3.select(this).attr(\"href\", 'data:application/octet-stream;base64,' + "
                "btoa(d3.select(\"#visualization\").html())).attr(\"download\", \"viz.svg\")})\n\n"
             << "function "
                "findPosition(e){correctArea=d3.selectAll(\".area\").filter(function(t){if(t.usage[0][0]<=e*1e3&&t."
                "usage[t.usage.length-1][0]>=e*1e3){return true}"
             << "return false});if(correctArea.empty()){return 0}var t=new "
                "Array;correctArea[0].forEach(function(n){t.push(findYValueinArea(n,e))});"
             << "max_elem=d3.max(t,function(e){return e.mem});var n=t.filter(function(e){return "
                "e.mem==max_elem});return n[0]}"
             << "function findYValueinArea(e,t){len=e.getTotalLength();var n=0;var r=len;for(var i=0;i<=len;i+=50){var "
                "s=e.getPointAtLength(i);"
             << "var o=x.invert(s.x);var u=y.invert(s.y);if(u>0&&o>t){n=Math.max(0,i-50);r=i;break}}var "
                "a=e.getPointAtLength(0);"
             << "var f=1;while(n<r){var "
                "l=(r+n)/"
                "2;a=e.getPointAtLength(l);target_x=x.invert(a.x);if((l==n||l==r)&&Math.abs(target_x-t)>.01){break}if("
                "target_x>t)r=l;"
             << "else if(target_x<t)n=l;else{break}if(f>50){break}f++}var c=new "
                "function(){this.mem=y.invert(a.y);this.name=e.__data__.name;"
             << "this.min=d3.min(e.__data__.usage,function(e){return "
                "e[0]/1e3});this.max=d3.max(e.__data__.usage,function(e){return e[0]/1e3});"
             << "this.ptime=Math.round(this.max-this.min);this.x=a.x;this.y=a.y};return c}\n</script></body></html>";
    return jsonbody.str();
}

template <>
inline void write_mem_log<HTML_FORMAT>(std::ostream & out, const tracker_storage & m)
{
    std::stringstream json_data;
    write_mem_log<JSON_FORMAT>(json_data, m);

    out << create_mem_html_header();
    out << create_mem_js_body(json_data.str());
}

#pragma pack(push, 1)
typedef struct mm_block
{
    size_t size;
    struct mm_block * next;
    struct mm_block * prev;
} mm_block_t;

typedef struct bfoot
{
    size_t size;
} mm_block_foot_t;
#pragma pack(pop)

#define ALIGNMENT sizeof(uint64_t)
#define ALIGNSPLIT(size) (((size)) & ~0x7)
#define ALIGN(size) (((size) + (ALIGNMENT - 1)) & ~0x7)
#define MM_BLOCK_OVERHEAD (sizeof(size_t) + sizeof(size_t))
#define MIN_BLOCKSIZE (ALIGN(sizeof(mm_block_t) + sizeof(mm_block_foot_t)))
#define UNMASK_SIZE(size) ((size) & ~1)
#define ISFREE(size) ((size)&1)
#define SETFREE(size) ((size) | 1)
#define SPLIT_THRESHOLD (MIN_BLOCKSIZE)

inline mm_block_t * block_cur(void * ptr)
{
    mm_block_t * bptr = (mm_block_t *)((uint8_t *)ptr - sizeof(size_t));
    return bptr;
}

/* given a block retrieve the previous block if any. nullptr otherwise */
inline mm_block_t * block_prev(mm_block_t * cur_bptr, mm_block_t * first)
{
    /* start of the heap? */
    if (cur_bptr == first) return nullptr;
    mm_block_foot_t * prev_foot = (mm_block_foot_t *)((uint8_t *)cur_bptr - sizeof(mm_block_foot_t));
    mm_block_t * prev_bptr = (mm_block_t *)((uint8_t *)cur_bptr - UNMASK_SIZE(prev_foot->size));
    return prev_bptr;
}

/* given a block retrieve the next block if any. nullptr otherwise */
inline mm_block_t * block_next(mm_block_t * cur_bptr, uint8_t * top)
{
    /* end of the heap? */
    if ((uint8_t *)((uint8_t *)cur_bptr + UNMASK_SIZE(cur_bptr->size)) >= top) return nullptr;

    mm_block_t * next_bptr = (mm_block_t *)((uint8_t *)cur_bptr + UNMASK_SIZE(cur_bptr->size));
    return next_bptr;
}

/* calculate the size of a memory block */
inline size_t block_size(void * ptr)
{
    mm_block_t * bptr = block_cur(ptr);
    return UNMASK_SIZE(bptr->size);
}

inline bool block_isfree(mm_block_t * ptr)
{
    return ((ptr->size) & 1ULL);
}

/* is the next block free */
inline bool block_nextfree(mm_block_t * ptr, uint8_t * top)
{
    mm_block_t * next = block_next(ptr, top);
    if (next && block_isfree(next)) return true;
    return false;
}

/* is the prev block free */
inline bool block_prevfree(mm_block_t * ptr, mm_block_t * begin)
{
    mm_block_t * prev = block_prev(ptr, begin);
    if (prev && block_isfree(prev)) return 1;
    return 0;
}

/* update the footer with a new size */
inline void foot_update(mm_block_t * ptr, size_t size)
{
    mm_block_foot_t * fptr = (mm_block_foot_t *)((uint8_t *)ptr + UNMASK_SIZE(size) - sizeof(mm_block_foot_t));
    fptr->size = size;
}

/* update the block with a new size */
inline void block_update(mm_block_t * ptr, size_t size)
{
    ptr->size = size;
    foot_update(ptr, size);
}

/* return the pointer to the "data" */
inline void * block_data(mm_block_t * ptr)
{
    return (void *)((uint8_t *)ptr + sizeof(size_t));
}

/* return size of the data that can be stored in the block */
inline size_t block_getdatasize(mm_block_t * ptr)
{
    size_t blocksize = UNMASK_SIZE(ptr->size);
    return blocksize - sizeof(size_t) - sizeof(mm_block_foot_t);
}

/* mark the block as free */
inline void block_markfree(mm_block_t * ptr)
{
    block_update(ptr, SETFREE(ptr->size));
}

/* mark the block as used */
inline void block_markused(mm_block_t * ptr)
{
    block_update(ptr, UNMASK_SIZE(ptr->size));
}

#ifndef _WIN32

class hugepage_allocator
{
  private:
    uint8_t * m_base = nullptr;
    mm_block_t * m_first_block = nullptr;
    uint8_t * m_top = nullptr;
    size_t m_total_size = 0;
    std::multimap<size_t, mm_block_t *> m_free_large;

  private:
    inline void block_print(int id, mm_block_t * bptr)
    {
        fprintf(stdout,
                "%d addr=%p size=%lu (%lu) free=%d\n",
                id,
                ((void *)bptr),
                UNMASK_SIZE(bptr->size),
                bptr->size,
                block_isfree(bptr));
        fflush(stdout);
    }

    inline uint64_t extract_number(std::string & line)
    {
        std::string num_str;
        for (size_t i = line.size() - 1; i + 1 >= 1; i--)
        {
            if (isdigit(line[i])) { num_str.insert(num_str.begin(), line[i]); }
            else
            {
                if (num_str.size() > 0) { break; }
            }
        }
        return std::strtoull(num_str.c_str(), nullptr, 10);
    }

    inline uint64_t extract_multiplier(std::string & line)
    {
        uint64_t num = 1;
        if (line[line.size() - 2] == 'k' || line[line.size() - 2] == 'K') { num = 1024; }
        if (line[line.size() - 2] == 'm' || line[line.size() - 2] == 'M') { num = 1024 * 1024; }
        if (line[line.size() - 2] == 'g' || line[line.size() - 2] == 'G') { num = 1024 * 1024 * 1024; }
        return num;
    }

    size_t determine_available_hugepage_memory()
    {
        size_t size_in_bytes = 0;
        size_t page_size_in_bytes = 0;
        size_t num_free_pages = 0;
        const std::string meminfo_file = "/proc/meminfo";
        const std::string ps_str = "Hugepagesize:";
        const std::string pf_str = "HugePages_Free:";
        std::ifstream mifs(meminfo_file);
        if (mifs.is_open())
        {
            // find size of one page
            std::string line;
            while (std::getline(mifs, line))
            {
                auto ps = std::mismatch(ps_str.begin(), ps_str.end(), line.begin());
                if (ps.first == ps_str.end()) { page_size_in_bytes = extract_number(line) * extract_multiplier(line); }
                auto pf = std::mismatch(pf_str.begin(), pf_str.end(), line.begin());
                if (pf.first == pf_str.end()) { num_free_pages = extract_number(line); }
            }
            size_in_bytes = page_size_in_bytes * num_free_pages;
        }
        else
        {
            throw std::system_error(ENOMEM,
                                    std::system_category(),
                                    "hugepage_allocator could not automatically determine available hugepages");
        }
        return size_in_bytes;
    }

    void coalesce_block(mm_block_t * block)
    {
        // std::cout << "coalesce_block()" << std::endl;
        mm_block_t * newblock = block;
        if (block_nextfree(block, m_top))
        {
            mm_block_t * next = block_next(block, m_top);
            /* remove the "next" block from the free list */
            remove_from_free_set(next);
            /* add the size of our block */
            block_update(block, UNMASK_SIZE(block->size) + UNMASK_SIZE(next->size));
        }
        if (block_prevfree(block, m_first_block))
        {
            mm_block_t * prev = block_prev(block, m_first_block);
            /* we remove the old prev block and readd it to the correct
               size list if necessary */
            remove_from_free_set(prev);
            newblock = prev;
            block_update(prev, UNMASK_SIZE(prev->size) + UNMASK_SIZE(block->size));
        }
        if (newblock)
        {
            block_markfree(newblock);
            insert_into_free_set(newblock);
        }
    }

    void split_block(mm_block_t * bptr, size_t size)
    {
        // std::cout << "split_block("<< (void*)bptr << ")" << std::endl;
        size_t blocksize = UNMASK_SIZE(bptr->size);
        // std::cout << "cur_block_size = " << blocksize << std::endl;
        /* only split if we get at least a small block
           out of it */
        int64_t newblocksize = ALIGNSPLIT(blocksize - ALIGN(size + MM_BLOCK_OVERHEAD));
        // std::cout << "new_block_size = " << newblocksize << std::endl;
        if (newblocksize >= (int64_t)SPLIT_THRESHOLD)
        {
            /* update blocksize of old block */
            // std::cout << "block_update = " << blocksize-newblocksize << std::endl;
            block_update(bptr, blocksize - newblocksize);
            mm_block_t * newblock = (mm_block_t *)((char *)bptr + (blocksize - newblocksize));
            // std::cout << "new block ptr = " << (void*)newblock << std::endl;
            block_update(newblock, newblocksize);
            coalesce_block(newblock);
        }
    }

    uint8_t * hsbrk(size_t size)
    {
        ptrdiff_t left = (ptrdiff_t)m_total_size - (m_top - m_base);
        if (left < (ptrdiff_t)size)
        { // enough space left?
            throw std::system_error(ENOMEM,
                                    std::system_category(),
                                    "hugepage_allocator: not enough hugepage memory available");
        }
        uint8_t * new_mem = m_top;
        m_top += size;
        return new_mem;
    }

    mm_block_t * new_block(size_t size)
    {
        // std::cout << "new_block(" << size << ")" << std::endl;
        size = ALIGN(size + MM_BLOCK_OVERHEAD);
        if (size < MIN_BLOCKSIZE) size = MIN_BLOCKSIZE;
        mm_block_t * ptr = (mm_block_t *)hsbrk(size);
        block_update(ptr, size);
        return ptr;
    }

    void remove_from_free_set(mm_block_t * block)
    {
        // std::cout << "remove_from_free_set()" << std::endl;
        auto eq_range = m_free_large.equal_range(block->size);
        // find the block amoung the blocks with equal size
        auto itr = eq_range.first;
        auto last = eq_range.second;
        auto found = m_free_large.end();
        while (itr != last)
        {
            if (itr->second == block) { found = itr; }
            ++itr;
        }
        if (found == m_free_large.end()) { found = last; }
        m_free_large.erase(found);
    }

    void insert_into_free_set(mm_block_t * block)
    {
        // std::cout << "insert_into_free_set("<< (void*)block << "," << UNMASK_SIZE(block->size) << ")" << std::endl;
        // std::cout << "insert_into_free_set("<< (void*)block << "," << block->size << ")" << std::endl;
        m_free_large.insert({ block->size, block });
    }

    mm_block_t * find_free_block(size_t size_in_bytes)
    {
        // std::cout << "find_free_block(" << size_in_bytes << ")" << std::endl;

        mm_block_t * bptr = nullptr;
        auto free_block = m_free_large.lower_bound(size_in_bytes);
        if (free_block != m_free_large.end())
        {
            bptr = free_block->second;
            m_free_large.erase(free_block);
        }
        return bptr;
    }

    mm_block_t * last_block()
    {
        mm_block_t * last = nullptr;
        // std::cout << "m_top = " << (void*)m_top << std::endl;
        // std::cout << "m_base = " << (void*)m_base << std::endl;
        if (m_top != m_base)
        {
            mm_block_foot_t * fptr = (mm_block_foot_t *)(m_top - sizeof(size_t));
            // std::cout << "foot of last = " << (void*)fptr << std::endl;
            // std::cout << "size of last = " << UNMASK_SIZE(fptr->size) << std::endl;
            last = (mm_block_t *)(((uint8_t *)fptr) - UNMASK_SIZE(fptr->size) + sizeof(size_t));
            // std::cout << "last = " << (void*)last << std::endl;
        }
        return last;
    }

    void print_heap()
    {
        mm_block_t * bptr = m_first_block;
        size_t id = 0;
        while (bptr)
        {
            block_print(id, bptr);
            id++;
            bptr = block_next(bptr, m_top);
        }
    }

  public:
    void init(SDSL_UNUSED size_t size_in_bytes = 0)
    {
#ifdef MAP_HUGETLB
        if (size_in_bytes == 0) { size_in_bytes = determine_available_hugepage_memory(); }

        m_total_size = size_in_bytes;
        m_base = (uint8_t *)mmap(nullptr,
                                 m_total_size,
                                 (PROT_READ | PROT_WRITE),
                                 (MAP_HUGETLB | MAP_ANONYMOUS | MAP_PRIVATE),
                                 0,
                                 0);
        if (m_base == MAP_FAILED)
        {
            throw std::system_error(ENOMEM, std::system_category(), "hugepage_allocator could not allocate hugepages");
        }
        else
        {
            // init the allocator
            m_top = m_base;
            m_first_block = (mm_block_t *)m_base;
        }
#else
        throw std::system_error(ENOMEM,
                                std::system_category(),
                                "hugepage_allocator: MAP_HUGETLB / hugepage support not available");
#endif
    }

    void * mm_realloc(void * ptr, size_t size)
    {
        // print_heap();
        // std::cout << "REALLOC(" << ptr << "," << size << ")" << std::endl;
        /* handle special cases first */
        if (nullptr == ptr) return mm_alloc(size);
        if (size == 0)
        {
            mm_free(ptr);
            return nullptr;
        }
        mm_block_t * bptr = block_cur(ptr);

        bool need_malloc = 0;
        size_t blockdatasize = block_getdatasize(bptr);
        /* we do nothing if the size is equal to the block */
        if (size == blockdatasize)
        {
            // std::cout << "return ptr = " << ptr << std::endl;
            return ptr; /* do nothing if size fits already */
        }
        if (size < blockdatasize)
        {
            /* we shrink */
            /* do we shrink enough to perform a split? */
            // std::cout << "shrink!" << std::endl;
            split_block(bptr, size);
        }
        else
        {
            // std::cout << "expand!" << std::endl;
            /* we expand */
            /* if the next block is free we could use it! */
            mm_block_t * next = block_next(bptr, m_top);
            if (!next)
            {
                // std::cout << "no next! -> expand!" << std::endl;
                // we are the last block so we just expand
                blockdatasize = block_getdatasize(bptr);
                size_t needed = ALIGN(size - blockdatasize);
                hsbrk(needed);
                block_update(bptr, UNMASK_SIZE(bptr->size) + needed);
                return block_data(bptr);
            }
            else
            {
                // we are not the last block
                // std::cout << "try combine next" << std::endl;
                if (next && block_isfree(next))
                {
                    /* do we have enough space if we use the next block */
                    if (blockdatasize + UNMASK_SIZE(next->size) >= size)
                    {
                        /* the next block is enough! */
                        /* remove the "next" block from the free list */
                        remove_from_free_set(next);
                        /* add the size of our block */
                        block_update(bptr, UNMASK_SIZE(bptr->size) + UNMASK_SIZE(next->size));
                    }
                    else
                    {
                        /* the next block is not enough. we allocate a new one instead */
                        need_malloc = true;
                    }
                }
                else
                {
                    /* try combing the previous block if free */
                    // std::cout << "try combine prev" << std::endl;
                    mm_block_t * prev = block_prev(bptr, m_first_block);
                    if (prev && block_isfree(prev))
                    {
                        if (blockdatasize + UNMASK_SIZE(prev->size) >= size)
                        {
                            remove_from_free_set(prev);
                            size_t newsize = UNMASK_SIZE(prev->size) + UNMASK_SIZE(bptr->size);
                            block_update(prev, newsize);
                            block_markused(prev);
                            /* move the data into the previous block */
                            ptr = memmove(block_data(prev), ptr, blockdatasize);
                        }
                        else
                        {
                            /* not enough in the prev block */
                            need_malloc = true;
                        }
                    }
                    else
                    {
                        /* prev block not free. get more memory */
                        need_malloc = true;
                    }
                }
            }
        }
        if (need_malloc)
        {
            // std::cout << "need_alloc in REALLOC!" << std::endl;
            void * newptr = mm_alloc(size);
            memcpy(newptr, ptr, size);
            mm_free(ptr);
            ptr = newptr;
        }
        // print_heap();
        // std::cout << "return ptr = " << ptr << std::endl;
        return ptr;
    }

    void * mm_alloc(size_t size_in_bytes)
    {
        // std::cout << "ALLOC(" << size_in_bytes << ")" << std::endl;
        mm_block_t * bptr = nullptr;
        if ((bptr = find_free_block(size_in_bytes + MM_BLOCK_OVERHEAD)) != nullptr)
        {
            // std::cout << "found free block = " << (void*)bptr << std::endl;
            block_markused(bptr);
            /* split if we have a block too large for us? */
            split_block(bptr, size_in_bytes);
        }
        else
        {
            // std::cout << "no free block found that is big enough!" << std::endl;
            // check if last block is free
            // std::cout << "check last block" << std::endl;
            bptr = last_block();
            if (bptr && block_isfree(bptr))
            {
                // std::cout << "last block is free. -> extend!" << std::endl;
                // extent last block as it is free
                size_t blockdatasize = block_getdatasize(bptr);
                size_t needed = ALIGN(size_in_bytes - blockdatasize);
                hsbrk(needed);
                remove_from_free_set(bptr);
                block_update(bptr, blockdatasize + needed + sizeof(size_t) + sizeof(mm_block_foot_t));
                // insert_into_free_set(bptr);
                block_markused(bptr);
            }
            else
            {
                bptr = new_block(size_in_bytes);
            }
        }
        // print_heap();
        // void* ptr = block_data(bptr);
        // std::cout << "return ptr = " << ptr << std::endl;
        return block_data(bptr);
    }

    void mm_free(void * ptr)
    {
        // print_heap();
        // std::cout << "FREE(" << ptr << ")" << std::endl;
        if (ptr)
        {
            mm_block_t * bptr = block_cur(ptr);
            block_markfree(bptr);
            /* coalesce if needed. otherwise just add */
            coalesce_block(bptr);
        }
        // print_heap();
    }

    bool in_address_space(void * ptr)
    {
        // check if ptr is in the hugepage address space
        if (ptr == nullptr) { return true; }
        if (ptr >= m_base && ptr < m_top) { return true; }
        return false;
    }
    static hugepage_allocator & the_allocator()
    {
        static hugepage_allocator a;
        return a;
    }
};
#endif

class memory_manager
{
  private:
    bool hugepages = false;

  private:
    static memory_manager & the_manager()
    {
        static memory_manager m;
        return m;
    }

  public:
    static uint64_t * alloc_mem(size_t size_in_bytes)
    {
#ifndef _WIN32
        auto & m = the_manager();
        if (m.hugepages) { return (uint64_t *)hugepage_allocator::the_allocator().mm_alloc(size_in_bytes); }
#endif
        return (uint64_t *)calloc(size_in_bytes, 1);
    }
    static void free_mem(uint64_t * ptr)
    {
#ifndef _WIN32
        auto & m = the_manager();
        if (m.hugepages and hugepage_allocator::the_allocator().in_address_space(ptr))
        {
            hugepage_allocator::the_allocator().mm_free(ptr);
            return;
        }
#endif
        std::free(ptr);
    }
    static uint64_t * realloc_mem(uint64_t * ptr, size_t size)
    {
#ifndef _WIN32
        auto & m = the_manager();
        if (m.hugepages and hugepage_allocator::the_allocator().in_address_space(ptr))
        {
            return (uint64_t *)hugepage_allocator::the_allocator().mm_realloc(ptr, size);
        }
#endif
        return (uint64_t *)realloc(ptr, size);
    }

  public:
    static void use_hugepages(size_t bytes = 0)
    {
#ifndef _WIN32
        auto & m = the_manager();
        hugepage_allocator::the_allocator().init(bytes);
        m.hugepages = true;
#else
        throw std::runtime_error(std::string("hugepages not supported on Windows"));
        // avoid error: unused parameter 'bytes' [-Werror=unused-parameter]
        (void)bytes;
#endif
    }
    template <class t_vec>
    static void resize(t_vec & v, const typename t_vec::size_type capacity)
    {
        uint64_t old_capacity_in_bytes = ((v.m_capacity + 63) >> 6) << 3;
        uint64_t new_capacity_in_bytes = ((capacity + 63) >> 6) << 3;
        bool do_realloc = old_capacity_in_bytes != new_capacity_in_bytes;
        v.m_capacity = ((capacity + 63) >> 6) << 6; // set new_capacity to a multiple of 64

        if (do_realloc || v.m_data == nullptr)
        {
            // Note that we allocate 8 additional bytes if m_capacity % 64 == 0.
            // We need this padding since rank data structures do a memory
            // access to this padding to answer rank(size()) if capacity()%64 ==0.
            // Note that this padding is not counted in the serialize method!
            size_t allocated_bytes = (size_t)(((v.m_capacity + 64) >> 6) << 3);
            v.m_data = memory_manager::realloc_mem(v.m_data, allocated_bytes);
            if (allocated_bytes != 0 && v.m_data == nullptr) { throw std::bad_alloc(); }

            // update stats
            if (do_realloc) { memory_monitor::record((int64_t)new_capacity_in_bytes - (int64_t)old_capacity_in_bytes); }
        }
    }
    template <class t_vec>
    static void clear(t_vec & v)
    {
        int64_t size_in_bytes = ((v.m_size + 63) >> 6) << 3;
        // remove mem
        memory_manager::free_mem(v.m_data);
        v.m_data = nullptr;

        // update stats
        if (size_in_bytes) { memory_monitor::record(size_in_bytes * -1); }
    }

    static int open_file_for_mmap(std::string & filename, std::ios_base::openmode mode)
    {
        if (is_ram_file(filename)) { return ram_fs::open(filename); }
#ifdef MSVC_COMPILER
        int fd = -1;
        if (!(mode & std::ios_base::out))
            _sopen_s(&fd, filename.c_str(), _O_BINARY | _O_RDONLY, _SH_DENYNO, _S_IREAD);
        else
            _sopen_s(&fd, filename.c_str(), _O_BINARY | _O_RDWR, _SH_DENYNO, _S_IREAD | _S_IWRITE);
        return fd;
#else
        if (!(mode & std::ios_base::out))
            return open(filename.c_str(), O_RDONLY);
        else
            return open(filename.c_str(), O_RDWR);
#endif
        return -1;
    }

    static void * mmap_file(int fd, uint64_t file_size, std::ios_base::openmode mode)
    {
        if (file_size == 0)
        {
            std::cout << "file_size=0" << std::endl;
            return nullptr;
        }
        if (is_ram_file(fd))
        {
            if (ram_fs::file_size(fd) < file_size) return nullptr;
            auto & file_content = ram_fs::content(fd);
            return file_content.data();
        }
        memory_monitor::record(file_size);
#ifdef _WIN32
        HANDLE fh = (HANDLE)_get_osfhandle(fd);
        if (fh == INVALID_HANDLE_VALUE) { return nullptr; }
        HANDLE fm;
        if (!(mode & std::ios_base::out))
        { // read only?
            fm = CreateFileMapping(fh, NULL, PAGE_READONLY, 0, 0, NULL);
        }
        else
            fm = CreateFileMapping(fh, NULL, PAGE_READWRITE, 0, 0, NULL);
        if (fm == NULL) { return nullptr; }
        void * map = nullptr;
        if (!(mode & std::ios_base::out))
        { // read only?
            map = MapViewOfFile(fm, FILE_MAP_READ, 0, 0, file_size);
        }
        else
            map = MapViewOfFile(fm, FILE_MAP_WRITE | FILE_MAP_READ, 0, 0, file_size);
        // we can close the file handle before we unmap the view: (see UnmapViewOfFile Doc)
        // Although an application may close the file handle used to create a file mapping object,
        // the system holds the corresponding file open until the last view of the file is unmapped.
        // Files for which the last view has not yet been unmapped are held open with no sharing restrictions.
        CloseHandle(fm);
        return map;
#else
        void * map = nullptr;
        if (!(mode & std::ios_base::out))
            map = mmap(NULL, file_size, PROT_READ, MAP_SHARED, fd, 0);
        else
            map = mmap(NULL, file_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
        if (map == MAP_FAILED) map = nullptr; // unify windows and unix error behaviour
        return map;
#endif
        return nullptr;
    }

    static int mem_unmap(int fd, void * addr, const uint64_t size)
    {
        if (addr == nullptr) { return 0; }
        if (is_ram_file(fd)) { return 0; }
        memory_monitor::record(-((int64_t)size));
#ifdef _WIN32
        if (UnmapViewOfFile(addr)) return 0;
        return -1;
#else
        return munmap(addr, size);
#endif
        return -1;
    }

    static int close_file_for_mmap(int fd)
    {
        if (is_ram_file(fd)) { return ram_fs::close(fd); }
#ifdef MSVC_COMPILER
        return _close(fd);
#else
        return close(fd);
#endif
        return -1;
    }

    static int truncate_file_mmap(int fd, const uint64_t new_size)
    {
        if (is_ram_file(fd)) { return ram_fs::truncate(fd, new_size); }
#ifdef _WIN32
        auto ret = _chsize_s(fd, new_size);
        if (ret != 0) ret = -1;
        return ret;
#else
        return ftruncate(fd, new_size);
#endif
        return -1;
    }
};

#undef ALIGNMENT
#undef ALIGNSPLIT
#undef ALIGN
#undef MM_BLOCK_OVERHEAD
#undef MIN_BLOCKSIZE
#undef UNMASK_SIZE
#undef ISFREE
#undef SETFREE
#undef SPLIT_THRESHOLD

} // namespace sdsl

#endif
