lob0impl.h

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#ifndef lob0impl_h
#define lob0impl_h
 
#include "btr0btr.h"
#include "fut0lst.h"
#include "lob0first.h"
#include "lob0lob.h"
#include "mach0data.h"
#include "mtr0log.h"
#include "mtr0mtr.h"
#include "mtr0types.h"
 
namespace lob {
 
struct z_index_entry_t;
struct z_first_page_t;
struct z_frag_page_t;
struct index_entry_t;
struct first_page_t;
 
using paddr_t = ulint;
 
/** The node of page list.  The page list is similar to the file list
(flst_node_t) except that it is completely within one page. */
class plist_node_t {
 public:
  /** Offset of the previous node. (2 bytes) */
  static const uint16_t OFFSET_PREV = 0;
 
  /** Offset of the next node. (2 bytes) */
  static const uint16_t OFFSET_NEXT = 2;
 
  /** The size of a page list node. */
  static const uint8_t SIZE = 4;
 
  /** Constructor.
  @param[in]    mtr     Mini-transaction context. */
  explicit plist_node_t(mtr_t *mtr)
      : m_frame(nullptr), m_node(nullptr), m_mtr(mtr) {}
 
  /** Default constructor. */
  plist_node_t() : m_frame(nullptr), m_node(nullptr), m_mtr(nullptr) {}
 
  /** Constructor.
  @param[in]    mtr     Mini-transaction context
  @param[in]    frame   the page frame of this plist. */
  plist_node_t(mtr_t *mtr, byte *frame)
      : m_frame(frame), m_node(nullptr), m_mtr(mtr) {}
 
  /** Constructor.
  @param[in]    frame   the page frame of this plist.
  @param[in]    node    the location of plist node. */
  plist_node_t(byte *frame, byte *node)
      : m_frame(frame), m_node(node), m_mtr(nullptr) {}
 
  /** Constructor.
  @param[in]    frame   Page frame where the page list node is
                          located.
  @param[in]    node    Location of page list node within page
                          frame.
  @param[in]    mtr     Mini-transaction context. */
  plist_node_t(byte *frame, byte *node, mtr_t *mtr)
      : m_frame(frame), m_node(node), m_mtr(mtr) {}
 
  /** Copy constructor. */
  plist_node_t(const plist_node_t &other) = default;
 
  plist_node_t &operator=(const plist_node_t &) = default;
 
  /** Check if the current node is before the given node in the
  page (w.r.t the offset).
  @param[in]    node    the other node.
  @return true if current node is before the given node.
  @return false if current node is after the given node. */
  bool is_before(const plist_node_t &node) const {
    ut_ad(!is_null());
    ut_ad(!node.is_null());
    return (addr() < node.addr());
  }
 
  /** Initialize the current page list node. The offset of next and
  previous nodes are set to 0. */
  void init() {
    ut_ad(!is_null());
    ut_ad(m_mtr != nullptr);
 
    mlog_write_ulint(m_node + OFFSET_PREV, 0, MLOG_2BYTES, m_mtr);
    mlog_write_ulint(m_node + OFFSET_NEXT, 0, MLOG_2BYTES, m_mtr);
  }
 
  /** Set the offset of the previous node.
  @param[in]    addr    the offset of previous node.*/
  void set_prev(paddr_t addr) {
    ut_ad(addr < UNIV_PAGE_SIZE);
    ut_ad(m_mtr != nullptr);
 
    mlog_write_ulint(m_node + OFFSET_PREV, addr, MLOG_2BYTES, m_mtr);
  }
 
  /** Set the previous page list node.
  @param[in]    prev    the previous page list node.*/
  void set_prev_node(plist_node_t &prev) { set_prev(prev.addr()); }
 
  /** Set the offset of the next node.
  @param[in]    addr    the offset of next node.*/
  void set_next(paddr_t addr) {
    ut_ad(!is_null());
    ut_ad(addr < UNIV_PAGE_SIZE);
    ut_ad(m_mtr != nullptr);
 
    mlog_write_ulint(m_node + OFFSET_NEXT, addr, MLOG_2BYTES, m_mtr);
  }
 
  /** Set the next page list node.
  @param[in]    next    the next page list node.*/
  void set_next_node(const plist_node_t &next) { set_next(next.addr()); }
 
  /** Get the offset of the previous page list node.
  @return offset of previous node of the page list. */
  paddr_t get_prev() const { return (mach_read_from_2(m_node + OFFSET_PREV)); }
 
  /** Get the offset of the next page list node.
  @return offset of next node of the page list. */
  paddr_t get_next() const { return (mach_read_from_2(m_node + OFFSET_NEXT)); }
 
  /** Get the next page list node.
  @return next node of the page list. */
  plist_node_t get_next_node() const {
    paddr_t addr = get_next();
    byte *node = nullptr;
 
    if (addr != 0) {
      node = m_frame + addr;
      ut_ad(addr < UNIV_PAGE_SIZE);
    }
 
    return (plist_node_t(m_frame, node, m_mtr));
  }
 
  /** Get the previous page list node.
  @return previous node of the page list. */
  plist_node_t get_prev_node() const {
    paddr_t addr = get_prev();
    byte *node = nullptr;
 
    if (addr != 0) {
      ut_ad(addr < UNIV_PAGE_SIZE);
      node = m_frame + addr;
    }
 
    return (plist_node_t(m_frame, node, m_mtr));
  }
 
  /** Obtain the offset of the page list node within the given
  page frame.
  @return offset from the beginning of the page. */
  paddr_t addr() const {
    return ((m_node == nullptr) ? 0 : (m_node - m_frame));
  }
 
  /** Obtain the memory location of the page list node.
  @return the pointer to the page list node. */
  byte *ptr() const { return (m_node); }
 
  /** Check if the given page list node is null.
  @return true if null, false otherwise. */
  bool is_null() const { return (m_node == nullptr); }
 
  /** Print the page list node into the given output stream.
  @param[in]    out     the output stream.
  @return the output stream. */
  std::ostream &print(std::ostream &out) const {
    out << "[plist_node_t: next=" << get_next() << ", prev=" << get_prev()
        << ", this=" << addr() << ", frame=" << (void *)m_frame
        << ", m_node=" << (void *)m_node << "]";
    return (out);
  }
 
  /** Set the page frame to the given value.
  @param[in]    frame   the page frame */
  void set_frame(byte *frame) { m_frame = frame; }
 
  /** Set the page list node to the given value.
  @param[in]    node    the page list node. */
  void set_node(byte *node) { m_node = node; }
 
  /** Set the mini-transaction context to the given value.
  @param[in]    mtr     Mini-transaction context. */
  void set_mtr(mtr_t *mtr) { m_mtr = mtr; }
 
  /** Get the page frame where this page list exists.
  @return the page frame. */
  byte *get_frame() const { return (m_frame); }
 
  bool is_equal(const plist_node_t &that) const {
    if (m_node == nullptr || that.m_node == nullptr) {
      return (false);
    }
    return (m_node == that.m_node);
  }
 
 private:
  /** The page frame where this page list exists. */
  byte *m_frame;
 
  /** The plist node is located at this address. */
  byte *m_node;
 
  /** The mini-transaction context. */
  mtr_t *m_mtr;
};
 
inline std::ostream &operator<<(std::ostream &out, const plist_node_t &obj) {
  return (obj.print(out));
}
 
/** The base node of page list. */
struct plist_base_node_t {
  /** The offset where the length of the page list is stored.
  This is 4 bytes long.*/
  static const ulint OFFSET_LEN = 0;
 
  /** The offset where the first node is located.
  This is 2 bytes long. */
  static const ulint OFFSET_FIRST = 4;
 
  /** The offset where the last node is located.
  This is 2 bytes long. */
  static const ulint OFFSET_LAST = 6;
 
  /** The total size (in bytes) of a page list base node. */
  static const ulint SIZE = 8;
 
  plist_base_node_t(byte *frame, byte *base, mtr_t *mtr)
      : m_frame(frame), m_base(base), m_mtr(mtr) {}
 
  void init() {
    ut_ad(m_mtr != nullptr);
 
    mlog_write_ulint(m_base + OFFSET_LEN, 0, MLOG_4BYTES, m_mtr);
    mlog_write_ulint(m_base + OFFSET_FIRST, 0, MLOG_2BYTES, m_mtr);
    mlog_write_ulint(m_base + OFFSET_LAST, 0, MLOG_2BYTES, m_mtr);
  }
 
  void remove(plist_node_t &node) {
    ut_ad(m_mtr != nullptr);
 
    plist_node_t prev = node.get_prev_node();
    plist_node_t next = node.get_next_node();
 
    if (prev.is_null()) {
      set_first(next.addr());
    } else {
      prev.set_next(next.addr());
    }
 
    if (next.is_null()) {
      set_last(prev.addr());
    } else {
      next.set_prev(prev.addr());
    }
 
    node.set_next(0);
    node.set_prev(0);
 
    decr_len();
  }
 
  void push_front(plist_node_t &node) {
    ut_ad(m_mtr != nullptr);
 
    if (get_len() == 0) {
      add_to_empty(node);
    } else {
      paddr_t cur_addr = node.addr();
      paddr_t first_addr = get_first();
      plist_node_t first_node = get_node(first_addr);
      node.set_next(first_addr);
      node.set_prev(0);
      first_node.set_prev(cur_addr);
      set_first(cur_addr);
      incr_len();
    }
  }
 
  /** Insert node2 after node1. */
  void insert_after(plist_node_t &node1, plist_node_t &node2) {
    ut_ad(m_mtr != nullptr);
 
    if (node1.is_null()) {
      push_back(node2);
    } else {
      plist_node_t node3 = node1.get_next_node();
      node1.set_next_node(node2);
      node2.set_next_node(node3);
 
      if (node3.is_null()) {
        set_last(node2.addr());
      } else {
        node3.set_prev_node(node2);
      }
 
      node2.set_prev_node(node1);
 
      incr_len();
    }
  }
 
  /** Insert node2 before node3. */
  void insert_before(plist_node_t &node3, plist_node_t &node2) {
    ut_ad(m_mtr != nullptr);
 
    if (node3.is_null()) {
      push_back(node2);
    } else {
      plist_node_t node1 = node3.get_prev_node();
 
      if (node1.is_null()) {
        set_first(node2.addr());
      } else {
        node1.set_next_node(node2);
      }
 
      node2.set_next_node(node3);
      node3.set_prev_node(node2);
      node2.set_prev_node(node1);
 
      incr_len();
    }
  }
 
  void add_to_empty(plist_node_t &node) {
    ut_ad(m_mtr != nullptr);
    ut_ad(get_len() == 0);
 
    set_first(node.addr());
    set_last(node.addr());
    incr_len();
  }
 
  void push_back(plist_node_t &node) {
    ut_ad(m_mtr != nullptr);
 
    if (get_len() == 0) {
      add_to_empty(node);
    } else {
      paddr_t cur_addr = node.addr();
      paddr_t last_addr = get_last();
      plist_node_t last_node = get_node(last_addr);
      node.set_next(0);
      node.set_prev_node(last_node);
      last_node.set_next(cur_addr);
      set_last(cur_addr);
      incr_len();
    }
  }
 
  bool empty() const { return (get_len() == 0); }
 
  ulint get_len() const { return (mach_read_from_4(m_base + OFFSET_LEN)); }
 
  paddr_t get_first() const {
    return (mach_read_from_2(m_base + OFFSET_FIRST));
  }
 
  plist_node_t get_first_node() const {
    plist_node_t result(m_mtr, m_frame);
 
    if (!empty()) {
      byte *node = m_frame + get_first();
      result.set_node(node);
    }
    return (result);
  }
 
  paddr_t get_last() const { return (mach_read_from_2(m_base + OFFSET_LAST)); }
 
  plist_node_t get_last_node() const {
    plist_node_t result(m_mtr, m_frame);
 
    if (!empty()) {
      result.set_node(m_frame + get_last());
    }
 
    return (result);
  }
 
  void set_len(ulint len) {
    ut_ad(m_mtr != nullptr);
 
    mlog_write_ulint(m_base + OFFSET_LEN, len, MLOG_4BYTES, m_mtr);
  }
 
  void incr_len() {
    ut_ad(m_mtr != nullptr);
 
    ulint len = mach_read_from_4(m_base + OFFSET_LEN);
    mlog_write_ulint(m_base + OFFSET_LEN, len + 1, MLOG_4BYTES, m_mtr);
  }
 
  void decr_len() {
    ut_ad(m_mtr != nullptr);
 
    ulint len = mach_read_from_4(m_base + OFFSET_LEN);
 
    ut_ad(len > 0);
 
    mlog_write_ulint(m_base + OFFSET_LEN, len - 1, MLOG_4BYTES, m_mtr);
  }
 
  void set_first(paddr_t addr) {
    ut_ad(m_mtr != nullptr);
 
    mlog_write_ulint(m_base + OFFSET_FIRST, addr, MLOG_2BYTES, m_mtr);
  }
 
  void set_last(paddr_t addr) {
    ut_ad(m_mtr != nullptr);
 
    mlog_write_ulint(m_base + OFFSET_LAST, addr, MLOG_2BYTES, m_mtr);
  }
 
  plist_node_t get_node(paddr_t addr) {
    byte *node = m_frame + addr;
    return (plist_node_t(m_frame, node, m_mtr));
  }
 
  paddr_t addr() const { return (m_base - m_frame); }
 
  std::ostream &print(std::ostream &out) const {
    out << "[plist_base_node_t: len=" << get_len() << ", first=" << get_first()
        << ", last=" << get_last() << ", this=" << addr() << "]";
    return (out);
  }
 
  std::ostream &print_list(std::ostream &out) const {
    print(out);
    out << std::endl;
 
    for (plist_node_t cur = get_first_node(); !cur.is_null();
         cur = cur.get_next_node()) {
      out << cur << std::endl;
    }
    return (out);
  }
 
#ifdef UNIV_DEBUG
  /** Validate the page list.
  @return true if valid, false otherwise. */
  bool validate() const;
#endif /* UNIV_DEBUG */
 
  byte *m_frame;
  byte *m_base;
  mtr_t *m_mtr;
};
 
inline std::ostream &operator<<(std::ostream &out,
                                const plist_base_node_t &obj) {
  return (obj.print(out));
}
 
using frag_id_t = ulint;
const ulint FRAG_ID_NULL = std::numeric_limits<uint16_t>::max();
const ulint KB16 = 16 * 1024;
 
/** The node page (also can be called as the index page) contains a list of
index_entry_t objects. */
struct node_page_t : public basic_page_t {
  /** Version information. One byte. */
  static const ulint OFFSET_VERSION = FIL_PAGE_DATA;
  static const ulint LOB_PAGE_DATA = OFFSET_VERSION + 1;
 
  void set_version_0() {
    mlog_write_ulint(frame() + OFFSET_VERSION, 0, MLOG_1BYTE, m_mtr);
  }
 
  /** Default ctor */
  node_page_t() = default;
 
  node_page_t(buf_block_t *block, mtr_t *mtr) : basic_page_t(block, mtr) {}
 
  node_page_t(buf_block_t *block, mtr_t *mtr, dict_index_t *index)
      : basic_page_t(block, mtr, index) {}
 
  node_page_t(mtr_t *mtr, dict_index_t *index)
      : basic_page_t(nullptr, mtr, index) {}
 
  /** Constructor
  @param[in]    block   the buffer block. */
  node_page_t(buf_block_t *block) : basic_page_t(block, nullptr, nullptr) {}
 
  /** Import the node page or the index page.
  @param[in]    trx_id  transaction identifier. */
  void import(trx_id_t trx_id);
 
  buf_block_t *alloc(first_page_t &first_page, bool bulk);
 
  buf_block_t *load_x(page_id_t page_id, page_size_t page_size) {
    m_block =
        buf_page_get(page_id, page_size, RW_X_LATCH, UT_LOCATION_HERE, m_mtr);
    return (m_block);
  }
 
  void dealloc() {
    btr_page_free_low(m_index, m_block, ULINT_UNDEFINED, m_mtr);
    m_block = nullptr;
  }
 
  static ulint payload() {
    return (UNIV_PAGE_SIZE - LOB_PAGE_DATA - FIL_PAGE_DATA_END);
  }
 
  static ulint max_space_available() { return (payload()); }
 
  /** Get the number of index entries this page can hold.
  @return Number of index entries this page can hold. */
  static ulint node_count();
 
  void set_page_type() {
    mlog_write_ulint(frame() + FIL_PAGE_TYPE, FIL_PAGE_TYPE_LOB_INDEX,
                     MLOG_2BYTES, m_mtr);
  }
 
  byte *nodes_begin() const { return (frame() + LOB_PAGE_DATA); }
};
 
/** An entry representing one fragment page. */
struct z_frag_entry_t {
 public:
  /** Offset within frag entry pointing to prev frag entry. */
  static const ulint OFFSET_PREV = 0;
 
  /** Offset within frag entry pointing to next frag entry. */
  static const ulint OFFSET_NEXT = OFFSET_PREV + FIL_ADDR_SIZE;
 
  /** Offset within frag entry holding the page number of frag page. */
  static const ulint OFFSET_PAGE_NO = OFFSET_NEXT + FIL_ADDR_SIZE;
 
  /** Number of used fragments. */
  static const ulint OFFSET_N_FRAGS = OFFSET_PAGE_NO + 4;
 
  /** Used space in bytes. */
  static const ulint OFFSET_USED_LEN = OFFSET_N_FRAGS + 2;
 
  /** Total free space in bytes. */
  static const ulint OFFSET_TOTAL_FREE_LEN = OFFSET_USED_LEN + 2;
 
  /** The biggest free frag space in bytes. */
  static const ulint OFFSET_BIG_FREE_LEN = OFFSET_TOTAL_FREE_LEN + 2;
 
  /** Total size of one frag entry. */
  static const ulint SIZE = OFFSET_BIG_FREE_LEN + 2;
 
  /** Constructor. */
  z_frag_entry_t(flst_node_t *node, mtr_t *mtr) : m_node(node), m_mtr(mtr) {}
 
  /** Constructor. */
  z_frag_entry_t() : m_node(nullptr), m_mtr(nullptr) {}
 
  /** Constructor. */
  z_frag_entry_t(mtr_t *mtr) : m_node(nullptr), m_mtr(mtr) {}
 
  /** Initialize the fragment entry contents.  For this to correctly
  work, the current object must be initialized with proper file list
  node and the mini-transaction context. */
  void init() {
    ut_ad(m_mtr != nullptr);
    ut_ad(m_node != nullptr);
 
    set_prev_null();
    set_next_null();
    set_page_no(FIL_NULL);
    set_n_frags(0);
    set_used_len(0);
    set_total_free_len(0);
    set_big_free_len(0);
  }
 
  /** Set the current fragment entry to null. */
  void set_null() { m_node = nullptr; }
 
  /** Check if the current fragment entry is null.
  @return true if the current fragment entry is null, false otherwise. */
  bool is_null() const { return (m_node == nullptr); }
 
  fil_addr_t get_self_addr() const {
    page_t *frame = page_align(m_node);
    page_no_t page_no = mach_read_from_4(frame + FIL_PAGE_OFFSET);
    uint16_t offset = static_cast<uint16_t>(m_node - frame);
    ut_ad(offset < UNIV_PAGE_SIZE);
    return (fil_addr_t(page_no, offset));
  }
 
  /** Update the current fragment entry with information about
  the given fragment page.
  @param[in]    frag_page       the fragment page whose information
                          will be stored in current fragment entry. */
  void update(const z_frag_page_t &frag_page);
 
  /** Remove this node from the given list.
  @param[in]    bnode   the base node of the list from which to remove
                          current node. */
  void remove(flst_base_node_t *bnode) {
    ut_ad(m_mtr != nullptr);
 
    flst_remove(bnode, m_node, m_mtr);
  }
 
  /** Add this node as the last node in the given list.
  @param[in]  bnode  the base node of the file list. */
  void push_back(flst_base_node_t *bnode) {
    ut_ad(m_mtr != nullptr);
 
    flst_add_last(bnode, m_node, m_mtr);
  }
 
  /** Add this node as the first node in the given list.
  @param[in]  bnode  the base node of the file list. */
  void push_front(flst_base_node_t *bnode) {
    ut_ad(m_mtr != nullptr);
 
    flst_add_first(bnode, m_node, m_mtr);
  }
 
  /** Point to another frag entry.
  @param[in]  node  point to this file list node. */
  void reset(flst_node_t *node) { m_node = node; }
 
  /** Set the previous frag entry as null. */
  void set_prev_null() {
    ut_ad(m_mtr != nullptr);
 
    flst_write_addr(m_node + OFFSET_PREV, fil_addr_null, m_mtr);
  }
 
  /** Set the previous frag entry as null. */
  void set_prev(const fil_addr_t &addr) {
    ut_ad(m_mtr != nullptr);
 
    flst_write_addr(m_node + OFFSET_PREV, addr, m_mtr);
  }
 
  /** Get the location of previous frag entry. */
  fil_addr_t get_prev() const {
    return (flst_read_addr(m_node + OFFSET_PREV, m_mtr));
  }
 
  /** Set the next frag entry as null. */
  void set_next_null() {
    ut_ad(m_mtr != nullptr);
 
    flst_write_addr(m_node + OFFSET_NEXT, fil_addr_null, m_mtr);
  }
 
  /** Set the next frag entry. */
  void set_next(const fil_addr_t &addr) {
    ut_ad(m_mtr != nullptr);
 
    flst_write_addr(m_node + OFFSET_NEXT, addr, m_mtr);
  }
 
  /** Get the location of next frag entry. */
  fil_addr_t get_next() const {
    return (flst_read_addr(m_node + OFFSET_NEXT, m_mtr));
  }
 
  /** Get the frag page number. */
  page_no_t get_page_no() const {
    return (mach_read_from_4(m_node + OFFSET_PAGE_NO));
  }
 
  /** Set the frag page number. */
  void set_page_no(page_no_t page_no) const {
    ut_ad(m_mtr != nullptr);
 
    mlog_write_ulint(m_node + OFFSET_PAGE_NO, page_no, MLOG_4BYTES, m_mtr);
  }
 
  /** Free the fragment page pointed to by this entry.
   @param[in]   mtr     Mini-transaction to be used for this operation.
   @param[in]   index   The index to which this LOB belongs. */
  void free_frag_page(mtr_t *mtr, dict_index_t *index);
 
  /** Get the frag page number. */
  ulint get_n_frags() const {
    return (mach_read_from_2(m_node + OFFSET_N_FRAGS));
  }
 
  /** Set the frag page number. */
  void set_n_frags(ulint frags) const {
    ut_ad(m_mtr != nullptr);
 
    mlog_write_ulint(m_node + OFFSET_N_FRAGS, frags, MLOG_2BYTES, m_mtr);
  }
 
  /** Get the used bytes. */
  ulint get_used_len() const {
    return (mach_read_from_2(m_node + OFFSET_USED_LEN));
  }
 
  /** Set the used bytes. */
  void set_used_len(ulint used) const {
    ut_ad(m_mtr != nullptr);
 
    mlog_write_ulint(m_node + OFFSET_USED_LEN, used, MLOG_2BYTES, m_mtr);
  }
 
  /** Get the total cumulative free bytes. */
  ulint get_total_free_len() const {
    return (mach_read_from_2(m_node + OFFSET_TOTAL_FREE_LEN));
  }
 
  /** Get the biggest free frag bytes. */
  ulint get_big_free_len() const {
    return (mach_read_from_2(m_node + OFFSET_BIG_FREE_LEN));
  }
 
  /** Set the total free bytes. */
  void set_total_free_len(ulint n) {
    ut_ad(m_mtr != nullptr);
 
    mlog_write_ulint(m_node + OFFSET_TOTAL_FREE_LEN, n, MLOG_2BYTES, m_mtr);
  }
 
  /** Set the big free frag bytes. */
  void set_big_free_len(ulint n) {
    ut_ad(m_mtr != nullptr);
 
    mlog_write_ulint(m_node + OFFSET_BIG_FREE_LEN, n, MLOG_2BYTES, m_mtr);
  }
 
  void purge(flst_base_node_t *used_lst, flst_base_node_t *free_lst);
 
  std::ostream &print(std::ostream &out) const;
 
 private:
  /** The location where the fragment entry node is located. */
  flst_node_t *m_node;
 
  /** The mini-transaction context for operating on this fragment
  entry. */
  mtr_t *m_mtr;
};
 
inline std::ostream &operator<<(std::ostream &out, const z_frag_entry_t &obj) {
  return (obj.print(out));
}
 
/** An index page containing an array of z_index_entry_t objects. */
struct z_index_page_t {
  /** Version information. One byte. */
  static const ulint OFFSET_VERSION = FIL_PAGE_DATA;
  static const ulint LOB_PAGE_DATA = OFFSET_VERSION + 1;
 
  /** Constructor.
  @param[in]    mtr     mini-transaction context. */
  explicit z_index_page_t(mtr_t *mtr) : m_block(nullptr), m_mtr(mtr) {}
 
  /** Constructor.
  @param[in]    block   the buffer block.
  @param[in]    mtr     mini-transaction context.
  @param[in]    index   the index to which the LOB belongs. */
  z_index_page_t(buf_block_t *block, mtr_t *mtr, dict_index_t *index)
      : m_block(block), m_mtr(mtr), m_index(index) {}
 
  /** Constructor.
  @param[in]    mtr     mini-transaction context.
  @param[in]    index   the index to which the LOB belongs. */
  z_index_page_t(mtr_t *mtr, dict_index_t *index)
      : z_index_page_t(nullptr, mtr, index) {}
 
  /** Constructor
  @param[in]    block   the buffer block. */
  explicit z_index_page_t(buf_block_t *block)
      : z_index_page_t(block, nullptr, nullptr) {}
 
  /** Constructor.
  @param[in]    block   the buffer block.
  @param[in]    index   the index to which the LOB belongs. */
  z_index_page_t(buf_block_t *block, dict_index_t *index)
      : z_index_page_t(block, nullptr, index) {}
 
  /** Write the space identifier to the page header, without generating
  redo log records.
  @param[in]    space_id        the space identifier. */
  void set_space_id_no_redo(space_id_t space_id) {
    mlog_write_ulint(frame() + FIL_PAGE_SPACE_ID, space_id, MLOG_4BYTES,
                     nullptr);
  }
 
  /** Set the correct page type. */
  void set_page_type(mtr_t *mtr) {
    mlog_write_ulint(frame() + FIL_PAGE_TYPE, FIL_PAGE_TYPE_ZLOB_INDEX,
                     MLOG_2BYTES, mtr);
  }
 
  void set_version_0() {
    mlog_write_ulint(frame() + OFFSET_VERSION, 0, MLOG_1BYTE, m_mtr);
  }
 
  /** Set the next page number. */
  void set_next_page_no(page_no_t page_no) {
    ut_ad(m_mtr != nullptr);
 
    mlog_write_ulint(frame() + FIL_PAGE_NEXT, page_no, MLOG_4BYTES, m_mtr);
  }
 
  /** Get the page number. */
  page_no_t get_page_no() const {
    return (mach_read_from_4(frame() + FIL_PAGE_OFFSET));
  }
 
  /** Get the next page number. */
  page_no_t get_next_page_no() const {
    return (mach_read_from_4(frame() + FIL_PAGE_NEXT));
  }
 
  /** Allocate an ZLOB index page.
  @return the buffer block of the allocated zlob index page. */
  buf_block_t *alloc(z_first_page_t &first, bool bulk);
 
  void import(trx_id_t trx_id);
 
  /** Load the given compressed LOB index page.
  @param[in]    page_no         compressed LOB index page number.
  @return       the buffer block of the given page number. */
  buf_block_t *load_x(page_no_t page_no) {
    page_id_t page_id(dict_index_get_space(m_index), page_no);
    page_size_t page_size(dict_table_page_size(m_index->table));
    m_block =
        buf_page_get(page_id, page_size, RW_X_LATCH, UT_LOCATION_HERE, m_mtr);
 
    ut_ad(m_block->get_page_type() == FIL_PAGE_TYPE_ZLOB_INDEX);
    return (m_block);
  }
 
  void dealloc() {
    btr_page_free_low(m_index, m_block, ULINT_UNDEFINED, m_mtr);
    m_block = nullptr;
  }
 
  void init(flst_base_node_t *free_lst, mtr_t *mtr);
 
  ulint payload() const {
    const page_size_t page_size(dict_table_page_size(m_index->table));
 
    return (page_size.physical() - FIL_PAGE_DATA_END - LOB_PAGE_DATA);
  }
 
  ulint get_n_index_entries() const;
 
  byte *frame() const { return (buf_block_get_frame(m_block)); }
 
  /** The buffer block of the compressed LOB index page. */
  buf_block_t *m_block;
 
  /** The mini-transaction context. */
  mtr_t *m_mtr;
 
  /** The index to which the LOB belongs. */
  dict_index_t *m_index;
};
 
/** The data page holding the zlob. */
struct z_data_page_t {
  /** Version information. One byte. */
  static const ulint OFFSET_VERSION = FIL_PAGE_DATA;
 
  /* The length of compressed data stored in this page. */
  static const ulint OFFSET_DATA_LEN = OFFSET_VERSION + 1;
 
  /* The transaction that created this page. */
  static const ulint OFFSET_TRX_ID = OFFSET_DATA_LEN + 4;
 
  /* The data stored in this page begins at this offset. */
  static const ulint OFFSET_DATA_BEGIN = OFFSET_TRX_ID + 6;
 
  ulint payload() {
    page_size_t page_size(dict_table_page_size(m_index->table));
    return (page_size.physical() - OFFSET_DATA_BEGIN - FIL_PAGE_DATA_END);
  }
 
  z_data_page_t(mtr_t *mtr, dict_index_t *index)
      : m_block(nullptr), m_mtr(mtr), m_index(index) {}
 
  z_data_page_t(buf_block_t *block, mtr_t *mtr, dict_index_t *index)
      : m_block(block), m_mtr(mtr), m_index(index) {}
 
  /* Constructor.
  @param[in]    block   the buffer block. */
  z_data_page_t(buf_block_t *block)
      : m_block(block), m_mtr(nullptr), m_index(nullptr) {}
 
  /** Write the space identifier to the page header, without generating
  redo log records.
  @param[in]    space_id        the space identifier. */
  void set_space_id_no_redo(space_id_t space_id) {
    mlog_write_ulint(frame() + FIL_PAGE_SPACE_ID, space_id, MLOG_4BYTES,
                     nullptr);
  }
 
  /** Allocate one data page.
  @param[in]    hint    hint page number for allocation.
  @param[in]    bulk    true if bulk operation (OPCODE_INSERT_BULK)
                          false otherwise.
  @return the allocated buffer block. */
  buf_block_t *alloc(page_no_t hint, bool bulk);
 
  /** Free this data page holding the zlob data. */
  void dealloc() {
    btr_page_free_low(m_index, m_block, ULINT_UNDEFINED, m_mtr);
    m_block = nullptr;
  }
 
  /** Set the correct page type. */
  void set_page_type() {
    ut_ad(m_mtr != nullptr);
 
    mlog_write_ulint(frame() + FIL_PAGE_TYPE, FIL_PAGE_TYPE_ZLOB_DATA,
                     MLOG_2BYTES, m_mtr);
  }
 
  void set_version_0() {
    ut_ad(m_mtr != nullptr);
 
    mlog_write_ulint(frame() + OFFSET_VERSION, 0, MLOG_1BYTE, m_mtr);
  }
 
  /** Set the next page. */
  void set_next_page(page_no_t page_no) {
    ut_ad(m_mtr != nullptr);
 
    mlog_write_ulint(frame() + FIL_PAGE_NEXT, page_no, MLOG_4BYTES, m_mtr);
  }
 
  void init() {
    ut_ad(m_mtr != nullptr);
 
    set_page_type();
    set_version_0();
    set_next_page(FIL_NULL);
    set_data_len(0);
    set_trx_id(0);
  }
 
  byte *begin_data_ptr() const { return (frame() + OFFSET_DATA_BEGIN); }
 
  void set_data_len(ulint len) {
    ut_ad(m_mtr != nullptr);
 
    mlog_write_ulint(frame() + OFFSET_DATA_LEN, len, MLOG_4BYTES, m_mtr);
  }
 
  ulint get_data_len() const {
    return (mach_read_from_4(frame() + OFFSET_DATA_LEN));
  }
 
  void set_trx_id(trx_id_t tid) {
    ut_ad(m_mtr != nullptr);
 
    byte *ptr = frame() + OFFSET_TRX_ID;
    mach_write_to_6(ptr, tid);
    mlog_log_string(ptr, 6, m_mtr);
  }
 
  /** Update the header with given transaction identifier, without
  writing redo log records.
  @param[in]    tid     transaction identifier.*/
  void set_trx_id_no_redo(trx_id_t tid) {
    byte *ptr = frame() + OFFSET_TRX_ID;
    mach_write_to_6(ptr, tid);
  }
 
  /** Get the page number. */
  page_no_t get_page_no() const {
    return (mach_read_from_4(frame() + FIL_PAGE_OFFSET));
  }
 
  fil_addr_t get_self_addr() const {
    page_no_t page_no = get_page_no();
    return (fil_addr_t(page_no, OFFSET_DATA_BEGIN));
  }
 
  byte *frame() const { return (buf_block_get_frame(m_block)); }
 
  buf_block_t *m_block;
  mtr_t *m_mtr;
  dict_index_t *m_index;
};
 
/** A frag nodes page containing an array of z_frag_entry_t objects. */
struct z_frag_node_page_t {
  /** Version information. One byte. */
  static const ulint OFFSET_VERSION = FIL_PAGE_DATA;
  static const ulint LOB_PAGE_DATA = OFFSET_VERSION + 1;
 
  z_frag_node_page_t(mtr_t *mtr, dict_index_t *index)
      : m_block(nullptr), m_mtr(mtr), m_index(index) {}
 
  /** Constructor
  @param[in]    block   the buffer block.*/
  explicit z_frag_node_page_t(buf_block_t *block)
      : m_block(block), m_mtr(nullptr), m_index(nullptr) {}
 
  /** Write the space identifier to the page header, without generating
  redo log records.
  @param[in]    space_id        the space identifier. */
  void set_space_id_no_redo(space_id_t space_id) {
    mlog_write_ulint(frame() + FIL_PAGE_SPACE_ID, space_id, MLOG_4BYTES,
                     nullptr);
  }
 
  /** Set the correct page type. */
  void set_page_type() {
    ut_ad(m_mtr != nullptr);
 
    mlog_write_ulint(frame() + FIL_PAGE_TYPE, FIL_PAGE_TYPE_ZLOB_FRAG_ENTRY,
                     MLOG_2BYTES, m_mtr);
  }
 
  /** Set the next page number. */
  void set_next_page_no(page_no_t page_no) {
    ut_ad(m_mtr != nullptr);
 
    mlog_write_ulint(frame() + FIL_PAGE_NEXT, page_no, MLOG_4BYTES, m_mtr);
  }
 
  void set_version_0() {
    ut_ad(m_mtr != nullptr);
 
    mlog_write_ulint(frame() + OFFSET_VERSION, 0, MLOG_1BYTE, m_mtr);
  }
 
  /** Get the page number. */
  page_no_t get_page_no() const {
    return (mach_read_from_4(frame() + FIL_PAGE_OFFSET));
  }
 
  /** Get the next page number. */
  page_no_t get_next_page_no() const {
    return (mach_read_from_4(frame() + FIL_PAGE_NEXT));
  }
 
  /** Allocate a fragment nodes page.
  @return buffer block of the allocated fragment nodes page or nullptr. */
  buf_block_t *alloc(z_first_page_t &first, bool bulk);
 
  void dealloc() {
    btr_page_free_low(m_index, m_block, ULINT_UNDEFINED, m_mtr);
    m_block = nullptr;
  }
 
  /** Load the given compressed LOB fragment page.
  @param[in]    page_no         compressed LOB fragment page number.
  @return       the buffer block of the given page number. */
  buf_block_t *load_x(page_no_t page_no) {
    page_id_t page_id(dict_index_get_space(m_index), page_no);
    page_size_t page_size(dict_table_page_size(m_index->table));
    m_block =
        buf_page_get(page_id, page_size, RW_X_LATCH, UT_LOCATION_HERE, m_mtr);
 
    ut_ad(m_block->get_page_type() == FIL_PAGE_TYPE_ZLOB_FRAG_ENTRY);
 
    return (m_block);
  }
 
  void init(flst_base_node_t *free_lst) {
    ut_ad(m_mtr != nullptr);
 
    ulint n = get_n_frag_entries();
    for (ulint i = 0; i < n; ++i) {
      byte *ptr = frame() + LOB_PAGE_DATA;
      ptr += (i * z_frag_entry_t::SIZE);
      z_frag_entry_t entry(ptr, m_mtr);
      entry.init();
      entry.push_back(free_lst);
    }
  }
 
  ulint payload() const {
    const page_size_t page_size = dict_table_page_size(m_index->table);
    return (page_size.physical() - FIL_PAGE_DATA_END - LOB_PAGE_DATA);
  }
 
  ulint get_n_frag_entries() const {
    return (payload() / z_frag_entry_t::SIZE);
  }
 
  byte *frame() const { return (buf_block_get_frame(m_block)); }
 
  /** The buffer block of the fragment page. */
  buf_block_t *m_block;
 
  /** The mini-transaction context. */
  mtr_t *m_mtr;
 
  /** The index to which the LOB belongs. */
  dict_index_t *m_index;
};  // struct z_frag_node_page_t
 
/** Print information about the given compressed lob.
@param[in]  index  the index dictionary object.
@param[in]  ref    the LOB reference
@param[out] out    the output stream where information is printed.
@return DB_SUCCESS on success, or an error code. */
dberr_t z_print_info(const dict_index_t *index, const lob::ref_t &ref,
                     std::ostream &out);
 
/** The fragment node represents one fragment. */
struct frag_node_t {
  /** The offset where the length of fragment is stored.  The length
  includes both the payload and the meta data overhead. */
  static const ulint OFFSET_LEN = plist_node_t::SIZE;
 
  /** The offset where fragment id is stored. */
  static const ulint OFFSET_FRAG_ID = OFFSET_LEN + 2;
 
  /** The offset where fragment data is stored. */
  static const ulint OFFSET_DATA = OFFSET_FRAG_ID + 2;
 
  /** The size of a page directory entry in a fragment page in bytes.
  This must be equal to z_frag_page_t::SIZE_OF_PAGE_DIR_ENTRY*/
  static const ulint SIZE_OF_PAGE_DIR_ENTRY = 2;
 
  /** Constructor.
  @param[in]    node    Page list node.
  @param[in]    mtr     Mini-transaction. */
  frag_node_t(const plist_node_t &node, mtr_t *mtr)
      : m_node(node), m_mtr(mtr) {}
 
  frag_node_t(byte *frame, byte *ptr) : m_node(frame, ptr), m_mtr(nullptr) {}
 
  /** Constructor.
  @param[in]    frame   Page frame where the fragment node is
                          located.
  @param[in]    ptr     Location of fragment node within page
                          frame.
  @param[in]    mtr     Mini-transaction context. */
  frag_node_t(byte *frame, byte *ptr, mtr_t *mtr)
      : m_node(frame, ptr, mtr), m_mtr(mtr) {}
 
  /** Amount of space that will be used up by meta data. When a free
  space is taken from the fragment page to be used as a fragment
  node, header and footer will be the overhead. Footer is the page dir
  entry. The page dir entry may not be contiguous with the fragment.*/
  static ulint overhead() { return (SIZE_OF_PAGE_DIR_ENTRY + OFFSET_DATA); }
 
  /** Only the header size. Don't include the page dir entry size here.*/
  static ulint header_size() { return (OFFSET_DATA); }
 
  /** Constructor.
  @param[in]    frame   Page frame where the fragment node is
                          located.
  @param[in]    ptr     Location of fragment node within page
                          frame.
  @param[in]    len     Length of the fragment.
  @param[in]    mtr     Mini-transaction context. */
  frag_node_t(byte *frame, byte *ptr, ulint len, mtr_t *mtr)
      : m_node(frame, ptr, mtr), m_mtr(mtr) {
    ut_ad(mtr != nullptr);
 
    mlog_write_ulint(m_node.ptr() + OFFSET_LEN, len, MLOG_2BYTES, mtr);
  }
 
  byte *frag_begin() const { return (m_node.ptr() + OFFSET_DATA); }
 
  byte *data_begin() const { return (m_node.ptr() + OFFSET_DATA); }
 
  void set_total_len(ulint len) {
    ut_ad(m_mtr != nullptr);
 
    mlog_write_ulint(m_node.ptr() + OFFSET_LEN, len, MLOG_2BYTES, m_mtr);
  }
 
  /** Increment the total length of this fragment by 2 bytes. */
  void incr_length_by_2() {
    ut_ad(m_mtr != nullptr);
 
    ulint len = mach_read_from_2(m_node.ptr() + OFFSET_LEN);
    mlog_write_ulint(m_node.ptr() + OFFSET_LEN, len + SIZE_OF_PAGE_DIR_ENTRY,
                     MLOG_2BYTES, m_mtr);
  }
 
  /** Decrement the total length of this fragment by 2 bytes. */
  void decr_length_by_2() {
    ut_ad(m_mtr != nullptr);
 
    ulint len = mach_read_from_2(m_node.ptr() + OFFSET_LEN);
    mlog_write_ulint(m_node.ptr() + OFFSET_LEN, len - SIZE_OF_PAGE_DIR_ENTRY,
                     MLOG_2BYTES, m_mtr);
  }
 
  bool is_before(const frag_node_t &frag) const {
    return (m_node.is_before(frag.m_node));
  }
 
  void set_frag_id_null() {
    ut_ad(m_mtr != nullptr);
 
    mlog_write_ulint(m_node.ptr() + OFFSET_FRAG_ID, FRAG_ID_NULL, MLOG_2BYTES,
                     m_mtr);
  }
 
  void set_frag_id(ulint id) {
    ut_ad(m_mtr != nullptr);
 
    mlog_write_ulint(m_node.ptr() + OFFSET_FRAG_ID, id, MLOG_2BYTES, m_mtr);
  }
 
  ulint get_frag_id() const {
    return (mach_read_from_2(m_node.ptr() + OFFSET_FRAG_ID));
  }
 
  /** Get the space available in this fragment for storing data. */
  ulint payload() const { return (get_total_len() - header_size()); }
 
  /** Get the total length of this fragment, including its metadata. */
  ulint get_total_len() const {
    return (mach_read_from_2(m_node.ptr() + OFFSET_LEN));
  }
 
  /** Get the offset of the current fragment within page.
  @return the offset of the current fragment within. */
  paddr_t addr() const { return (m_node.addr()); }
 
  /** Gets the pointer to the beginning of the current fragment.  Note
  that the beginning of the fragment contains meta data.
  @return pointer to the beginning of the current fragment. */
  byte *ptr() const {
    ut_ad(!m_node.is_null());
    return (m_node.ptr());
  }
 
  /** Gets the pointer just after the current fragment.  The pointer
  returned does not belong to this fragment.  This is used to check
  adjacency.
  @return pointer to the end of the current fragment. */
  byte *end_ptr() const {
    ut_ad(!m_node.is_null());
    return (ptr() + get_total_len());
  }
 
  /** Get the page frame.
  @return the page frame. */
  byte *frame() const { return (m_node.get_frame()); }
 
  std::ostream &print(std::ostream &out) const {
    if (!m_node.is_null()) {
      ulint len = get_total_len();
      out << "[frag_node_t: " << m_node << ", len=" << len << "/" << payload()
          << ", frag_id=" << get_frag_id() << "]";
    } else {
      out << "[frag_node_t: null, len=0]";
    }
    return (out);
  }
 
  frag_node_t get_next_frag() {
    ut_ad(!is_null());
    plist_node_t next = m_node.get_next_node();
    return (frag_node_t(next, m_mtr));
  }
 
  frag_node_t get_next_node() { return (get_next_frag()); }
 
  frag_node_t get_prev_node() { return (get_prev_frag()); }
 
  frag_node_t get_prev_frag() {
    ut_ad(!is_null());
    plist_node_t prev = m_node.get_prev_node();
    return (frag_node_t(prev, m_mtr));
  }
 
  /** Merge the current fragment node with the given next fragment node.
  This will succeed only if they are adjacent to each other.
  Detailed Note: There is a new page type FIL_PAGE_TYPE_ZLOB_FRAG_ENTRY
  - and we can call it the fragment pages.  Each fragment page contains
  one or more fragments.  Each fragment is represented by a frag_node_t.
  And each fragment can be of different size.  Consider a fragment page
  containing 4 fragments - f1, f2, f3 and f4.  Suppose we free f2 and
  f3, then we can merge them into one single bigger fragment which is
  free.
  @param[in]    next    the next fragment.
  @return true if merge done, false otherwise. */
  bool merge(frag_node_t &next) {
    ut_ad(m_mtr != nullptr);
 
    byte *p1 = ptr();
    ulint len1 = get_total_len();
    byte *p2 = next.ptr();
    ulint len2 = next.get_total_len();
 
    if (p2 == (p1 + len1)) {
      set_total_len(len1 + len2);
      return (true);
    }
 
    return (false);
  }
 
  bool is_null() const { return (m_node.is_null()); }
 
  bool is_equal(const frag_node_t &that) const {
    return (m_node.is_equal(that.m_node));
  }
 
  bool is_equal(const plist_node_t &node) const {
    return (m_node.is_equal(node));
  }
 
  /** The page list node. */
  plist_node_t m_node;
 
 private:
  /** The mini-transaction context.  It is only in-memory. */
  mtr_t *m_mtr;
};
 
inline std::ostream &operator<<(std::ostream &out, const frag_node_t &obj) {
  return (obj.print(out));
}
 
/** The fragment page.  This page will contain fragments from different
zlib streams. */
struct z_frag_page_t {
  /** Version information. One byte. */
  static const ulint OFFSET_VERSION = FIL_PAGE_DATA;
 
  /** The location of z_frag_entry_t for this page. */
  static const ulint OFFSET_FRAG_ENTRY = OFFSET_VERSION + 1;
 
  /** The offset within page where the free space list begins. */
  static const ulint OFFSET_FREE_LIST = OFFSET_FRAG_ENTRY + FIL_ADDR_SIZE;
 
  /** The offset within page where the fragment list begins. */
  static const ulint OFFSET_FRAGS_LIST =
      OFFSET_FREE_LIST + plist_base_node_t::SIZE;
 
  /** The offset within page where the fragments can occupy . */
  static const ulint OFFSET_FRAGS_BEGIN =
      OFFSET_FRAGS_LIST + plist_base_node_t::SIZE;
 
  /** Offset of number of page directory entries (from end) */
  static const ulint OFFSET_PAGE_DIR_ENTRY_COUNT = FIL_PAGE_DATA_END + 2;
 
  /** Offset of first page directory entry (from end) */
  static const ulint OFFSET_PAGE_DIR_ENTRY_FIRST =
      OFFSET_PAGE_DIR_ENTRY_COUNT + 2;
 
  static const ulint SIZE_OF_PAGE_DIR_ENTRY = 2; /* bytes */
 
  /** Constructor.
  @param[in]    block   Buffer block containing the fragment page.
  @param[in]    mtr     Mini-transaction context.
  @param[in]    index   Clustered index to which LOB belongs. */
  z_frag_page_t(buf_block_t *block, mtr_t *mtr, dict_index_t *index)
      : m_block(block), m_mtr(mtr), m_index(index) {
    static_assert(frag_node_t::SIZE_OF_PAGE_DIR_ENTRY ==
                  z_frag_page_t::SIZE_OF_PAGE_DIR_ENTRY);
  }
 
  /** Constructor.
  @param[in]    mtr     Mini-transaction context.
  @param[in]    index   Clustered index to which LOB belongs. */
  z_frag_page_t(mtr_t *mtr, dict_index_t *index)
      : z_frag_page_t(nullptr, mtr, index) {}
 
  /** Constructor.
  @param[in]    block   the buffer block containing the fragment page.*/
  explicit z_frag_page_t(buf_block_t *block)
      : m_block(block), m_mtr(nullptr), m_index(nullptr) {
    static_assert(frag_node_t::SIZE_OF_PAGE_DIR_ENTRY ==
                  z_frag_page_t::SIZE_OF_PAGE_DIR_ENTRY);
  }
 
  /** Write the space identifier to the page header, without generating
  redo log records.
  @param[in]    space_id        the space identifier. */
  void set_space_id_no_redo(space_id_t space_id) {
    mlog_write_ulint(frame() + FIL_PAGE_SPACE_ID, space_id, MLOG_4BYTES,
                     nullptr);
  }
 
  z_frag_entry_t get_frag_entry_x();
  z_frag_entry_t get_frag_entry_s();
 
  void update_frag_entry() {
    z_frag_entry_t entry = get_frag_entry_x();
    entry.update(*this);
  }
 
  void set_version_0() {
    mlog_write_ulint(frame() + OFFSET_VERSION, 0, MLOG_1BYTE, m_mtr);
  }
 
  flst_node_t *addr2ptr_x(fil_addr_t &addr) {
    space_id_t space = dict_index_get_space(m_index);
    const page_size_t page_size = dict_table_page_size(m_index->table);
    return (fut_get_ptr(space, page_size, addr, RW_X_LATCH, m_mtr));
  }
 
  flst_node_t *addr2ptr_s(fil_addr_t &addr) {
    space_id_t space = dict_index_get_space(m_index);
    const page_size_t page_size = dict_table_page_size(m_index->table);
    return (fut_get_ptr(space, page_size, addr, RW_S_LATCH, m_mtr));
  }
 
  void set_frag_entry(const fil_addr_t &addr) const {
    ut_a(addr.boffset < get_page_size());
    return (flst_write_addr(frame() + OFFSET_FRAG_ENTRY, addr, m_mtr));
  }
 
  /** Obtain the file address of the fragment entry that denotes the
  current fragment page.
  @return the file address of the fragment entry. */
  fil_addr_t get_frag_entry() const {
    return (flst_read_addr(frame() + OFFSET_FRAG_ENTRY, m_mtr));
  }
 
  void set_frag_entry_null() const {
    return (flst_write_addr(frame() + OFFSET_FRAG_ENTRY, fil_addr_null, m_mtr));
  }
 
  ulint get_n_dir_entries() const {
    byte *ptr = frame() + get_page_size() - OFFSET_PAGE_DIR_ENTRY_COUNT;
    return (mach_read_from_2(ptr));
  }
 
  void set_n_dir_entries(ulint n) const {
    byte *ptr = frame() + get_page_size() - OFFSET_PAGE_DIR_ENTRY_COUNT;
    mlog_write_ulint(ptr, n, MLOG_2BYTES, m_mtr);
  }
 
  bool is_border_frag(const frag_node_t &node) const {
    return (slots_end_ptr() == node.end_ptr());
  }
 
  byte *slots_end_ptr() const {
    ulint n = get_n_dir_entries();
    byte *first = frame() + get_page_size() - OFFSET_PAGE_DIR_ENTRY_COUNT;
    byte *ptr = first - (n * SIZE_OF_PAGE_DIR_ENTRY);
    return (ptr);
  }
 
  paddr_t frag_id_to_addr(ulint frag_id) const {
    byte *first = frame() + get_page_size() - OFFSET_PAGE_DIR_ENTRY_FIRST;
    byte *ptr = first - (frag_id * SIZE_OF_PAGE_DIR_ENTRY);
    return (mach_read_from_2(ptr));
  }
 
  ulint get_nth_dir_entry(ulint frag_id) {
    byte *first = frame() + get_page_size() - OFFSET_PAGE_DIR_ENTRY_FIRST;
    byte *ptr = first - (frag_id * SIZE_OF_PAGE_DIR_ENTRY);
    return (mach_read_from_2(ptr));
  }
 
  void set_nth_dir_entry(ulint frag_id, paddr_t val) {
    byte *first = frame() + get_page_size() - OFFSET_PAGE_DIR_ENTRY_FIRST;
    byte *ptr = first - (frag_id * SIZE_OF_PAGE_DIR_ENTRY);
    mlog_write_ulint(ptr, val, MLOG_2BYTES, m_mtr);
  }
 
  ulint init_last_dir_entry() {
    ulint n = get_n_dir_entries();
    set_nth_dir_entry(n - 1, 0);
    return (n - 1);
  }
 
  void incr_n_dir_entries() const {
    byte *ptr = frame() + get_page_size() - OFFSET_PAGE_DIR_ENTRY_COUNT;
    ulint n = mach_read_from_2(ptr);
    ut_a(n < FRAG_ID_NULL);
    mlog_write_ulint(ptr, n + 1, MLOG_2BYTES, m_mtr);
  }
 
  void decr_n_dir_entries() const {
    byte *ptr = frame() + get_page_size() - OFFSET_PAGE_DIR_ENTRY_COUNT;
    ulint n = mach_read_from_2(ptr);
    ut_a(n > 0);
    mlog_write_ulint(ptr, n - 1, MLOG_2BYTES, m_mtr);
  }
 
  ulint get_page_size() const {
    const page_size_t page_size = dict_table_page_size(m_index->table);
    return (page_size.physical());
  }
 
  ulint space_used_by_dir() const {
    ulint n = get_n_dir_entries();
    return (n * SIZE_OF_PAGE_DIR_ENTRY);
  }
 
  ulint locate_free_slot() {
    ulint n = get_n_dir_entries();
 
    for (ulint frag_id = 0; frag_id < n; frag_id++) {
      ulint paddr = get_nth_dir_entry(frag_id);
 
      if (paddr == 0) {
        return (frag_id);
      }
    }
 
    return (FRAG_ID_NULL);
  }
 
  /** Allocate a fragment id.
  @return On success, return fragment id.
  @return On failure, return FRAG_ID_NULL. */
  ulint alloc_frag_id() {
    ulint id = locate_free_slot();
 
    if (id == FRAG_ID_NULL) {
      return (alloc_dir_entry());
    }
 
    return (id);
  }
 
  std::ostream &print_frag_id(std::ostream &out) {
    ulint n = get_n_dir_entries();
    out << "FRAG IDS: " << std::endl;
 
    for (ulint frag_id = 0; frag_id < n; frag_id++) {
      out << "id=" << frag_id << ", addr=" << frag_id_to_addr(frag_id)
          << std::endl;
    }
 
    return (out);
  }
 
  /** Grow the frag directory by one entry.
  @return the fragment identifier that was newly added. */
  ulint alloc_dir_entry();
 
  /** Set the next page. */
  void set_page_next(page_no_t page_no) {
    mlog_write_ulint(frame() + FIL_PAGE_NEXT, page_no, MLOG_4BYTES, m_mtr);
  }
 
  /** Set the prev page. */
  void set_page_prev(page_no_t page_no) { set_page_prev(page_no, m_mtr); }
 
  /** Set the prev page. */
  void set_page_prev(page_no_t page_no, mtr_t *mtr) {
    mlog_write_ulint(frame() + FIL_PAGE_PREV, page_no, MLOG_4BYTES, mtr);
  }
 
  /** Get the next page number.
  @return next page number. */
  page_no_t get_next_page_no() const { return (m_block->get_next_page_no()); }
 
  /** Get the prev page number (FIL_PAGE_PREV).
  @param[in]  mtr  Mini-transaction latch context.
  @return prev page number. */
  page_no_t get_prev_page_no(mtr_t *mtr) const {
    return (mtr_read_ulint(frame() + FIL_PAGE_PREV, MLOG_4BYTES, mtr));
  }
 
  /** Get the prev page number.
  @return prev page number. */
  page_no_t get_prev_page_no() const { return (get_prev_page_no(m_mtr)); }
 
  /** Allocate the fragment page.
  @param[in]    first   first page of this LOB.
  @param[in]    hint    hint page number for allocation.
  @param[in]    bulk    true if bulk operation (OPCODE_INSERT_BULK)
                          false otherwise.
  @return the allocated buffer block. */
  buf_block_t *alloc(z_first_page_t &first, page_no_t hint, bool bulk);
 
  /** Free the fragment page along with its entry.
  @param[in]   first   first page of LOB.
  @param[in]   alloc_mtr  mini trx to perform this modification. */
  void dealloc_with_entry(z_first_page_t &first, mtr_t *alloc_mtr);
 
  /** Free the fragment page. */
  void dealloc() {
    btr_page_free_low(m_index, m_block, ULINT_UNDEFINED, m_mtr);
    m_block = nullptr;
  }
 
  buf_block_t *load_x(page_no_t page_no) {
    page_id_t page_id(dict_index_get_space(m_index), page_no);
    page_size_t page_size(dict_table_page_size(m_index->table));
    m_block =
        buf_page_get(page_id, page_size, RW_X_LATCH, UT_LOCATION_HERE, m_mtr);
    return (m_block);
  }
 
  void merge_free_frags() {
    plist_base_node_t free_lst = free_list();
    frag_node_t frag(free_lst.get_first_node(), m_mtr);
    frag_node_t next = frag.get_next_frag();
 
    while (!next.is_null() && frag.merge(next)) {
      free_lst.remove(next.m_node);
      next = frag.get_next_frag();
    }
  }
 
  void merge_free_frags(frag_node_t &frag) {
    ut_ad(!frag.is_null());
    plist_base_node_t free_lst = free_list();
    frag_node_t next = frag.get_next_frag();
 
    while (!next.is_null() && frag.merge(next)) {
      free_lst.remove(next.m_node);
      next = frag.get_next_frag();
    }
  }
 
  bool validate_lists() const {
    plist_base_node_t free_lst = free_list();
    plist_base_node_t frag_lst = frag_list();
    plist_node_t free_node = free_lst.get_first_node();
 
    while (!free_node.is_null()) {
      plist_node_t frag_node = frag_lst.get_first_node();
 
      while (!frag_node.is_null()) {
        ut_ad(frag_node.addr() != free_node.addr());
        frag_node = frag_node.get_next_node();
      }
 
      free_node = free_node.get_next_node();
    }
    return (true);
  }
 
  void insert_into_free_list(frag_node_t &frag) {
    ut_ad(frag.get_frag_id() == FRAG_ID_NULL);
 
    plist_base_node_t free_lst = free_list();
 
    plist_node_t node = free_lst.get_first_node();
    plist_node_t prev_node(m_mtr);
 
    while (!node.is_null()) {
      ut_ad(frag.addr() != node.addr());
      if (frag.addr() < node.addr()) {
        break;
      }
      prev_node = node;
      node = node.get_next_node();
    }
 
    free_lst.insert_before(node, frag.m_node);
 
    if (prev_node.is_null()) {
      merge_free_frags();
    } else {
      frag_node_t prev_frag(prev_node, m_mtr);
      merge_free_frags(prev_frag);
    }
  }
 
  /** Insert the given fragment node into the fragment list.
  @param[in,out]        frag    the fragment node to be inserted.*/
  void insert_into_frag_list(frag_node_t &frag) {
    plist_base_node_t frag_lst = frag_list();
    plist_node_t node = frag_lst.get_first_node();
 
    while (!node.is_null()) {
      ut_ad(frag.addr() != node.addr());
      if (frag.addr() < node.addr()) {
        break;
      }
      node = node.get_next_node();
    }
 
    frag_lst.insert_before(node, frag.m_node);
  }
 
  /** Split one free fragment into two. This is not splitting a
  fragment page.  This is just splitting one free fragment into two.
  When we want to allocate one fragment, we identify a big enough free
  fragment and split it into two - one will be the allocated portion and
  other will become a free fragment.
  @param[in]  free_frag  the free fragment that will be split.
  @param[in]  size  the payload size in bytes. */
  void split_free_frag(frag_node_t &free_frag, ulint size) {
    ut_ad(size < free_frag.payload());
    const ulint old_total_len = free_frag.get_total_len();
    plist_base_node_t free_lst = free_list();
 
    /* Locate the next fragment */
    byte *p2 = free_frag.data_begin() + size;
 
    ulint remain =
        free_frag.get_total_len() - frag_node_t::header_size() - size;
 
    ut_a(remain >= frag_node_t::OFFSET_DATA);
 
    free_frag.set_total_len(frag_node_t::header_size() + size);
 
    frag_node_t frag2(frame(), p2, remain, m_mtr);
    frag2.set_total_len(remain);
    frag2.set_frag_id_null();
    free_lst.insert_after(free_frag.m_node, frag2.m_node);
 
    ut_a(free_frag.get_total_len() + frag2.get_total_len() == old_total_len);
 
    ut_ad(validate_lists());
  }
 
  frag_node_t get_frag_node(frag_id_t id) const {
    ut_ad(id != FRAG_ID_NULL);
 
    paddr_t off = frag_id_to_addr(id);
    byte *f = frame();
    return (frag_node_t(f, f + off));
  }
 
  void dealloc_fragment(ulint frag_id) {
    ut_ad(frag_id != FRAG_ID_NULL);
 
    paddr_t off = frag_id_to_addr(frag_id);
    byte *f = frame();
    frag_node_t frag(f, f + off, m_mtr);
    dealloc_fragment(frag);
    dealloc_frag_id(frag_id);
 
    /* Update the index entry. */
    update_frag_entry();
  }
 
  /** Allocate a fragment with the given payload.
  @param[in]  size  the payload size.
  @param[in]  entry the index entry of the given frag page.
  @return the frag_id of the allocated fragment.
  @return FRAG_ID_NULL if fragment could not be allocated. */
  frag_id_t alloc_fragment(ulint size, z_frag_entry_t &entry);
 
  plist_base_node_t free_list() const {
    byte *f = frame();
    return (plist_base_node_t(f, f + OFFSET_FREE_LIST, m_mtr));
  }
 
  plist_base_node_t frag_list() const {
    byte *f = frame();
    return (plist_base_node_t(f, f + OFFSET_FRAGS_LIST, m_mtr));
  }
 
  void set_page_type() {
    byte *ptr = frame() + FIL_PAGE_TYPE;
    mlog_write_ulint(ptr, FIL_PAGE_TYPE_ZLOB_FRAG, MLOG_2BYTES, m_mtr);
  }
 
  page_type_t get_page_type() const {
    return (mach_read_from_2(frame() + FIL_PAGE_TYPE));
  }
 
  const char *get_page_type_str() const {
    page_type_t type = get_page_type();
    ut_a(type == FIL_PAGE_TYPE_ZLOB_FRAG);
    return ("FIL_PAGE_TYPE_ZLOB_FRAG");
  }
 
  /** The maximum free space available in a fragment page. Adjustment
  needs to be done with the frag_node_t::overhead().*/
  ulint payload() { return (z_frag_page_t::max_payload(m_index)); }
 
  /** The maximum free space available in a fragment page. Adjustment
  needs to be done with the frag_node_t::overhead().*/
  static ulint max_payload(dict_index_t *index) {
    page_size_t page_size(dict_table_page_size(index->table));
    return (page_size.physical() - OFFSET_FRAGS_BEGIN -
            OFFSET_PAGE_DIR_ENTRY_COUNT);
  }
 
  /** Determine if the given length of data can fit into a fragment
  page.
  @param[in]   index   the clust index into which LOB is inserted.
  @param[in]   data_size  The length of data to operate.
  @return true if data can fit into fragment page, false otherwise. */
  static bool can_data_fit(dict_index_t *index, ulint data_size);
 
  /** Get the frag page number. */
  page_no_t get_page_no() const { return (m_block->get_page_no()); }
 
  byte *frame() const { return (buf_block_get_frame(m_block)); }
 
  std::ostream &print(std::ostream &out) const {
    print_free_list(out);
    print_frag_list(out);
    print_frags_in_order(out);
    print_page_dir(out);
    return (out);
  }
 
  /** Get the total amount of stored data in this page. */
  ulint get_total_stored_data() const;
 
  /** Get the total cumulative free space in this page. */
  ulint get_total_free_len() const;
 
  /** Get the big free space in this page. */
  ulint get_big_free_len() const;
 
  /** Get the number of fragments in this frag page. */
  ulint get_n_frags() const {
    plist_base_node_t frag_lst = frag_list();
    return (frag_lst.get_len());
  }
 
  std::ostream &print_frags_in_order(std::ostream &out) const;
 
  std::ostream &print_free_list(std::ostream &out) const {
    if (m_block == nullptr) {
      return (out);
    }
 
    plist_base_node_t free_lst = free_list();
    out << "[Free List: " << free_lst << "]" << std::endl;
 
    for (plist_node_t cur = free_lst.get_first_node(); !cur.is_null();
         cur = cur.get_next_node()) {
      frag_node_t frag(cur, m_mtr);
      out << frag << std::endl;
    }
    return (out);
  }
 
  std::ostream &print_frag_list(std::ostream &out) const {
    if (m_block == nullptr) {
      return (out);
    }
 
    plist_base_node_t frag_lst = frag_list();
    out << "[Frag List: " << frag_lst << "]" << std::endl;
 
    for (plist_node_t cur = frag_lst.get_first_node(); !cur.is_null();
         cur = cur.get_next_node()) {
      frag_node_t frag(cur, m_mtr);
      out << frag << std::endl;
    }
    return (out);
  }
 
  std::ostream &print_page_dir(std::ostream &out) const {
    if (m_block == nullptr) {
      return (out);
    }
 
    ulint n = get_n_dir_entries();
 
    for (ulint frag_id = 0; frag_id < n; ++frag_id) {
      paddr_t off = frag_id_to_addr(frag_id);
      out << "[frag_id=" << frag_id << ", addr=" << off << "]" << std::endl;
    }
 
    return (out);
  }
 
  void set_mtr(mtr_t *mtr) { m_mtr = mtr; }
 
  void set_index(dict_index_t *index) { m_index = index; }
 
  void set_block_null() { m_block = nullptr; }
 
  /** Determine if the given fragment node is the last fragment
  node adjacent to the directory.
  @return true if it is last fragment node, false otherwise. */
  bool is_last_frag(const frag_node_t &node) const {
    return (node.end_ptr() == slots_end_ptr());
  }
 
 private:
  fil_addr_t get_frag_entry_addr() const {
    return (flst_read_addr(frame() + OFFSET_FRAG_ENTRY, m_mtr));
  }
 
  void dealloc_fragment(frag_node_t &frag) {
    plist_base_node_t frag_lst = frag_list();
    frag_lst.remove(frag.m_node);
    frag.set_frag_id_null();
    insert_into_free_list(frag);
  }
 
  /** Deallocate all the free slots from the end of the page
  directory. */
  void dealloc_frag_id();
 
  /** Deallocate the given fragment id.
  @param[in] frag_id The fragment that needs to be deallocated. */
  void dealloc_frag_id(ulint frag_id) {
    set_nth_dir_entry(frag_id, 0);
    dealloc_frag_id();
  }
 
  buf_block_t *m_block;
  mtr_t *m_mtr;
  dict_index_t *m_index;
};
 
/** Insert one chunk of input.  The maximum size of a chunk is Z_CHUNK_SIZE.
@param[in]  index      Clustered index in which LOB is inserted.
@param[in]  first      First page of the LOB.
@param[in]  trx        Transaction doing the insertion.
@param[in]  blob       Uncompressed LOB to be inserted.
@param[in]  len        Length of the blob.
@param[out] out_entry  Newly inserted index entry. can be NULL.
@param[in]  mtr        Mini-transaction
@param[in]  bulk       true if it is bulk operation, false otherwise.
@return DB_SUCCESS on success, error code on failure. */
dberr_t z_insert_chunk(dict_index_t *index, z_first_page_t &first, trx_t *trx,
                       byte *blob, ulint len, z_index_entry_t *out_entry,
                       mtr_t *mtr, bool bulk);
 
}  // namespace lob
 
#endif  // lob0impl_h