page0size.h

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/** @file include/page0size.h
 A class describing a page size.
 
 Created Nov 14, 2013 Vasil Dimov
 *******************************************************/
 
#ifndef page0size_t
#define page0size_t
 
#include "fsp0types.h"
 
constexpr size_t FIELD_REF_SIZE = 20;
 
/** A BLOB field reference full of zero, for use in assertions and
tests.Initially, BLOB field references are set to zero, in
dtuple_convert_big_rec(). */
extern const byte field_ref_zero[FIELD_REF_SIZE];
 
constexpr size_t PAGE_SIZE_T_SIZE_BITS = 17;
 
/** Page size descriptor. Contains the physical and logical page size, as well
as whether the page is compressed or not. */
class page_size_t {
 public:
  /** Constructor from (physical, logical, is_compressed).
  @param[in]    physical        physical (on-disk/zipped) page size
  @param[in]    logical         logical (in-memory/unzipped) page size
  @param[in]    is_compressed   whether the page is compressed */
  page_size_t(uint32_t physical, uint32_t logical, bool is_compressed) {
    if (physical == 0) {
      physical = UNIV_PAGE_SIZE_ORIG;
    }
    if (logical == 0) {
      logical = UNIV_PAGE_SIZE_ORIG;
    }
 
    m_physical = static_cast<unsigned>(physical);
    m_logical = static_cast<unsigned>(logical);
    m_is_compressed = static_cast<unsigned>(is_compressed);
 
    ut_ad(physical <= (1 << PAGE_SIZE_T_SIZE_BITS));
    ut_ad(logical <= (1 << PAGE_SIZE_T_SIZE_BITS));
 
    ut_ad(ut_is_2pow(physical));
    ut_ad(ut_is_2pow(logical));
 
    ut_ad(logical <= UNIV_PAGE_SIZE_MAX);
    ut_ad(logical >= physical);
    ut_ad(!is_compressed || physical <= UNIV_ZIP_SIZE_MAX);
  }
 
  /** Constructor from (fsp_flags).
  @param[in]    fsp_flags       filespace flags */
  explicit page_size_t(uint32_t fsp_flags) {
    uint32_t ssize = FSP_FLAGS_GET_PAGE_SSIZE(fsp_flags);
 
    /* If the logical page size is zero in fsp_flags, then use the
    legacy 16k page size. */
    ssize = (0 == ssize) ? UNIV_PAGE_SSIZE_ORIG : ssize;
 
    /* Convert from a 'log2 minus 9' to a page size in bytes. */
    const ulint size = ((UNIV_ZIP_SIZE_MIN >> 1) << ssize);
 
    ut_ad(size <= UNIV_PAGE_SIZE_MAX);
    ut_ad(size <= (1 << PAGE_SIZE_T_SIZE_BITS));
 
    m_logical = size;
 
    ssize = FSP_FLAGS_GET_ZIP_SSIZE(fsp_flags);
 
    /* If the fsp_flags have zero in the zip_ssize field, then
    it means that the tablespace does not have compressed pages
    and the physical page size is the same as the logical page
    size. */
    if (ssize == 0) {
      m_is_compressed = false;
      m_physical = m_logical;
    } else {
      m_is_compressed = true;
 
      /* Convert from a 'log2 minus 9' to a page size
      in bytes. */
      const ulint phy = ((UNIV_ZIP_SIZE_MIN >> 1) << ssize);
 
      ut_ad(phy <= UNIV_ZIP_SIZE_MAX);
      ut_ad(phy <= (1 << PAGE_SIZE_T_SIZE_BITS));
 
      m_physical = phy;
    }
  }
 
  /** Retrieve the physical page size (on-disk).
  @return physical page size in bytes */
  inline size_t physical() const {
    ut_ad(m_physical > 0);
 
    return (m_physical);
  }
 
  /** Retrieve the logical page size (in-memory).
  @return logical page size in bytes */
  inline size_t logical() const {
    ut_ad(m_logical > 0);
    return (m_logical);
  }
 
  page_no_t extent_size() const {
    page_no_t size = 0;
    switch (m_physical) {
      case 4096:
        size = 256;
        break;
      case 8192:
        size = 128;
        break;
      case 16384:
      case 32768:
      case 65536:
        size = 64;
        break;
      default:
        ut_d(ut_error);
    }
    return (size);
  }
 
  size_t extents_per_xdes() const { return (m_physical / extent_size()); }
 
  /** Check whether the page is compressed on disk.
  @return true if compressed */
  inline bool is_compressed() const { return (m_is_compressed); }
 
  /** Copy the values from a given page_size_t object.
  @param[in]    src     page size object whose values to fetch */
  inline void copy_from(const page_size_t &src) {
    m_physical = src.physical();
    m_logical = src.logical();
    m_is_compressed = src.is_compressed();
  }
 
  /** Check if a given page_size_t object is equal to the current one.
  @param[in]    a       page_size_t object to compare
  @return true if equal */
  inline bool equals_to(const page_size_t &a) const {
    return (a.physical() == m_physical && a.logical() == m_logical &&
            a.is_compressed() == (bool)m_is_compressed);
  }
 
  inline void set_flag(uint32_t fsp_flags) {
    uint32_t ssize = FSP_FLAGS_GET_PAGE_SSIZE(fsp_flags);
 
    /* If the logical page size is zero in fsp_flags, then
    use the legacy 16k page size. */
    ssize = (0 == ssize) ? UNIV_PAGE_SSIZE_ORIG : ssize;
 
    /* Convert from a 'log2 minus 9' to a page size in bytes. */
    const uint32_t size = ((UNIV_ZIP_SIZE_MIN >> 1) << ssize);
 
    ut_ad(size <= UNIV_PAGE_SIZE_MAX);
    ut_ad(size <= (1 << PAGE_SIZE_T_SIZE_BITS));
 
    m_logical = size;
 
    ssize = FSP_FLAGS_GET_ZIP_SSIZE(fsp_flags);
 
    /* If the fsp_flags have zero in the zip_ssize field,
    then it means that the tablespace does not have
    compressed pages and the physical page size is the same
    as the logical page size. */
    if (ssize == 0) {
      m_is_compressed = false;
      m_physical = m_logical;
    } else {
      m_is_compressed = true;
 
      /* Convert from a 'log2 minus 9' to a page size
      in bytes. */
      const ulint phy = ((UNIV_ZIP_SIZE_MIN >> 1) << ssize);
 
      ut_ad(phy <= UNIV_ZIP_SIZE_MAX);
      ut_ad(phy <= (1 << PAGE_SIZE_T_SIZE_BITS));
 
      m_physical = phy;
    }
  }
 
  page_size_t &operator=(const page_size_t &) = default;
  page_size_t(const page_size_t &) = default;
 
 private:
  /* For non compressed tablespaces, physical page size is equal to
  the logical page size and the data is stored in buf_page_t::frame
  (and is also always equal to univ_page_size (--innodb-page-size=)).
 
  For compressed tablespaces, physical page size is the compressed
  page size as stored on disk and in buf_page_t::zip::data. The logical
  page size is the uncompressed page size in memory - the size of
  buf_page_t::frame (currently also always equal to univ_page_size
  (--innodb-page-size=)). */
 
  /** Physical page size. */
  unsigned m_physical : PAGE_SIZE_T_SIZE_BITS;
 
  /** Logical page size. */
  unsigned m_logical : PAGE_SIZE_T_SIZE_BITS;
 
  /** Flag designating whether the physical page is compressed, which is
  true IFF the whole tablespace where the page belongs is compressed. */
  unsigned m_is_compressed : 1;
};
 
/* Overloading the global output operator to conveniently print an object
of type the page_size_t.
@param[in,out]  out     the output stream
@param[in]      obj     an object of type page_size_t to be printed
@retval the output stream */
inline std::ostream &operator<<(std::ostream &out, const page_size_t &obj) {
  out << "[page size: physical=" << obj.physical()
      << ", logical=" << obj.logical() << ", compressed=" << obj.is_compressed()
      << "]";
  return (out);
}
 
extern page_size_t univ_page_size;
 
#endif /* page0size_t */