db: Define PAGESZ, inline mmap() args

laumann

Jan 19, 2024, 5:41 AM

TDOR2JDR2SO7FF5LVBJ4GYQXHK7MPLJQJPZMRO6EIRT6AYQNH6CQC

Dependencies

• [2] ZYBYX2TB Add new pristine subcommand
• [3] HUOUNPBG db: replace err() macro with die()

Change contents

• edit in db.h at line 3
  [2.110]

  [2.110]
  +

  + /**

  + * The sanakirja database exists to allow the creation of data

  + * structures that most naturally lives in memory-mapped files.

  + *

  + * It is structured around pages, through two traits AllocPage and

  + * LoadPage. The assumption is that pages have 4K bytes.

  + *

  + * There is a Storable macro that types can implement to indicate they

  + * can be stored on disk. Implementations should allow for comparing

  + * types, getting references from a page to other pages (if they

  + * exist).

  + */

  + #define PAGESZ 4096
• replacement in db.c at line 66
  [2.1783]→[2.1783:2001](∅→∅)
  − usize length = 4096;

  − int prot = PROT_READ; // memory protection; PROT_{EXEC,READ,WRITE,NONE}

  − int flags = MAP_PRIVATE; // determines visibility

  − off_t offset = 0;

  − addr = mmap(NULL, length, prot, flags, fd, offset);
  [2.1783]

  [2.2001]
  + addr = mmap(NULL, PAGESZ, PROT_READ, MAP_PRIVATE, fd, 0);
• replacement in db.c at line 71
  [2.2072]→[2.2072:2095](∅→∅)
  − munmap(addr, length);
  [2.2072]

  [2.2095]
  + munmap(addr, PAGESZ);
• replacement in db.c at line 79
  [2.2258]→[2.2258:2313](∅→∅)
  − addr = mmap(NULL, length, prot, flags, fd, i << 12);
  [2.2258]

  [2.2313]
  + addr = mmap(NULL, PAGESZ, PROT_READ, MAP_PRIVATE, fd, i << 12);
• replacement in db.c at line 83
  [2.2387]→[2.2387:2411](∅→∅)
  − munmap(addr, length);
  [2.2387]

  [2.2411]
  + munmap(addr, PAGESZ);