mmap memory maps a DB's data file.
(db *DB, sz int)
| 53 | |
| 54 | // mmap memory maps a DB's data file. |
| 55 | func mmap(db *DB, sz int) error { |
| 56 | // Map the data file to memory. |
| 57 | b, err := unix.Mmap(int(db.file.Fd()), 0, sz, syscall.PROT_READ, syscall.MAP_SHARED|db.MmapFlags) |
| 58 | if err != nil { |
| 59 | return err |
| 60 | } |
| 61 | |
| 62 | // Advise the kernel that the mmap is accessed randomly. |
| 63 | err = unix.Madvise(b, syscall.MADV_RANDOM) |
| 64 | if err != nil && err != syscall.ENOSYS { |
| 65 | // Ignore not implemented error in kernel because it still works. |
| 66 | return fmt.Errorf("madvise: %s", err) |
| 67 | } |
| 68 | |
| 69 | // Save the original byte slice and convert to a byte array pointer. |
| 70 | db.dataref = b |
| 71 | db.data = (*[common.MaxMapSize]byte)(unsafe.Pointer(&b[0])) |
| 72 | db.datasz = sz |
| 73 | return nil |
| 74 | } |
| 75 | |
| 76 | // munmap unmaps a DB's data file from memory. |
| 77 | func munmap(db *DB) error { |