khenaidoo | 2672188 | 2021-08-11 17:42:52 -0400 | [diff] [blame] | 1 | // +build aix |
| 2 | |
| 3 | package bbolt |
| 4 | |
| 5 | import ( |
| 6 | "fmt" |
| 7 | "syscall" |
| 8 | "time" |
| 9 | "unsafe" |
| 10 | |
| 11 | "golang.org/x/sys/unix" |
| 12 | ) |
| 13 | |
| 14 | // flock acquires an advisory lock on a file descriptor. |
| 15 | func flock(db *DB, exclusive bool, timeout time.Duration) error { |
| 16 | var t time.Time |
| 17 | if timeout != 0 { |
| 18 | t = time.Now() |
| 19 | } |
| 20 | fd := db.file.Fd() |
| 21 | var lockType int16 |
| 22 | if exclusive { |
| 23 | lockType = syscall.F_WRLCK |
| 24 | } else { |
| 25 | lockType = syscall.F_RDLCK |
| 26 | } |
| 27 | for { |
| 28 | // Attempt to obtain an exclusive lock. |
| 29 | lock := syscall.Flock_t{Type: lockType} |
| 30 | err := syscall.FcntlFlock(fd, syscall.F_SETLK, &lock) |
| 31 | if err == nil { |
| 32 | return nil |
| 33 | } else if err != syscall.EAGAIN { |
| 34 | return err |
| 35 | } |
| 36 | |
| 37 | // If we timed out then return an error. |
| 38 | if timeout != 0 && time.Since(t) > timeout-flockRetryTimeout { |
| 39 | return ErrTimeout |
| 40 | } |
| 41 | |
| 42 | // Wait for a bit and try again. |
| 43 | time.Sleep(flockRetryTimeout) |
| 44 | } |
| 45 | } |
| 46 | |
| 47 | // funlock releases an advisory lock on a file descriptor. |
| 48 | func funlock(db *DB) error { |
| 49 | var lock syscall.Flock_t |
| 50 | lock.Start = 0 |
| 51 | lock.Len = 0 |
| 52 | lock.Type = syscall.F_UNLCK |
| 53 | lock.Whence = 0 |
| 54 | return syscall.FcntlFlock(uintptr(db.file.Fd()), syscall.F_SETLK, &lock) |
| 55 | } |
| 56 | |
| 57 | // mmap memory maps a DB's data file. |
| 58 | func mmap(db *DB, sz int) error { |
| 59 | // Map the data file to memory. |
| 60 | b, err := unix.Mmap(int(db.file.Fd()), 0, sz, syscall.PROT_READ, syscall.MAP_SHARED|db.MmapFlags) |
| 61 | if err != nil { |
| 62 | return err |
| 63 | } |
| 64 | |
| 65 | // Advise the kernel that the mmap is accessed randomly. |
| 66 | if err := unix.Madvise(b, syscall.MADV_RANDOM); err != nil { |
| 67 | return fmt.Errorf("madvise: %s", err) |
| 68 | } |
| 69 | |
| 70 | // Save the original byte slice and convert to a byte array pointer. |
| 71 | db.dataref = b |
| 72 | db.data = (*[maxMapSize]byte)(unsafe.Pointer(&b[0])) |
| 73 | db.datasz = sz |
| 74 | return nil |
| 75 | } |
| 76 | |
| 77 | // munmap unmaps a DB's data file from memory. |
| 78 | func munmap(db *DB) error { |
| 79 | // Ignore the unmap if we have no mapped data. |
| 80 | if db.dataref == nil { |
| 81 | return nil |
| 82 | } |
| 83 | |
| 84 | // Unmap using the original byte slice. |
| 85 | err := unix.Munmap(db.dataref) |
| 86 | db.dataref = nil |
| 87 | db.data = nil |
| 88 | db.datasz = 0 |
| 89 | return err |
| 90 | } |