// Ensure the file ahs room for more data.
func (file *File) Ensure(more uint64) (err error) {
if file.Append+more <= file.Size {
return
}
if file.Buf != nil {
if err = file.Buf.Unmap(); err != nil {
return
}
}
if _, err = file.Fh.Seek(0, os.SEEK_END); err != nil {
return
}
if _, err = file.Fh.Write(make([]byte, file.Growth)); err != nil {
return
}
if err = file.Fh.Sync(); err != nil {
return
}
if file.Buf, err = gommap.Map(file.Fh, gommap.RDWR, 0); err != nil {
return
}
file.Size += file.Growth
log.Printf("File %s has grown %d bytes\n", file.Name, file.Growth)
return file.Ensure(more)
}
// Open (create if non-exist) the file.
func Open(name string, growth uint64) (file *File, err error) {
if growth < 1 {
err = errors.New(fmt.Sprintf("Opening %s, file growth (%d) is too small", name, growth))
}
file = &File{Name: name, Growth: growth}
if file.Fh, err = os.OpenFile(name, os.O_CREATE|os.O_RDWR, 0600); err != nil {
return
}
fsize, err := file.Fh.Seek(0, os.SEEK_END)
if err != nil {
return
}
file.Size = uint64(fsize)
if file.Size == 0 {
file.CheckSizeAndEnsure(file.Growth)
return
}
if file.Buf, err = gommap.Map(file.Fh, gommap.RDWR, 0); err != nil {
return
}
// find append position
for pos := file.Size - 1; pos > 0; pos-- {
if file.Buf[pos] != 0 {
file.Append = pos + 1
break
}
}
return
}
// Open (create if non-exist) the file.
func Open(name string, growth uint64) (file *File, err error) {
if growth < 1 {
err = errors.New(fmt.Sprintf("Opening %s, file growth (%d) is too small", name, growth))
}
file = &File{Name: name, Growth: growth, Sync: new(sync.RWMutex)}
if file.Fh, err = os.OpenFile(name, os.O_CREATE|os.O_RDWR, 0600); err != nil {
return
}
fsize, err := file.Fh.Seek(0, os.SEEK_END)
if err != nil {
return
}
if int(fsize) < 0 {
log.Panicf("File %s is too large to mmap", name)
}
file.Size = uint64(fsize)
if file.Size == 0 {
return file, file.Ensure(file.Growth)
}
if file.Buf, err = gommap.Map(file.Fh, gommap.RDWR, 0); err != nil {
return
}
// find append position
for low, mid, high := uint64(0), file.Size/2, file.Size; ; {
switch {
case high-mid == 1:
if file.Buf[mid] == 0 {
if file.Buf[mid-1] == 0 {
file.Append = mid - 1
} else {
file.Append = mid
}
return
}
file.Append = high
return
case file.Buf[mid] == 0:
high = mid
mid = low + (mid-low)/2
default:
low = mid
mid = mid + (high-mid)/2
}
}
return
}
// Open (create if non-exist) the file.
func Open(name string, growth uint64) (file *File, err error) {
if growth < 1 {
err = errors.New(fmt.Sprintf("Growth size (%d) is too small (opening %s)", growth, name))
}
file = &File{Name: name, Growth: growth}
if file.Fh, err = os.OpenFile(name, os.O_CREATE|os.O_RDWR, 0600); err != nil {
return
}
fsize, err := file.Fh.Seek(0, os.SEEK_END)
if err != nil {
return
}
file.Size = uint64(fsize)
if file.Size == 0 {
file.CheckSizeAndEnsure(file.Growth)
return
}
if file.Buf, err = gommap.Map(file.Fh, gommap.RDWR, 0); err != nil {
return
}
// find used size
for low, mid, high := uint64(0), file.Size/2, file.Size; ; {
switch {
case high-mid == 1:
if file.Buf[mid] == 0 {
if file.Buf[mid-1] == 0 {
file.UsedSize = mid - 1
} else {
file.UsedSize = mid
}
return
}
file.UsedSize = high
return
case file.Buf[mid] == 0:
high = mid
mid = low + (mid-low)/2
default:
low = mid
mid = mid + (high-mid)/2
}
}
log.Printf("%s has %d bytes out of %d bytes in-use", name, file.UsedSize, file.Size)
return
}
// Ensure the file ahs room for more data.
func (file *File) CheckSizeAndEnsure(more uint64) {
if file.UsedSize+more <= file.Size {
return
}
var err error
if file.Buf != nil {
if err = file.Buf.Unmap(); err != nil {
panic(err)
}
}
if _, err = file.Fh.Seek(0, os.SEEK_END); err != nil {
panic(err)
}
// grow the file incrementally
zeroBuf := make([]byte, FILE_GROWTH_INCREMENTAL)
for i := uint64(0); i < file.Growth; i += FILE_GROWTH_INCREMENTAL {
var slice []byte
if i+FILE_GROWTH_INCREMENTAL > file.Growth {
slice = zeroBuf[0 : i+FILE_GROWTH_INCREMENTAL-file.Growth]
} else {
slice = zeroBuf
}
if _, err = file.Fh.Write(slice); err != nil {
panic(err)
}
}
if err = file.Fh.Sync(); err != nil {
panic(err)
}
if file.Buf, err = gommap.Map(file.Fh, gommap.RDWR, 0); err != nil {
panic(err)
}
file.Size += file.Growth
log.Printf("File %s has grown %d bytes\n", file.Name, file.Growth)
file.CheckSizeAndEnsure(more)
}
