func (f *flt) setHead(h, atoms int64, fi Filer) (err error) {
switch {
case atoms < 1:
panic(atoms)
case atoms >= maxFLTRq:
pb := buffer.Get(7)
defer buffer.Put(pb)
b := *pb
if _, err = fi.WriteAt(h2b(b[:], h), 8*13+1); err != nil {
return
}
f[13].head = h
return
default:
lg := mathutil.Log2Uint16(uint16(atoms))
g := f[lg:]
for i := range f {
if atoms < g[i+1].minSize {
pb := buffer.Get(7)
defer buffer.Put(pb)
b := *pb
if _, err = fi.WriteAt(h2b(b[:], h), 8*int64(i+lg)+1); err != nil {
return
}
g[i].head = h
return
}
}
panic("internal error")
}
}
// cBstr returns a Go byte slice from C char*. Caller is expected to recycle
// the returned buffer when no more needed.
//
// p := cBstr(s)
// b := *b
// ... use b, finally
// buffer.Put(p)
func cBstr(s *int8) *[]byte {
pb := buffer.Get(16)
b := (*pb)[:0]
for p := (*uintptr)(unsafe.Pointer(&s)); *s != 0; (*p)++ {
if cap(b) == 0 {
npb := buffer.Get(2 * len(b))
copy(*npb, b)
buffer.Put(pb)
pb = npb
b = (*pb)[:len(b)]
}
b = append(b, byte(*s))
}
return pb
}
func writeTo(f Interface, w io.Writer) (n int64, err error) {
p := buffer.Get(copyBufSize)
b := *p
defer buffer.Put(p)
var off int64
var werr error
for {
rn, rerr := f.ReadAt(b, off)
if rn != 0 {
_, werr = w.Write(b[:rn])
n += int64(rn)
off += int64(rn)
}
if rerr != nil {
if !fileutil.IsEOF(rerr) {
err = rerr
}
break
}
if werr != nil {
err = werr
break
}
}
return n, err
}
func readFrom(f Interface, r io.Reader) (n int64, err error) {
f.Truncate(0)
p := buffer.Get(copyBufSize)
b := *p
defer buffer.Put(p)
var off int64
var werr error
for {
rn, rerr := r.Read(b)
if rn != 0 {
_, werr = f.WriteAt(b[:rn], off)
n += int64(rn)
off += int64(rn)
}
if rerr != nil {
if !fileutil.IsEOF(rerr) {
err = rerr
}
break
}
if werr != nil {
err = werr
break
}
}
return n, err
}
func (a *Allocator) write(off int64, b ...[]byte) (err error) {
rq := 0
for _, part := range b {
rq += len(part)
}
pbuf := buffer.Get(rq)
defer buffer.Put(pbuf)
buf := *pbuf
buf = buf[:0]
for _, part := range b {
buf = append(buf, part...)
}
return a.writeAt(buf, off)
}
// Alloc allocates storage space for b and returns the handle of the new block
// with content set to b or an error, if any. The returned handle is valid only
// while the block is used - until the block is deallocated. No two valid
// handles share the same value within the same Filer, but any value of a
// handle not referring to any used block may become valid any time as a result
// of Alloc.
//
// Invoking Alloc on an empty Allocator is guaranteed to return handle with
// value 1. The intended use of content of handle 1 is a root "directory" of
// other data held by an Allocator.
//
// Passing handles not obtained initially from Alloc or not anymore valid to
// any other Allocator methods can result in an irreparably corrupted database.
func (a *Allocator) Alloc(b []byte) (handle int64, err error) {
pbuf := buffer.Get(zappy.MaxEncodedLen(len(b)))
defer buffer.Put(pbuf)
buf := *pbuf
buf, _, cc, err := a.makeUsedBlock(buf, b)
if err != nil {
return
}
if handle, err = a.alloc(buf, cc); err == nil {
a.cadd(b, handle)
}
return
}
func (f *flt) load(fi Filer, off int64) (err error) {
pb := buffer.Get(fltSz)
defer buffer.Put(pb)
b := *pb
if _, err = fi.ReadAt(b[:], off); err != nil {
return
}
for i := range *f {
off := 8*i + 1
f[i].head = b2h(b[off:])
}
return
}
// Set h.next = n
func (a *Allocator) next(h, n int64) (err error) {
pb := buffer.Get(7)
defer buffer.Put(pb)
b := *pb
off := h2off(h)
if err = a.read(b[:1], off); err != nil {
return
}
switch tag := b[0]; tag {
default:
return &ErrILSEQ{Type: ErrExpFreeTag, Off: off, Arg: int64(tag)}
case tagFreeShort:
off += 8
case tagFreeLong:
off += 15
}
return a.writeAt(h2b(b[:7], n), off)
}
// nfo returns h's tag. If it's a free block then return also (s)ize (in
// atoms), (p)rev and (n)ext. If it's a used block then only (s)ize is returned
// (again in atoms). If it's a used relocate block then (n)ext is set to the
// relocation target handle.
func (a *Allocator) nfo(h int64) (tag byte, s, p, n int64, err error) {
off := h2off(h)
rq := int64(22)
sz, err := a.f.Size()
if err != nil {
return
}
if off+rq >= sz {
if rq = sz - off; rq < 15 {
err = io.ErrUnexpectedEOF
return
}
}
pbuf := buffer.Get(22)
defer buffer.Put(pbuf)
buf := *pbuf
if err = a.read(buf[:rq], off); err != nil {
return
}
switch tag = buf[0]; tag {
default:
s = int64(n2atoms(int(tag)))
case tagUsedLong:
s = int64(n2atoms(m2n(int(buf[1])<<8 | int(buf[2]))))
case tagFreeLong:
if rq < 22 {
err = io.ErrUnexpectedEOF
return
}
s, p, n = b2h(buf[1:]), b2h(buf[8:]), b2h(buf[15:])
case tagUsedRelocated:
s, n = 1, b2h(buf[1:])
case tagFreeShort:
s, p, n = 1, b2h(buf[1:]), b2h(buf[8:])
}
return
}
func (a *Allocator) writeUsedBlock(h int64, cc byte, b []byte) (err error) {
n := len(b)
rq := n2atoms(n) << 4
pbuf := buffer.Get(rq)
defer buffer.Put(pbuf)
buf := *pbuf
switch n <= maxShort {
case true:
buf[0] = byte(n)
copy(buf[1:], b)
case false:
m := n2m(n)
buf[0], buf[1], buf[2] = tagUsedLong, byte(m>>8), byte(m)
copy(buf[3:], b)
}
if p := n2padding(n); p != 0 {
copy(buf[rq-1-p:], zeros[:])
}
buf[rq-1] = cc
return a.writeAt(buf, h2off(h))
}
// leftNfo returns nfo for h's left neighbor if h > 1 and the left neighbor is
// a free block. Otherwise all zero values are returned instead.
func (a *Allocator) leftNfo(h int64) (tag byte, s, p, n int64, err error) {
if !(h > 1) {
return
}
pbuf := buffer.Get(8)
defer buffer.Put(pbuf)
buf := *pbuf
off := h2off(h)
if err = a.read(buf[:], off-8); err != nil {
return
}
switch tag := buf[7]; tag {
case tagFreeShort:
return a.nfo(h - 1)
case tagFreeLong:
return a.nfo(h - b2h(buf[:]))
}
return
}
// Make the filer image @h a free block.
func (a *Allocator) makeFree(h, atoms, prev, next int64) (err error) {
pbuf := buffer.Get(22)
defer buffer.Put(pbuf)
buf := *pbuf
switch {
case atoms == 1:
buf[0], buf[15] = tagFreeShort, tagFreeShort
h2b(buf[1:], prev)
h2b(buf[8:], next)
if err = a.write(h2off(h), buf[:16]); err != nil {
return
}
default:
buf[0] = tagFreeLong
h2b(buf[1:], atoms)
h2b(buf[8:], prev)
h2b(buf[15:], next)
if err = a.write(h2off(h), buf[:22]); err != nil {
return
}
h2b(buf[:], atoms)
buf[7] = tagFreeLong
if err = a.write(h2off(h+atoms)-8, buf[:8]); err != nil {
return
}
}
if prev != 0 {
if err = a.next(prev, h); err != nil {
return
}
}
if next != 0 {
err = a.prev(next, h)
}
return
}
func (a *Allocator) realloc(handle int64, b []byte) (err error) {
var dlen, needAtoms0 int
pb8 := buffer.Get(8)
defer buffer.Put(pb8)
b8 := *pb8
pdst := buffer.Get(zappy.MaxEncodedLen(len(b)))
defer buffer.Put(pdst)
dst := *pdst
b, needAtoms0, cc, err := a.makeUsedBlock(dst, b)
if err != nil {
return
}
needAtoms := int64(needAtoms0)
off := h2off(handle)
if err = a.read(b8[:], off); err != nil {
return
}
switch tag := b8[0]; tag {
default:
dlen = int(b8[0])
case tagUsedLong:
dlen = m2n(int(b8[1])<<8 | int(b8[2]))
case tagUsedRelocated:
if err = a.free(b2h(b8[1:]), handle, false); err != nil {
return err
}
dlen = 0
case tagFreeShort, tagFreeLong:
return &ErrINVAL{"Allocator.Realloc: invalid handle", handle}
}
atoms := int64(n2atoms(dlen))
retry:
switch {
case needAtoms < atoms:
// in place shrink
if err = a.writeUsedBlock(handle, cc, b); err != nil {
return
}
fh, fa := handle+needAtoms, atoms-needAtoms
sz, err := a.f.Size()
if err != nil {
return err
}
if h2off(fh)+16*fa == sz {
return a.f.Truncate(h2off(fh))
}
return a.free2(fh, fa)
case needAtoms == atoms:
// in place replace
return a.writeUsedBlock(handle, cc, b)
}
// case needAtoms > atoms:
// in place extend or relocate
var sz int64
if sz, err = a.f.Size(); err != nil {
return
}
off = h2off(handle)
switch {
case off+atoms*16 == sz:
// relocating tail block - shortcut
return a.writeUsedBlock(handle, cc, b)
default:
if off+atoms*16 < sz {
// handle is not a tail block, check right neighbour
rh := handle + atoms
rtag, ratoms, p, n, e := a.nfo(rh)
if e != nil {
return e
}
if rtag == tagFreeShort || rtag == tagFreeLong {
// Right neighbour is a free block
if needAtoms <= atoms+ratoms {
// can expand in place
if err = a.unlink(rh, ratoms, p, n); err != nil {
return
}
atoms += ratoms
goto retry
}
}
}
}
if atoms > 1 {
if err = a.realloc(handle, nil); err != nil {
return
}
}
var newH int64
if newH, err = a.alloc(b, cc); err != nil {
return err
}
prb := buffer.CGet(16)
defer buffer.Put(prb)
rb := *prb
rb[0] = tagUsedRelocated
h2b(rb[1:], newH)
if err = a.writeAt(rb[:], h2off(handle)); err != nil {
return
}
return a.writeUsedBlock(newH, cc, b)
}
// Get returns the data content of a block referred to by handle or an error if
// any. The returned slice may be a sub-slice of buf if buf was large enough
// to hold the entire content. Otherwise, a newly allocated slice will be
// returned. It is valid to pass a nil buf.
//
// If the content was stored using compression then it is transparently
// returned decompressed.
//
// Handle must have been obtained initially from Alloc and must be still valid,
// otherwise invalid data may be returned without detecting the error.
//
// Get is safe for concurrent access by multiple goroutines iff no other
// goroutine mutates the DB.
func (a *Allocator) Get(buf []byte, handle int64) (b []byte, err error) {
buf = buf[:cap(buf)]
a.mu.Lock() // X1+
if n, ok := a.m[handle]; ok {
a.lru.moveToFront(n)
b = need(len(n.b), buf)
copy(b, n.b)
a.expHit++
a.hit++
a.mu.Unlock() // X1-
return
}
a.expMiss++
a.miss++
if a.miss > 10 && len(a.m) < 500 {
if 100*a.hit/a.miss < 95 {
a.cacheSz++
}
a.hit, a.miss = 0, 0
}
a.mu.Unlock() // X1-
defer func(h int64) {
if err == nil {
a.mu.Lock() // X2+
a.cadd(b, h)
a.mu.Unlock() // X2-
}
}(handle)
pfirst := buffer.Get(16)
defer buffer.Put(pfirst)
first := *pfirst
relocated := false
relocSrc := handle
reloc:
if handle <= 0 || handle > maxHandle {
return nil, &ErrINVAL{"Allocator.Get: handle out of limits", handle}
}
off := h2off(handle)
if err = a.read(first, off); err != nil {
return
}
switch tag := first[0]; tag {
default:
dlen := int(tag)
atoms := n2atoms(dlen)
switch atoms {
case 1:
switch tag := first[15]; tag {
default:
return nil, &ErrILSEQ{Type: ErrTailTag, Off: off, Arg: int64(tag)}
case tagNotCompressed:
b = need(dlen, buf)
copy(b, first[1:])
return
case tagCompressed:
return zappy.Decode(buf, first[1:dlen+1])
}
default:
pcc := buffer.Get(1)
defer buffer.Put(pcc)
cc := *pcc
dlen := int(tag)
atoms := n2atoms(dlen)
tailOff := off + 16*int64(atoms) - 1
if err = a.read(cc, tailOff); err != nil {
return
}
switch tag := cc[0]; tag {
default:
return nil, &ErrILSEQ{Type: ErrTailTag, Off: off, Arg: int64(tag)}
case tagNotCompressed:
b = need(dlen, buf)
off += 1
if err = a.read(b, off); err != nil {
b = buf[:0]
}
return
case tagCompressed:
pzbuf := buffer.Get(dlen)
defer buffer.Put(pzbuf)
zbuf := *pzbuf
off += 1
if err = a.read(zbuf, off); err != nil {
return buf[:0], err
}
return zappy.Decode(buf, zbuf)
}
}
case 0:
return buf[:0], nil
case tagUsedLong:
pcc := buffer.Get(1)
defer buffer.Put(pcc)
cc := *pcc
dlen := m2n(int(first[1])<<8 | int(first[2]))
atoms := n2atoms(dlen)
tailOff := off + 16*int64(atoms) - 1
if err = a.read(cc, tailOff); err != nil {
return
}
switch tag := cc[0]; tag {
default:
return nil, &ErrILSEQ{Type: ErrTailTag, Off: off, Arg: int64(tag)}
case tagNotCompressed:
b = need(dlen, buf)
off += 3
if err = a.read(b, off); err != nil {
b = buf[:0]
}
return
case tagCompressed:
pzbuf := buffer.Get(dlen)
defer buffer.Put(pzbuf)
zbuf := *pzbuf
off += 3
if err = a.read(zbuf, off); err != nil {
return buf[:0], err
}
return zappy.Decode(buf, zbuf)
}
case tagFreeShort, tagFreeLong:
return nil, &ErrILSEQ{Type: ErrExpUsedTag, Off: off, Arg: int64(tag)}
case tagUsedRelocated:
if relocated {
return nil, &ErrILSEQ{Type: ErrUnexpReloc, Off: off, Arg: relocSrc}
}
handle = b2h(first[1:])
relocated = true
goto reloc
}
}