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index.go
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index.go
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package procs
import (
"errors"
"io"
"sort"
"sync"
"github.com/Roman2K/scat"
"github.com/Roman2K/scat/checksum"
"github.com/Roman2K/scat/index"
"github.com/Roman2K/scat/seriessort"
)
type IndexProc interface {
Proc
EndProc
}
type indexProc struct {
w io.Writer
order seriessort.Series
orderMu sync.Mutex
finals map[checksum.Hash]*finals
finalsMu sync.RWMutex
}
type finals struct {
num int
entries []indexEntry
complete bool
mu sync.Mutex
}
type indexEntry struct {
num int
hash checksum.Hash
targetSize int
}
var (
ErrIndexUnprocessedChunk = errors.New("unprocessed chunk")
ErrIndexProcessEnded = errors.New("process already ended")
ErrIndexDup = errors.New("won't process dup chunk")
)
func NewIndexProc(w io.Writer) IndexProc {
return &indexProc{
w: w,
order: seriessort.Series{},
finals: make(map[checksum.Hash]*finals),
}
}
func (idx *indexProc) Process(c *scat.Chunk) <-chan Res {
idx.setOrder(c)
ch := make(chan Res, 1)
defer close(ch)
idx.finalsMu.Lock()
defer idx.finalsMu.Unlock()
if _, ok := idx.finals[c.Hash()]; !ok {
idx.finals[c.Hash()] = &finals{
num: c.Num(),
entries: make([]indexEntry, 0, 1),
}
ch <- Res{Chunk: c}
}
return ch
}
func (idx *indexProc) ProcessFinal(c, final *scat.Chunk) error {
entry := indexEntry{
num: final.Num(),
hash: final.Hash(),
targetSize: final.TargetSize(),
}
finals, ok := idx.getFinals(c.Hash())
if !ok {
return ErrIndexUnprocessedChunk
}
finals.mu.Lock()
defer finals.mu.Unlock()
if finals.complete {
return ErrIndexProcessEnded
}
if finals.num != c.Num() {
return ErrIndexDup
}
finals.entries = append(finals.entries, entry)
return nil
}
func (idx *indexProc) ProcessEnd(c *scat.Chunk) (err error) {
err = idx.setFinalsComplete(c)
if err != nil {
return
}
return idx.flush()
}
func (idx *indexProc) getFinals(hash checksum.Hash) (f *finals, ok bool) {
idx.finalsMu.RLock()
defer idx.finalsMu.RUnlock()
f, ok = idx.finals[hash]
return
}
func (idx *indexProc) setFinalsComplete(c *scat.Chunk) error {
finals, ok := idx.getFinals(c.Hash())
if !ok {
return ErrIndexUnprocessedChunk
}
finals.mu.Lock()
defer finals.mu.Unlock()
if finals.num != c.Num() {
return nil
}
finals.complete = true
return nil
}
func (idx *indexProc) Finish() error {
idx.orderMu.Lock()
len := idx.order.Len()
idx.orderMu.Unlock()
if len > 0 {
return ErrShort
}
return nil
}
func (idx *indexProc) flush() (err error) {
idx.orderMu.Lock()
defer idx.orderMu.Unlock()
sorted := idx.order.Sorted()
i := 0
defer func() {
idx.order.Drop(i)
}()
for n := len(sorted); i < n; i++ {
hash := sorted[i].(checksum.Hash)
finals, ok := idx.completeFinals(hash)
if !ok {
return
}
entries := finals.entries
num := func(i int) int {
return entries[i].num
}
sort.Slice(entries, func(i, j int) bool {
return num(i) < num(j)
})
err = writeEntries(idx.w, entries)
if err != nil {
return
}
}
return
}
func (idx *indexProc) completeFinals(hash checksum.Hash) (f *finals, ok bool) {
f, ok = idx.getFinals(hash)
if !ok {
return
}
f.mu.Lock()
defer f.mu.Unlock()
ok = f.complete
return
}
func (idx *indexProc) setOrder(c *scat.Chunk) {
idx.orderMu.Lock()
defer idx.orderMu.Unlock()
idx.order.Add(c.Num(), c.Hash())
}
func writeEntries(w io.Writer, entries []indexEntry) (err error) {
for _, entry := range entries {
_, err = index.Write(w, entry.hash, entry.targetSize)
if err != nil {
return
}
}
return
}
var IndexUnproc Proc = ChunkIterFunc(indexUnprocess)
func indexUnprocess(c *scat.Chunk) scat.ChunkIter {
return index.NewScanner(c.Num(), c.Data().Reader())
}