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package idxfile
import (
"bytes"
"fmt"
"math"
"sort"
"sync"
"gopkg.in/src-d/go-git.v4/plumbing"
"gopkg.in/src-d/go-git.v4/utils/binary"
)
// objects implements sort.Interface and uses hash as sorting key.
type objects []Entry
// Writer implements a packfile Observer interface and is used to generate
// indexes.
type Writer struct {
m sync.Mutex
count uint32
checksum plumbing.Hash
objects objects
offset64 uint32
finished bool
index *MemoryIndex
added map[plumbing.Hash]struct{}
}
// Index returns a previously created MemoryIndex or creates a new one if
// needed.
func (w *Writer) Index() (*MemoryIndex, error) {
w.m.Lock()
defer w.m.Unlock()
if w.index == nil {
return w.createIndex()
}
return w.index, nil
}
// Add appends new object data.
func (w *Writer) Add(h plumbing.Hash, pos uint64, crc uint32) {
w.m.Lock()
defer w.m.Unlock()
if w.added == nil {
w.added = make(map[plumbing.Hash]struct{})
}
if _, ok := w.added[h]; !ok {
w.added[h] = struct{}{}
w.objects = append(w.objects, Entry{h, crc, pos})
}
}
func (w *Writer) Finished() bool {
return w.finished
}
// OnHeader implements packfile.Observer interface.
func (w *Writer) OnHeader(count uint32) error {
w.count = count
w.objects = make(objects, 0, count)
return nil
}
// OnInflatedObjectHeader implements packfile.Observer interface.
func (w *Writer) OnInflatedObjectHeader(t plumbing.ObjectType, objSize int64, pos int64) error {
return nil
}
// OnInflatedObjectContent implements packfile.Observer interface.
func (w *Writer) OnInflatedObjectContent(h plumbing.Hash, pos int64, crc uint32, _ []byte) error {
w.Add(h, uint64(pos), crc)
return nil
}
// OnFooter implements packfile.Observer interface.
func (w *Writer) OnFooter(h plumbing.Hash) error {
w.checksum = h
w.finished = true
_, err := w.createIndex()
if err != nil {
return err
}
return nil
}
// creatIndex returns a filled MemoryIndex with the information filled by
// the observer callbacks.
func (w *Writer) createIndex() (*MemoryIndex, error) {
if !w.finished {
return nil, fmt.Errorf("the index still hasn't finished building")
}
idx := new(MemoryIndex)
w.index = idx
sort.Sort(w.objects)
// unmap all fans by default
for i := range idx.FanoutMapping {
idx.FanoutMapping[i] = noMapping
}
buf := new(bytes.Buffer)
last := -1
bucket := -1
for i, o := range w.objects {
fan := o.Hash[0]
// fill the gaps between fans
for j := last + 1; j < int(fan); j++ {
idx.Fanout[j] = uint32(i)
}
// update the number of objects for this position
idx.Fanout[fan] = uint32(i + 1)
// we move from one bucket to another, update counters and allocate
// memory
if last != int(fan) {
bucket++
idx.FanoutMapping[fan] = bucket
last = int(fan)
idx.Names = append(idx.Names, make([]byte, 0))
idx.Offset32 = append(idx.Offset32, make([]byte, 0))
idx.Crc32 = append(idx.Crc32, make([]byte, 0))
}
idx.Names[bucket] = append(idx.Names[bucket], o.Hash[:]...)
offset := o.Offset
if offset > math.MaxInt32 {
offset = w.addOffset64(offset)
}
buf.Truncate(0)
binary.WriteUint32(buf, uint32(offset))
idx.Offset32[bucket] = append(idx.Offset32[bucket], buf.Bytes()...)
buf.Truncate(0)
binary.WriteUint32(buf, uint32(o.CRC32))
idx.Crc32[bucket] = append(idx.Crc32[bucket], buf.Bytes()...)
}
for j := last + 1; j < 256; j++ {
idx.Fanout[j] = uint32(len(w.objects))
}
idx.Version = VersionSupported
idx.PackfileChecksum = w.checksum
return idx, nil
}
func (w *Writer) addOffset64(pos uint64) uint64 {
buf := new(bytes.Buffer)
binary.WriteUint64(buf, pos)
w.index.Offset64 = append(w.index.Offset64, buf.Bytes()...)
index := uint64(w.offset64 | (1 << 31))
w.offset64++
return index
}
func (o objects) Len() int {
return len(o)
}
func (o objects) Less(i int, j int) bool {
cmp := bytes.Compare(o[i].Hash[:], o[j].Hash[:])
return cmp < 0
}
func (o objects) Swap(i int, j int) {
o[i], o[j] = o[j], o[i]
}
|
