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authorJavi Fontan <jfontan@gmail.com>2018-07-19 23:27:16 +0200
committerJavi Fontan <jfontan@gmail.com>2018-07-26 14:17:56 +0200
commit355cfc3df3a64d1bd438e0e17e1c4ba21350badf (patch)
tree176ff325d5af77af5c1119f9350a8d71c51aebb8 /plumbing/format/idxfile
parentce91d71f96097ede2bb77d2af444aee6fff73183 (diff)
downloadgo-git-355cfc3df3a64d1bd438e0e17e1c4ba21350badf.tar.gz
plumbing: idxfile, add idxfile.Writer with Observer interface
It's still not complete: * 64 bit offsets * IdxChecksum Signed-off-by: Javi Fontan <jfontan@gmail.com>
Diffstat (limited to 'plumbing/format/idxfile')
-rw-r--r--plumbing/format/idxfile/writer.go132
1 files changed, 132 insertions, 0 deletions
diff --git a/plumbing/format/idxfile/writer.go b/plumbing/format/idxfile/writer.go
new file mode 100644
index 0000000..aac68b5
--- /dev/null
+++ b/plumbing/format/idxfile/writer.go
@@ -0,0 +1,132 @@
+package idxfile
+
+import (
+ "bytes"
+ "math"
+ "sort"
+
+ "gopkg.in/src-d/go-git.v4/plumbing"
+ "gopkg.in/src-d/go-git.v4/utils/binary"
+)
+
+type object struct {
+ hash plumbing.Hash
+ offset int64
+ crc uint32
+}
+
+type objects []object
+
+// Writer implements a packfile Observer interface and is used to generate
+// indexes.
+type Writer struct {
+ count uint32
+ checksum plumbing.Hash
+ objects objects
+}
+
+// Create index returns a filled MemoryIndex with the information filled by
+// the observer callbacks.
+func (w *Writer) CreateIndex() (*MemoryIndex, error) {
+ idx := new(MemoryIndex)
+ 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[:]...)
+
+ // TODO: implement 64 bit offsets
+ if o.offset > math.MaxInt32 {
+ panic("64 bit offsets not implemented")
+ }
+
+ buf.Truncate(0)
+ binary.WriteUint32(buf, uint32(o.offset))
+ idx.Offset32[bucket] = append(idx.Offset32[bucket], buf.Bytes()...)
+
+ buf.Truncate(0)
+ binary.WriteUint32(buf, uint32(o.crc))
+ idx.Crc32[bucket] = append(idx.Crc32[bucket], buf.Bytes()...)
+ }
+
+ for j := last + 1; j < 256; j++ {
+ idx.Fanout[j] = uint32(len(w.objects))
+ }
+
+ idx.PackfileChecksum = w.checksum
+ // TODO: fill IdxChecksum
+
+ return idx, nil
+}
+
+// Add appends new object data.
+func (w *Writer) Add(h plumbing.Hash, pos int64, crc uint32) {
+ w.objects = append(w.objects, object{h, pos, crc})
+}
+
+// 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) error {
+ w.Add(h, pos, crc)
+ return nil
+}
+
+// OnFooter implements packfile.Observer interface.
+func (w *Writer) OnFooter(h plumbing.Hash) error {
+ w.checksum = h
+ return nil
+}
+
+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]
+}