Reduce calls to git cat-file -s (#14682)

* Reduce calls to git cat-file -s

There are multiple places where there are repeated calls to git cat-file
-s due to the blobs not being created with their size.

Through judicious use of git ls-tree -l and slight adjustments to the
indexer code we can avoid a lot of these calls.

* simplify by always expecting the long format

* Also always set the sized field and tell the indexer the update is sized

modules/git/parse_nogogit.go

@@ -10,9 +10,10 @@ import (
 	"bytes"
 	"fmt"
 	"strconv"
+	"strings"
 )
 
-// ParseTreeEntries parses the output of a `git ls-tree` command.
+// ParseTreeEntries parses the output of a `git ls-tree -l` command.
 func ParseTreeEntries(data []byte) ([]*TreeEntry, error) {
 	return parseTreeEntries(data, nil)
 }
@@ -20,7 +21,7 @@ func ParseTreeEntries(data []byte) ([]*TreeEntry, error) {
 func parseTreeEntries(data []byte, ptree *Tree) ([]*TreeEntry, error) {
 	entries := make([]*TreeEntry, 0, 10)
 	for pos := 0; pos < len(data); {
-		// expect line to be of the form "<mode> <type> <sha>\t<filename>"
+		// expect line to be of the form "<mode> <type> <sha> <space-padded-size>\t<filename>"
 		entry := new(TreeEntry)
 		entry.ptree = ptree
 		if pos+6 > len(data) {
@@ -56,7 +57,16 @@ func parseTreeEntries(data []byte, ptree *Tree) ([]*TreeEntry, error) {
 		entry.ID = id
 		pos += 41 // skip over sha and trailing space
 
-		end := pos + bytes.IndexByte(data[pos:], '\n')
+		end := pos + bytes.IndexByte(data[pos:], '\t')
+		if end < pos {
+			return nil, fmt.Errorf("Invalid ls-tree -l output: %s", string(data))
+		}
+		entry.size, _ = strconv.ParseInt(strings.TrimSpace(string(data[pos:end])), 10, 64)
+		entry.sized = true
+
+		pos = end + 1
+
+		end = pos + bytes.IndexByte(data[pos:], '\n')
 		if end < pos {
 			return nil, fmt.Errorf("Invalid ls-tree output: %s", string(data))
 		}