21696: Speed up PortableDataHash by not using regexp.

Arvados-DCO-1.1-Signed-off-by: Tom Clegg <tom@curii.com>

diff --git a/sdk/go/arvados/collection.go b/sdk/go/arvados/collection.go
index 389fe4e4841b0006405aee66a697f607c414ce0d..b157c4c8a8dc8a2dd5963d2bd914d7bbd8eb04a5 100644 (file)
--- a/sdk/go/arvados/collection.go
+++ b/sdk/go/arvados/collection.go
@@ -104,28 +104,35 @@ type CollectionList struct {
        Limit          int          `json:"limit"`
 }
 
-var (
-       blkRe = regexp.MustCompile(`^ [0-9a-f]{32}\+\d+`)
-       tokRe = regexp.MustCompile(` ?[^ ]*`)
-)
-
 // PortableDataHash computes the portable data hash of the given
 // manifest.
 func PortableDataHash(mt string) string {
        h := md5.New()
        size := 0
-       _ = tokRe.ReplaceAllFunc([]byte(mt), func(tok []byte) []byte {
-               if m := blkRe.Find(tok); m != nil {
-                       // write hash+size, ignore remaining block hints
-                       tok = m
+       todo := []byte(mt)
+       for len(todo) > 0 {
+               sp := bytes.IndexByte(todo, ' ')
+               if sp < 0 {
+                       n, _ := h.Write(todo)
+                       size += n
+                       break
                }
-               n, err := h.Write(tok)
-               if err != nil {
-                       panic(err)
+               if sp >= 34 && todo[32] == '+' && bytes.IndexByte(todo[:32], ':') == -1 {
+                       sizeend := bytes.IndexByte(todo[33:sp], '+')
+                       if sizeend < 0 {
+                               sizeend = sp
+                       } else {
+                               sizeend += 33
+                       }
+                       n, _ := h.Write(todo[:sizeend])
+                       h.Write([]byte{' '})
+                       size += n + 1
+               } else {
+                       n, _ := h.Write(todo[:sp+1])
+                       size += n
                }
-               size += n
-               return nil
-       })
+               todo = todo[sp+1:]
+       }
        return fmt.Sprintf("%x+%d", h.Sum(nil), size)
 }