reuse timestamps

while time.Now is not really slow, thanks to vDSO (cf.
https://git.io/J4SOH), it will be even faster to just call it once at
the start of the processing; also:
https://twitter.com/davidcrawshaw/status/1414243408936280073

> Turns out http://time.Now was taking its usual amount of time on
linux, ~50 nanoseconds [...]

1 files changed, 14 insertions, 6 deletions

diff --git a/skate/reduce.go b/skate/reduce.go
index e03bea1..3978ee9 100644
--- a/skate/reduce.go
+++ b/skate/reduce.go
@@ -54,6 +54,7 @@ func groupLogf(g *zipkey.Group, s string, vs ...interface{}) {
 // match result, e.g. for doi matches.
 func ZippyExact(releases, refs io.Reader, matchResult MatchResult, w io.Writer) error {
 	var (
+		ts      = timeNow().UTC().Format(time.RFC3339)
 		enc     = json.NewEncoder(xio.NewSyncWriter(w))
 		keyer   = makeKeyFunc("\t", 1)
 		grouper = func(g *zipkey.Group) error {
@@ -77,7 +78,7 @@ func ZippyExact(releases, refs io.Reader, matchResult MatchResult, w io.Writer)
 				}
 				bref.Reset()
 				bref.Key = fmt.Sprintf("%s_%d", ref.ReleaseIdent, ref.Index+1)
-				bref.IndexedTs = timeNow().UTC().Format(time.RFC3339)
+				bref.IndexedTs = ts
 				bref.SourceReleaseIdent = ref.ReleaseIdent
 				bref.SourceWorkIdent = ref.WorkIdent
 				bref.SourceReleaseStage = ref.ReleaseStage
@@ -369,6 +370,7 @@ func ZippyVerifyRefsOpenLibrary(olr, refs io.Reader, w io.Writer) error {
 // write a bref document for each match.
 func ZippyWayback(refs, cdx io.Reader, w io.Writer) error {
 	var (
+		ts      = timeNow().UTC().Format(time.RFC3339)
 		enc     = json.NewEncoder(xio.NewSyncWriter(w))
 		keyer   = makeKeyFunc("\t", 1)
 		grouper = func(g *zipkey.Group) error {
@@ -390,7 +392,7 @@ func ZippyWayback(refs, cdx io.Reader, w io.Writer) error {
 			_, _ = h.Write([]byte(cdx.Line))
 			hashedURL := fmt.Sprintf("%x", h.Sum(nil))
 			bref.Key = fmt.Sprintf("web_%s_%s", ref.ReleaseIdent, hashedURL)
-			bref.IndexedTs = timeNow().UTC().Format(time.RFC3339)
+			bref.IndexedTs = ts
 			bref.SourceReleaseIdent = ref.ReleaseIdent
 			bref.SourceWorkIdent = ref.WorkIdent
 			bref.SourceReleaseStage = ref.ReleaseStage
@@ -550,7 +552,10 @@ func deduplicateBrefs(brefs []*BiblioRef) []*BiblioRef {
 // did not result in a match (determined by e.g. ref key and index).  XXX: We
 // may have duplicate refs as well - how to distinguish them?
 func matchedRefsExtend(matched []*BiblioRef, refs []*Ref, stats *statsAugment) []*BiblioRef {
-	seen := set.New() // store "key + index" of matched items
+	var (
+		seen = set.New() // store "key + index" of matched items
+		ts   = timeNow().UTC().Format(time.RFC3339)
+	)
 	for _, m := range matched {
 		s := m.RefKey + fmt.Sprintf("%d", m.RefIndex)
 		seen.Add(s)
@@ -565,7 +570,7 @@ func matchedRefsExtend(matched []*BiblioRef, refs []*Ref, stats *statsAugment) [
 		}
 		// Assemble bref from unmatched ref.
 		var bref BiblioRef
-		bref.IndexedTs = timeNow().UTC().Format(time.RFC3339)
+		bref.IndexedTs = ts
 		bref.Key = fmt.Sprintf("%s_%d", r.ReleaseIdent, r.Index)
 		bref.RefIndex = r.Index
 		bref.RefKey = r.Key
@@ -625,7 +630,10 @@ func matchedRefsExtend(matched []*BiblioRef, refs []*Ref, stats *statsAugment) [
 // "skate-bref-id" post-processing here as well (but there is surely a better
 // place for that).
 func uniqueMatches(docs []string, stats *statsAugment) (result []*BiblioRef, err error) {
-	var brefs []*BiblioRef
+	var (
+		brefs []*BiblioRef
+		ts    = timeNow().UTC().Format(time.RFC3339)
+	)
 	for _, doc := range docs {
 		var bref BiblioRef
 		if err := json.Unmarshal([]byte(doc), &bref); err != nil {
@@ -634,7 +642,7 @@ func uniqueMatches(docs []string, stats *statsAugment) (result []*BiblioRef, err
 		// On-the-fly add elasticsearch "_id" and indexed timestamp, if not already set.
 		if bref.Key == "" && bref.SourceReleaseIdent != "" {
 			bref.Key = fmt.Sprintf("%s_%d", bref.SourceReleaseIdent, bref.RefIndex)
-			bref.IndexedTs = timeNow().UTC().Format(time.RFC3339)
+			bref.IndexedTs = ts
 		}
 		brefs = append(brefs, &bref)
 	}