parser: Add BenchmarkFrontmatterTags

The list handling is surprisingly expensive:

```
▶ go test -run="NONE" -bench="BenchmarkFrontmatterTags" -test.benchmem=true ./parser | prettybench
PASS
benchmark                               iter         time/iter   bytes alloc           allocs
---------                               ----         ---------   -----------           ------
BenchmarkFrontmatterTags/JSON:1-4    1000000     2039.00 ns/op      912 B/op     20 allocs/op
BenchmarkFrontmatterTags/JSON:11-4    300000     5202.00 ns/op     1640 B/op     44 allocs/op
BenchmarkFrontmatterTags/JSON:21-4    200000     7993.00 ns/op     2392 B/op     65 allocs/op
BenchmarkFrontmatterTags/YAML:1-4     200000     9359.00 ns/op     5928 B/op     66 allocs/op
BenchmarkFrontmatterTags/YAML:11-4    100000    21218.00 ns/op     8408 B/op    140 allocs/op
BenchmarkFrontmatterTags/YAML:21-4     50000    32852.00 ns/op    10920 B/op    211 allocs/op
BenchmarkFrontmatterTags/TOML:1-4     100000    21505.00 ns/op     9231 B/op    173 allocs/op
BenchmarkFrontmatterTags/TOML:11-4     20000    82919.00 ns/op    19808 B/op    625 allocs/op
BenchmarkFrontmatterTags/TOML:21-4     10000   141847.00 ns/op    31200 B/op   1106 allocs/op
ok      github.com/spf13/hugo/parser    17.890s
```

See #3464

diff --git a/parser/frontmatter_test.go b/parser/frontmatter_test.go
index 5aef3562f0b9f97b6a892ebf55e547424fde1cc0..85c7c1874c1bea199d935609c32e3a16a591a1cd 100644 (file)
--- a/parser/frontmatter_test.go
+++ b/parser/frontmatter_test.go
@@ -15,7 +15,9 @@ package parser
 
 import (
        "bytes"
+       "fmt"
        "reflect"
+       "strings"
        "testing"
 )
 
@@ -317,3 +319,71 @@ func TestRemoveTOMLIdentifier(t *testing.T) {
                }
        }
 }
+
+func BenchmarkFrontmatterTags(b *testing.B) {
+
+       for _, frontmatter := range []string{"JSON", "YAML", "TOML"} {
+               for i := 1; i < 30; i += 10 {
+                       doBenchmarkFrontmatter(b, frontmatter, i)
+               }
+       }
+}
+
+func doBenchmarkFrontmatter(b *testing.B, fileformat string, numTags int) {
+       yamlTemplate := `---
+name: "Tags"
+tags:
+%s
+---
+`
+       tomlTemplate := `+++
+name = "Tags"
+tags = %s
++++
+`
+
+       jsonTemplate := `{
+       "name": "Tags",
+       "tags": [
+               %s
+       ]
+}`
+       name := fmt.Sprintf("%s:%d", fileformat, numTags)
+       b.Run(name, func(b *testing.B) {
+               tags := make([]string, numTags)
+               var (
+                       tagsStr             string
+                       frontmatterTemplate string
+               )
+               for i := 0; i < numTags; i++ {
+                       tags[i] = fmt.Sprintf("Hugo %d", i+1)
+               }
+               if fileformat == "TOML" {
+                       frontmatterTemplate = tomlTemplate
+                       tagsStr = strings.Replace(fmt.Sprintf("%q", tags), " ", ", ", -1)
+               } else if fileformat == "JSON" {
+                       frontmatterTemplate = jsonTemplate
+                       tagsStr = strings.Replace(fmt.Sprintf("%q", tags), " ", ", ", -1)
+               } else {
+                       frontmatterTemplate = yamlTemplate
+                       for _, tag := range tags {
+                               tagsStr += "\n- " + tag
+                       }
+               }
+
+               frontmatter := fmt.Sprintf(frontmatterTemplate, tagsStr)
+
+               p := page{frontmatter: []byte(frontmatter)}
+
+               b.ResetTimer()
+               for i := 0; i < b.N; i++ {
+                       meta, err := p.Metadata()
+                       if err != nil {
+                               b.Fatal(err)
+                       }
+                       if meta == nil {
+                               b.Fatal("Meta is nil")
+                       }
+               }
+       })
+}