hugolib: Add site building benchmarks

To run a subset of these benchmark, one can do something like this:

```
go test -run="NONE" -bench="BenchmarkSiteBuilding/tags_per_page=0.*shortcodes=true.*render=false"  -test.benchmem=true ./hugolib
```

Which will run without any tags, with shortcodes, but will skip rendering.

Fixes #3535

diff --git a/hugolib/site_benchmark_test.go b/hugolib/site_benchmark_test.go
new file mode 100644 (file)
index 0000000..1bb1f92
--- /dev/null
+++ b/hugolib/site_benchmark_test.go
@@ -0,0 +1,182 @@
+// Copyright 2017-present The Hugo Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package hugolib
+
+import (
+       "fmt"
+       "math/rand"
+       "path/filepath"
+       "strings"
+       "testing"
+
+       "github.com/spf13/afero"
+)
+
+type siteBuildingBenchmarkConfig struct {
+       NumPages     int
+       RootSections int
+       Render       bool
+       Shortcodes   bool
+       TagsPerPage  int
+}
+
+func (s siteBuildingBenchmarkConfig) String() string {
+       return fmt.Sprintf("num_root_sections=%d|num_pages=%d|tags_per_page=%d|shortcodes=%t|render=%t", s.RootSections, s.NumPages, s.TagsPerPage, s.Shortcodes, s.Render)
+}
+
+func BenchmarkSiteBuilding(b *testing.B) {
+       var conf siteBuildingBenchmarkConfig
+       for _, rootSections := range []int{1, 5} {
+               conf.RootSections = rootSections
+               for _, tagsPerPage := range []int{0, 1, 5, 20} {
+                       conf.TagsPerPage = tagsPerPage
+                       for _, numPages := range []int{10, 100, 500, 1000, 5000} {
+                               conf.NumPages = numPages
+                               for _, render := range []bool{false, true} {
+                                       conf.Render = render
+                                       for _, shortcodes := range []bool{false, true} {
+                                               conf.Shortcodes = shortcodes
+                                               doBenchMarkSiteBuilding(conf, b)
+                                       }
+                               }
+                       }
+               }
+       }
+}
+
+func doBenchMarkSiteBuilding(conf siteBuildingBenchmarkConfig, b *testing.B) {
+       b.Run(conf.String(), func(b *testing.B) {
+               sites := createHugoBenchmarkSites(b, b.N, conf)
+               b.ResetTimer()
+               for i := 0; i < b.N; i++ {
+                       h := sites[0]
+
+                       err := h.Build(BuildCfg{SkipRender: !conf.Render})
+                       if err != nil {
+                               b.Fatal(err)
+                       }
+
+                       // Try to help the GC
+                       sites[0] = nil
+                       sites = sites[1:len(sites)]
+               }
+       })
+}
+
+func createHugoBenchmarkSites(b *testing.B, count int, cfg siteBuildingBenchmarkConfig) []*HugoSites {
+       someMarkdown := `
+An h1 header
+============
+
+Paragraphs are separated by a blank line.
+
+2nd paragraph. *Italic* and **bold**. Itemized lists
+look like:
+
+  * this one
+  * that one
+  * the other one
+
+Note that --- not considering the asterisk --- the actual text
+content starts at 4-columns in.
+
+> Block quotes are
+> written like so.
+>
+> They can span multiple paragraphs,
+> if you like.
+
+Use 3 dashes for an em-dash. Use 2 dashes for ranges (ex., "it's all
+in chapters 12--14"). Three dots ... will be converted to an ellipsis.
+Unicode is supported. ☺
+`
+
+       someMarkdownWithShortCode := someMarkdown + `
+
+{{< myShortcode >}}
+
+`
+
+       pageTemplate := `+++
+title = "%s"
+tags = %s
++++
+%s
+
+`
+
+       siteConfig := `
+baseURL = "http://example.com/blog"
+
+paginate = 10
+defaultContentLanguage = "en"
+
+[Taxonomies]
+tag = "tags"
+category = "categories"
+`
+       var (
+               contentPagesContent [3]string
+               tags                = make([]string, cfg.TagsPerPage)
+       )
+
+       for i := 0; i < len(tags); i++ {
+               tags[i] = fmt.Sprintf("Hugo %d", i)
+       }
+
+       tagsStr := "[]"
+       if cfg.TagsPerPage > 0 {
+               tagsStr = strings.Replace(fmt.Sprintf("%q", tags[0:cfg.TagsPerPage]), " ", ", ", -1)
+       }
+
+       if cfg.Shortcodes {
+               contentPagesContent = [3]string{
+                       someMarkdownWithShortCode,
+                       strings.Repeat(someMarkdownWithShortCode, 2),
+                       strings.Repeat(someMarkdownWithShortCode, 3),
+               }
+       } else {
+               contentPagesContent = [3]string{
+                       someMarkdown,
+                       strings.Repeat(someMarkdown, 2),
+                       strings.Repeat(someMarkdown, 3),
+               }
+       }
+
+       sites := make([]*HugoSites, count)
+       for i := 0; i < count; i++ {
+               // Maybe consider reusing the Source fs
+               mf := afero.NewMemMapFs()
+               th, h := newTestSitesFromConfig(b, mf, siteConfig,
+                       "layouts/_default/single.html", `Single HTML|{{ .Title }}|{{ .Content }}`,
+                       "layouts/_default/list.html", `List HTML|{{ .Title }}|{{ .Content }}`,
+                       "layouts/shortcodes/myShortcode.html", `<p>MyShortcode</p>`)
+
+               fs := th.Fs
+
+               pagesPerSection := cfg.NumPages / cfg.RootSections
+
+               for i := 0; i < cfg.RootSections; i++ {
+                       for j := 0; j < pagesPerSection; j++ {
+                               content := fmt.Sprintf(pageTemplate, fmt.Sprintf("Title%d_%d", i, j), tagsStr, contentPagesContent[rand.Intn(3)])
+
+                               writeSource(b, fs, filepath.Join("content", fmt.Sprintf("sect%d", i), fmt.Sprintf("page%d.md", j)), content)
+                       }
+               }
+
+               sites[i] = h
+       }
+
+       return sites
+}