Introduce a tree map for all content

This commit introduces a new data structure to store pages and their resources.

This data structure is backed by radix trees.

This simplies tree operations, makes all pages a bundle,  and paves the way for #6310.

It also solves a set of annoying issues (see list below).

Not a motivation behind this, but this commit also makes Hugo in general a little bit faster and more memory effective (see benchmarks). Especially for partial rebuilds on content edits, but also when taxonomies is in use.

```
name                                   old time/op    new time/op    delta
SiteNew/Bundle_with_image/Edit-16        1.32ms ± 8%    1.00ms ± 9%  -24.42%  (p=0.029 n=4+4)
SiteNew/Bundle_with_JSON_file/Edit-16    1.28ms ± 0%    0.94ms ± 0%  -26.26%  (p=0.029 n=4+4)
SiteNew/Tags_and_categories/Edit-16      33.9ms ± 2%    21.8ms ± 1%  -35.67%  (p=0.029 n=4+4)
SiteNew/Canonify_URLs/Edit-16            40.6ms ± 1%    37.7ms ± 3%   -7.20%  (p=0.029 n=4+4)
SiteNew/Deep_content_tree/Edit-16        56.7ms ± 0%    51.7ms ± 1%   -8.82%  (p=0.029 n=4+4)
SiteNew/Many_HTML_templates/Edit-16      19.9ms ± 2%    18.3ms ± 3%   -7.64%  (p=0.029 n=4+4)
SiteNew/Page_collections/Edit-16         37.9ms ± 4%    34.0ms ± 2%  -10.28%  (p=0.029 n=4+4)
SiteNew/Bundle_with_image-16             10.7ms ± 0%    10.6ms ± 0%   -1.15%  (p=0.029 n=4+4)
SiteNew/Bundle_with_JSON_file-16         10.8ms ± 0%    10.7ms ± 0%   -1.05%  (p=0.029 n=4+4)
SiteNew/Tags_and_categories-16           43.2ms ± 1%    39.6ms ± 1%   -8.35%  (p=0.029 n=4+4)
SiteNew/Canonify_URLs-16                 47.6ms ± 1%    47.3ms ± 0%     ~     (p=0.057 n=4+4)
SiteNew/Deep_content_tree-16             73.0ms ± 1%    74.2ms ± 1%     ~     (p=0.114 n=4+4)
SiteNew/Many_HTML_templates-16           37.9ms ± 0%    38.1ms ± 1%     ~     (p=0.114 n=4+4)
SiteNew/Page_collections-16              53.6ms ± 1%    54.7ms ± 1%   +2.09%  (p=0.029 n=4+4)

name                                   old alloc/op   new alloc/op   delta
SiteNew/Bundle_with_image/Edit-16         486kB ± 0%     430kB ± 0%  -11.47%  (p=0.029 n=4+4)
SiteNew/Bundle_with_JSON_file/Edit-16     265kB ± 0%     209kB ± 0%  -21.06%  (p=0.029 n=4+4)
SiteNew/Tags_and_categories/Edit-16      13.6MB ± 0%     8.8MB ± 0%  -34.93%  (p=0.029 n=4+4)
SiteNew/Canonify_URLs/Edit-16            66.5MB ± 0%    63.9MB ± 0%   -3.95%  (p=0.029 n=4+4)
SiteNew/Deep_content_tree/Edit-16        28.8MB ± 0%    25.8MB ± 0%  -10.55%  (p=0.029 n=4+4)
SiteNew/Many_HTML_templates/Edit-16      6.16MB ± 0%    5.56MB ± 0%   -9.86%  (p=0.029 n=4+4)
SiteNew/Page_collections/Edit-16         16.9MB ± 0%    16.0MB ± 0%   -5.19%  (p=0.029 n=4+4)
SiteNew/Bundle_with_image-16             2.28MB ± 0%    2.29MB ± 0%   +0.35%  (p=0.029 n=4+4)
SiteNew/Bundle_with_JSON_file-16         2.07MB ± 0%    2.07MB ± 0%     ~     (p=0.114 n=4+4)
SiteNew/Tags_and_categories-16           14.3MB ± 0%    13.2MB ± 0%   -7.30%  (p=0.029 n=4+4)
SiteNew/Canonify_URLs-16                 69.1MB ± 0%    69.0MB ± 0%     ~     (p=0.343 n=4+4)
SiteNew/Deep_content_tree-16             31.3MB ± 0%    31.8MB ± 0%   +1.49%  (p=0.029 n=4+4)
SiteNew/Many_HTML_templates-16           10.8MB ± 0%    10.9MB ± 0%   +1.11%  (p=0.029 n=4+4)
SiteNew/Page_collections-16              21.4MB ± 0%    21.6MB ± 0%   +1.15%  (p=0.029 n=4+4)

name                                   old allocs/op  new allocs/op  delta
SiteNew/Bundle_with_image/Edit-16         4.74k ± 0%     3.86k ± 0%  -18.57%  (p=0.029 n=4+4)
SiteNew/Bundle_with_JSON_file/Edit-16     4.73k ± 0%     3.85k ± 0%  -18.58%  (p=0.029 n=4+4)
SiteNew/Tags_and_categories/Edit-16        301k ± 0%      198k ± 0%  -34.14%  (p=0.029 n=4+4)
SiteNew/Canonify_URLs/Edit-16              389k ± 0%      373k ± 0%   -4.07%  (p=0.029 n=4+4)
SiteNew/Deep_content_tree/Edit-16          338k ± 0%      262k ± 0%  -22.63%  (p=0.029 n=4+4)
SiteNew/Many_HTML_templates/Edit-16        102k ± 0%       88k ± 0%  -13.81%  (p=0.029 n=4+4)
SiteNew/Page_collections/Edit-16           176k ± 0%      152k ± 0%  -13.32%  (p=0.029 n=4+4)
SiteNew/Bundle_with_image-16              26.8k ± 0%     26.8k ± 0%   +0.05%  (p=0.029 n=4+4)
SiteNew/Bundle_with_JSON_file-16          26.8k ± 0%     26.8k ± 0%   +0.05%  (p=0.029 n=4+4)
SiteNew/Tags_and_categories-16             273k ± 0%      245k ± 0%  -10.36%  (p=0.029 n=4+4)
SiteNew/Canonify_URLs-16                   396k ± 0%      398k ± 0%   +0.39%  (p=0.029 n=4+4)
SiteNew/Deep_content_tree-16               317k ± 0%      325k ± 0%   +2.53%  (p=0.029 n=4+4)
SiteNew/Many_HTML_templates-16             146k ± 0%      147k ± 0%   +0.98%  (p=0.029 n=4+4)
SiteNew/Page_collections-16                210k ± 0%      215k ± 0%   +2.44%  (p=0.029 n=4+4)
```

Fixes #6312
Fixes #6087
Fixes #6738
Fixes #6412
Fixes #6743
Fixes #6875
Fixes #6034
Fixes #6902
Fixes #6173
Fixes #6590

1 files changed, 37 insertions, 48 deletions

diff --git a/hugolib/site_render.go b/hugolib/site_render.go
index dd79a7264..5327cbfc9 100644
--- a/hugolib/site_render.go
+++ b/hugolib/site_render.go
@@ -77,22 +77,17 @@ func (s *Site) renderPages(ctx *siteRenderContext) error {
 
 	cfg := ctx.cfg
 
-	if !cfg.PartialReRender && ctx.outIdx == 0 && len(s.headlessPages) > 0 {
-		wg.Add(1)
-		go headlessPagesPublisher(s, wg)
-	}
-
-L:
-	for _, page := range s.workAllPages {
-		if cfg.shouldRender(page) {
+	s.pageMap.pageTrees.Walk(func(ss string, n *contentNode) bool {
+		if cfg.shouldRender(n.p) {
 			select {
 			case <-s.h.Done():
-				break L
+				return true
 			default:
-				pages <- page
+				pages <- n.p
 			}
 		}
-	}
+		return false
+	})
 
 	close(pages)
 
@@ -107,15 +102,6 @@ L:
 	return nil
 }
 
-func headlessPagesPublisher(s *Site, wg *sync.WaitGroup) {
-	defer wg.Done()
-	for _, p := range s.headlessPages {
-		if err := p.renderResources(); err != nil {
-			s.SendError(p.errorf(err, "failed to render page resources"))
-		}
-	}
-}
-
 func pageRenderer(
 	ctx *siteRenderContext,
 	s *Site,
@@ -126,15 +112,15 @@ func pageRenderer(
 	defer wg.Done()
 
 	for p := range pages {
-		f := p.outputFormat()
-
-		// TODO(bep) get rid of this odd construct. RSS is an output format.
-		if f.Name == "RSS" && !s.isEnabled(kindRSS) {
-			continue
+		if p.m.buildConfig.PublishResources {
+			if err := p.renderResources(); err != nil {
+				s.SendError(p.errorf(err, "failed to render page resources"))
+				continue
+			}
 		}
 
-		if err := p.renderResources(); err != nil {
-			s.SendError(p.errorf(err, "failed to render page resources"))
+		if !p.render {
+			// Nothing more to do for this page.
 			continue
 		}
 
@@ -145,7 +131,7 @@ func pageRenderer(
 		}
 
 		if !found {
-			s.logMissingLayout("", p.Kind(), f.Name)
+			s.logMissingLayout("", p.Kind(), p.f.Name)
 			continue
 		}
 
@@ -235,10 +221,6 @@ func (s *Site) renderPaginator(p *pageState, templ tpl.Template) error {
 }
 
 func (s *Site) render404() error {
-	if !s.isEnabled(kind404) {
-		return nil
-	}
-
 	p, err := newPageStandalone(&pageMeta{
 		s:    s,
 		kind: kind404,
@@ -253,6 +235,10 @@ func (s *Site) render404() error {
 		return err
 	}
 
+	if !p.render {
+		return nil
+	}
+
 	var d output.LayoutDescriptor
 	d.Kind = kind404
 
@@ -274,10 +260,6 @@ func (s *Site) render404() error {
 }
 
 func (s *Site) renderSitemap() error {
-	if !s.isEnabled(kindSitemap) {
-		return nil
-	}
-
 	p, err := newPageStandalone(&pageMeta{
 		s:    s,
 		kind: kindSitemap,
@@ -291,6 +273,10 @@ func (s *Site) renderSitemap() error {
 		return err
 	}
 
+	if !p.render {
+		return nil
+	}
+
 	targetPath := p.targetPaths().TargetFilename
 
 	if targetPath == "" {
@@ -303,10 +289,6 @@ func (s *Site) renderSitemap() error {
 }
 
 func (s *Site) renderRobotsTXT() error {
-	if !s.isEnabled(kindRobotsTXT) {
-		return nil
-	}
-
 	if !s.Cfg.GetBool("enableRobotsTXT") {
 		return nil
 	}
@@ -324,6 +306,10 @@ func (s *Site) renderRobotsTXT() error {
 		return err
 	}
 
+	if !p.render {
+		return nil
+	}
+
 	templ := s.lookupLayouts("robots.txt", "_default/robots.txt", "_internal/_default/robots.txt")
 
 	return s.renderAndWritePage(&s.PathSpec.ProcessingStats.Pages, "Robots Txt", p.targetPaths().TargetFilename, p, templ)
@@ -332,15 +318,16 @@ func (s *Site) renderRobotsTXT() error {
 
 // renderAliases renders shell pages that simply have a redirect in the header.
 func (s *Site) renderAliases() error {
-	for _, p := range s.workAllPages {
-
+	var err error
+	s.pageMap.pageTrees.WalkRenderable(func(ss string, n *contentNode) bool {
+		p := n.p
 		if len(p.Aliases()) == 0 {
-			continue
+			return false
 		}
 
 		for _, of := range p.OutputFormats() {
 			if !of.Format.IsHTML {
-				continue
+				return false
 			}
 
 			plink := of.Permalink()
@@ -372,14 +359,16 @@ func (s *Site) renderAliases() error {
 					a = path.Join(lang, a)
 				}
 
-				if err := s.writeDestAlias(a, plink, f, p); err != nil {
-					return err
+				err = s.writeDestAlias(a, plink, f, p)
+				if err != nil {
+					return true
 				}
 			}
 		}
-	}
+		return false
+	})
 
-	return nil
+	return err
 }
 
 // renderMainLanguageRedirect creates a redirect to the main language home,