Fix some change detection issues on server reloads

* Fix change detection when .GetPage/site.GetPage is used from shortcode
* Fix stale content for GetPage results with short name lookups on server reloads

Fixes #7623
Fixes #7624
Fixes #7625

14 files changed, 228 insertions, 28 deletions

diff --git a/deps/deps.go b/deps/deps.go
index 82a16ba59..07fe2fc7d 100644
--- a/deps/deps.go
+++ b/deps/deps.go
@@ -97,6 +97,9 @@ type Deps struct {
 	// This is common/global for all sites.
 	BuildState *BuildState
 
+	// Whether we are in running (server) mode
+	Running bool
+
 	*globalErrHandler
 }
 
@@ -279,6 +282,7 @@ func New(cfg DepsCfg) (*Deps, error) {
 		FileCaches:              fileCaches,
 		BuildStartListeners:     &Listeners{},
 		BuildState:              buildState,
+		Running:                 cfg.Running,
 		Timeout:                 time.Duration(timeoutms) * time.Millisecond,
 		globalErrHandler:        errorHandler,
 	}
diff --git a/hugolib/content_map.go b/hugolib/content_map.go
index 43ad7745d..33ef4f8dd 100644
--- a/hugolib/content_map.go
+++ b/hugolib/content_map.go
@@ -95,21 +95,23 @@ func newContentMap(cfg contentMapConfig) *contentMap {
 
 	m.pageReverseIndex = &contentTreeReverseIndex{
 		t: []*contentTree{m.pages, m.sections, m.taxonomies},
-		initFn: func(t *contentTree, m map[interface{}]*contentNode) {
-			t.Walk(func(s string, v interface{}) bool {
-				n := v.(*contentNode)
-				if n.p != nil && !n.p.File().IsZero() {
-					meta := n.p.File().FileInfo().Meta()
-					if meta.Path() != meta.PathFile() {
-						// Keep track of the original mount source.
-						mountKey := filepath.ToSlash(filepath.Join(meta.Module(), meta.PathFile()))
-						addToReverseMap(mountKey, n, m)
+		contentTreeReverseIndexMap: &contentTreeReverseIndexMap{
+			initFn: func(t *contentTree, m map[interface{}]*contentNode) {
+				t.Walk(func(s string, v interface{}) bool {
+					n := v.(*contentNode)
+					if n.p != nil && !n.p.File().IsZero() {
+						meta := n.p.File().FileInfo().Meta()
+						if meta.Path() != meta.PathFile() {
+							// Keep track of the original mount source.
+							mountKey := filepath.ToSlash(filepath.Join(meta.Module(), meta.PathFile()))
+							addToReverseMap(mountKey, n, m)
+						}
 					}
-				}
-				k := strings.TrimPrefix(strings.TrimSuffix(path.Base(s), cmLeafSeparator), cmBranchSeparator)
-				addToReverseMap(k, n, m)
-				return false
-			})
+					k := strings.TrimPrefix(strings.TrimSuffix(path.Base(s), cmLeafSeparator), cmBranchSeparator)
+					addToReverseMap(k, n, m)
+					return false
+				})
+			},
 		},
 	}
 
@@ -1030,12 +1032,21 @@ func (c *contentTreeRef) getSections() page.Pages {
 
 type contentTreeReverseIndex struct {
 	t []*contentTree
-	m map[interface{}]*contentNode
+	*contentTreeReverseIndexMap
+}
 
+type contentTreeReverseIndexMap struct {
+	m      map[interface{}]*contentNode
 	init   sync.Once
 	initFn func(*contentTree, map[interface{}]*contentNode)
 }
 
+func (c *contentTreeReverseIndex) Reset() {
+	c.contentTreeReverseIndexMap = &contentTreeReverseIndexMap{
+		initFn: c.initFn,
+	}
+}
+
 func (c *contentTreeReverseIndex) Get(key interface{}) *contentNode {
 	c.init.Do(func() {
 		c.m = make(map[interface{}]*contentNode)
diff --git a/hugolib/hugo_sites.go b/hugolib/hugo_sites.go
index d1e3a146d..702e51abb 100644
--- a/hugolib/hugo_sites.go
+++ b/hugolib/hugo_sites.go
@@ -997,7 +997,6 @@ func (h *HugoSites) resetPageStateFromEvents(idset identity.Identities) {
 		}
 		return false
 	})
-
 }
 
 // Used in partial reloading to determine if the change is in a bundle.
diff --git a/hugolib/hugo_sites_rebuild_test.go b/hugolib/hugo_sites_rebuild_test.go
index f0c9f8f09..4c4741385 100644
--- a/hugolib/hugo_sites_rebuild_test.go
+++ b/hugolib/hugo_sites_rebuild_test.go
@@ -259,3 +259,66 @@ Output Shortcode AMP Edited
 	})
 
 }
+
+// Issues #7623 #7625
+func TestSitesRebuildOnFilesIncludedWithGetPage(t *testing.T) {
+	b := newTestSitesBuilder(t).Running()
+	b.WithContent("pages/p1.md", `---
+title: p1
+---
+P3: {{< GetPage "pages/p3" >}}
+`)
+
+	b.WithContent("pages/p2.md", `---
+title: p2
+---
+P4: {{< site_GetPage "pages/p4" >}}
+P5: {{< site_GetPage "p5" >}}
+P6: {{< dot_site_GetPage "p6" >}}
+`)
+
+	b.WithContent("pages/p3/index.md", "---\ntitle: p3\nheadless: true\n---\nP3 content")
+	b.WithContent("pages/p4/index.md", "---\ntitle: p4\nheadless: true\n---\nP4 content")
+	b.WithContent("pages/p5.md", "---\ntitle: p5\n---\nP5 content")
+	b.WithContent("pages/p6.md", "---\ntitle: p6\n---\nP6 content")
+
+	b.WithTemplates(
+		"_default/single.html", `{{ .Content }}`,
+		"shortcodes/GetPage.html", `
+{{ $arg := .Get 0 }}
+{{ $p := .Page.GetPage $arg }}
+{{ $p.Content }}
+	`,
+		"shortcodes/site_GetPage.html", `
+{{ $arg := .Get 0 }}
+{{ $p := site.GetPage $arg }}
+{{ $p.Content }}
+	`, "shortcodes/dot_site_GetPage.html", `
+{{ $arg := .Get 0 }}
+{{ $p := .Site.GetPage $arg }}
+{{ $p.Content }}
+	`,
+	)
+
+	b.Build(BuildCfg{})
+
+	b.AssertFileContent("public/pages/p1/index.html", "P3 content")
+	b.AssertFileContent("public/pages/p2/index.html", `P4 content
+P5 content
+P6 content
+`)
+
+	b.EditFiles("content/pages/p3/index.md", "---\ntitle: p3\n---\nP3 changed content")
+	b.EditFiles("content/pages/p4/index.md", "---\ntitle: p4\n---\nP4 changed content")
+	b.EditFiles("content/pages/p5.md", "---\ntitle: p5\n---\nP5 changed content")
+	b.EditFiles("content/pages/p6.md", "---\ntitle: p6\n---\nP6 changed content")
+
+	b.Build(BuildCfg{})
+
+	b.AssertFileContent("public/pages/p1/index.html", "P3 changed content")
+	b.AssertFileContent("public/pages/p2/index.html", `P4 changed content
+P5 changed content
+P6 changed content
+`)
+
+}
diff --git a/hugolib/page.go b/hugolib/page.go
index 28ef1e156..ca93bf18b 100644
--- a/hugolib/page.go
+++ b/hugolib/page.go
@@ -78,6 +78,7 @@ type pageContext interface {
 	posOffset(offset int) text.Position
 	wrapError(err error) error
 	getContentConverter() converter.Converter
+	addDependency(dep identity.Provider)
 }
 
 // wrapErr adds some context to the given error if possible.
@@ -93,6 +94,18 @@ type pageSiteAdapter struct {
 	s *Site
 }
 
+func (pa pageSiteAdapter) GetPageWithTemplateInfo(info tpl.Info, ref string) (page.Page, error) {
+	p, err := pa.GetPage(ref)
+	if p != nil {
+		// Track pages referenced by templates/shortcodes
+		// when in server mode.
+		if im, ok := info.(identity.Manager); ok {
+			im.Add(p)
+		}
+	}
+	return p, err
+}
+
 func (pa pageSiteAdapter) GetPage(ref string) (page.Page, error) {
 	p, err := pa.s.getPageNew(pa.p, ref)
 	if p == nil {
@@ -127,6 +140,10 @@ func (p *pageState) Eq(other interface{}) bool {
 	return p == pp
 }
 
+func (p *pageState) GetIdentity() identity.Identity {
+	return identity.NewPathIdentity(files.ComponentFolderContent, filepath.FromSlash(p.Path()))
+}
+
 func (p *pageState) GitInfo() *gitmap.GitInfo {
 	return p.gitInfo
 }
diff --git a/hugolib/site.go b/hugolib/site.go
index ac65931d0..dad5ab538 100644
--- a/hugolib/site.go
+++ b/hugolib/site.go
@@ -1538,6 +1538,7 @@ func (s *Site) resetBuildState(sourceChanged bool) {
 	s.init.Reset()
 
 	if sourceChanged {
+		s.pageMap.contentMap.pageReverseIndex.Reset()
 		s.PageCollections = newPageCollections(s.pageMap)
 		s.pageMap.withEveryBundlePage(func(p *pageState) bool {
 			p.pagePages = &pagePages{}
@@ -1587,6 +1588,18 @@ func (s *SiteInfo) GetPage(ref ...string) (page.Page, error) {
 	return p, err
 }
 
+func (s *SiteInfo) GetPageWithTemplateInfo(info tpl.Info, ref ...string) (page.Page, error) {
+	p, err := s.GetPage(ref...)
+	if p != nil {
+		// Track pages referenced by templates/shortcodes
+		// when in server mode.
+		if im, ok := info.(identity.Manager); ok {
+			im.Add(p)
+		}
+	}
+	return p, err
+}
+
 func (s *Site) permalink(link string) string {
 	return s.PathSpec.PermalinkForBaseURL(link, s.PathSpec.BaseURL.String())
 }
diff --git a/hugolib/template_test.go b/hugolib/template_test.go
index 6f37b4164..39f1b9e2e 100644
--- a/hugolib/template_test.go
+++ b/hugolib/template_test.go
@@ -599,7 +599,7 @@ title: P1
 
 	idset := make(map[identity.Identity]bool)
 	collectIdentities(idset, templ.(tpl.Info))
-	b.Assert(idset, qt.HasLen, 10)
+	b.Assert(idset, qt.HasLen, 11)
 
 }
 
diff --git a/identity/identity.go b/identity/identity.go
index ac3558d16..8fce16479 100644
--- a/identity/identity.go
+++ b/identity/identity.go
@@ -129,6 +129,8 @@ func (im *identityManager) Reset() {
 	im.Unlock()
 }
 
+// TODO(bep) these identities are currently only read on server reloads
+// so there should be no concurrency issues, but that may change.
 func (im *identityManager) GetIdentities() Identities {
 	im.Lock()
 	defer im.Unlock()
diff --git a/identity/identity_test.go b/identity/identity_test.go
index adebcad91..c315df1e7 100644
--- a/identity/identity_test.go
+++ b/identity/identity_test.go
@@ -14,6 +14,9 @@
 package identity
 
 import (
+	"fmt"
+	"math/rand"
+	"strconv"
 	"testing"
 
 	qt "github.com/frankban/quicktest"
@@ -29,6 +32,54 @@ func TestIdentityManager(t *testing.T) {
 	c.Assert(im.Search(testIdentity{name: "notfound"}), qt.Equals, nil)
 }
 
+func BenchmarkIdentityManager(b *testing.B) {
+
+	createIds := func(num int) []Identity {
+		ids := make([]Identity, num)
+		for i := 0; i < num; i++ {
+			ids[i] = testIdentity{name: fmt.Sprintf("id%d", i)}
+		}
+		return ids
+
+	}
+
+	b.Run("Add", func(b *testing.B) {
+		c := qt.New(b)
+		b.StopTimer()
+		ids := createIds(b.N)
+		im := NewManager(testIdentity{"first"})
+		b.StartTimer()
+
+		for i := 0; i < b.N; i++ {
+			im.Add(ids[i])
+		}
+
+		b.StopTimer()
+		c.Assert(im.GetIdentities(), qt.HasLen, b.N+1)
+	})
+
+	b.Run("Search", func(b *testing.B) {
+		c := qt.New(b)
+		b.StopTimer()
+		ids := createIds(b.N)
+		im := NewManager(testIdentity{"first"})
+
+		for i := 0; i < b.N; i++ {
+			im.Add(ids[i])
+		}
+
+		b.StartTimer()
+
+		for i := 0; i < b.N; i++ {
+			name := "id" + strconv.Itoa(rand.Intn(b.N))
+			id := im.Search(testIdentity{name: name})
+			c.Assert(id.GetIdentity().Name(), qt.Equals, name)
+		}
+
+	})
+
+}
+
 type testIdentity struct {
 	name string
 }
diff --git a/resources/page/page.go b/resources/page/page.go
index de417178f..0b402c4e7 100644
--- a/resources/page/page.go
+++ b/resources/page/page.go
@@ -18,8 +18,11 @@ package page
 import (
 	"html/template"
 
+	"github.com/gohugoio/hugo/identity"
+
 	"github.com/bep/gitmap"
 	"github.com/gohugoio/hugo/config"
+	"github.com/gohugoio/hugo/tpl"
 
 	"github.com/gohugoio/hugo/common/hugo"
 	"github.com/gohugoio/hugo/common/maps"
@@ -97,6 +100,9 @@ type GetPageProvider interface {
 	// This will return nil when no page could be found, and will return
 	// an error if the ref is ambiguous.
 	GetPage(ref string) (Page, error)
+
+	// GetPageWithTemplateInfo is for internal use only.
+	GetPageWithTemplateInfo(info tpl.Info, ref string) (Page, error)
 }
 
 // GitInfoProvider provides Git info.
@@ -260,6 +266,9 @@ type PageWithoutContent interface {
 	// e.g. GetTerms("categories")
 	GetTerms(taxonomy string) Pages
 
+	// Used in change/dependency tracking.
+	identity.Provider
+
 	DeprecatedWarningPageMethods
 }
 
diff --git a/resources/page/page_nop.go b/resources/page/page_nop.go
index c24792157..293b399c7 100644
--- a/resources/page/page_nop.go
+++ b/resources/page/page_nop.go
@@ -19,7 +19,10 @@ import (
 	"html/template"
 	"time"
 
+	"github.com/gohugoio/hugo/identity"
+
 	"github.com/gohugoio/hugo/hugofs/files"
+	"github.com/gohugoio/hugo/tpl"
 
 	"github.com/gohugoio/hugo/hugofs"
 
@@ -170,6 +173,10 @@ func (p *nopPage) GetPage(ref string) (Page, error) {
 	return nil, nil
 }
 
+func (p *nopPage) GetPageWithTemplateInfo(info tpl.Info, ref string) (Page, error) {
+	return nil, nil
+}
+
 func (p *nopPage) GetParam(key string) interface{} {
 	return nil
 }
@@ -484,3 +491,7 @@ func (p *nopPage) Weight() int {
 func (p *nopPage) WordCount() int {
 	return 0
 }
+
+func (p *nopPage) GetIdentity() identity.Identity {
+	return identity.NewPathIdentity("content", "foo/bar.md")
+}
diff --git a/resources/page/testhelpers_test.go b/resources/page/testhelpers_test.go
index dcd37c41e..17a795a20 100644
--- a/resources/page/testhelpers_test.go
+++ b/resources/page/testhelpers_test.go
@@ -20,6 +20,8 @@ import (
 	"time"
 
 	"github.com/gohugoio/hugo/hugofs/files"
+	"github.com/gohugoio/hugo/identity"
+	"github.com/gohugoio/hugo/tpl"
 
 	"github.com/gohugoio/hugo/modules"
 
@@ -218,6 +220,10 @@ func (p *testPage) GetPage(ref string) (Page, error) {
 	panic("not implemented")
 }
 
+func (p *testPage) GetPageWithTemplateInfo(info tpl.Info, ref string) (Page, error) {
+	panic("not implemented")
+}
+
 func (p *testPage) GetParam(key string) interface{} {
 	panic("not implemented")
 }
@@ -565,6 +571,10 @@ func (p *testPage) WordCount() int {
 	panic("not implemented")
 }
 
+func (p *testPage) GetIdentity() identity.Identity {
+	panic("not implemented")
+}
+
 func createTestPages(num int) Pages {
 	pages := make(Pages, num)
 
diff --git a/tpl/fmt/fmt.go b/tpl/fmt/fmt.go
index aa6b8c1a6..924d27a1d 100644
--- a/tpl/fmt/fmt.go
+++ b/tpl/fmt/fmt.go
@@ -23,10 +23,17 @@ import (
 
 // New returns a new instance of the fmt-namespaced template functions.
 func New(d *deps.Deps) *Namespace {
-	return &Namespace{
+	ns := &Namespace{
 		errorLogger: helpers.NewDistinctLogger(d.Log.ERROR),
 		warnLogger:  helpers.NewDistinctLogger(d.Log.WARN),
 	}
+
+	d.BuildStartListeners.Add(func() {
+		ns.errorLogger.Reset()
+		ns.warnLogger.Reset()
+	})
+
+	return ns
 }
 
 // Namespace provides template functions for the "fmt" namespace.
diff --git a/tpl/tplimpl/template_funcs.go b/tpl/tplimpl/template_funcs.go
index a688abb77..25ace365d 100644
--- a/tpl/tplimpl/template_funcs.go
+++ b/tpl/tplimpl/template_funcs.go
@@ -64,7 +64,8 @@ var _ texttemplate.ExecHelper = (*templateExecHelper)(nil)
 var zero reflect.Value
 
 type templateExecHelper struct {
-	funcs map[string]reflect.Value
+	running bool // whether we're in server mode.
+	funcs   map[string]reflect.Value
 }
 
 func (t *templateExecHelper) GetFunc(tmpl texttemplate.Preparer, name string) (reflect.Value, bool) {
@@ -91,14 +92,15 @@ func (t *templateExecHelper) GetMapValue(tmpl texttemplate.Preparer, receiver, k
 }
 
 func (t *templateExecHelper) GetMethod(tmpl texttemplate.Preparer, receiver reflect.Value, name string) (method reflect.Value, firstArg reflect.Value) {
-	// This is a hot path and receiver.MethodByName really shows up in the benchmarks.
-	// Page.Render is the only method with a WithTemplateInfo as of now, so let's just
-	// check that for now.
-	// TODO(bep) find a more flexible, but still fast, way.
-	if name == "Render" {
-		if info, ok := tmpl.(tpl.Info); ok {
-			if m := receiver.MethodByName(name + "WithTemplateInfo"); m.IsValid() {
-				return m, reflect.ValueOf(info)
+	if t.running {
+		// This is a hot path and receiver.MethodByName really shows up in the benchmarks,
+		// so we maintain a list of method names with that signature.
+		switch name {
+		case "GetPage", "Render":
+			if info, ok := tmpl.(tpl.Info); ok {
+				if m := receiver.MethodByName(name + "WithTemplateInfo"); m.IsValid() {
+					return m, reflect.ValueOf(info)
+				}
 			}
 		}
 	}
@@ -133,7 +135,8 @@ func newTemplateExecuter(d *deps.Deps) (texttemplate.Executer, map[string]reflec
 	}
 
 	exeHelper := &templateExecHelper{
-		funcs: funcsv,
+		running: d.Running,
+		funcs:   funcsv,
 	}
 
 	return texttemplate.NewExecuter(