Add a HTTP cache for remote resources.

Fixes #12502
Closes #11891

2 files changed, 44 insertions, 2 deletions

diff --git a/commands/commandeer.go b/commands/commandeer.go
index 59fe32f74..f18a95bb9 100644
--- a/commands/commandeer.go
+++ b/commands/commandeer.go
@@ -48,6 +48,7 @@ import (
 	"github.com/gohugoio/hugo/helpers"
 	"github.com/gohugoio/hugo/hugofs"
 	"github.com/gohugoio/hugo/hugolib"
+	"github.com/gohugoio/hugo/identity"
 	"github.com/gohugoio/hugo/resources/kinds"
 	"github.com/spf13/afero"
 	"github.com/spf13/cobra"
@@ -103,6 +104,9 @@ type rootCommand struct {
 	commonConfigs *lazycache.Cache[int32, *commonConfig]
 	hugoSites     *lazycache.Cache[int32, *hugolib.HugoSites]
 
+	// changesFromBuild received from Hugo in watch mode.
+	changesFromBuild chan []identity.Identity
+
 	commands []simplecobra.Commander
 
 	// Flags
@@ -304,7 +308,7 @@ func (r *rootCommand) ConfigFromProvider(key int32, cfg config.Provider) (*commo
 
 func (r *rootCommand) HugFromConfig(conf *commonConfig) (*hugolib.HugoSites, error) {
 	h, _, err := r.hugoSites.GetOrCreate(r.configVersionID.Load(), func(key int32) (*hugolib.HugoSites, error) {
-		depsCfg := deps.DepsCfg{Configs: conf.configs, Fs: conf.fs, LogOut: r.logger.Out(), LogLevel: r.logger.Level()}
+		depsCfg := r.newDepsConfig(conf)
 		return hugolib.NewHugoSites(depsCfg)
 	})
 	return h, err
@@ -316,12 +320,16 @@ func (r *rootCommand) Hugo(cfg config.Provider) (*hugolib.HugoSites, error) {
 		if err != nil {
 			return nil, err
 		}
-		depsCfg := deps.DepsCfg{Configs: conf.configs, Fs: conf.fs, LogOut: r.logger.Out(), LogLevel: r.logger.Level()}
+		depsCfg := r.newDepsConfig(conf)
 		return hugolib.NewHugoSites(depsCfg)
 	})
 	return h, err
 }
 
+func (r *rootCommand) newDepsConfig(conf *commonConfig) deps.DepsCfg {
+	return deps.DepsCfg{Configs: conf.configs, Fs: conf.fs, LogOut: r.logger.Out(), LogLevel: r.logger.Level(), ChangesFromBuild: r.changesFromBuild}
+}
+
 func (r *rootCommand) Name() string {
 	return "hugo"
 }
@@ -408,6 +416,8 @@ func (r *rootCommand) PreRun(cd, runner *simplecobra.Commandeer) error {
 		return err
 	}
 
+	r.changesFromBuild = make(chan []identity.Identity, 10)
+
 	r.commonConfigs = lazycache.New(lazycache.Options[int32, *commonConfig]{MaxEntries: 5})
 	// We don't want to keep stale HugoSites in memory longer than needed.
 	r.hugoSites = lazycache.New(lazycache.Options[int32, *hugolib.HugoSites]{
diff --git a/commands/hugobuilder.go b/commands/hugobuilder.go
index 32b7e1de8..99bd8a04a 100644
--- a/commands/hugobuilder.go
+++ b/commands/hugobuilder.go
@@ -43,6 +43,7 @@ import (
 	"github.com/gohugoio/hugo/hugofs"
 	"github.com/gohugoio/hugo/hugolib"
 	"github.com/gohugoio/hugo/hugolib/filesystems"
+	"github.com/gohugoio/hugo/identity"
 	"github.com/gohugoio/hugo/livereload"
 	"github.com/gohugoio/hugo/resources/page"
 	"github.com/gohugoio/hugo/watcher"
@@ -343,6 +344,24 @@ func (c *hugoBuilder) newWatcher(pollIntervalStr string, dirList ...string) (*wa
 	go func() {
 		for {
 			select {
+			case changes := <-c.r.changesFromBuild:
+				unlock, err := h.LockBuild()
+				if err != nil {
+					c.r.logger.Errorln("Failed to acquire a build lock: %s", err)
+					return
+				}
+				c.changeDetector.PrepareNew()
+				err = c.rebuildSitesForChanges(changes)
+				if err != nil {
+					c.r.logger.Errorln("Error while watching:", err)
+				}
+				if c.s != nil && c.s.doLiveReload {
+					if c.changeDetector == nil || len(c.changeDetector.changed()) > 0 {
+						livereload.ForceRefresh()
+					}
+				}
+				unlock()
+
 			case evs := <-watcher.Events:
 				unlock, err := h.LockBuild()
 				if err != nil {
@@ -1019,6 +1038,19 @@ func (c *hugoBuilder) rebuildSites(events []fsnotify.Event) error {
 	return h.Build(hugolib.BuildCfg{NoBuildLock: true, RecentlyVisited: c.visitedURLs, ErrRecovery: c.errState.wasErr()}, events...)
 }
 
+func (c *hugoBuilder) rebuildSitesForChanges(ids []identity.Identity) error {
+	c.errState.setBuildErr(nil)
+	h, err := c.hugo()
+	if err != nil {
+		return err
+	}
+	whatChanged := &hugolib.WhatChanged{}
+	whatChanged.Add(ids...)
+	err = h.Build(hugolib.BuildCfg{NoBuildLock: true, WhatChanged: whatChanged, RecentlyVisited: c.visitedURLs, ErrRecovery: c.errState.wasErr()})
+	c.errState.setBuildErr(err)
+	return err
+}
+
 func (c *hugoBuilder) reloadConfig() error {
 	c.r.Reset()
 	c.r.configVersionID.Add(1)