commands: Handle mass content etc. edits in server mode

Fixes #4563

Gopkg.toml

@@ -145,3 +145,7 @@
 [[constraint]]
   name = "github.com/sanity-io/litter"
   version = "1.1.0"
+
+[[constraint]]
+  branch = "master"
+  name = "github.com/bep/debounce"

commands/commandeer.go

@@ -17,6 +17,7 @@ import (
 	"os"
 	"path/filepath"
 	"sync"
+	"time"
 
 	"github.com/spf13/cobra"
 
@@ -26,6 +27,7 @@ import (
 
 	"github.com/gohugoio/hugo/hugolib"
 
+	"github.com/bep/debounce"
 	"github.com/gohugoio/hugo/common/types"
 	"github.com/gohugoio/hugo/deps"
 	"github.com/gohugoio/hugo/helpers"
@@ -51,6 +53,9 @@ type commandeer struct {
 	// We can do this only once.
 	fsCreate sync.Once
 
+	// Used in cases where we get flooded with events in server mode.
+	debounce func(f func())
+
 	serverPorts []int
 	languages   helpers.Languages
 
@@ -90,10 +95,20 @@ func (c *commandeer) initFs(fs *hugofs.Fs) error {
 
 func newCommandeer(running bool, doWithCommandeer func(c *commandeer) error, subCmdVs ...*cobra.Command) (*commandeer, error) {
 
+	var rebuildDebouncer func(f func())
+	if running {
+		// The time value used is tested with mass content replacements in a fairly big Hugo site.
+		// It is better to wait for some seconds in those cases rather than get flooded
+		// with rebuilds.
+		rebuildDebouncer, _ = debounce.New(4 * time.Second)
+	}
+
 	c := &commandeer{
 		doWithCommandeer: doWithCommandeer,
 		subCmdVs:         append([]*cobra.Command{hugoCmdV}, subCmdVs...),
-		visitedURLs:      types.NewEvictingStringQueue(10)}
+		visitedURLs:      types.NewEvictingStringQueue(10),
+		debounce:         rebuildDebouncer,
+	}
 
 	return c, c.loadConfig(running)
 }

commands/hugo.go

@@ -851,6 +851,16 @@ func (c *commandeer) rebuildSites(events []fsnotify.Event) error {
 	return Hugo.Build(hugolib.BuildCfg{RecentlyVisited: visited}, events...)
 }
 
+func (c *commandeer) fullRebuild() {
+	if err := c.loadConfig(true); err != nil {
+		jww.ERROR.Println("Failed to reload config:", err)
+	} else if err := c.recreateAndBuildSites(true); err != nil {
+		jww.ERROR.Println(err)
+	} else if !buildWatch && !c.Cfg.GetBool("disableLiveReload") {
+		livereload.ForceRefresh()
+	}
+}
+
 // newWatcher creates a new watcher to watch filesystem events.
 func (c *commandeer) newWatcher(dirList ...string) (*watcher.Batcher, error) {
 	if runtime.GOOS == "darwin" {
@@ -887,6 +897,13 @@ func (c *commandeer) newWatcher(dirList ...string) (*watcher.Batcher, error) {
 		for {
 			select {
 			case evs := <-watcher.Events:
+				if len(evs) > 50 {
+					// This is probably a mass edit of the content dir.
+					// Schedule a full rebuild for when it slows down.
+					c.debounce(c.fullRebuild)
+					continue
+				}
+
 				c.Logger.INFO.Println("Received System Events:", evs)
 
 				staticEvents := []fsnotify.Event{}
@@ -900,13 +917,7 @@ func (c *commandeer) newWatcher(dirList ...string) (*watcher.Batcher, error) {
 							continue
 						}
 						// Config file changed. Need full rebuild.
-						if err := c.loadConfig(true); err != nil {
-							jww.ERROR.Println("Failed to reload config:", err)
-						} else if err := c.recreateAndBuildSites(true); err != nil {
-							jww.ERROR.Println(err)
-						} else if !buildWatch && !c.Cfg.GetBool("disableLiveReload") {
-							livereload.ForceRefresh()
-						}
+						c.fullRebuild()
 						break
 					}