Add reload-sync action

Close #2816

CHANGELOG.md

@@ -12,6 +12,18 @@ CHANGELOG
   # Send actions to the server
   curl -XPOST localhost:6266 -d 'reload(seq 100)+change-prompt(hundred> )'
   ```
+- New event
+    - Added `load` event that is triggered when the input stream is complete
+      and the initial processing of the list is complete.
+      ```sh
+      # Change the prompt to "loaded" when the input stream is complete
+      (seq 10; sleep 1; seq 11 20) | fzf --prompt 'Loading> ' --bind 'load:change-prompt:Loaded> '
+
+      # You can use it instead of 'start' event without `--sync` if asynchronous
+      # trigger is not an issue.
+      (seq 10; sleep 1; seq 11 20) | fzf --bind 'load:last'
+      ```
+- New actions
     - Added `pos(...)` action to move the cursor to the numeric position
         - `first` and `last` are equivalent to `pos(1)` and `pos(-1)` respectively
       ```sh
@@ -21,15 +33,13 @@ CHANGELOG
       # Put the cursor on the 10th to last item
       seq 100 | fzf --sync --bind 'start:pos(-10)'
       ```
-- Added `load` event that is triggered when the input stream is complete and
-  the initial processing of the list is complete.
+    - Added `reload-sync(...)` action which replaces the current list only after
+      the reload process is complete. This is useful when the command takes
+      a while to produce the initial output and you don't want fzf to run against
+      an empty list while the command is running.
       ```sh
-  # Change the prompt to "loaded" when the input stream is complete
-  (seq 10; sleep 1; seq 11 20) | fzf --prompt 'Loading> ' --bind 'load:change-prompt:Loaded> '
-
-  # You can use it instead of 'start' event without `--sync` if asynchronous
-  # trigger is not an issue.
-  (seq 10; sleep 1; seq 11 20) | fzf --bind 'load:last'
+      # You can still filter and select entries from the initial list for 3 seconds
+      seq 100 | fzf --bind 'load:reload-sync(sleep 3; seq 1000)+unbind(load)'
       ```
     - Added `next-selected` and `prev-selected` actions to move between selected
       items
@@ -58,6 +68,7 @@ CHANGELOG
       # Can only type numbers
       fzf --bind 'change:transform-query(sed 's/[^0-9]//g' <<< {q})'
       ```
+- Improvements
     - `put` action can optionally take an argument string
       ```sh
       # a will put 'alpha' on the prompt, ctrl-b will put 'bravo'

man/man1/fzf.1

@@ -1019,6 +1019,7 @@ A key or an event can be bound to one or more of the following actions.
     \fBrefresh-preview\fR
     \fBrebind(...)\fR                (rebind bindings after \fBunbind\fR)
     \fBreload(...)\fR                (see below for the details)
+    \fBreload-sync(...)\fR           (see below for the details)
     \fBreplace-query\fR              (replace query string with the current selection)
     \fBselect\fR
     \fBselect-all\fR                 (select all matches)
@@ -1122,6 +1123,16 @@ e.g.
        fzf --bind "change:reload:$RG_PREFIX {q} || true" \\
            --ansi --disabled --query "$INITIAL_QUERY"\fR
 
+\fBreload-sync(...)\fR is a synchronous version of \fBreload\fR that replaces
+the list only when the command is complete. This is useful when the command
+takes a while to produce the initial output and you don't want fzf to run
+against an empty list while the command is running.
+
+
+e.g.
+     \fB# You can still filter and select entries from the initial list for 3 seconds
+     seq 100 | fzf --bind 'load:reload-sync(sleep 3; seq 1000)+unbind(load)'\fR
+
 .SS PREVIEW BINDING
 
 With \fBpreview(...)\fR action, you can specify multiple different preview

src/core.go

@@ -213,15 +213,6 @@ func Run(opts *Options, version string, revision string) {
 	clearSelection := util.Once(false)
 	ticks := 0
 	var nextCommand *string
-	restart := func(command string) {
-		reading = true
-		clearCache = util.Once(true)
-		clearSelection = util.Once(true)
-		chunkList.Clear()
-		itemIndex = 0
-		header = make([]string, 0, opts.HeaderLines)
-		go reader.restart(command)
-	}
 	eventBox.Watch(EvtReadNew)
 	total := 0
 	query := []rune{}
@@ -236,6 +227,25 @@ func Run(opts *Options, version string, revision string) {
 			terminal.startChan <- fitpad{-1, -1}
 		}
 	}
+
+	useSnapshot := false
+	var snapshot []*Chunk
+	var prevSnapshot []*Chunk
+	var count int
+	restart := func(command string) {
+		reading = true
+		clearCache = util.Once(true)
+		clearSelection = util.Once(true)
+		// We should not update snapshot if reload is triggered again while
+		// the previous reload is in progress
+		if useSnapshot && prevSnapshot != nil {
+			snapshot, count = chunkList.Snapshot()
+		}
+		chunkList.Clear()
+		itemIndex = 0
+		header = make([]string, 0, opts.HeaderLines)
+		go reader.restart(command)
+	}
 	for {
 		delay := true
 		ticks++
@@ -267,7 +277,13 @@ func Run(opts *Options, version string, revision string) {
 					} else {
 						reading = reading && evt == EvtReadNew
 					}
-					snapshot, count := chunkList.Snapshot()
+					if useSnapshot && evt == EvtReadFin {
+						useSnapshot = false
+						prevSnapshot = nil
+					}
+					if !useSnapshot {
+						snapshot, count = chunkList.Snapshot()
+					}
 					total = count
 					terminal.UpdateCount(total, !reading, value.(*string))
 					if opts.Sync {
@@ -286,6 +302,9 @@ func Run(opts *Options, version string, revision string) {
 					case searchRequest:
 						sort = val.sort
 						command = val.command
+						if command != nil {
+							useSnapshot = val.sync
+						}
 					}
 					if command != nil {
 						if reading {
@@ -296,7 +315,9 @@ func Run(opts *Options, version string, revision string) {
 						}
 						break
 					}
-					snapshot, _ := chunkList.Snapshot()
+					if !useSnapshot {
+						snapshot, _ = chunkList.Snapshot()
+					}
 					reset := clearCache()
 					matcher.Reset(snapshot, input(reset), true, !reading, sort, reset)
 					delay = false

src/options.go

@@ -892,7 +892,7 @@ const (
 
 func init() {
 	executeRegexp = regexp.MustCompile(
-		`(?si)[:+](execute(?:-multi|-silent)?|reload|preview|change-query|change-prompt|change-preview-window|change-preview|(?:re|un)bind|pos|put|transform-query)`)
+		`(?si)[:+](execute(?:-multi|-silent)?|reload(?:-sync)?|preview|change-query|change-prompt|change-preview-window|change-preview|(?:re|un)bind|pos|put|transform-query)`)
 	splitRegexp = regexp.MustCompile("[,:]+")
 	actionNameRegexp = regexp.MustCompile("(?i)^[a-z-]+")
 }
@@ -1185,6 +1185,8 @@ func isExecuteAction(str string) actionType {
 	switch prefix {
 	case "reload":
 		return actReload
+	case "reload-sync":
+		return actReloadSync
 	case "unbind":
 		return actUnbind
 	case "rebind":

src/terminal.go

@@ -335,6 +335,7 @@ const (
 	actFirst
 	actLast
 	actReload
+	actReloadSync
 	actDisableSearch
 	actEnableSearch
 	actSelect
@@ -353,6 +354,7 @@ type placeholderFlags struct {
 
 type searchRequest struct {
 	sort    bool
+	sync    bool
 	command *string
 }
 
@@ -2540,6 +2542,7 @@ func (t *Terminal) Loop() {
 	}()
 	for looping {
 		var newCommand *string
+		var reloadSync bool
 		changed := false
 		beof := false
 		queryChanged := false
@@ -3030,7 +3033,7 @@ func (t *Terminal) Loop() {
 						}
 					}
 				}
-			case actReload:
+			case actReload, actReloadSync:
 				t.failed = nil
 
 				valid, list := t.buildPlusList(a.a, false)
@@ -3044,6 +3047,7 @@ func (t *Terminal) Loop() {
 				if valid {
 					command := t.replacePlaceholder(a.a, false, string(t.input), list)
 					newCommand = &command
+					reloadSync = a.t == actReloadSync
 					t.reading = true
 				}
 			case actUnbind:
@@ -3173,7 +3177,7 @@ func (t *Terminal) Loop() {
 		t.mutex.Unlock() // Must be unlocked before touching reqBox
 
 		if changed || newCommand != nil {
-			t.eventBox.Set(EvtSearchNew, searchRequest{sort: t.sort, command: newCommand})
+			t.eventBox.Set(EvtSearchNew, searchRequest{sort: t.sort, sync: reloadSync, command: newCommand})
 		}
 		for _, event := range events {
 			t.reqBox.Set(event, nil)

test/test_go.rb

@@ -2161,6 +2161,15 @@ class TestGoFZF < TestBase
     tmux.until { |lines| assert_includes lines[1], '4' }
   end
 
+  def test_reload_sync
+    tmux.send_keys "seq 100 | #{FZF} --bind 'load:reload-sync(sleep 1; seq 1000)+unbind(load)'", :Enter
+    tmux.until { |lines| assert_equal 100, lines.item_count }
+    tmux.send_keys '00'
+    tmux.until { |lines| assert_equal 1, lines.match_count }
+    # After 1 second
+    tmux.until { |lines| assert_equal 10, lines.match_count }
+  end
+
   def test_scroll_off
     tmux.send_keys "seq 1000 | #{FZF} --scroll-off=3 --bind l:last", :Enter
     tmux.until { |lines| assert_equal 1000, lines.item_count }