fix(daemon): decouple preview wakes from target ack

commit: bfbfc090851f3e7308f4ff8c9f715aa37609e404
author: brice · 3mo ago · 2026-07-11 18:35 UTC
parent: f50c254
signature: GPG VerifiedCD88F9E564E0102646FB6077A1A07C7C7C3E349D · arch-gpg Verified for the committer email

1 file · +37 -10

M internal/usecase/daemon/render_coordinator.go +37 -10


@@ -109,7 +109,11 @@ type renderCoordinator struct {
109	109		pending bool
110	110		pendingReset bool
111	111		pendingUrgent bool
112		-	coalesced int
	112	+	// pendingPreview is accounted separately from the target primary wake:
	113	+	// viewers may consume a coalesced target snapshot while that target is
	114	+	// still ACK-blocked.
	115	+	pendingPreview bool
	116	+	coalesced int
113	117		// outputPressure carries recent bulk-burst pressure between completed
114	118		// batches. It selects a bounded 8–16ms deadline without letting a busy
115	119		// batch perpetually reset its own timer.

@@ -187,13 +191,17 @@ func (c *renderCoordinator) invalidate(inv renderInvalidation) {
187	191		c.opts.onInvalidate(inv)
188	192		}
189	193		c.metrics.invalidations.Add(1)
190		-	wasPending, wasUrgent := c.pending, c.pendingUrgent
	194	+	wasPending, wasUrgent, wasPreviewPending := c.pending, c.pendingUrgent, c.pendingPreview
191	195		c.pending = true
192	196		c.pendingReset = c.pendingReset \|\| inv.reset
193	197		c.pendingUrgent = c.pendingUrgent \|\| inv.class == invalidateUrgent
	198	+	c.pendingPreview = c.pendingPreview \|\| c.previewWake != nil \|\| len(c.previewWakes) != 0
194	199		c.coalesced++
195		-	// Cap one normal deadline; an urgent transition may supersede it.
196		-	arm := !wasPending \|\| (!wasUrgent && c.pendingUrgent)
	200	+	// Cap one normal deadline for each primary or preview batch. Once a
	201	+	// preview has been delivered while the target is ACK-blocked, a later
	202	+	// target transition needs its own deadline even though the primary remains
	203	+	// pending.
	204	+	arm := !wasPending \|\| (!wasUrgent && c.pendingUrgent) \|\| (!wasPreviewPending && c.pendingPreview)
197	205		if arm {
198	206		c.generation++
199	207		c.cancelNormalTimerLocked()

@@ -360,6 +368,7 @@ func (c renderCoordinator) noteDetach(ac attachedClient) {
360	368		if c.attachment == ac {
361	369		c.attachment = nil
362	370		c.pending = false
	371	+	c.pendingPreview = false
363	372		c.generation++
364	373		c.armed = false
365	374		c.cancelNormalTimerLocked()

@@ -375,6 +384,7 @@ func (c renderCoordinator) noteReplace(old, replacement attachedClient) {
375	384		if c.attachment == old {
376	385		c.attachment = replacement
377	386		c.pending = false
	387	+	c.pendingPreview = false
378	388		c.generation++
379	389		c.armed = false
380	390		c.cancelNormalTimerLocked()

@@ -394,6 +404,7 @@ func (c *renderCoordinator) noteSessionTeardown() {
394	404		c.previewWake = nil
395	405		c.previewWakes = nil
396	406		c.pending = false
	407	+	c.pendingPreview = false
397	408		c.generation++
398	409		c.armed = false
399	410		c.cancelNormalTimerLocked()

@@ -487,11 +498,13 @@ func (c *renderCoordinator) fire(gen uint64, watchdog bool) {
487	498		c.mu.Unlock()
488	499		return
489	500		}
	501	+	w := renderWake{reset: c.pendingReset, urgent: c.pendingUrgent, coalesced: c.coalesced, watchdog: watchdog}
	502	+	preview, previews := c.takePendingPreviewsLocked()
490	503		if c.opts.ackReady != nil && !c.opts.ackReady() {
491	504		c.mu.Unlock()
	505	+	c.notifyPreviews(w, preview, previews)
492	506		return
493	507		}
494		-	w := renderWake{reset: c.pendingReset, urgent: c.pendingUrgent, coalesced: c.coalesced, watchdog: watchdog}
495	508		c.metrics.wakes.Add(1)
496	509		c.metrics.coalesced.Add(uint64(w.coalesced))
497	510		if !w.urgent {

@@ -506,15 +519,29 @@ func (c *renderCoordinator) fire(gen uint64, watchdog bool) {
506	519		}
507	520		c.cancelNormalTimerLocked()
508	521		c.pending, c.pendingReset, c.pendingUrgent, c.coalesced, c.armed = false, false, false, 0, false
509		-	wake, preview := c.opts.wake, c.previewWake
510		-	previews := make([]func(renderWake), 0, len(c.previewWakes))
511		-	for _, fn := range c.previewWakes {
512		-	previews = append(previews, fn)
513		-	}
	522	+	wake := c.opts.wake
514	523		c.mu.Unlock()
515	524		if wake != nil {
516	525		wake(w)
517	526		}
	527	+	c.notifyPreviews(w, preview, previews)
	528	+	}
	529	+
	530	+	// takePendingPreviewsLocked snapshots and consumes the preview delivery for
	531	+	// this target generation. Unlike the target primary, this is never ACK-gated.
	532	+	func (c *renderCoordinator) takePendingPreviewsLocked() (func(renderWake), []func(renderWake)) {
	533	+	if !c.pendingPreview {
	534	+	return nil, nil
	535	+	}
	536	+	c.pendingPreview = false
	537	+	previews := make([]func(renderWake), 0, len(c.previewWakes))
	538	+	for _, fn := range c.previewWakes {
	539	+	previews = append(previews, fn)
	540	+	}
	541	+	return c.previewWake, previews
	542	+	}
	543	+
	544	+	func (c *renderCoordinator) notifyPreviews(w renderWake, preview func(renderWake), previews []func(renderWake)) {
518	545		if preview != nil {
519	546		preview(w)
520	547		}

 	pending       bool
 	pendingReset  bool
 	pendingUrgent bool
-	coalesced     int
+	// pendingPreview is accounted separately from the target primary wake:
+	// viewers may consume a coalesced target snapshot while that target is
+	// still ACK-blocked.
+	pendingPreview bool
+	coalesced      int
 	// outputPressure carries recent bulk-burst pressure between completed
 	// batches. It selects a bounded 8–16ms deadline without letting a busy
 	// batch perpetually reset its own timer.
 		c.opts.onInvalidate(inv)
 	}
 	c.metrics.invalidations.Add(1)
-	wasPending, wasUrgent := c.pending, c.pendingUrgent
+	wasPending, wasUrgent, wasPreviewPending := c.pending, c.pendingUrgent, c.pendingPreview
 	c.pending = true
 	c.pendingReset = c.pendingReset || inv.reset
 	c.pendingUrgent = c.pendingUrgent || inv.class == invalidateUrgent
+	c.pendingPreview = c.pendingPreview || c.previewWake != nil || len(c.previewWakes) != 0
 	c.coalesced++
-	// Cap one normal deadline; an urgent transition may supersede it.
+	// Cap one normal deadline for each primary or preview batch. Once a
-	arm := !wasPending || (!wasUrgent && c.pendingUrgent)
+	// preview has been delivered while the target is ACK-blocked, a later
+	// target transition needs its own deadline even though the primary remains
+	// pending.
+	arm := !wasPending || (!wasUrgent && c.pendingUrgent) || (!wasPreviewPending && c.pendingPreview)
 	if arm {
 		c.generation++
 		c.cancelNormalTimerLocked()
 	if c.attachment == ac {
 		c.attachment = nil
 		c.pending = false
+		c.pendingPreview = false
 		c.generation++
 		c.armed = false
 		c.cancelNormalTimerLocked()
 	if c.attachment == old {
 		c.attachment = replacement
 		c.pending = false
+		c.pendingPreview = false
 		c.generation++
 		c.armed = false
 		c.cancelNormalTimerLocked()
 	c.previewWake = nil
 	c.previewWakes = nil
 	c.pending = false
+	c.pendingPreview = false
 	c.generation++
 	c.armed = false
 	c.cancelNormalTimerLocked()
 		c.mu.Unlock()
 		return
 	}
+	w := renderWake{reset: c.pendingReset, urgent: c.pendingUrgent, coalesced: c.coalesced, watchdog: watchdog}
+	preview, previews := c.takePendingPreviewsLocked()
 	if c.opts.ackReady != nil && !c.opts.ackReady() {
 		c.mu.Unlock()
+		c.notifyPreviews(w, preview, previews)
 		return
 	}
-	w := renderWake{reset: c.pendingReset, urgent: c.pendingUrgent, coalesced: c.coalesced, watchdog: watchdog}
 	c.metrics.wakes.Add(1)
 	c.metrics.coalesced.Add(uint64(w.coalesced))
 	if !w.urgent {
 	}
 	c.cancelNormalTimerLocked()
 	c.pending, c.pendingReset, c.pendingUrgent, c.coalesced, c.armed = false, false, false, 0, false
-	wake, preview := c.opts.wake, c.previewWake
+	wake := c.opts.wake
-	previews := make([]func(renderWake), 0, len(c.previewWakes))
-	for _, fn := range c.previewWakes {
-		previews = append(previews, fn)
-	}
 	c.mu.Unlock()
 	if wake != nil {
 		wake(w)
 	}
+	c.notifyPreviews(w, preview, previews)
+}
+// takePendingPreviewsLocked snapshots and consumes the preview delivery for
+// this target generation. Unlike the target primary, this is never ACK-gated.
+func (c *renderCoordinator) takePendingPreviewsLocked() (func(renderWake), []func(renderWake)) {
+	if !c.pendingPreview {
+		return nil, nil
+	}
+	c.pendingPreview = false
+	previews := make([]func(renderWake), 0, len(c.previewWakes))
+	for _, fn := range c.previewWakes {
+		previews = append(previews, fn)
+	}
+	return c.previewWake, previews
+}
+func (c *renderCoordinator) notifyPreviews(w renderWake, preview func(renderWake), previews []func(renderWake)) {
 	if preview != nil {
 		preview(w)
 	}