[#29772][prism] Handle EventTime Timers.

sdks/go/pkg/beam/core/timers/timers.go

@@ -51,8 +51,10 @@ type TimerMap struct {
 	FireTimestamp, HoldTimestamp mtime.Time
 }
 
+// timerConfig is used transiently to hold configuration from the functional options.
 type timerConfig struct {
 	Tag           string
+	HoldSet       bool // Whether the HoldTimestamp was set.
 	HoldTimestamp mtime.Time
 }
 
@@ -68,6 +70,7 @@ func WithTag(tag string) timerOptions {
 // WithOutputTimestamp sets the output timestamp for the timer.
 func WithOutputTimestamp(outputTimestamp time.Time) timerOptions {
 	return func(tm *timerConfig) {
+		tm.HoldSet = true
 		tm.HoldTimestamp = mtime.FromTime(outputTimestamp)
 	}
 }
@@ -108,7 +111,7 @@ func (et EventTime) Set(p Provider, FiringTimestamp time.Time, opts ...timerOpti
 		opt(&tc)
 	}
 	tm := TimerMap{Family: et.Family, Tag: tc.Tag, FireTimestamp: mtime.FromTime(FiringTimestamp), HoldTimestamp: mtime.FromTime(FiringTimestamp)}
-	if !tc.HoldTimestamp.ToTime().IsZero() {
+	if tc.HoldSet {
 		tm.HoldTimestamp = tc.HoldTimestamp
 	}
 	p.Set(tm)
@@ -142,7 +145,7 @@ func (pt ProcessingTime) Set(p Provider, FiringTimestamp time.Time, opts ...time
 		opt(&tc)
 	}
 	tm := TimerMap{Family: pt.Family, Tag: tc.Tag, FireTimestamp: mtime.FromTime(FiringTimestamp), HoldTimestamp: mtime.FromTime(FiringTimestamp)}
-	if !tc.HoldTimestamp.ToTime().IsZero() {
+	if tc.HoldSet {
 		tm.HoldTimestamp = tc.HoldTimestamp
 	}
 

sdks/go/pkg/beam/runners/prism/internal/coders.go

@@ -200,7 +200,7 @@ func pullDecoder(c *pipepb.Coder, coders map[string]*pipepb.Coder) func(io.Reade
 	}
 }
 
-// pullDecoderNoAlloc returns a function that decodes a single eleemnt of the given coder.
+// pullDecoderNoAlloc returns a function that decodes a single element of the given coder.
 // Intended to only be used as an internal function for pullDecoder, which will use a io.TeeReader
 // to extract the bytes.
 func pullDecoderNoAlloc(c *pipepb.Coder, coders map[string]*pipepb.Coder) func(io.Reader) {

sdks/go/pkg/beam/runners/prism/internal/engine/data.go

@@ -32,13 +32,20 @@ type StateData struct {
 	Multimap map[string][][]byte
 }
 
+// TimerKey is for use as a key for timers.
+type TimerKey struct {
+	Transform, Family string
+}
+
 // TentativeData is where data for in progress bundles is put
 // until the bundle executes successfully.
 type TentativeData struct {
 	Raw map[string][][]byte
 
 	// state is a map from transformID + UserStateID, to window, to userKey, to datavalues.
 	state map[LinkID]map[typex.Window]map[string]StateData
+	// timers is a map from the Timer transform+family to the encoded timer.
+	timers map[TimerKey][][]byte
 }
 
 // WriteData adds data to a given global collectionID.
@@ -49,6 +56,15 @@ func (d *TentativeData) WriteData(colID string, data []byte) {
 	d.Raw[colID] = append(d.Raw[colID], data)
 }
 
+// WriteTimers adds timers to the associated transform handler.
+func (d *TentativeData) WriteTimers(transformID, familyID string, timers []byte) {
+	if d.timers == nil {
+		d.timers = map[TimerKey][][]byte{}
+	}
+	link := TimerKey{Transform: transformID, Family: familyID}
+	d.timers[link] = append(d.timers[link], timers)
+}
+
 func (d *TentativeData) toWindow(wKey []byte) typex.Window {
 	if len(wKey) == 0 {
 		return window.GlobalWindow{}