From 241148d9c5dc3bd33cdf2c3feacf1efd5094081d Mon Sep 17 00:00:00 2001
From: David Florness <david@florness.com>
Date: Mon, 15 Feb 2021 11:01:33 -0500
Subject: [PATCH] Calculate local voter's sum as soon as we have the final eval

instead of using a needless WaitGroup in the main goroutine
---
 cmd/tallyard/main.go | 10 ++++++++--
 election/msg.go      | 13 ++++++++++++-
 election/voter.go    | 30 +++++++++++++-----------------
 3 files changed, 33 insertions(+), 20 deletions(-)

diff --git a/cmd/tallyard/main.go b/cmd/tallyard/main.go
index 3bd810c..3e40b02 100644
--- a/cmd/tallyard/main.go
+++ b/cmd/tallyard/main.go
@@ -3,6 +3,7 @@ package main
 import (
 	"fmt"
 	"os"
+	"time"
 
 	"github.com/kyoh86/xdg"
 	log "github.com/sirupsen/logrus"
@@ -150,8 +151,13 @@ func main() {
 	}
 
 	// send sum if needed
-	if el.LocalVoter != nil && el.LocalVoter.SumID == nil {
-		fmt.Println("waiting for evals...")
+	if el.LocalVoter != nil {
+		if el.LocalVoter.Sum == nil {
+			fmt.Println("waiting for evals...")
+			for el.LocalVoter.Sum == nil {
+				time.Sleep(time.Millisecond * 200)
+			}
+		}
 		err = el.SendSum(client, elections.EventStore)
 		if err != nil {
 			panic(err)
diff --git a/election/msg.go b/election/msg.go
index f35d140..c134c48 100644
--- a/election/msg.go
+++ b/election/msg.go
@@ -410,6 +410,17 @@ func (elections *ElectionsMap) onEvalsMessage(evt *event.Event) (success bool) {
 	}
 	voter.Eval = new(big.Int).SetBytes(decryptedOutput)
 
+	for _, voterID := range *el.FinalJoinIDs {
+		if el.Joins[voterID].Eval == nil {
+			return true
+		}
+	}
+	sum := big.NewInt(0)
+	for _, voterID := range *el.FinalJoinIDs {
+		sum.Add(sum, el.Joins[voterID].Eval)
+	}
+	el.LocalVoter.Sum = sum
+
 	return true
 }
 
@@ -489,7 +500,7 @@ func (elections *ElectionsMap) onSumMessage(evt *event.Event) (success bool) {
 		return
 	}
 
-	if voter.Sum != nil {
+	if voter.SumID != nil {
 		warnf("voter submitted multiple sum events")
 		return
 	}
diff --git a/election/voter.go b/election/voter.go
index cad9221..6cab9ff 100644
--- a/election/voter.go
+++ b/election/voter.go
@@ -7,8 +7,6 @@ import (
 	"fmt"
 	"io"
 	"math/big"
-	"sync"
-	"time"
 
 	"golang.org/x/crypto/nacl/box"
 	"maunium.net/go/mautrix"
@@ -147,6 +145,7 @@ func (el *Election) StartElection(client *mautrix.Client, eventStore *EventStore
 func (el *Election) SendEvals(client *mautrix.Client, eventStore *EventStore) error {
 	el.RLock()
 	if el.StartID == nil {
+		el.RUnlock()
 		return errors.New("SendEvals called before election started")
 	}
 
@@ -183,28 +182,25 @@ func (el *Election) SendEvals(client *mautrix.Client, eventStore *EventStore) er
 }
 
 func (el *Election) SendSum(client *mautrix.Client, eventStore *EventStore) error {
-	sum := big.NewInt(0)
+	el.RLock()
+	if el.LocalVoter.Sum == nil {
+		el.RUnlock()
+		return errors.New("SendSum called before local sum was calculated")
+	}
+
 	var evalsIDs []id.EventID
-	var wg sync.WaitGroup
-	for _, voterJoinId := range *el.FinalJoinIDs {
-		wg.Add(1)
-		go func(voter *Voter) {
-			for voter.EvalsID == nil {
-				time.Sleep(time.Millisecond * 100)
-			}
-			evalsIDs = append(evalsIDs, *voter.EvalsID)
-			sum.Add(sum, voter.Eval)
-			wg.Done()
-		}(el.Joins[voterJoinId])
-	}
-	wg.Wait()
+	for _, joinID := range *el.FinalJoinIDs {
+		voter := el.Joins[joinID]
+		evalsIDs = append(evalsIDs, *voter.EvalsID)
+	}
 
 	resp, err := client.SendMessageEvent(el.RoomID, SumMessage, SumMessageContent{
 		Version:  Version,
 		EvalsIDs: evalsIDs,
 		JoinID:   el.LocalVoter.JoinEvt.ID,
-		Sum:      base64.StdEncoding.EncodeToString(sum.Bytes()),
+		Sum:      base64.StdEncoding.EncodeToString(el.LocalVoter.Sum.Bytes()),
 	})
+	el.RUnlock()
 	if err != nil {
 		return err
 	}
-- 
2.38.4