From 8c939acb699f227cd277c682f30221b705425f2f Mon Sep 17 00:00:00 2001
From: David Florness <david@florness.com>
Date: Mon, 8 Jun 2020 19:24:53 -0600
Subject: [PATCH] Ensure we have everyones' inputs after getting everyones'
 sums

---
 voter.go | 60 ++++++++++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 54 insertions(+), 6 deletions(-)

diff --git a/voter.go b/voter.go
index cfaeb0f..edd1b10 100644
--- a/voter.go
+++ b/voter.go
@@ -137,6 +137,7 @@ func handleCmd(cmd string, rw *bufio.ReadWriter, stream network.Stream) {
 		}
 		peer.Lock()
 		peer.input = new(big.Int).SetBytes(inputBytes)
+		logger.Infof("%s input: %s", peer.addrInfo.ID, peer.input)
 		peer.Unlock()
 		output := me.poly.Eval(peer.input)
 		rw.WriteString(base58.Encode(output.Bytes()))
@@ -151,6 +152,18 @@ func handleCmd(cmd string, rw *bufio.ReadWriter, stream network.Stream) {
 		}
 		rw.WriteString(base58.Encode(me.sum.Bytes()))
 		rw.Flush()
+	case "input":
+		me.RLock()
+		defer me.RUnlock()
+		if me.input == nil {
+			logger.Info("peer attempted to fetch input "+
+				"before we had one:", stream.Conn().RemotePeer())
+			return
+		}
+		rw.WriteString(base58.Encode(me.input.Bytes()))
+		rw.Flush()
+	default:
+		logger.Warningf("uknown command %s", cmd)
 	}
 }
 
@@ -216,7 +229,7 @@ func findPeers(closeElection <-chan int) {
 	logger.Info("done finding peers")
 }
 
-func (voter *Voter) fetchNumber(cmd string, args ...string) *big.Int {
+func (voter *Voter) fetchNumber(done chan<- *big.Int, cmd string, args ...string) {
 	printErr := func(err error, msg string) {
 		logger.Errorf("%s: %s fetcing `%s'; retrying in 2 seconds",
 			voter.addrInfo.ID, msg, cmd)
@@ -263,7 +276,7 @@ retry:
 		printErr(err, "couldn't base58-decode contents from stream")
 		goto retry
 	}
-	return new(big.Int).SetBytes(retBytes)
+	done <- new(big.Int).SetBytes(retBytes)
 }
 
 func startVoting() {
@@ -272,6 +285,7 @@ func startVoting() {
 	if err != nil {
 		panic(err)
 	}
+	logger.Infof("our input: %s", me.input)
 
 	ballot := vote(candidates)
 
@@ -283,10 +297,19 @@ func startVoting() {
 	for _, voter := range election.remoteVoters {
 		wg.Add(1)
 		go func(voter *Voter) {
-			voter.output = voter.fetchNumber("eval",
+			done := make(chan *big.Int, 1)
+			me.RLock()
+			go voter.fetchNumber(done, "eval",
 				base58.Encode(me.input.Bytes()))
+			me.RUnlock()
+			output := <- done
+			voter.Lock()
+			voter.output = output
+			voter.Unlock()
+			voter.RLock()
 			logger.Infof("voter %s output: %s",
 				voter.addrInfo.ID, voter.output)
+			voter.RUnlock()
 			wg.Done()
 		}(voter)
 	}
@@ -304,17 +327,42 @@ func startVoting() {
 	for _, voter := range election.remoteVoters {
 		wg.Add(1)
 		go func(voter *Voter) {
+			done := make(chan *big.Int, 1)
 			me.RLock()
-			voter.sum = voter.fetchNumber("sum",
-				base58.Encode(me.sum.Bytes()))
+			go voter.fetchNumber(done, "sum", base58.Encode(me.sum.Bytes()))
+			me.RUnlock()
+			sum := <- done
+			voter.Lock()
+			voter.sum = sum
+			voter.Unlock()
+			voter.RLock()
 			logger.Infof("voter %s sum: %s",
 				voter.addrInfo.ID, voter.sum)
-			me.RUnlock()
+			voter.RUnlock()
 			wg.Done()
 		}(voter)
 	}
 	wg.Wait()
 
+	// ensure we have everyone's inputs
+	for _, voter := range election.remoteVoters {
+		voter.RLock()
+		haveInput := voter.input != nil
+		voter.RUnlock()
+		if !haveInput {
+			wg.Add(1)
+			go func(voter *Voter) {
+				done := make(chan *big.Int, 1)
+				go voter.fetchNumber(done, "input")
+				input := <- done
+				voter.Lock()
+				voter.input = input
+				voter.Unlock()
+			}(voter)
+		}
+	}
+	wg.Wait()
+
 	// temporary
 	select {}
 }
-- 
2.38.4