From 99dda4a43abe43343ad54ade5583ccd947ab534a Mon Sep 17 00:00:00 2001
From: Cian Johnston <cian@coder.com>
Date: Thu, 25 Apr 2024 16:54:51 +0100
Subject: [PATCH] fix(agent): keep track of lastReportIndex between invocations
 of reportLifecycle() (#13075)

---
 agent/agent.go | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/agent/agent.go b/agent/agent.go
index abbe9c8ea4..b6eb60519c 100644
--- a/agent/agent.go
+++ b/agent/agent.go
@@ -240,10 +240,11 @@ type agent struct {
 	sshServer                    *agentssh.Server
 	sshMaxTimeout                time.Duration
 
-	lifecycleUpdate   chan struct{}
-	lifecycleReported chan codersdk.WorkspaceAgentLifecycle
-	lifecycleMu       sync.RWMutex // Protects following.
-	lifecycleStates   []agentsdk.PostLifecycleRequest
+	lifecycleUpdate            chan struct{}
+	lifecycleReported          chan codersdk.WorkspaceAgentLifecycle
+	lifecycleMu                sync.RWMutex // Protects following.
+	lifecycleStates            []agentsdk.PostLifecycleRequest
+	lifecycleLastReportedIndex int // Keeps track of the last lifecycle state we successfully reported.
 
 	network       *tailnet.Conn
 	addresses     []netip.Prefix
@@ -625,7 +626,6 @@ func (a *agent) reportMetadata(ctx context.Context, conn drpc.Conn) error {
 // changes are reported in order.
 func (a *agent) reportLifecycle(ctx context.Context, conn drpc.Conn) error {
 	aAPI := proto.NewDRPCAgentClient(conn)
-	lastReportedIndex := 0 // Start off with the created state without reporting it.
 	for {
 		select {
 		case <-a.lifecycleUpdate:
@@ -636,20 +636,20 @@ func (a *agent) reportLifecycle(ctx context.Context, conn drpc.Conn) error {
 		for {
 			a.lifecycleMu.RLock()
 			lastIndex := len(a.lifecycleStates) - 1
-			report := a.lifecycleStates[lastReportedIndex]
-			if len(a.lifecycleStates) > lastReportedIndex+1 {
-				report = a.lifecycleStates[lastReportedIndex+1]
+			report := a.lifecycleStates[a.lifecycleLastReportedIndex]
+			if len(a.lifecycleStates) > a.lifecycleLastReportedIndex+1 {
+				report = a.lifecycleStates[a.lifecycleLastReportedIndex+1]
 			}
 			a.lifecycleMu.RUnlock()
 
-			if lastIndex == lastReportedIndex {
+			if lastIndex == a.lifecycleLastReportedIndex {
 				break
 			}
 			l, err := agentsdk.ProtoFromLifecycle(report)
 			if err != nil {
 				a.logger.Critical(ctx, "failed to convert lifecycle state", slog.F("report", report))
 				// Skip this report; there is no point retrying.  Maybe we can successfully convert the next one?
-				lastReportedIndex++
+				a.lifecycleLastReportedIndex++
 				continue
 			}
 			payload := &proto.UpdateLifecycleRequest{Lifecycle: l}
@@ -662,13 +662,13 @@ func (a *agent) reportLifecycle(ctx context.Context, conn drpc.Conn) error {
 			}
 
 			logger.Debug(ctx, "successfully reported lifecycle state")
-			lastReportedIndex++
+			a.lifecycleLastReportedIndex++
 			select {
 			case a.lifecycleReported <- report.State:
 			case <-a.lifecycleReported:
 				a.lifecycleReported <- report.State
 			}
-			if lastReportedIndex < lastIndex {
+			if a.lifecycleLastReportedIndex < lastIndex {
 				// Keep reporting until we've sent all messages, we can't
 				// rely on the channel triggering us before the backlog is
 				// consumed.