From c0155e78d4e8947d83d62a98731b6be7c62bef40 Mon Sep 17 00:00:00 2001
From: Reese Norris <reese.norris@gmail.com>
Date: Sun, 25 May 2025 11:57:06 -0700
Subject: [PATCH] store client coords as a single atomic unit

---
 fsd/client.go       | 11 +++++++++--
 fsd/http_service.go |  5 +++--
 fsd/postoffice.go   |  9 +++++----
 3 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/fsd/client.go b/fsd/client.go
index 4fd8270..1fa91e1 100644
--- a/fsd/client.go
+++ b/fsd/client.go
@@ -16,7 +16,8 @@ type Client struct {
 	cancelCtx func()
 	sendChan  chan string
 
-	lat, lon, visRange            atomic.Float64
+	coords                        atomic.Value
+	visRange                      atomic.Float64
 	closestVelocityClientDistance float64 // The closest Velocity-compatible client in meters
 
 	flightPlan         atomic.String
@@ -37,6 +38,7 @@ type Client struct {
 }
 
 type LatLon struct {
+	lat, lon float64
 }
 
 func newClient(ctx context.Context, conn net.Conn, scanner *bufio.Scanner, loginData loginData) (client *Client) {
@@ -125,5 +127,10 @@ func (s *Server) eventLoop(client *Client) {
 }
 
 func (c *Client) latLon() [2]float64 {
-	return [2]float64{c.lat.Load(), c.lon.Load()}
+	latLon := c.coords.Load().(LatLon)
+	return [2]float64{latLon.lat, latLon.lon}
+}
+
+func (c *Client) setLatLon(lat, lon float64) {
+	c.coords.Store(LatLon{lat: lat, lon: lon})
 }
diff --git a/fsd/http_service.go b/fsd/http_service.go
index ff94976..bdef9fa 100644
--- a/fsd/http_service.go
+++ b/fsd/http_service.go
@@ -110,13 +110,14 @@ func (s *Server) handleGetOnlineUsers(c *gin.Context) {
 	}
 
 	for _, client := range clientMap {
+		latLon := client.latLon()
 		genData := OnlineUserGeneralData{
 			Callsign:      client.callsign,
 			CID:           client.cid,
 			Name:          client.realName,
 			NetworkRating: int(client.networkRating),
-			Latitude:      client.lat.Load(),
-			Longitude:     client.lon.Load(),
+			Latitude:      latLon[0],
+			Longitude:     latLon[1],
 			LogonTime:     client.loginTime,
 			LastUpdated:   client.lastUpdated.Load(),
 		}
diff --git a/fsd/postoffice.go b/fsd/postoffice.go
index 0438297..5b4d6c7 100644
--- a/fsd/postoffice.go
+++ b/fsd/postoffice.go
@@ -68,8 +68,7 @@ func (p *postOffice) updatePosition(client *Client, newCenter [2]float64, newVis
 	oldMin, oldMax := calculateBoundingBox(client.latLon(), client.visRange.Load())
 	newMin, newMax := calculateBoundingBox(newCenter, newVisRange)
 
-	client.lat.Store(newCenter[0])
-	client.lon.Store(newCenter[1])
+	client.setLatLon(newCenter[0], newCenter[1])
 	client.visRange.Store(newVisRange)
 
 	// Avoid redundant updates
@@ -100,12 +99,14 @@ func (p *postOffice) search(client *Client, callback func(recipient *Client) boo
 		}
 
 		if foundClient.protoRevision == 101 {
-			dist := distance(client.lat.Load(), client.lon.Load(), foundClient.lat.Load(), foundClient.lon.Load())
+			clientLatLon := client.latLon()
+			foundClientLatLon := foundClient.latLon()
+			dist := distance(clientLatLon[0], clientLatLon[1], foundClientLatLon[0], foundClientLatLon[1])
 			if dist < client.closestVelocityClientDistance {
 				client.closestVelocityClientDistance = dist
 			}
 		}
-		
+
 		return callback(foundClient)
 	})
 	p.treeLock.RUnlock()