bugfix: ensure sentry username/id values are correct

Previously there were wrong under high concurrency due to
using the global hub instead of a per-request hub.

internal/context.go

@@ -48,19 +48,24 @@ func RequestContext(ctx context.Context) context.Context {
 }
 
 // add the user ID to this request context. Need to have called RequestContext first.
-func SetRequestContextUserID(ctx context.Context, userID, deviceID string) {
+func AssociateUserIDWithRequest(ctx context.Context, userID, deviceID string) context.Context {
 	d := ctx.Value(ctxData)
 	if d == nil {
-		return
+		return ctx
 	}
 	da := d.(*data)
 	da.userID = userID
 	da.deviceID = deviceID
-	if hub := sentry.GetHubFromContext(ctx); hub != nil {
-		sentry.ConfigureScope(func(scope *sentry.Scope) {
-			scope.SetUser(sentry.User{Username: userID})
-		})
-	}
+	hub := sentry.GetHubFromContext(ctx)
+	if hub == nil {
+		// Basing the sentry-wrangling on the sentry-go net/http integration, see e.g.
+		// https://github.com/getsentry/sentry-go/blob/02e712a638c40cd9701ad52d5d1309d65d556ef9/http/sentryhttp.go#L84
+		hub = sentry.CurrentHub().Clone()
+	}
+	hub.ConfigureScope(func(scope *sentry.Scope) {
+		scope.SetUser(sentry.User{Username: userID, ID: deviceID})
+	})
+	return sentry.SetHubOnContext(ctx, hub)
 }
 
 func SetConnBufferInfo(ctx context.Context, bufferLen, nextLen, bufferCap int) {

sync2/poller.go

@@ -503,10 +503,7 @@ func (p *poller) Poll(since string) {
 	// caller and passed down?
 	hub := sentry.CurrentHub().Clone()
 	hub.ConfigureScope(func(scope *sentry.Scope) {
-		scope.SetUser(sentry.User{Username: p.userID})
-		scope.SetContext(internal.SentryCtxKey, map[string]interface{}{
-			"device_id": p.deviceID,
-		})
+		scope.SetUser(sentry.User{Username: p.userID, ID: p.deviceID})
 	})
 	ctx := sentry.SetHubOnContext(context.Background(), hub)
 

sync3/handler/handler.go

@@ -385,7 +385,7 @@ func (h *SyncLiveHandler) setupConnection(req *http.Request, cancel context.Canc
 		Str("device", token.DeviceID).
 		Str("conn", syncReq.ConnID).
 		Logger()
-	internal.SetRequestContextUserID(req.Context(), token.UserID, token.DeviceID)
+	req = req.WithContext(internal.AssociateUserIDWithRequest(req.Context(), token.UserID, token.DeviceID))
 	internal.Logf(req.Context(), "setupConnection", "identified access token as user=%s device=%s", token.UserID, token.DeviceID)
 
 	// Record the fact that we've recieved a request from this token