internal/lsp: log snapshot IDs, don't log context cancellation

Updates golang/go#36772

Change-Id: Id6f1be9511f37865d5c6efcff10230e03724b27d
Reviewed-on: https://go-review.googlesource.com/c/tools/+/216497
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Heschi Kreinick <heschi@google.com>

internal/lsp/diagnostics.go

@@ -36,6 +36,8 @@ func (s *Server) diagnose(ctx context.Context, snapshot source.Snapshot) {
 	ctx, done := trace.StartSpan(ctx, "lsp:background-worker")
 	defer done()
 
+	ctx = telemetry.Snapshot.With(ctx, snapshot.ID())
+
 	// Diagnose all of the packages in the workspace.
 	go func() {
 		wsPackages, err := snapshot.WorkspacePackages(ctx)
@@ -148,7 +150,9 @@ func (s *Server) publishReports(ctx context.Context, snapshot source.Snapshot, r
 			URI:         protocol.NewURI(fileID.URI),
 			Version:     fileID.Version,
 		}); err != nil {
-			log.Error(ctx, "publishReports: failed to deliver diagnostic", err, telemetry.File)
+			if ctx.Err() == nil {
+				log.Error(ctx, "publishReports: failed to deliver diagnostic", err, telemetry.File)
+			}
 			continue
 		}
 		// Update the delivered map.

internal/lsp/telemetry/telemetry.go

@@ -25,6 +25,7 @@ const (
 	Package       = tag.Key("package")
 	PackagePath   = tag.Key("package_path")
 	Query         = tag.Key("query")
+	Snapshot      = tag.Key("snapshot")
 )
 
 var (