server: remove unused context hook

I can no longer remember what motivated me to add this in the first place, but
it is not used anywhere and was confusingly named, so it's gone now.

server/tailsql/options.go

@@ -83,12 +83,6 @@ type Options struct {
 	// by the rule replaces the original string.
 	UIRewriteRules []UIRewriteRule `json:"-"`
 
-	// If non-nil, this function is called to annotate ctx before passing it in
-	// to a database query for the given source. If the callback is nil, or if
-	// it returns nil, ctx is used unmodified. Otherwise the returned value
-	// replaces ctx in the query.
-	QueryContext func(ctx context.Context, src, query string) context.Context `json:"-"`
-
 	// If non-nil, send logs to this logger. If nil, use log.Printf.
 	Logf logger.Logf `json:"-"`
 }

server/tailsql/tailsql.go

@@ -114,7 +114,6 @@ type Server struct {
 	rules     []UIRewriteRule
 	authorize func(string, *apitype.WhoIsResponse) error
 	qtimeout  time.Duration
-	qcontext  func(ctx context.Context, src, query string) context.Context
 	logf      logger.Logf
 
 	mu  sync.Mutex
@@ -167,7 +166,6 @@ func NewServer(opts Options) (*Server, error) {
 		rules:     opts.UIRewriteRules,
 		authorize: opts.authorize(),
 		qtimeout:  opts.QueryTimeout.Duration(),
-		qcontext:  opts.QueryContext,
 		logf:      opts.logf(),
 		dbs:       dbs,
 	}, nil
@@ -434,7 +432,7 @@ func (s *Server) queryContext(ctx context.Context, caller, src, query string) (*
 		defer cancel()
 	}
 
-	return runQueryInTx(s.getQueryContext(ctx, src, query), h,
+	return runQueryInTx(ctx, h,
 		func(fctx context.Context, tx *sql.Tx) (_ *dbResult, err error) {
 			start := time.Now()
 			var out dbResult
@@ -612,13 +610,3 @@ func (s *Server) getHandles() []*dbHandle {
 	// data are only ever appended to the end.
 	return s.dbs
 }
-
-// getQueryContext decorates ctx if necessary using the context hook for src and query.
-func (s *Server) getQueryContext(ctx context.Context, src, query string) context.Context {
-	if s.qcontext != nil {
-		if qctx := s.qcontext(ctx, src, query); qctx != nil {
-			return qctx
-		}
-	}
-	return ctx
-}

server/tailsql/tailsql_test.go

@@ -20,7 +20,6 @@ import (
 	"testing"
 	"time"
 
-	"github.com/google/go-cmp/cmp"
 	"github.com/tailscale/setec/client/setec"
 	"github.com/tailscale/setec/setectest"
 	"github.com/tailscale/tailsql/authorizer"
@@ -187,20 +186,14 @@ func TestServer(t *testing.T) {
 			},
 		},
 	}
-	var contextHookData [2]string
 	s, err := tailsql.NewServer(tailsql.Options{
 		LocalClient: fc,
 		UILinks: []tailsql.UILink{
 			{Anchor: testAnchor, URL: testURL},
 		},
 		UIRewriteRules: testUIRules,
 		Authorize:      authorizer.ACLGrants(nil),
-		QueryContext: func(ctx context.Context, src, query string) context.Context {
-			contextHookData[0] = src
-			contextHookData[1] = query
-			return ctx
-		},
-		Logf: t.Logf,
+		Logf:           t.Logf,
 	})
 	if err != nil {
 		t.Fatalf("NewServer: unexpected error: %v", err)
@@ -217,15 +210,6 @@ func TestServer(t *testing.T) {
 	defer htest.Close()
 	cli := htest.Client()
 
-	t.Run("ContextHook", func(t *testing.T) {
-		q := url.Values{"q": {"select count(*) from users"}}
-		url := htest.URL + "?" + q.Encode()
-		mustGet(t, cli, url)
-		if diff := cmp.Diff(contextHookData, [2]string{"main", "select count(*) from users"}); diff != "" {
-			t.Errorf("Context hook result (-got, +want):\n%s", diff)
-		}
-	})
-
 	t.Run("UI", func(t *testing.T) {
 		q := make(url.Values)
 		q.Set("q", "select location from users where name = 'alice'")