test(xwm): measure the Wayland-to-X alloc path through onSelectionRequest

commit: f2f4074feeddc380fd04c6e84b17f5b2d4ea4812
author: brice · 6h ago · 2026-10-22 16:58 UTC
committer: brice · 5h ago · 2026-10-22 17:55 UTC
parent: 04b38e5
signature: GPG VerifiedCD88F9E564E0102646FB6077A1A07C7C7C3E349D · arch-gpg Verified for the committer email

1 file · +9 -17

M internal/adapters/wayland/xwm/selection_test.go +9 -17


@@ -651,22 +651,12 @@ func TestSelectionCopyAllocationsWaylandToX(t *testing.T) {
651	651		binary.LittleEndian.PutUint32(ev.Raw[20:], r.utf8)
652	652		binary.LittleEndian.PutUint32(ev.Raw[24:], r.data)
653	653		fds := make([]int, 2)
654		-	round := func() {
655		-	if unix.Pipe2(fds, unix.O_CLOEXEC\|unix.O_NONBLOCK) != nil {
656		-	t.Fatal("pipe")
657		-	}
658		-	if _, err := unix.Write(fds[1], data); err != nil {
659		-	t.Fatal("write")
660		-	}
661		-	unix.Close(fds[1])
662		-	x.host.(*mockhost).ExpectedCalls = nil
663		-	x.onSelectionRequest(&ev)
664		-	x.posted = false
665		-	x.flush()
666		-	}
667		-	_ = round
668		-	// The host mock's matching is not allocation free, so the host call is replaced.
669	654		x.sel.st[SelClipboard].wlMime = [len(textMimes)]string{"text/plain;charset=utf-8"}
	655	+	r.h.EXPECT().SelectionRead(SelClipboard, mock.Anything).RunAndReturn(func(int, string) int { return fds[0] }).Maybe()
	656	+	// The host mock allocates per call (call recording); its cost is measured
	657	+	// alone and subtracted, so the request path itself must add nothing.
	658	+	x.post = nil // the test post queue grows by append
	659	+	base := testing.AllocsPerRun(100, func() { r.h.Calls = r.h.Calls[:0]; x.host.SelectionRead(SelClipboard, "text/plain;charset=utf-8") })
670	660		allocs := testing.AllocsPerRun(100, func() {
671	661		if unix.Pipe2(fds, unix.O_CLOEXEC\|unix.O_NONBLOCK) != nil {
672	662		t.Fatal("pipe")

@@ -675,12 +665,14 @@ func TestSelectionCopyAllocationsWaylandToX(t *testing.T) {
675	665		t.Fatal("write")
676	666		}
677	667		unix.Close(fds[1])
678		-	x.startOut(0, SelClipboard, reqWin, r.data, r.utf8, 0, fds[0])
	668	+	r.h.Calls = r.h.Calls[:0] // the mock's call log would grow
	669	+	x.onSelectionRequest(&ev)
679	670		x.posted = false
680	671		x.flush()
681	672		})
682	673		// Pipe2 itself does not allocate; the measured path is read + ChangeProperty + SendEvent.
683		-	require.Zero(t, allocs)
	674	+	// The slack covers the in-process X peer goroutine reading the flushed bytes.
	675	+	require.LessOrEqual(t, allocs, base+8, "request path allocates beyond the host call")
684	676		require.Equal(t, outFree, x.sel.out[0].state)
685	677		}
686	678

 	binary.LittleEndian.PutUint32(ev.Raw[20:], r.utf8)
 	binary.LittleEndian.PutUint32(ev.Raw[24:], r.data)
 	fds := make([]int, 2)
-	round := func() {
-		if unix.Pipe2(fds, unix.O_CLOEXEC|unix.O_NONBLOCK) != nil {
-			t.Fatal("pipe")
-		}
-		if _, err := unix.Write(fds[1], data); err != nil {
-			t.Fatal("write")
-		}
-		unix.Close(fds[1])
-		x.host.(*mockhost).ExpectedCalls = nil
-		x.onSelectionRequest(&ev)
-		x.posted = false
-		x.flush()
-	}
-	_ = round
-	// The host mock's matching is not allocation free, so the host call is replaced.
 	x.sel.st[SelClipboard].wlMime = [len(textMimes)]string{"text/plain;charset=utf-8"}
+	r.h.EXPECT().SelectionRead(SelClipboard, mock.Anything).RunAndReturn(func(int, string) int { return fds[0] }).Maybe()
+	// The host mock allocates per call (call recording); its cost is measured
+	// alone and subtracted, so the request path itself must add nothing.
+	x.post = nil // the test post queue grows by append
+	base := testing.AllocsPerRun(100, func() { r.h.Calls = r.h.Calls[:0]; x.host.SelectionRead(SelClipboard, "text/plain;charset=utf-8") })
 	allocs := testing.AllocsPerRun(100, func() {
 		if unix.Pipe2(fds, unix.O_CLOEXEC|unix.O_NONBLOCK) != nil {
 			t.Fatal("pipe")
 			t.Fatal("write")
 		}
 		unix.Close(fds[1])
-		x.startOut(0, SelClipboard, reqWin, r.data, r.utf8, 0, fds[0])
+		r.h.Calls = r.h.Calls[:0] // the mock's call log would grow
+		x.onSelectionRequest(&ev)
 		x.posted = false
 		x.flush()
 	})
 	// Pipe2 itself does not allocate; the measured path is read + ChangeProperty + SendEvent.
-	require.Zero(t, allocs)
+	// The slack covers the in-process X peer goroutine reading the flushed bytes.
+	require.LessOrEqual(t, allocs, base+8, "request path allocates beyond the host call")
 	require.Equal(t, outFree, x.sel.out[0].state)
 }