Re: [PATCH 08/10] reftable/reader: keep readers alive during iteration

On Fri, Aug 23, 2024 at 03:21:27AM -0700, karthik nayak wrote:

Patrick Steinhardt [off-list ref] writes:

quoted

diff --git a/reftable/stack_test.c b/reftable/stack_test.c
index bc3bf77274..91e716dc0a 100644
--- a/reftable/stack_test.c
+++ b/reftable/stack_test.c

@@ -1076,6 +1076,54 @@ static void test_reftable_stack_compaction_concurrent_clean(void)
 	clear_dir(dir);
 }

+static void test_reftable_stack_read_across_reload(void)
+{
+	struct reftable_write_options opts = { 0 };
+	struct reftable_stack *st1 = NULL, *st2 = NULL;
+	struct reftable_ref_record rec = { 0 };
+	struct reftable_iterator it = { 0 };
+	char *dir = get_tmp_dir(__LINE__);
+	int err;
+
+	/* Create a first stack and set up an iterator for it. */
+	err = reftable_new_stack(&st1, dir, &opts);
+	EXPECT_ERR(err);
+	write_n_ref_tables(st1, 2);
+	EXPECT(st1->merged->readers_len == 2);
+	reftable_stack_init_ref_iterator(st1, &it);
+	err = reftable_iterator_seek_ref(&it, "");
+	EXPECT_ERR(err);
+
+	/* Set up a second stack for the same directory and compact it. */
+	err = reftable_new_stack(&st2, dir, &opts);
+	EXPECT_ERR(err);
+	EXPECT(st2->merged->readers_len == 2);
+	err = reftable_stack_compact_all(st2, NULL);

Shouldn't we verify that `EXPECT(st2->merged->readers_len == 1);` here?

Yes, we should.

quoted

+	EXPECT_ERR(err);
+
+	/*
+	 * Verify that we can continue to use the old iterator even after we
+	 * have reloaded its stack.
+	 */
+	err = reftable_stack_reload(st1);
+	EXPECT_ERR(err);
+	EXPECT(st2->merged->readers_len == 1);

Oh we do it here, I would've expected it above the `st1` reload. And
probably expected `EXPECT(st1->merged->readers_len == 2);` here to
confirm that we still have the readers.

And yes, this was a typo, it should've been `st1` indeed. Good eyes,
thanks!

Patrick